Medical Biology Lecture 1 Review Questions PDF

MEDICAL BIOLOGY LECTURE 1 REVIEW QUESTIONS 1. What are the most famous scientific works of these scientists? A. Leeuwenhoek: Discovered first living cells in algae, free-living and parasitic microscopic protists, bacteria, s...

MEDICAL BIOLOGY LECTURE 1 REVIEW QUESTIONS 1. What are the most famous scientific works of these scientists? A. Leeuwenhoek: Discovered first living cells in algae, free-living and parasitic microscopic protists, bacteria, sperm cells, blood cells, microscopic nematodes and rotifers, and much more. M. Schleiden: Described that all plants are made of cells. Formulated Cell theory. T. Schwann: Formulated Cell theory. (All living things are made of one or more cells.) R. Virchow: Contributed to the Cell theory. (All cells come from other cells.) J. Mendel: Discovered herditary “factors” or ‘’units” (now is called genes)’’ and ‘’alleles’’, and the fundemental laws of Inheritance. A. Garod: Discovered that a defective gene gives rise to a defective enzyme’ and prefigured “one gene- one enzyme”, also discovered alkaptonuria, understanding its inheritance. Beadle and Tatum: Proved that ’’a gene is responsible for the production of an enzyme’’. 2. What kind of abilities define life? (What a cell can do?) Cells that form our bodies can grow, reproduce, process information respond to stimuli, carry out an amazing array of chemical reactions. 3. what is a zygote? How many different types of cells are in the human body ?Zygote is the union of an egg and a sperm. Human body is made up of about 200 different types of cells. 4. What is cell: modern cell theory and commonality and diversity of cells? The cell is structural & functional unit of all living things. According to the modern cell theory; all organisms are made up of cells, cells are the basic structural unit of all organisms and that all cells come from pre-existing cells. All cells share certain structual features and carry out many complicated processes in basically the same way. Cells come in amazing variety shapes and sizes. Also they have different movement styles, different environmental conditions for living, unicellular/multicellular types... 5. Living things obtain and use energy. How living things can be classify based on their energy sources? Examples? Producers, also called autotrophs or inorganotrophs Plants, alg, some bacteria (cyanobacteria), archae Consumers, also called heterotrophs or organotrophs Herbivores (rabbit), carnivores (lion), omnivores (humans, Gut bacteria-E.Coli) Decomposers vultures, millipedes, dung beetles, fungi (the only organisms that can decompose wood) 6. What are three domains and six kingdoms of life? Domains: Eukarya, Archaea, Bacteria Kingdoms: Protists, Fungi, Plants, Animals, Archaea, Bacteria 7. What are the characteristics of pro- and eukaryotic cells and archaea? What are the major differencies? Archaea: Structure and form is similar to bacteria but their molecular biology is closely related to eukaryotes. Prokaryotic cells: No nucleus, DNA in nucleoid, no membrane bound organelles, smaller in size and cytoplasm is bound by the plasma membrane Eukaryotic cells: DNA in nucleus, membrane bound organelles, larger in size and cytoplasm is between plasma membrane and nucleus 8.Prokaryotic cells do not have a nucleus. What do they have in its place? DNA in an unbound region called the nucleoid. 9. How single-celled (unicellular) organisms can help and harm us, what are the some of the examples of it? How they hurt us: Certain plasmodium species cause harmful Malaria , fungal diseases such as athlete’s foot are also unpleasant. How they help us: Yeast & mold have an important ecological role in breaking down plant and animal remains for reuse. 10. Why viruses are the ultimate parasites? Virus infect a host cell and use it to grow and reproduce which can be devastatingly destructive. 11. What are the major small molecules and their functions of the eukaryotic cells? Adenosine Triphosphate (ATP): ATP is the primary energy currency of cells. It stores and transfers energy for cellular processes such as muscle contraction, active transport, and synthesis of macromolecules. Nucleotides: Nucleotides are the building blocks of nucleic acids (DNA and RNA). They are involved in genetic information storage, transmission, and protein synthesis. Amino Acids: Amino acids are the building blocks of proteins. They are involved in protein synthesis, enzymatic reactions, cell signaling, and structural support. Glucose: Glucose is a simple sugar and a major source of energy in cells. It is metabolized through cellular respiration to produce ATP. Lipids: Lipids are a diverse group of molecules, including fatty acids, phospholipids, and steroids. They serve as structural components of cell membranes, energy storage, and signaling molecules. Glycerol: Glycerol is a component of lipids and is involved in lipid metabolism and energy storage... 