Lecture 1-10 Slides PDF

CARBOHYDRATE ALL LIVING THINGS ARE MADE UP OF FOUR CLASSES OFLARGE BIOLOGICAL MOLECULES : CARBOHYDRATES, LIPIDS, PROTEINS, NUCLEIC ACIDS MACROMOLECULES ARE LARGE MOLECULES(POLYMERS) COMPOSED OF THOUSANDS OF COVALENTLY CONNECTED (MONOMERS). A POLYMER IS A LONG MOLECULE CONSISTING OF MANY REPEATED MON...

CARBOHYDRATE ALL LIVING THINGS ARE MADE UP OF FOUR CLASSES OFLARGE BIOLOGICAL MOLECULES : CARBOHYDRATES, LIPIDS, PROTEINS, NUCLEIC ACIDS MACROMOLECULES ARE LARGE MOLECULES(POLYMERS) COMPOSED OF THOUSANDS OF COVALENTLY CONNECTED (MONOMERS). A POLYMER IS A LONG MOLECULE CONSISTING OF MANY REPEATED MONOMERS. THREE OF THE FOUR CLASSES OF LIFE’S LARGE ORGANIC MOLECULES ARE POLYMERS: - CARBOHYDRATES/ POLYSACCHARIDES FROM MONOSACCHARIDE - PROTEINS FROM AMINO ACIDS - NUCLEIC ACIDS FROM NUCLEOTIDE NOTE: LIPIDS ARE NOT POLYMERS ‫ﻟﻴﺶ؟؟ ﻷﻧﻬﺎ ﺗﺘﺮﻛﺐ ﻣﻦ ﺟﺰيء ﻣﺘﻜﺮر وﺟﺰﻳﺌﺎت أﺧﺮى وﻟﻴﺴﺖ ﺳﻼﺳﻞ ﻃﻮﻳﻠﺔ‬ A CONDENSATION OR DEHYDRATION REACTION OCCURS WHEN TWO MONOMERS BOND TOGETHER THROUGH THE LOSS OF A WATER MOLECULE. POLYMERS ARE DISASSEMBLED TO MONOMERS BY HYDROLYSIS, THE REVERSE OF THE DEHYDRATION REACTION. Carbohydrate Carbohydrates serve as fuel ( source of energy) and building material (for plants and fungus). *Carbohydrates include sugars and polymers of sugars. *The simplest carbohydrates are monosaccharides, or single sugars *Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks. *Monosaccharides have molecular formulas that are usually multiples of CH2O. (from 3 to 6 ‫) ﻋﺎدة‬ *Glucose (C6H12O6) is the most common monosaccharide *Monosaccharides are classified by : -The location of the carbonyl group (as aldose C1 or Ketose C2). -The number of carbons in the carbon skeleton (3C to 6C). Monosaccharides serve as a major fuel for cells and as raw material for building molecules. A disaccharide is formed when a dehydration reaction joins only two monosaccharides. This covalent bond is called a glycosidic linkage / bond. Glycosidic bond, a linkage which joins carbs together or between carbs monomers Lactose intolerance: Inability to breakdown lactose (glucose + galactose) in dairy products due to lactase deficiency Clinical symptoms: abdominal pain, diarrhea, gas and bloating Treatment: Use dairy-free alternatives or Lactose-free milk Polysaccharides: polymers of sugars, have storage and structural roles. The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages. Starch, a storage polysaccharide of plants, consists entirely of glucose monomers. Plants store surplus starch as granules within chloroplasts and other plastids. Glycogen is a storage polysaccharide in animals (in liver and muscle cells). Hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases. The polysaccharide cellulose is a major component of the tough wall of plant cells. Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ. The difference is based on two ring forms for glucose: alpha and beta. Polymers with alpha glucose are helical. Polymers with beta glucose are straight. In straight structures, H atoms on one strand can bond with OH groups on other strands. Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for plants. Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze bets linkages in cellulose. Cellulose in human food passes through the digestive tract as insoluble fiber. Some microbes use enzymes to digest cellulose. Many herbivores, from cows to termites, have symbiotic relationships with these microbes. Summary for Polysaccharides Storage structural Plants Animals Plants cellulose Glycogen Amylose Amylopectin very branched Unbranched branched Unbranched which of the following is not a polymer? A- protein B-Nucleic Acid C- Starch D- Fat Answer: D Monosaccharides have molecular formulas that are usually multiples of........ A-CH2O2 B-CH2O C-C2H2O D-C2H2O2 Answer: B Practice reaction occurs when two monomers bond together? A- Dehydration B- Hydrolysis C- Hydrogenation D- Hydration Answer: A which of the following polysaccharide is storage, branched and found in plant? A- Cellulose B- Amylose C- Amylopectine D- Glycogen Answer: C Extra practice 1- Monosaccharide is classified according to: A- the location of the carbonyl group only B- the location of the carbonyl group and the number of bonds C- the location of the carbonyl group and number of carbons D-the number of carbons and the number of the bonds Answer: C 2- The polysaccharide that is responsible for storage in plant cell is? A-Glucose B-Starch C-Glycogen D-Cellulose Answer: B 3- The carbonyl group location in a monosaccharide determines: A-Aldehyde ketone B-carboxyl group (OH) C- Polysaccharides Answer: A 4- the storage polysaccharide in plants is: A- Starch B- cellulose C-glycogen D- chitin Answer: A 5-the difference between the starch and cellulose is based on the type of: A- glucose B- glycogen C- galactose D- fructose Answer: A 6- all of the following are large molecules needed for living, but which one of them is not a true polymer? A- carbohydrates B- nucleic acid C- proteins D- lipids Answer: D EXTRA PRACTICE 7-Two monosaccharides are joined together in prosses known as ________ reaction. A-phosphorylation B-dephosphorylation C-dehydration D-oxidation Answer: C 9- The bond which forms between 2 monosaccharide is - Glycosidic linkage 11- Which of the following macromolecules does not form polymers? A- Carbohydrates B- Lipids C- Proteins D- Nucleic Acids Answer: B 8-In aqueous solution sugars form.......... skeleton. A-liner B-rings C-branched D-unbranched Answer: B 10- The carbohydrate fructose is classified as ____ A- Monosaccharide B- Disaccharide C- Polysaccharide D- Oligosaccharide Answer: A 12-which of the following is NOT a polymer? A-Glucose B- Starch C- DNA D-RNA Answer:A EXTRA PRACTICE 13-Which of the following is true about Dehydration and hydrolysis? A-Dehydration reaction creates polymers, and hydrolysis reaction breaks into monomers B- dehydration reaction occurs after hydrolysis reaction C- Dehydration and hydrolysis reactions are the same D-hydrolysis reaction creates polymers, and dehydration reaction breaks into monomers Answer: A 15- People who are lactose intolerance cannot extract energy from milk lactose (because) A-Lack of enzymes that perform hydrolysis on lactose B- Lactose is too big to be digested C- Milk is fermented a by-product, which cannot be digested D- They don’t have the bacteria that digest lactoce Answer: A 17- What causes lactose intolerance in some individuals? A-lactose breakdown B- Lactase deficiency C-Milk composition D- Lack of gut bacteria Answer: B 14- Which of the following describes the structure below? A- Triose, Aldoses sugar B-Triose, Ketoses sugar C- Pentose, Aldoses sugar D- Pentose, Ketoses sugar Anwer: A 16-what is the chemical reaction that break down biomolecules into monomers ? A- Hydrogenation reaction B- Dehydration reaction C-Hydrolysis reaction D- Condensation reaction Answer: C 18- Which of the following contributes towards the cellulose structural strength? A-Hydrogen bonds B-Its helical structure C- Its alpha glucose monomers D- Its presence in plants cell walls Answer: A EXTRA PRACTICE 19- which of the following is not considered as a polymer: A- RNA B- Cholesterol C- Cellulose D- Collagen 22-which of the following is disaccharide: A- Galactose B- Glyceraldehyde C- Lactose D- Ribose Answer: B Answer: C 20- Excess sugar in animal muscle and liver cell is: A_ Glycogen B- Glucose C- Cellulose D- Starch 23- Herbivorous animals can digest cellulose because: A- Cellulose forms an insoluble fiber B- Cellulose is helical polymer and easily digested C- They can produce enzymes that can breakdown beta-linkage D- they have symbiotic bacteria in their guts that can breakdown cellulose Answer : A Answer: D 24- Which of the following carbohydrate is a monosaccharide ? 21- Microfibrils are made by parallel cellulose attached to each other by: Cellulose A- Hydrogen bond Amylopectin B- Ionic Bond Galactose C- Glycosidic Chitin D- Van der wall Force Answer: C Answer: A EXTRA PRACTICE 25- What is the covalent bond between two monosaccharides called ? A- Glycosidic bond B- Ester C- Peptide D- Phosphodiester Answer: A 26- What type of reaction can break down the polysaccharide glycogen to glucose units ? A- Hydrolysis B- Condensation reaction C- Dehydration reaction D- Isomerization Answer: A 27- what are the four biological macro molecules present in the living system? A- Protein, nucleic acid, carbohydrates, lipids B- RNA, DNA, protein, carbohydrates C- monosaccharide, lipid, polysaccharides, protein D- protein, DNA, RNA, steroids Answer: A LIPIDS Lipids are a diverse group of hydrophobic molecules Lipids are the one class of large biological molecules that do not form polymers (not a real Macromolecule). Lipids are hydrophobic They don’t mix well with water! Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds The most biologically important lipids are: 1-Fats, 2-Phospholipids, 3-Steroids Fats are constructed from two types of smaller molecules: I- glycerol, II- fatty acids Glycerol: is a three-carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton (hydrocarbon). Fats separate from water because water molecules hydrogen-bond to each other and exclude the fats. In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride The fatty acids in a fat can be all the same or of two or three different kinds Fatty acids vary in length (number of carbons) and in the number and locations of double bonds Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds. Unsaturated fatty acids have one or more double bonds. Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature. Most animal fats are saturated. Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature. Plant fats and fish fats are usually unsaturated. A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits. Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen. Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds. These trans fats may contribute more than saturated fats to cardiovascular disease. The major function of fats is energy storage. Humans and other mammals store their long-term food reserves in adipose cells. Adipose tissue also cushions vital organs and insulates the body. In a phospholipid, two fatty acids and a phosphate group are attached to glycerol. The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head. When phospholipids are added to water, they self-assemble into a bilayer, with the hydrophobic tails pointing toward the interior. The structure of phospholipids results in a bilayer arrangement found in cell membranes. Phospholipids are the major component of all cell membranes. Steroids are lipids characterized by a carbon skeleton consisting of four fused rings. Cholesterol, a type of steroid, is a component in animal cell membranes and a precursor from which other steroids are synthesized. A high level of cholesterol in the blood may contribute to cardiovascular disease. Quiz 1- At which type of lipid there are three fatty acids are joined to glycerol? A- Fat B- cholesterol C- Phospholipid Answer: A 2-The bond that found in fat is... A- Glycolipid B- Glycosidic C- Ester D- Lipoprteinic Answer: C 3-Which of the following does not contribute in cardiovascular disease? A- Saturated Fat B- cholesterol C- Trans Fat D- phospholipid Answer: D Extra practice 1- A lipid that is characterized by having 4 fused rings? - Steroid 3- Identify the category of the lipid "cholesterol": A- Fats B- Steroid C- Phospholipid D- Glycerol Answer:B 5-Which of the following teams best describe the overall characteristics Property of the phospholipids? A- Hydrophilic B-Hydrophobic C-Amphipathic D- Polar Answer:C 2- A lipid that has hydrophilic head and hydrophobic tails? - Phospholipid 4- What is the type of bond that joins fatty acids to glycerol in lipids? A-Peptide bond B-Glycosidic bond C-Phosphodiester bond D-Ester bond Answer: D 6-What makes unsaturated fatty acids fluid at room temperature? A-Presence of single bonds only B- Having a higher amount of glycerol C- Presence of Cis double bond D- A longer carbon chain Answer: C 7- A high level in blood of which of the following lipids in the blood contributes to cardiovascular disease? A-Unsaturated fatty acids from plant fats B- Saturated fatty acid from animal fats C- Cholesterol D- Phospholipid Answer: C Extra practice 8-How many fatty acid can join to glycerol macromolecules? A- 1 B- 2 C- 3 D- 4 Answer: C 9- Which of the following molecules results from the joining of a glycerol molecule with a fatty acid molecule? A- Saturated fatty acids B- Cholesterol C- Fats D- Phospholipids Answer: C 10- Which part of the glycerol interacts with the carboxyl group of the fatty acid to create the ester linkage? A- The hydrogen B- The carbon C- The carbonyl group D- The hydroxyl group Answer: D 11- When describing fatty acids, what does saturated mean? A- Saturated with carbons B- Saturated with fatty acids C- Saturated with hydrogen D- Saturated with double bonds Answer: C 12- Which of the following is true about hydrogenation? A- It converts unsaturated fats to saturated fats by adding hydrogen B- It converts saturated fats to unsaturated fats by adding hydrogen C- It converts unsaturated fats to saturate fats by removing hydrogen D- It converts saturated fats to unsatur fats by removing hydrogen Answer: A Extra practice 13- Define the structure in figure A- Polysaccharide B- Unsaturated fatty acid C- Saturated fatty acid D- Phospholipid Answer: B 14- Which of the following is attached to three fatty acids to form Triacylglycerol ? A- Glucose B- Glycerol C- Glycogen D- Guanine Answer: B PROTEINS Proteins have many structures, resulting in a wide range of functions. Proteins account for more than 50% of the dry mass of most cells. Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances. Most Enzymes are proteins that act as a catalyst to speed up chemical reactions. Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life. Polypeptides are polymers built from the same set of 20 amino acids. A protein may consist of one or more polypeptides. Amino acids are organic molecules with carboxyl and amino groups. Amino acids differ in their properties due to differing side chains, called R groups. Note: amino acid according to R side chain are divided into 3 groups: 1- Hydrophobic (Non polar) has H, CH3, or benzene. 2- Hydrophilic (Polar) has O, OH, SH. 3- Charged (Polar) -ve charge means acid, and +ve charge means base. Amino acids are linked by covalent bonds called peptide bonds. A polypeptide is a polymer of amino acids. Polypeptides range in length from a few to more than 1,000 monomers. Each polypeptide has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus). A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape. The sequence of amino acids determines a protein’s three dimensional structure. A protein’s structure determines how it works. The function of a protein usually depends on its ability to recognize and bind to some other molecule. Levels of protein Primary The primary structure of a protein is its unique sequence of amino acids Primary structure, the sequence of amino acids in a protein, is like the order of letters in a long word. Secondary Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain (α helix, β sheets). The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone. Typical secondary structures are a coil called an alpha helix and a folded structure called a beta pleated sheet. Tertiary Quaternary Tertiary structure is determined by Quaternary structure results interactions among various side chains (R when a protein consists of multiple groups). polypeptide chains. Tertiary structure is determined by Quaternary structure results interactions between R groups, rather than when two or more polypeptide interactions between backbone chains form one macromolecule. constituents. Collagen is a fibrous protein These interactions between R groups consisting of three polypeptides include hydrogen bonds, ionic bonds, coiled like a rope hydrophobic interactions, and van der Waals Hemoglobin is a globular protein interactions. consisting of four polypeptides: Strong covalent bonds called disulfide two alpha and two beta chains bridges may reinforce the protein’s structure. Sickle-Cell Disease: A Change in Primary Structure A slight change in primary structure can affect a protein’s structure and ability to function. Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin. The abnormal hemoglobin molecules cause the red blood cells to aggregate into chains and to deform into a sickle shape. What Else Determines Protein Structure? In addition to primary structure, physical and chemical conditions can affect structure. Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel. This loss of a protein’s native structure is called denaturation. A denatured protein is biologically inactive. Protein Folding in the Cell It is hard to predict a protein’s structure from its primary structure. Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with misfolded proteins. Scientists use X-ray crystallography to determine a protein’s structure. Another method is nuclear magnetic resonance (NMR) spectroscopy, which does not require protein crystallization. Quiz 1-Most of enzymes are: A- Carbohydrates B- Proteins C- Nucleic acid D-Lipids Answer: B 2-What is the bond that make proteins: A- Glycosidic bond B- Ester bond C- peptide bond D- hydrogen bond Answer: C 3-beta pleated sheet is a....... structure: A- primary B- Secondary C-Tertiary D- Quaternary Answer: B 4- Used to predict protein structure: A- nuclear magnetic resonance B- X-ray radiation C- CT scan Answer: A Extra Practice 1- What protein structure forms by side chains interactions? - Tertiary 2- According to the figure, what is the structure? - Alpha helix structure 3- Which bond in the tertiary structure reinforces the protein’s shape? - Disulfide bridges 6-In this given figure which one describes the peptide bond? A) a. B) b. C) c. D) d. Answer: C 4-the main function of the Insulin protein is? a) Coordinating cell’s activities. b) transport substances. c) protection against diseases. d) storage of amino acids. Answer: A 7- Which of the following is found in a secondary structure protein? A- sequence of amino acids. B- R group interactions. C- polypeptide interaction. D- beta pleated sheet. Answer: D 5-What is the name of the bond that is found in secondary protein structure? a) Hydrophobic b) Hydrogen c) Ionic d) Disulfide Answer: B 8- A protein consists of 4 polypeptides: 2 Alpha and 2 Beta: A- Collagen B- Keratin C- Hemoglobin D- Myosin Answer: C Extra Practice 9- What determines the tertiary structure of amino acid? A-the polypeptide bonds B-interactions between R groups C-interactions between polypeptide D- the hydrogen bonds Answer: B 10- What is the type of the bond between the carbonyl group (C=O) and the amine group (NH2) in the secondary structure? A- Hydrogen bond B- Ionic bond C-Peptide linkage D- Polar bond Answer: A 11- what is the function of the protein shown in the figure? A-transport minerals B-reception in nerves' cells C- defense against diseases D- coordination of an organism's activities Answer: C 12- what is the function of the organelle shown in the figure? A-making