BIOL 1111 Ch. 3 Partial Notes - pdf.pdf

THE MOLECULES OF CELLS Biol 1111, Ch. 3...

THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Organic Molecules: The Basics Life’s Molecular Diversity is Based on Carbon Almost all molecules that cells make are composed of carbon atoms, bonded to one another and to atoms of other elements (especially H, O, and N) Carbon can make four covalent bonds _______________________, making it particularly suited to forming large diverse molecules Molecules synthesised by cells and containing both carbon and hydrogen are known as organic molecules nonpolar bonds lots of energy released - Carbon Skeletons Carbon chains form the skeletons of organic molecules Molecular diversity arises from variation _______________________ in carbon skeletons Carbon chains vary in length and shape Hydrocarbons Hydrocarbons are organic molecules consisting ONLY of C and H Many organic molecules contain hydrocarbon components Hydrocarbons can undergo reactions that release large amounts of _______________________ energy Would you expect hydrocarbons to be hydrophilic or hydrophobic? Isomers molecular formula Isomers are compounds with the same_______________________ but different _______________________ Structures and _______________________ properties Isomers are important in biology: o Organisms are sensitive to even subtle variations in molecules o different effects Two isomers of a drug may have _______________________ Give one example of two isomers that have different biological consequences:  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Functional Groups specific configuration of atoms Functional group = a _______________________ commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions Number and arrangement of functional groups gives each molecule its _______________________ unique properties All functional groups are polar, making them hydrophilic and soluble therefore _______________________ in water o Methyl _______________________ groups also impact molecular shape and function, but they are nonpolar and not reactive Details Matter! For example, a slight change in functional groups impacts which secondary sex characteristics might develop Note the placement of methyl groups (CH3), and carbonyl vs hydroxyl group General Structure of Large Biomolecules Large Biomolecules Cells make a huge number of large molecules from a small set of small molecules covalently Macromolecules are large molecules, often composed of thousands of _______________________ atoms connected Cells may contain thousands or millions of different macromolecules There are four classes of macromolecules: 1. Carbohydrates 2. Proteins 3. Nucleic acids (DNA and RNA) 4. Lipids  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Monomers and Polymers Polymer = large molecule consisting of a chain of many identical or similar molecular units strung together building blocks Monomer = units that serve as_______________________ of polymers Three of the four classes of life’s organic molecules involve polymers: 1. Carbohydrates 2. Proteins 3. Nucleic acids The variety of polymers accounts for the uniqueness of each organism 10-50 monomers The trillions of different polymers that exist are made by only _______________________ o The infinite amount of proteins are made up only 20 amino acids o DNA is made up of only four nucleotides The key to this variation is the sequence in which monomers are strung together Building Polymers Cells link monomers together to form polymers by dehydration synthesis hydrogen ati s One monomer gives up a _______________________, and another · monomer gives up a _______________________ group covalent bonds Water is released, and a new _______________________ forms between the two monomers breakpart Breakdown of Polymers - Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the _______________________ reverse of a dehydration reaction 11 Hydrolysis = “water break” The bond between monomers is broken by the addition of a water molecule How many molecules of water would be needed to completely hydrolyse a polymer that is six monomers long?  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Carbohydrates Carbohydrates Carbohydrates include sugars, and the polymers of sugars single sugars The simplest carbohydrates are monosaccharides, or _______________________ Carbohydrate macromolecules are polysaccharides, polymers composed of many monosaccharides _______________________ Monosaccharides Monosaccharides have molecular formulas that are multiples of (CH2O)n Can have 3-7 carbon atoms Glucose (C6H12O6) is the most common monosaccharide Monosaccharides, especially glucose, are the main fuel molecules for cellular work _______________________ It is convenient to draw sugars as if their carbon skeletons are linear, but most 5 and 6 carbon sugars form rings in aqueous solutions What would be the chemical formula for a sugar possessing 5 carbons? Disaccharides Cells link sugars into disaccharides (double sugars) o