12. Why water is important? ✓ Most abundant biological medium ✓ A small, fast molecule ✓ A polar molecule, a dipolar molecule. Which allows formation of hydrogen bonds. ✓ Cohesive: surface tension ✓ Ability to moderate temperature ✓ Expansion upon freezing ✓ Versatile solvent 13. What are the works of the eukaryotic cells? Being able to: Produce energy: ATP Produce their own external environment: Extracellular matrix. which they are separated from, by the help of plasma / cell membrane Change shape & move: Cytoskeleton Grow & divide: Mitosis & Meiosis Sense & send info: transmission of signals, receptors Die: Apoptosis 14. Why we need to do look at the genom on evolutionary perpective? Because many genes controlling development are remarkably similar in humans and other animals. MEDICAL BIOLOGY LECTURE 2 REVIEW QUESTIONS What is the cell membrane composed of? Basic structure of a cell membrane bilayer? How phospholipids are positioned in a symetrical phospholipid bilayer? A two layered shell of phospholipids. Cholesterol (animal tissues) and various proteins are embedded in the bilayer. Also carbohydrates included. (shown as glycolipids and glycoproteins.) What Is a Fluid mosaic model of cell membranes? According to the fluid mosaic model, membrane is viewed as a two dimensional mosaic of phospholipid and protein molecules. Function of the cell membranes? Main functions and specific functions? Protection, regulation of passage of materials, maintenance of differintial distribution of ions, response to the environment, communication with the neighbouring cells. What are the main membrane lipids? What is the differences between phosphogliserides ,sphingolipids and glycolipids? phosphoglycerides (phospholipids) have a glycerol backbone, sphingolipids have a sphingosine backbone, and Glycolipids contain a sugar unit instead of a phosphate group..  What are the examples of gliserophosholipids,sphingolipids and glycolipids? ❖ Phosphatidylcholine (PC) Phosphatidylethanolamine (PE) Phosphatidylserine (PS) Phosphatidylinositol (PI) ❖ Sphingomyelin (SM) ❖ Gangliosides,Cerebrosides What is the cholesterol and its function in the cell membranes? Why is the cholesterol is an amphipathic molecule? Cholesterol, the major steroidal constituent of animal tissues. It is amphipathic because its hydroxyl group can interact with water. How cholesterol interacts with water? How cholesterol and other phospholipids affect the membrane fluidity, thickness and curvature? Spontaneously form either planar bilayers (micelle)or liposomes when dispersed in aqueous solutions. In general, membrane fluidity; is decreased by sphingolipids and cholesterol and is increased by phosphoglycerides. Which of the prokaryotes do have cholesterol in its cell membrane and not have a cell wall? In prokaryotes, only mycoplasmas have cholesterol in their cell membrane. What are the membrane proteins? How are they placed in a cell membrane? Functions of membrane proteins? Main functions of of integral and peripheral proteins? a) Integral proteins - inserted in the bilayer; mainly involved in transport. 1.) carrier proteins - bind to specific substances & transport them across the cell membrane. 2.) channel proteins - proteins with a channel through which small, water-soluble substances move across the cell membrane. b) Peripheral proteins - usually attached to membrane surface; some are enzymes; some are involved in the electron transport chain and/or photosynthesis, others are involved in the changes in cell shape that occur during cell division. c) Lipid-anchor proteins - three different type of proteins including prenylated proteins which are particularly important for eukaryotic cell growth, differentiation and morphology. What are the function of carbohydrate groups of glycoproteins or glycolipids? Bound Carbohydrates to Proteins:  Increase the hydrophilic character of lipids and proteins  Maintain stability of the membrane   Facilitate cell–cell interactions  Glycolipids and glycoproteins are involved in human