proteins B-making lipids C-folding protein D-making DNA Answer: C 13-Four polypeptides that are joined together to make functional protein represent in which of level protein structure? A-a primary structure B-a tertiary structure C-a secondary structure D-a quaternary structure Answer: D 14- The structural formula below represent a/an A- Steroid B- Amino acid C- Phospholipid D- cholesterol Answer: B Extra Practice 15- Many amino acids bond together to produce a polymer called ? A-Polysaccharide B- Polypeptide C- Polynucleotide D- Triacylglycerol Answer: B 16- A functional protein is ? Active folded protein inactive protein primary protein structure secondary protein structure Answer: A 17-Which one of these classifications is an amino acid with a negatively charged side chain? A- Acidic B- basic C- polar D- nonpolar Answer: A 18- Hydrogen bond between amino acids side chains within the polypeptide is feature of.. A- Primary structure B- Secondary structure C- Tertiary structure D- Quaternary structure Answer: C 19- When the fever of the patients becomes high, what is the effect on the protein? A- The peptide link in the protein break down B- The protein will lose his native structure C- Protein-protein recognition D- The protein renaturation Answer: B 20- Which of the following is true about protein? A- X-ray crystallography used to determine the primary structure B- amino sequence affect the cell's function C- All proteins have quaternary structure D- Denaturation does not affect protein Answer: B Extra Practice 21- Which of the following is a component of all proteins? A. Phosphate group B. Carboxyl group C. Polypeptide D. Nitrogenous bases Answer: B 22- Which of the following is not a typical function of protein? A. Signal transduction B. Protein synthesis C. Enzymatic activity D. cell to cell recognition Answer: B Extra Practice 23- Amino acids are linked together with: ِA- Peptide bond B- Hydrogen bond C- Amino acid bond D- Ester bond Answer: A 24- Polypeptide are polymer made of: A- Amino acid B- Lipid C- Sugar D- Nucleic acid Answer: A 25- Which of the following proteins functions as a selective accelerator for chemical reaction? A- Enzymatic proteins B- Hormonal proteins C- Hemoglobin proteins D- Transmembrane proteins Answer: A 26- Which of the following determines the secondary structure of a protein? A- Interactions between R groups of the amino acids B- The sequence of amino acids in a protein C- The hydrogen bonds between amino acids in polypeptide backbone D- The formation of a macromolecule from two or more polypeptide chains. Answer: C 27- The cause of sickle cell disease is...... A- Single amino acid substitution in the primary structure of protein B- Single amino acid deletion in the primary structure of protein C- A misfolded tertiary structure D- Denatured hemoglobin Answer: A Extra Practice 28- Where is the peptide bond ? A- A B- B C- C D- D Answer: C 29- Which of the following proteins structures contains hydrogen and peptide bonds only? A- quaternary B- secondary C- tertiary D- primary Answer: B NUCLEIC ACID Nucleic acids store, transmit, and help express hereditary information The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene Genes consist of DNA, a nucleic acid made of monomers called nucleotides Nucleic Acids: why the name? Nucleic: found in the nucleus Acids: acidic (phosphoric acid: phosphate groups) The Roles of Nucleic Acids There are two types of nucleic acids Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis. This process is called gene expression The Structure of Nucleic Acids Nucleic acids are polymers called polynucleotides. Each polynucleotide is made of monomers called nucleotides. Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group. The portion of a nucleotide without the phosphate group is called a nucleoside. Nucleotide Monomers There are two families of nitrogenous bases: Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose The DNA Double Helix A DNA molecule has two polynucleotides spiraling around an imaginary axis, forming a double helix In the DNA double helix, the two backbones run in opposite 5¢ → 3¢ directions from each other, an arrangement referred to as antiparallel The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) Our DNA is very long So how does it all fit into the nucleus? It is stored in chromosomes CONCEPT 16.3: A chromosome consists of a DNA molecule packed together with proteins Eukaryotic chromosomes have linear DNA molecules associated with a large amount of protein. In the eukaryotic cell, DNA is precisely combined with proteins in a complex called chromatin. Chromosomes fit into the nucleus through an elaborate, multilevel system of packing Proteins called histones are responsible for the main level of DNA packing in chromatin Most chromatin is loosely packed in the nucleus during cell interphase and condenses prior to cell division Loosely packed chromatin is called euchromatin highly condensed chromatin is called heterochromatin Dense packing of the heterochromatin makes it difficult for the cell to express genetic information coded in these regions (switch genes ON/OFF and by how much) Chromatin undergoes changes in packing during the cell cycle As the cell prepares for cell division, the chromatin is organized into loops and coils, eventually condensing into short, thick metaphase chromosomes The amino end of each histone (the histone tail) extends outward from the nucleosome, can be modified and is involved in regulation of chromatin condensation and gene expression The width of a chromatid is 700 nm Chromatin is organized into fibers 10-nm fiber DNA winds around histones to form nucleosome “beads” Nucleosomes are strung together like beads on a string by linker DNA 30-nm fiber Interactions between nucleosomes cause the thin fiber to coil or fold into this thicker fiber 300-nm fiber The 30-nm fiber forms looped domains that attach to (scaffold) proteins Metaphase chromosome The looped domains coil further Quiz 1- which of the following is not a component of nucleic acid? A- P group B- N base C- 5 Sugar D- 6 Sugar Answer: D 2- Gene expression is: A- Making protein from DNA B- Making Lipid from DNA C- Making Sugar from DNA D-Making vitamins from DNA Answer: A 3-what is the diameter of "beads on string structure A- 10 nm B- 30 nm C- 300 nm D- 700 nm Answer: A Extra practice 1- In a DNA molecule, if Guanine forms 24% of the nucleotides, what is the percentage of Adenine? - 26% 2- In a single DNA strand, what is the bond that forms between nucleotides? - Phosphodiester bond 3- What is the bond that keeps two strands of DNA together? -Hydrogen bond 4- What is the sugar in RNA? - Ribose 5- What does the chromatin consist of? - DNA and histones 6) Complimentary paring 5’TAACGA3’? A) 5’ATTGCT3’ B) 3’ATTGCT5’ C) 5’UTTGCT3’ D) 3’UTTGCT5’ Answer: B Extra practice 7- What does the figure refer to? A- Pyrimidine B- Purine C- ester D- amino acid Answer: B 10- what is the unit referred to as A? A- Chromatin B- nucleosomes C- Chromosome D- DNA Answer: B 8) Identify the type of sugar in DNA? A- Ribose B- Deoxyribose c- Sucrose D- Fructose Answer: B 11-Nucleic acid form bonds between sugar and____, to form the backbone of the DNA: A-phosphate B-carbonate C-nucleotides D- Sulfate Answer: A 9- what is the protein that binds to DNA in DNA packing? A- Hemoglobin B- Actin C- Histones D- Transcription factor Answer: C 12- The structure below represent a/an: A- Purine bases B- pyrimidines bases C- amino acid D- steroid Answer: A Extra practice 13- Based on the complementary nitrogenous bases , if a sample of DNA were composed of 10% Adenine it will attach to: A- 30% Uracil B- 30% Thymine C- 10% Uracil D- 10% Thymine Answer: D 16- Which of the following is the lowest structure of chromatin in packaging/ condensation? 14- Which of the following is not common in all polynucleotides? A-phosphate group B- adenine C- nucleoside D- Ribose sugar Answer: D 17- If one strand of DNA double helix contains 20% adenine. Which of the following is correct? A- Metaphase chromosome B- Looped domain C- 30 nm fiber D- beads on string Answer: D A- The same strand contains 20% Thymine (T) B- The same strand contains 20% Uracil (U) C- The second strand contains 20% Thymine (T) 15- In DNA, what holds the two strands of polynucleotides together? A- Hydrogen bonds between nitrogenous bases B- Ionic bonds between phosphate and sugar groups C- Covalent bonds between hydroxyl groups of nucleotides D- Hydrophobic interactions Answer: A D- The second strand contains 20% Uracil (U) Answer: C Extra practice 18- The monomers of nucleic acids are? A. Pyrimidines B. Nucleosides C. Nucleotides D. Polypeptides Answer: C 19- The nitrogenous base that RNA only has? A. Thymine B. Adenine C. Guanine D. Uracil Answer: D 20- Which of the following is a purine? A. Adenine (A) B. Guanine (G) C. Cytosine (C) D. Uracil (U) Answer: A Extra practice 21- What are nucleic acid polymers called? A- Polypeptide B- Polysaccharides C- Polynucleotide D- Pyrimidine Answer: C 22- Which of the following is a nitrogenous base from the the family of purine? A- Cytosine C B- Thymine T C- Adenine A D- Uracil U Answer: A 23- It is difficult for the cell to express genitc information coded in which of the following region: A- Highly condensed chromatin (hetrochromatin) B- Loosely packed chromatin (euchromatin) C- Nucleosomes, beads D- 10 nm fibers Answer: A 24- The best description for flow genetic information in eukaryotic cell A- DNA - Protein - RNA B- RNA - DNA - Protein C- Protein - DNA - RNA D- DNA - RNA - Protein Answer: D 25- Which of the following sugars