Can be two of the same sugar, e.g., maltose (2 glucoses) o Can be two different sugars, e.g., sucrose (glucose + fructose) Sweetness Scale Various types of molecules, including non-sugars, taste sweet because they bind to “sweet” receptors on the tongue CONSIDER: Which is “healthier”, honey or sugar? honey : Contains vitamins - more sugar only contains sucrose  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Polysaccharides Polysaccharides = polymers of 100’s- 1000’s of monosaccharides linked together by dehydration reactions Examples include: o Starch o Glycogen o Cellulose Storage Polysaccharides: Starch and Glycogen Starch = storage polysaccharide of plants _______________________ Glycogen = storage polysaccharide of animals _______________________ (vertebrates store glycogen mainly in liver and muscle _______________________cells) Starch and glycogen consist of glucose monomers: o Starch polysaccharides can be branched or unbranched o Glycogen polysaccharides are more compact and highly branched Structural Polysaccharides: Cellulose plant cell wall Cellulose = structural polysaccharide in plants, and a main component of _______________________________ Also made of glucose monomers, but linked differently than in starch and glycogen, instead forming unbranched Chains _______________________ Multiple unbranched chains hydrogen bond to one another to form cellulose fibers Cellulose is the most abundant organic material on earth, but only certain microorganisms and some fungi can hydrolyse _______________________ it  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Lipids Lipids Carbon Lipids consist mostly of _______________________ by_______________________________ nonpolar covalent bonds hydrogen and _______________________ atoms linked together Lipids are the one class of macromolecule that is NOT formed of monomers Lipids are a diverse group, classified together based on the fact that they are all hydrophobic o The most biologically important lipids are fats, phospholipids, and steroids Fats/Triglycerides Another name for fat is triglyceride, a term that comes from how fat is structured: three fatty acids linked to one glycerol molecule Each fatty acid is linked to glycerol via a dehydration reaction _______________________ than starch!) energy storage The main function of fats is _______________________ (2x better What are some other functions of fat? storing energy protects organs · Supports cell growth keep warm/insulation · Fatty Acids number Fatty acids vary in length (number of carbons) and in the _______________________ and location _______________________ of double bonds no double bond Saturated fatty acids have the maximum number of hydrogen atoms possible, and _______________________ o They are solid at room temperature, and mainly derived from animals Unsaturated fatty acids have one or more double bonds o Double bonds cause kinks in the carbon chain o They are liquid at room temperature, and mainly derived from plants  1-1 If C- i - c it THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Cis and Trans Fatty Acids Unsaturated fatty acids may be cis or trans, depending on whether the H atoms attached to the double bonded carbon are on same side the_________________________ opposite side (cis) or _______________________ (trans) of the double bond o Cis and trans fatty acids are structurally and biologically distinct from one another Hydrogenation and Trans Fatty Acids Hydrogenation = process by which unsaturated fatty acids are converted to saturated fatty acids by adding hydrogen liquid This changes fats from _______________________ to solid _______________________, and improves overall shelf life Historically, processed fats were partially hydrogenated, resulting in a Semi-solid texture at room temperature _______________________ An undesirable side effect of partial hydrogenation is trans fatty acids, which have been linked to heart disease _______________________ – modern processes try to minimize the amount of trans fats in processed oil products Lipids: Phospholipids phosphate group Phospholipids are similar to fats, but a _______________________ replaces one fatty acid The addition of this group makes phospholipids amphipathic, hydrophilic meaning they have both _______________________ and hydrophobic _______________________ regions The amphipathic nature of phospholipids causes them to form bilayers, which are the basis of cellular membranes  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Lipids: Steroids Steroids are lipids with carbon skeletons that are bent to form four fused rings Cholesterol, a steroid and common component of animal cell membranes _______________________________, is also the starter molecule for making other steroids o Other naturally occurring steroids include Vitamins _______________________, bile acids, and hormones _______________________ Proteins Proteins Proteins are essential to the structure and activities of life: proteins do things! most diverse They are the _______________________of the major categories of macromolecules There are seven classes of proteins: 1. Structural (silk, hair, tendons) 2. Contractile (actin, myosin) 3. Storage (ovalbumin) 4. Defensive (antibodies) 5. Transport (hemoglobin) 6. Signaling proteins (hormones) 7. Enzymes Enzymes chemical Catalyst Enzymes are proteins that serve as a _______________________, meaning they change the rate of a chemical reaction without being changed _______________________ themselves in the process Enzymes control all chemical reactions in organisms  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Proteins are amino acids linked together The monomers of proteins are amino acids 20 There are _______________________ different amino acids: o All have the same general structure, with different R groups o R group = variable chemical group, may be hydrophilic or hydrophobic Amino acids are linked together by dehydration reactions that result in peptide bonds covalent linkage Peptide bonds are a specific type of _______________________that amino group occurs between a carboxyl group and an Chain The resulting _______________________ of amino acids that forms via dehydration synthesis is called a polypeptide Proteins have four different structural levels 1. Primary structure = the precise sequence of amino acids in the polypeptide chain 2. Secondary structure = the structures that result from the coiling or folding of ________________________ the polypeptide chain into local patterns (alpha helix or beta pleated sheet), maintained by hydrogen bonds _______________________ between atoms in the polypeptide backbone 3. Tertiary structure = the overall three-dimensional shape of a protein, stabilised by interactions between R groups (e.g. clustering between hydrophobic _______________________ R groups, hydrogen bonds, ionic bonds, disulfide bridges) 4. Quaternary structure = some proteins are composed of multiple polypeptides and _______________________, they way in which these subunits associate is the quaternary structure  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Which structural level of a protein would be the LEAST affected by a disruption in hydrogen bonding? Protein shape and function are intricately linked In addition to the sequence of amino acids, physical and chemical conditions can affect a protein’s ultimate three- dimensional structure PH Alterations in _______________________, temperature salt concentration, _______________________, and other environmental factors can cause a protein to unravel Denaturation = loss of a protein’s native (i.e., properly folded) structure o a denatured protein will not function _______________________ as it should Nucleic Acids Nucleic Acids Nucleic acids are the macromolecules that encode information required to build proteins The monomers of nucleic acid polymers are nucleotides, and the sequence of nucleotides determines the amino acids sequence of _______________________ polypeptide chains along a _______________________ There are two main types of nucleic acids: o DNA (deoxyribonucleic acid) o RNA (ribonucleic acid)  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Nucleotides Nucleotides all have the same general structure: o All have a phosphate group and a pentose sugar o Nucleotides differ by having different nitrogenous bases DNA nucleotides can have one of four different bases: o Adenine (A) o Thymine (T) o Cytosine (C) o Guanine (G) RNA nucleotides also have four different bases, but uracil (U) replaces thymine Nucleic acid polymers are made by dehydration Synthesis of nucleotides _______________________ The sugar of one nucleotide bonds to the phosphate group of the next monomer, resulting in a repeating sugar- phosphate backbone The sequence of bases along a DNA or RNA polymer is _______________________ unique for each gene RNA and DNA RNA usually consists of a single polynucleotide strand DNA molecules contain two polynucleotide strands, which wind together to form a double helix The two strands in DNA are held together by hydrogen bonds, according to the following base _______________________: pairing rules o A pairs with T o C pairs with G The two DNA strands are said to be complementary to one another  THE MOLECULES OF CELLS Biol 1111, Ch. 3 Dr. Kyra Janot Fall Term 2024 Complementary base pairing is the key to how genetic information is passed on The same base-pair rules that result in the double helix structure of DNA also allow for DNA to provide directions for its own replication _______________________ The DNA helix “unzips”, and new complimentary strands are assembled along the original separated strands transcription Base pairing also accounts for the precise _______________________ of information from DNA to RNA, though in this case it is uracil _______________________ (not thymine) that pairs with adenine _______________________ In transcription, the DNA double helix unzips and a single RNA strand is assembled using one of the two DNA strands as a template