can be found in the sugar phosphate backbone of DNA? A- Ribose B- Fructose C- Deoxyribose D- Glucose Answer: C Extra practice 26- Which of the following is correct regarding the two strands that make a DNA double helix molecule? A- Contain ribose and deoxyribose in opposite strand B- Cannot be separated C- Are hold together by H bonds D- Are attached via phosphate group to hold the strands together Answer: C 27- What type of bonds link single strand DNA nucleotides together? A- Hydrogen bonds B- Ester bonds C- Phosphodiester bonds D- Glycosidic bonds Answer: C Cell Structure and Function Overview: The Fundamental Units of Life (cells) All organisms are made of cells Cells are the simplest collection of matter that can be consider to be alive. In multicellular organisms, the cell forms the basic unit of structure and function of tissues and organs. All cells arise from pre-existing cells: they grow, divide to give rise to new cells and die. Microscopy Microscopes are used to visualize cells. In a light microscope (LM), visible light is passed through a specimen and then through glass lenses. –The lenses refracts (bends) the light which magnifies the image of the specimen. –The image is then projected into the eye or camera. The quality of an image depends on: –Magnification, the ratio of an object’s image size to its real size. LMs can magnify effectively to about 1,000 times the size of the actual specimen –Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points. –Contrast, visible differences in parts of the sample. Various techniques enhance contrast and enable cell components to be stained or labeled to be seen. Most subcellular structures, including organelles (membrane-enclosed compartments), are too small to be resolved by an LM. Recent advances in light microscopy: –Labeling individual cells with fluorescent markers improves the level of detail that can be seen –Confocal microscopy and deconvolution microscopy provide sharper images of three-dimensional tissues and cells Electron Microscope Two basic types of electron microscopes (EMs) are used to study subcellular structures Scanning electron microscopes (SEMs): focus a beam of electrons onto the surface of a specimen, providing images that look 3-D Transmission electron microscopes (TEMs): focus a beam of electrons through a specimen TEMs are used mainly to study the internal structure of cells (i.e. organelles) Microscopes Summary Light Microscope Electrone Microscope Scanning Electrone Microscope Transmission Electrone Microscope There are only Two types of cells The basic structural and functional unit of every organism is one of two types of cells: prokaryotic or eukaryotic. Only organisms of the domains Bacteria and Archaea*consist of prokaryotic cells. Protists, fungi, animals, and plants all consist of eukaryotic cells. prokaryotic cells Common features eukaryotic cells No nucleus Plasma membrane DNA in a nucleus that is bound by a membranous nuclear envelope Semifluid substance called cytosol Membrane-bound organelles Chromosomes (carry genes) Cytoplasm in the region between the plasma membrane and nucleus Ribosomes (make proteins) larger than prokaryotic cells DNA in an unbound region called the nucleoid No membrane-bound organelles Cytoplasm bound by the plasmamembrane Difference between animal and plant cells Presence of cell wall. Large vacuoles. Chloroplasts (photosynthesis). Plasmodesmata versus intercellular junctions (cell signaling lecture). Plasma Membrane The plasma membrane is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell. The general structure of a biological membrane is a double layer of phospholipids. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes. The nucleus contains most of the DNA in a eukaryotic cell (chromosomes/genes). Ribosomes use the information from the DNA (mRNA) to make proteins. The nuclear membrane is a double membrane; each membrane consists of a lipid bilayer. The Nucleus: Information Central Pores regulate the entry and exit of molecules from the nucleus. The shape of the nucleus is maintained by the nuclear lamina, which is composed of protein. In the nucleus, DNA and proteins form genetic material called chromatin. The nucleolus is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis Ribosomes: Protein Factories Ribosomes are particles made of ribosomal RNA and protein. Ribosomes carry out protein synthesis in two locations: –In the cytosol (free ribosomes). –On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes). The Golgi apparatus: Shipping and receiving center. The golgi apparatus consists of flattened membranous sacs called cisternae. Functions of the golgi apparatus: - Modifies products of the ER - Manufactures certain macromolecules (some polysaccharides). - Sort and packages materials into transport vesicles. Lysosomes: Digestive Compartments A lysosome is a membranous sac of hydrolytic enzymes that can digest macromolecules. Lysosomal enzymes work best in the acidic environment inside the lysosome. Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids. Some lysosomes probably arise by budding from the trans face of the Golgi apparatus. Mitochondria and chloroplasts change energy from one form to another Mitochondria are the sites of cellular respiration, a metabolic process that generates ATP. – use Oxygen to extract ATP from sugars, fats and other fuels Chloroplasts, found in plants and algae, are the sites of photosynthesis -use sunlight to generate sugar from CO2 and water (produce oxygen) Mitochondria and chloroplasts –Have a double membrane. –Have proteins made by free ribosomes. –Contain their own DNA. Mitochondria: Chemical Energy Conversion Mitochondria are found in nearly all eukaryotic cells They have a smooth outer membrane and an inner membrane folded into cristae The inner membrane creates two compartments: intermembrane space and mitochondrial matrix Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix Cristae present a large surface area for enzymes that synthesize ATP Peroxisomes: Oxidation Peroxisomes are oxidative organelles. Peroxisomes are specialized metabolic compartments bounded by a single membrane. Oxygen is used to break down different types of molecules. They contain enzymes that remove hydrogen atoms from various substances and transfer them to oxygen. Peroxisomes produce hydrogen peroxide (as a by producing of oxidation) and because it is toxic it is then converted to water. Functions of peroxisomes –Some use oxygen to break fatty acids into smaller molecules, eventually used for fuel for respiration. –In the liver, they detoxify alcohol and other harmful compounds The Cytoskeleton: Support and Motility The cytoskeleton is a network of fibers extending throughout the cytoplasm. It helps to support the cell and maintain its shape. –It organizes the cell’s structures and activities, anchoring many organelles. It interacts with motor proteins to allow cell motility. –Inside the cell, vesicles and other organelles can use motor protein “feet” to travel along tracks provided by the cytoskeleton. Components of the Cytoskeleton Three main types of fibers make up the cytoskeleton: –Microtubules are the thickest of the three components of the cytoskeleton. –Microfilaments, also called actin filaments, are the thinnest components. –Intermediate filaments are fibers with diameters in a middle range. Centrosomes and Centrioles In animal cells, microtubules grow out from a centrosome near the nucleus In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring Other eukaryotic cells organize microtubules in the absence of centrosomes with centrioles Cilia and Flagella Microtubules control the beating of flagella and cilia, microtubule-containing extensions that project from some cells Many unicellular protists are propelled through water by cilia or flagella Motile cilia are found in large numbers on a cell surface, whereas flagella are limited to one or a few per cell Cilia and flagella differ in their beating patterns Extracellular components and connections between cells help coordinate cellular activities. Most cells synthesize and secrete materials that are external to the plasma membrane. These extracellular structures include: –Cell walls of plants. –The extracellular matrix (ECM) of animal cells. These extracellular materials and structures are involved in many essential cellular functions. The Extracellular Matrix (ECM) of Animal Cells Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM). The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin. ECM proteins bind to receptor proteins in the plasma membrane called integrins. Integrins: integrate signals between ECM (outside) and cytoskeleton (inside). The ECM has an influential role in the lives of cells The ECM can regulate a cell’s behavior by communicating with a cell through integrins. The ECM around a cell can influence the activity of genes in the nucleus. Mechanical signaling may occur through cytoskeletal changes that trigger chemical signals in the cell. Functions of ECM: - support - Adhesion - Movement - Regulation Quiz 1-which of the following microscopes focus a beam of electrons through a specimen: A- light microscope B- transmission electron microscope C- Scanning electron microscope Answer: B 2-Presence of the nucleus can be used to compare: A- tiger cell and banana cell B- human cell and lion cell C- Bacterial cell and apple cell Answer: C 3- which of the following organelles produce energy: A- Ribosome B- mitochondria C- ER D- nucleus E- flagella Answer: B Extra practice 1- Which organelle contains DNA? -Mitochondria 2- Based on the figure, which organelle is responsible for synthesizing carbohydrate and sorting? - Golgi Apparatus 3- According to the figure, which organelle has the largest amount of water in the cell? - Central Vacuole (C) 4- D in the figure is? Plasmodesmata 5) cristae, DNA, and ribosomes are all component of: A. Chloroplasts B. Mitochondria C. Nuclei D. Peroximes Answer: B 6- What is the cytoskeleton? A- Network of Fibronectin B- Gel inside the cell C- Network of Fibers D- The outer structure Answer: C Extra practice 7- In the following figure, what does structure A refer to? A- microfilaments B- microtubules C- intermediate filaments D- proteoglycan Answer: A 8- What part of the cytoskeleton is responsible for chromosome movement during cell division? A- microfilaments B- microtubules C- intermediate filaments D- proteoglycan Answer: B 9- Which of the following is found only in plant cells? A- Cell wall B- Cytoplasm C- Ribosome D- Plasma Membrane Answer: A 10- If a cell lacks ribosomes, it will face problems with _____? A- Lipids synthesis B- Protein synthesis C- Carbohydrate synthesis D- It will not face any problems Answer: B Extra practice 11- Which of the following is the appropriate device to measure and observe the size of ribosomes in prokaryotic cells A-Using magnifying glass B-Light microscope C-Scanning electron microscope D-transmission electron microscope ِAnswer: D 19 ‫ﺣﺴﺐ اﺟﺎﺑﺎت ﺑﺎﺗﺶ‬ 14-Which of the following organelles convert energy from one form to another? A-Golgi apparatus B- Endoplasmic reticulum C- Peroxisome D- mitochondria Answer: D 12-Disruption of the nuclear pores complexes, which Interfere with transport molecules (in and out), which of the following molecules will be affected? A-DNA B-amino acid C-mRNA D-phospholipid Answer: C 15-Which of the following is found in animal, plant, bacteria cell ? A-Mitochondria B-Ribosome C-Chloroplast D-Lysosomes Answer: B 13- Where is DNA present in the prokaryotic cell? A nucleus B cytoplasm C nucleoid D ribosomes Answer: C 16-Some of the extracelluler matrix component in eukaryotes cell include? A-Proteoglycan B-Integrins C-Phospholipids D-Cellular wall Answer:A Extra practice 17-Which microscope reveals the inner structure of the mitochondria? A- Light compound microscope B- Light dissecting microscope C- Scanning electron microscope D- Transmission electron microscope 18-The best used instrument for studying the internal structure of cells? A. Light microscope B. Telescope C. Scanning electron microscope D. Transmission electron microscope Answer: D 19- Where does the digestion of macromolecules occur in eukaryotic cells? A. Lysosomes B. Peroxisomes C. Mitochondria D. Golgi Apparatus Answer: A Extra practice 20- Prokaryotic differs from eukaryotic such that prokaryotic lack? A- Ribosomes B- Plasma membrane C- Endoplasmic reticulum D- Cell wall Answer: C 21- Most eukaryotic genetic information is housed in: A- Ribosomes B- Nucleus C- Mitochondria D- Rough ER Answer: B 22- What is the function of the nucleolus? A- Production of ribosomal RNA B- DNA synthesis C- Protein synthesis D- Lipid synthesis Answer: A 23- Which of the following is used to view the internal structure of cellular? A- Transmission electron microscopes B- Scanning electron microscopes C- Light microscope D- Magnification lens Answer: A 24- Which part of cell structure can be found in both eukaryotic and prokaryotic? A- Nucleus B- Chloroplasts C- Mitochondria D- Ribosomes Answer: D 25- Which of the following would not occur if chloroplasts were removed from plants cell? A- Photosynthesis B- ADP synthesis C- ATP synthesis D- Hydrolysis Answer: A Extra practice 26- The function of centrosome to organize is which of the following? 29- Flagella is type of.. containing structure. A- Microtubules B- Microfilaments C- Intermediate filaments D- Cell wall Answer: A A- Microfilaments B- Intermediate filaments C- Microtubules D- Proteoglycan Answer: C 27- Extracellular matrix (ECM) helps in: 30- Which of the following cellular structures is found in both prokaryotic and eukaryotic cells A- Regulating cell's behavior B- Cytoplasmic streaming C- Organization cytoskeleton D- Anchoring organelles Answer: A A- Nucleus B- Ribosomes C- Mitochondria D- chloroplasts Answer: B 28- In addition to the nucleus, which of the following organelles contain DNA: A- Ribosomes B- Mitochondria C- Golgi bodies D- Lysosomes Answer: B 31- Which of the following structures is found in eukaryotic cells not prokaryotic cells? A- Mitochondria B- Ribosomes C- Cytosole D- Plasma membrane Answer: A Extra practice 32- What is the function of motor proteins in the cytoskeleton? A- Synthesis ATP B- Cell motility and organelles movements C- Digestion of macromolecule D- Detoxify toxic compounds Answer: B 33- Which of the following organelles found in eukaryotic cells functions by breaking down fatty acids to produce fuel? A- Rough ER B- Golgi apparatus C- Mitochondria D- Peroxisomes Answer: D cell membrane Structure and Function Overview: Life at the Edge The plasma membrane (PM) is the boundary that separates the living cell from its surroundings. The plasma membrane exhibits selective permeability, allowing some substances to cross it more easily than others (semi-permeable). How does the plasma membrane regulate inbound and outbound traffic? Some small molecules move across the cell membrane using passive transport—no input of energy— and may require transport proteins. Some small molecules use active transport, which requires both energy and a transport protein. Large molecules move in and out, using bulk transport; exocytosis or endocytosis. CONCEPT 8.1: Cellular membranes are fluid mosaics of lipids and proteins Lipids and proteins are the main components of membranes, but carbohydrates are also important. Membranes are composed mainly of phospholipids. Phospholipids are amphipathic molecules, containing hydrophobic (“water-fearing”) and hydrophilic (“water-loving”) regions. Phospholipids form a bilayer with hydrophobic tails inside the membrane, and hydrophilic heads exposed to water on either side. Most membrane proteins are also amphipathic. Hydrophilic regions of the protein are oriented toward the cytosol and extracellular fluid inside and outside the membrane. Hydrophobic regions are embedded in the bilayer. The fluid mosaic model of membrane structure depicts the membrane as a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids. Proteins are not randomly distributed in the membrane; they often form groups that carry out common functions. The Fluidity of Membranes Membranes are held together mainly by weak hydrophobic interactions. Most of the lipids and some proteins can move sideways within the membrane. Rarely, a lipid may flip-flop across the membrane, from one phospholipid layer to the other. As temperatures cool, membranes switch from a fluid state to a solid state. The temperature at which a membrane solidifies depends on the types of lipids. Membranes rich in unsaturated fatty acids are more fluid than those rich in saturated fatty acids. Membranes must be fluid to work properly. Cholesterol is a membrane component in animal cells that has variable effects on membrane fluidity at different temperatures. –At warm temperatures (such as 37ºC), cholesterol restrains movement of phospholipids. –At cool temperatures, it maintains fluidity by preventing tight packing. Plants use different but related steroid lipids to buffer membrane fluidity. Membranes must be fluid to work properly; fluidity affects both permeability and movement of transport proteins. Membranes that are too fluid cannot support protein function. Organisms living in extreme temperatures have adaptive differences in membrane lipid composition. Cell fusion experiment Evolution of Differences in Membrane Lipid Composition The lipid composition of the cell membrane appears to be adapted to environmental conditions in many species. –For example, cell membranes have a high proportion of unsaturated hydrocarbon tails in fish that live in extreme cold Organisms living in variable temperature conditions are able to change lipid composition in response to changing temperature. –For example, in winter wheat, the percentage of unsaturated phospholipids increases in autumn to prevent membrane solidification during winter. Membrane Proteins and Their Functions A membrane is a collage of different proteins, often clustered in groups, embedded in the fluid matrix of the lipid bilayer. This structure resembles a tile mosaic. Phospholipids form the main fabric of the membrane, but proteins determine most of the membrane’s functions. The protein composition of membranes varies among cells within an organism, and among intracellular membranes within a cell. There are two major types of membrane proteins: –Peripheral proteins are bound to the surface of the membrane –Integral proteins penetrate the hydrophobic core Transmembrane proteins are integral proteins that span the membrane Hydrophobic regions of an integral protein consist of nonpolar amino acids, often coiled into α helices Some membrane proteins are held in place by attachment to the cytoskeleton inside the cell. Other proteins, attach to materials outside the cell. –For example, proteins called integrins attach to fibers of the extracellular matrix. Cell-surface membrane proteins can carry out several functions: –Transport –Enzymatic activity –Signal transduction –Cell-cell recognition –Intercellular joining –Attachment to the cytoskeleton and extracellular matrix (ECM) Cell-surface proteins are important in medicine –For example, HIV enters immune cells by binding to cell-surface protein CD4 and a “co-receptor” CCR5. –Individuals lacking CCR5 are immune to HIV infection. –Drugs are in development to mask CCR5 and block HIV entrance in nonimmune individuals. The Role of Membrane Carbohydrates in CellCell Recognition Cells recognize each other by binding to molecules on the surface of the membrane Many of these surface molecules are bonded to short, branched chains of carbohydrates – Glycolipids are carbohydrates bonded to lipids – Glycoproteins are carbohydrates bonded to proteins The diversity of surface carbohydrates enables them to function as markers for cell identification CONCEPT 8.2: Membrane structure results in selective permeability The plasma membrane controls the exchange of materials between the cell and its surroundings. Membranes exhibit selective permeability; some substances cross more easily than others. The fluid mosaic model explains how membranes regulate molecular traffic across the membrane. The Permeability of the Lipid Bilayer Hydrophobic (nonpolar) molecules dissolve in the lipid bilayer and pass through the membrane rapidly. –For example, hydrocarbons, CO2 and O2 pass easily through the membrane. The hydrophobic interior of the membrane impedes the passage of hydrophilic (polar) molecules. –For example, sugars, water and ions pass through slowly, if at all. Transport Proteins Hydrophilic substances cross membranes more quickly by passing through transport proteins. Channel proteins have a hydrophilic channel that certain molecules or ions can use as a tunnel. Carrier proteins, bind to molecules and change shape to shuttle them across the membrane. Transport proteins move only specific substances. –For example, glucose carrier proteins only transport glucose; they will not transport fructose, a structural isomer of glucose. The selective permeability of a membrane is dependent on both the lipid bilayer and the specific transport proteins it contains. Passive transport is diffusion of a substance across a membrane with no energy investment. Diffusion is the movement of particles of any substance so that they spread out evenly into the available space. At dynamic equilibrium, as many molecules cross the membrane in one direction as in the other Substances diffuse down their concentration gradient, the region along which the density of a chemical substance increases or decreases. Each substance moves down its own concentration gradient, unaffected by the concentrations of other substances. The diffusion of a substance across a biological membrane is passive transport because no energy is expended by the cell. Effects of Osmosis on Water Balance Osmosis is the diffusion of free water (water molecules not clustered around another substance) across a selectively permeable membrane. Free water molecules diffuse across a membrane from the region of lower solute concentration to the region of higher solute concentration. Water keeps moving until the solute concentration is equal on both sides. Channel proteins called aquaporins facilitate the passage of water across membranes. Water Balance of Cells Without Cell Walls Tonicity is the ability of a surrounding solution to cause a cell to gain or lose water. Tonicity depends on the concentration of solutes in the solution that cannot cross the membrane, relative to that inside the cell. If the solution has a higher concentration of these solutes than the inside of the cell, water will tend to leave the cell, and vice versa. A solution is isotonic if its solute concentration is the same as that inside the cell. Water diffuses across the membrane at the same rate in both directions; there is no net movement of water across the membrane. The volume of a cell without a cell wall is stable in an isotonic solution. A solution is hypertonic if the solute concentration is greater than that inside the cell. Net diffusion of water is from inside the cell to the surrounding solution. Cells without cell walls will lose water, shrivel, and likely die in hypertonic solution. A solution is hypotonic if the solute concentration is less than that inside the cell. Net diffusion of water is from the surrounding solution to the inside of the cell. Cells without cell walls will gain water, swell and lyse (burst) in a hypotonic solution. Facilitated Diffusion: Passive Transport Aided by Proteins. In facilitated diffusion, transport proteins speed the passive movement of molecules across the plasma membrane. Transport proteins include channel proteins and carrier proteins. Channel proteins Channel proteins provide corridors that allow a specific molecule or ion to cross the membrane. Aquaporins facilitate the diffusion of water. Ion channels facilitate the transport of ions. Some ion channels, called gated channels, open or close in response to a stimulus. For example, in nerve cells, potassium ion channels open in response to electrical stimulus. Other gated channels open in response to chemical stimulus—binding of a specific substance to the protein. Carrier proteins Carrier proteins undergo a subtle shape change that moves the solute-binding site across the membrane. This change in shape can be triggered by the binding and release of the transported molecule. Carrier proteins involved in facilitated diffusion move substances down their concentration gradients; no energy input is required. CONCEPT 8.4: Active transport uses energy to move solutes against their gradients. Facilitated diffusion is passive because the solute moves down its concentration gradient, and the transport requires no energy. Some transport proteins use energy to move solutes against their concentration gradients. The Need for Energy in Active Transport Active transport requires energy, usually in the form of ATP hydrolysis, to move substances against their concentration gradients. All proteins involved in active transport are carrier proteins. Active transport enables cells to maintain solute concentrations that differ from the environment. –For example, the concentration of potassium ions (K+) is higher and the concentration of sodium ions (Na+) is lower inside animal cells than their surroundings. –Transfer of a phosphate group from ATP to the sodium-potassium pump energizes the transport of K+ into the cell and Na+ out of the cell. How Ion Pumps Maintain Membrane Potential Membrane potential is the voltage across a membrane. Voltage is created by differences in the distribution of positive and negative ions across a membrane. The inside of the cell is negative in charge relative to the outside, favoring passive transport of cations (+ve) into and anions (-ve) out of the cell Two combined forces, collectively called the electrochemical gradient, drive the diffusion of ions across a membrane. –A chemical force (the ion’s concentration gradient). –An electrical force (the effect of the membrane potential on the ion’s movement). An ion diffuses down its electrochemical gradient. An electrogenic pump is a transport protein that generates voltage across a membrane, storing energy that can be used for cellular work. The main electrogenic pump differs between plants and animals: –In animals, it is the sodium-potassium pump. –In plants, fungi, and bacteria, it is the proton pump, which actively transports hydrogen ions (H+) out of the cell. Cotransport: Coupled Transport by a Membrane Protein Cotransport occurs when active transport of a solute indirectly drives transport of other substances. The “downhill” diffusion of solute is coupled to the “uphill” transport of a second substance against its own concentration gradient. How Ion Pumps Maintain Membrane Potential Plant cells use proton pumps to generate an H+ gradient across the cell membrane. A cotransporter couples the movement of H+ back down its concentration gradient to the active transport of sucrose into the cell. This is how plants load sucrose into their veins for transport around the plant body. Animal cells use a similar cotransporter to couple the active transport of glucose to the diffusion of Na+ into cells lining the intestine. Sodium potassium pumps actively transport Na+ out of the cell to maintain the electrochemical gradient. Normally, sodium in waste is reabsorbed in the colon to maintain a constant level in the body. When a person has diarrhea, waste is expelled too fast for reabsorption, causing sodium levels to drop. A rapid drop in sodium can be life-threatening. Drinking a concentrated salt (NaCl) and glucose solution enables uptake through the Na+/glucose transporters in the intestine. Quiz 1-Which of the following type of transport require energy?? A- Passive B- Facilitated C- Active Answer: C 2-What is the role of cholesterol in cell membrane?? A- Balance fluidity B- Support the structure C- Act as a receptor Answer: A 3- Forces that drive the diffusion of ions across a membrane are: A- Electrical force B- Chemical force C- Electrochemical force Answer: C Extra Practice 1- What is the role of cholesterol? - Maintains the membrane fluidity 5- What is voltage across a membrane? - Membrane potential 2- How does the ratio of saturated fats and unsaturated fats contribute to the plasma membrane? - Maintain the membrane’s fluidity 6- How does water get into the cell membrane? -Facilitated Diffusion 3- ECM are connected to membrane by? - Integrins 7- Which receptor protein affects the ratio of ions in the cell membrane? -Ion gated channel 4-According to the figure, what is this structure? - Transmembrane proteins 8- Sodium-potassium pump is an example of? Active transport Extra Practice 9- What happens when the amount of unsaturated fats increases? A- Fluidity increases B- Fluidity decreases C- Cholesterol increases Answer: A 10- What is the name of protein (A) which is shown in the figure? A- storage protein B- transmembrane protein C- Peripheral protein D- glycoprotein Answer: B 11- The function of Cholesterol in the cell membrane A- increase fluidity B- decrease fluidity C- balance fluidity Answer: C 12- The fluid-mosaic model describes: A. selective permeability B. cell membrane structure C. concentration inside the cell Answer: B 13-If an animal cell was put in a cold temperature. How will the cholesterol affect the fluidity of the plasma membrane? A- Have no effect B- Decrease the fluidity C- Maintain the fluidity Answer: C Extra Practice 14-What is the type of diffusion in the shown figure? A- Simple diffusion B- Active diffusion C- Facilitated diffusion D- Electrical diffusion Answer: C 17-Which statement describes the simple diffusion correctly? A- Solutes movement via transport protein B- Solutes movement Against concentration gradient C- Tendency for solutes to move evenly D- The difference in membrane potential Answer: C 15- water diffusion by aquaporin channel is considered as A. Simple diffusion B. Facilitated diffusion C. Active diffusion D. Ionic diffusion Answer: B 16- ion diffusion is driven by which gradient? A. Concentration gradient B. Electrical gradient C. Electrochemical gradient D. Mechanical gradient Answer: C 18- Which environment results in the turgidity of plant cells? A- Hypertonic B- Hypotonic C- Isotonic D- Neutral Answer: B 19-Hydrogen is preamble through plasma membrane whereas a sodium ion is impermeable. Which object cannot pass the plasma membrane? A- Hydrogen B-Sodium Ion C- Hydrogen and Sodium ion D- Neither Answer: B Extra Practice 20- Which of the following is NOT a function of transmembrane proteins? A-Enzymatic activity B-Signal transduction C-Synthesis of mRNA D-Cell-Cell recognition Answer: C 21-Which of the following regulate the fluidity? A-membrane carbohydrates B-membrane protein C-mosaic fluid model D-cholesterol Answer: D 22-Integral proteins that span plasma membrane are called? A-Peripheral proteins B-Transmembrane proteins C-Carbohydrate protein D-defense Proteins Answer: B 23-Which transport mechanism moves molecules against concentration gradient: A-Osmosis B-Active transport C-Passive transport D Diffusion Answer: B 24-Which of the following molecules is would likely cross through a lipid bilayer of a plasma membrane most rapidly? A-Sucrose B- O2 C- hydrophilic peptide D Na+ Answer: B 25-Proteins bound to the inner surface of the plasma membrane are known as: A-Peripheral Proteins B-Integral Proteins C- Channel Proteins D- Carrier Proteins Answer: A Extra Practice 26-Carbohydrates present on the plasma membrane are essential for? A-intercellular joining B-attachment to the cytoskeleton and extra cellular matrix C-cell-cell recognition D-enzymatic activity Answer: C 27-The increase of the fluidity in plasma membrane in cells is increased by increasing the... A-saturated fatty acids B-unsaturated fatty acids C-cholesterol D-Proteins Answer: B 28- Which of the following statements best describes characteristic feature of integral membrane proteins and a phospholipid molecule? A- Hydrophobic B- Hydrophilic C- Amphipathic D- They are localized in the interior surface of the cell Answer: C 29-Which of the following allows the movement of water across the plasma membrane? A- Ions channels B- Ligands channels C- Aquaporins channels D- Gated channels Answer: C 30- A solution that has the same solute concentration on both sides of the cell membrane is known as? A- Isotonic solution B- Hypotonic solution C- Hypertonic solution D- Osmotic solution Answer: A 31- Which of the following examples of plasma membrane protein requires energy? A- Active transport B- Facilitated diffusion C- Simple diffusion D- Osmosis Answer: A Extra Practice 32- Membrane potential is caused by the unequal distribution of _______ across cell membrane. A-Starch B-Water C-Glucose D-Ions Answer: D 33- The solutions in the two arms of this U tube are separated by a hydrophobic and polysaccharide membrane. Side A is half filled with a solution of 2 M sucrose and 1 M glucose. Side B is half filled with 1 mole sucrose and 2 M glucose. If this solutions reach the equilibrium, the concentration of the two solutes will be A- 1M sucrose, 2M glucose B- 3M glucose, 3M sucrose C- 2M sucrose, 1M glucose D- 1.5 sucrose, 1.5 glucose Answer: D 34- The solution that does not cause a change in the cell volume, its describe ? A-Hypotonic B-Isotonic C-Hypertonic D-Acidic Answer: B 35- Which of the following statement best explains why the sodium potassium pump is an electrogenic pump ? A- it transports equal quantities of Na+ and K+ across the membrane in opposite direction. B- it is used to drive the transport of glucose against a concentration “gradient”. C-it decreases the voltage difference across the membrane. D-generates voltage across the membrane. Answer: D 36- It is the difference in electric potential between the interior and the exterior of a biological cell. A-Electrical gradient B-Chemical gradient C-Membrane potential D-Electrochemical gradient Answer: C Extra Practice 37-Cotransport dependent on: A- Passive transportation of a solute indirectly drive the transportation of another solute B- Active transportation of a solute indirectly drive the transportation of another solute C-Osmosis of a solute indirectly drive the transportation of another solute D- facilitated diffusion of a solute indirectly drive the transportation of another solute Answer:B 38- Transportation of hydrophobic substances across the plasma membrane occurs by: A passive diffusion through lipid bilayer B facilitated diffusion through channel proteins C facilitated diffusion through carrier proteins D active transport through channel proteins Answer: A 39- What statement is correct about active transport? A-moves sunstances down their concentration gradient B-requires energy, usually as ATP C-is preformed by phospholipid embeed at the membranes D-is the same as passive diffusion Answer: B 40-Which of the following describes Dynamic equilibrium across the membrane? A-no movement any molecules B-movement of molecules in one direction C-molecule A on side equal molecule B in the other side D-as many molecules cross one way as cross on the other way Answer: D 41- Which of the following best describes protiens embedded in the phospholipid biliayer in the cell membrane? A. Peripheral protiens B. Proteoglycan C. Integral protiens D. Glycolipid Answer: C 42- Which of the following best describes the ability of the plasma membrane that allows some substances to enter or exit the cell more easily than others? A. Permeability B. Selectivity C. Selective permeability D. Nonselective permeability Answer: C Extra Practice 43- - A common treatment of dehydration due excess 46- Which of the following is integral protein? Na loss in diarrhea patients is to give them.... ? A- A B- B A- Plenty of water C- C B- A diluted sugar solution D- D C- A concentrated salt (NaCI) solution D- A concentrated salt (NaCi) and glucose solution Answer: C Answer: D 44- Which of the following molecules is major component that of plasma membrane? A- Glycerol B- Proteins C- Sugars D- Phospholipids Answer: D 45- Which of following cell parts is described " fluid mosaic"? A- Cholesterol B- Vacuole C- Cell membrane D- Chloroplast Answer: C 47- Which of the following is a characteristic of plasma membranes? A- Selective permeability B- Negative permeability C- Random permeability D- Positive permeability Answer: A 48- How would cholesterol maintain the phospholipids fluidity? A- Cholesterol prevents the tight packaging of phospholipids at low temperatures and reduces phospholipids movement at moderate temperatures B- Cholesterol increases the tight packaging of phospholipids at low temperatures and reduces phospholipids movement at moderate temperatures C- Cholesterol prevents the tight packaging of phospholipids at low temperatures and increases phospholipids movement at moderate temperatures D- Cholesterol increases the tight packaging of phospholipids at low temperatures and increases phospholipids movement at moderate temperatures Answer: A Extra Practice 49- Which of the following is associated with active transport? A- Sodium-potassium pump B- Facilitated diffusion C- Simple diffusion D- lons channel Answer: A 50- Which of the following can be considered as the voltage across all membrane ? A- Water potential B- Osmosis potential C- Chemical gradients D- Membrane potential Answer: D 51- Which of the following describes panel A from the figure? A- Isotonic B- Hypertonic C- Hypotonic D- Neutral Answer: C 52- Which of the following transfers small molecules across plasma membrane by carrier proteins with down their concentration gradients? A- Facilitated diffusion B- Active transport C- Endocytosis D- Exocytosis Answer: A 53- What's the name of the voltage across the membrane: A- Chemical gradient B- Membrane Mosaic model C- Membrane potential D- Toncinty Answer: C 54- Transport of solute against the concentration with the usage of ATP is A- Active transport B- Exocytosis C- Facilitate protein D- Osmosis Answer: A Extra Practice 55- What transmembrane proteins are? A- Proteins that are bound to the surface of the membrane B- proteins that span the entire membrane C- Proteins that partially penetrate the hydrophobic region of the membrane. D- Cycloplasmic proteins receptors Answer: B 26- how do cell-surface membrane protein, contribute to HIV infection? A- they prevent HIV to bind on cell surface of immune system B- they prevent antibiotics to bind on cell surface C- They promote the entry of HIV into immune system D- They protect the cell from HIV Answer: C The Endomembrane System Concept: The endomembrane systemregulates protein traffic and performs metabolic functions The endomembrane system consists of: –Nuclear envelope –Endoplasmic reticulum –Golgi apparatus –Lysosomes –Vacuoles –Plasma membrane These components are either continuous or connected via transfer by vesicles The Endoplasmic Reticulum: Biosynthetic Factory The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic cells The ER membrane is continuous with the nuclear envelope There are two distinct regions of ER: –Smooth ER, which lacks ribosomes.. Synthesizes lipids. Detoxifies drugs and poisons. Stores calcium ions. Metabolizes carbohydrates. –Rough ER, whose surface is studded with ribosomes. –Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates). –Distributes transport vesicles, secretory proteins surrounded by membranes. –Is a protein and membrane factory for the cell. The Golgi Apparatus: Shipping and Receiving Center The Golgi apparatus consists of flattened membranous sacs called cisternae The Golgi apparatus –Modifies products of the ER (mostly sugars) –Manufactures certain macromolecules (polysaccharides) –Sorts and packages materials into transport vesicles Transport vesicles At Plasma membrane: exocytosis and endocytosis (bulk transportation) Two main pathways (inside > outside) –ER > Golgi Apparatus >Plasma membrane –ER > Golgi Apparatus >lysosomes One pathway (outside > inside) Plasma membrane > endosomes > lysosomes Protein synthesis/trafficking ER Golgi Apparatus ER Golgi Apparatus Mediated by transport vesicles Plasma Membrane Lysosomes Vacuoles: Diverse Maintenance Compartments Vacuoles are large vesicles derived from the ER and Golgi apparatus Vacuoles perform a variety of functions in different kinds of cells ‫ﻣﺤﺬوﻓﺔ‬ 1) In ER: Carbohydrates are added to proteins = glycoprotein 2) Golgi apparatus: glycoproteins undergo further carbohydrate modification & lipids acquire carbohydrates becoming glycolipids 3) Glycolipids, glycoproteins and secretory proteins are transported in vesicles to PM 4) Fusion, exocytosis and carbohydrate portions of tran-membrane proteins are positioned to the outside Concept: Bulk transport across the plasma membrane occurs by exocytosis and endocytosis Small molecules and water enter or leave the cell through the lipid bilayer or via transport proteins. Large molecules, such as polysaccharides and protein, cross the membrane in bulk inside vesicles. In exocytosis, transport vesicles migrate to the membrane, fuse with it, and release their contents outside the cell. Many secretory cells use exocytosis to export their products –For example, cells in the pancreas secrete insulin by exocytosis In endocytosis, macromolecules are taken into the cell in vesicles The membrane forms a pocket that deepens and pinches off forming a vesicle around the material for transport There are three types of endocytosis: –Phagocytosis (“cellular eating”) –Pinocytosis (“cellular drinking”) –Receptor-mediated endocytosis types of endocytosis phagocytosis In phagocytosis,a cell engulfs a particle by extending pseudopodia around it and packing it in a membranous sac called a food vacuole such as WBCs engulfing bacteria The vacuole fuses with a lysosome to digest the particle pinocytosis In pinocytosis, molecules are taken up when extracellular fluid is “gulped” into tiny vesicles Pinocytosis is nonspecific for the substances it transports; any and all solutes are taken into the cell Parts of the plasma membrane that form vesicles are lined on the inner side with coat proteins, forming coated vesicles receptor-mediated endocytosis In receptor-mediated endocytosis, binding of ligands to receptors triggers vesicle formation A ligand is any molecule that binds specifically to a receptor site of another molecule Human cells use receptor-mediated endocytosis to take in cholesterol, which is carried in particles called low-density lipoproteins (LDLs) Individuals with familial hypercholesterolemia have missing or defective LDL receptor proteins Cholesterol accumulates in the blood, building up lipids and narrowing the space in the blood vessels, resulting in potential heart damage or stroke Quiz 1-Which of the following cellular organelles is not a component of endomembrane system: A- Cell membrane B- Golgi apparatus C-Lysosome D- Mitochondria Answer: D 2- which of the following organelles synthesize lipid?? A- Rough ribosome B- Smooth ribosome C- Golgi apparatus D- Nucleus Answer: B 3- which of the following terms refer to "cellular eating": A- phagocytosis B- pinocytosis C- Exocytosis D- receptor-mediated endocytosis Answer: A Extra Practice Which part of the cell is most crucial for getting membrane proteins to their proper location? plasma membrane mitochondrion chloroplast Golgi apparatus lysosome Answer: D 1- One of the endomembrane systems that controls the packaging? A- Nucleus B- Mitochondria C- Golgi Apparatus D- ER Answer: C 2-Which of the following is responsible for the synthesis of lipids and steroids? A- Rough Endoplasmic reticulum B- Golgi Apparatus C- Smooth Endoplasmic reticulum D- Nucleus Answer: C Extra Practice 3- what mediate between endoplasmic reticulum and Golgi apparatus A-cytoplasm B-proteins C- ribosomes D- vesicles Answer: D 4- The cell can swallow droplets of extracellular fluids in small vesicles by: a- Pinocytosis b- Phagocytosis c- Exocytosis d- Osmosis Answer: A 5- Which of the following is NOT a component of the endomembrane system: a- Mitochondrion b- Nuclear envelope c- Golgi apparatus d- Vacuole Answer: a Extra Practice 6- Which of the following describes the describes the process that can bring large particles into the eukaryotic cell: a- Endocytosis b- Exocytosis c- Diffusion d- Trafficking Answer: A 7-Which of the following describes the process that can bring large particles into the eukaryotic cell: A endocytosis C diffusion B exocytosis D trafficking Answer: A 8- Which of the following organelles plays a primary role in the digestion of bacteria engulfed by white blood cells: A Lysosomes B Vacuoles C Golgi vesicles D secretory vesicles Answer:A Extra Practice 9-The plasma membrane receives transport vesicles carrying modified proteins and lipids from the? A-Rough ER B- Cis-face of Golgi Apparatus C- Smooth ER D-Trans-face of Golgi Apparatus Answer: D 10- Detoxification of poisons and drugs happens mostly in the liver. Which of the following endomembrane structures would likely be abundant in liver cells so they adopt to this function? A-Smooth ER B-Golgi Apparatus C-Rough ER D-Nuclear envelope Answer: A 11-Which of the following processes best describes the process wherewhite blood cells engulf and destroy pathogens such as bacteria? A- Exocytosis B- Pinocytosis C-Phagocytosis D-Receptor-mediated endocytosis Answer: C Extra Practice 12- Glycoproteins are synthesized in: A lysosomes C Smooth ER B Ribosome D Rough ER Answer: D 13-Which of the following describe the process of exocytosis A Rough ER > Smooth ER> Golgi apparatus> plasma membrane B Smooth ER> Golgi apparatus> vesicles> plasma membrane C Plasma membrane> lysosomes> mitochondria D Rough ER> Golgi apparatus> vesicles> plasma membrane Answer: D 14- If you were studying mutant cells and found that many proteins are going to the wrong compartments, where is the mutation having the greatest effect? A Nuclear envelope B Peroxisome C Golgi apparatus D Mitochondrion Answer: C Extra Practice 15- Which organelle is storge site for calcium ions? A Smooth ER B Golgi apparatus C Rough ER D Lysosomes Answer: A 16- Which of the following process is used by white blood cells when engulfing bacteria? A Phagocytosis B Osmosis C Pinocytosis D Receptor-mediated exocytosis Answer: A 17- What is the correct path for endocytosis? A. Plasma membrane → Endosomes → Lysosomes B. Endoplasmic reticulum → Golgi apparatus → Plasma membrane C. Endoplasmic reticulum → Lysosomes → Plasma membrane D. Plasma membrane → Golgi apparatus → Mitochondria Answer: A 18- When a cell takes up specific molecules into it, this process is known as: A. Exocytosis B. Receptor-mediated endocytosis C. cell signaling D. Phagocytosis Answer: B Extra Practice 19- Glycoproteins are secreted by which of the following endomembrane system? A- Plasma membrane B- Golgi apparatus C- Smooth ER D- Rough ER 22- The process by which the white blood cells engulf bacteria A- Exocytosis B- Pinocytosis C- Phagocytosis D- Diffusion Answer: D Answer: C 20- What is the transportation that enables polysaccharides to cross the plasma membrane? A- Active transport B- Facilitated diffusion C- Bulk transportation D- Passive diffusion 23- Which of the following processes known as cellular drinking ? A- Exocytosis B- Pinocytosis C- Phagocytosis D- Diffusion Answer: C Answer: B 21- Which one of the following is NOT a component of the endomembrane A- Plasma membrane B- Golgi apparatus C- Nuclear envelope D- Mitochondria Answer: D 24- In the context of protein trafficking. What is the sequence of locations a protein might through A- Plasma membrane > ER > Golgi apparatus B- ER > Golgi apparatus > Plasma membrane C-ER > Plasma membrane > Golgi apparatus D- Plasma membrane > ER > Golgi apparatus Answer: B Extra Practice 25- Which of the following accurately describes receptor-mediated endocytosis? A- It is non specific form of endocytosis B- It uptakes specific molecules depends on their cell's protein C- It is unglup D- It exports Answer: B