blood-group antigens Functions of Bound Carbohydrates to Lipids: ♦ Increase the hydrophilic character of lipids and proteins. ♦ Maintain stability of the membrane. ♦ Facilitate cell–cell interactions. ♦ Glycolipids and glycoproteins are involved in human blood group antigens. ♦ Glycolipids acts as receptors for viruses and other pathogens to enter cells. How is the asymmetrical distribution of many membrane lipids and proteins? What is the importance of the cell membrane asymetrical distribution of many membrane lipids and proteins? All integral proteins and glycolipids bind asymmetrically to the lipid bilayer with respect to the cytosolic and exoplasmic faces. Phospholipids and sphingolipids are asymmetrically distributed in the two leaflets of the bilayer Such asymmetry is an essential aspect of the structure and function of biological membranes. Can membrane phosholipids and membrane proteins flip-flop? No, they can’t Can membrane proteins laterally move? Yes, they can. What are the functions of membrane proteins in the membrane transport, in passive and active transport? For example: Transporters, ion channels, in the passive transport and ATPases pumps in active transport. Ion channels facilitate movement specific ions into or out of cells, along the concentration gradient of the ions Transport proteins catalyze the movement of specific solutes across plasma membranes by a process called passive transport or catalyzed transport (and sometimes called facilitated diffusion) Four classes of ATPases function in primary active transport: P-class transporters move ions against their gradients, F-class and Vclass transporters pump protons against their concentration gradients, and ABCclass transporters move drugs, ions, and xenobiotics against their gradients.  What type of proteins synthesized on the bound or free ribosomes (where to go- trafficking)? When Ribosomes bind to endoplasmic reticulum and when they remain free? Ribosomes bind to endoplasmic reticulum when proteins they are synthesizing contain an N-terminal signal sequence or leader sequence. Proteins destined to function in lysosomes receive a mannose-6- phosphate tag in the Golgi. Proteins secreted from the cell are released either in a constitutive or in a regulated manner. Proteins synthesized on free ribosomes will remain in the cytosol unless they contain a tag to direct them to the nucleus, mitochondria, or peroxisomes. What are the two types of secretions of proteins from the cells? Proteins secreted from the cell are released either in a constitutive or in a regulated manner. MEDICAL BIOLOGY LECTURE 3 REVIEW QUESTIONS + What are the major organelles and their functions? Endosomes internalize plasma-membrane proteins and soluble materials from the extracellular medium, and they sort them back to the membranes or to lysosomes for degradation. Lysosomes, which have an acidic lumen, degrade material internalized by the cell and worn- out cellular membranes and organelles. Vacuole stores water, ions, and nutrients, degrades macromolecules, and functions in cell elongation during growth Peroxisomes detoxify various molecules and also break down fatty acids to produce acetyl groups for biosynthesis without the production of ATP Smooth endoplasmic reticulum (ER) synthesizes lipids and detoxifies certain hydrophobic compounds. Rough endoplasmic reticulum (RER) functions in the synthesis, processing, and sorting of secreted proteins, lysosomal proteins, and certain membranes. Ribosomes are the sites of protein synthesis (where amino acids are assembled into polypeptides) Golgi complex processes and sorts secreted proteins, lysosomal proteins, and membrane proteins synthesized on the rough ER. Secretory vesicles store secreted proteins and fuse with the plasma membrane to release their contents. Nucleus: carrier of the hereditary information, which exerts a continuing influence over the ongoing activities of the cell through protein synthesis; "control center of the cell." isolates the DNA in eukaryotic cells. In dividing cells is site of mRNA and tRNA synthesis. Nucleolus is a nuclear subcompartment where most of the cell's rRNA is synthesized. Nucleolus is a nuclear subcompartment of the nucleus and is not surrounded by a membrane. Mitochondria, which are surrounded by a double membrane, generate ATP by oxidation of glucose and fatty acids. Chloroplasts, which carry out photosynthesis, are surrounded by a double membrane and contain a network of internal membrane bounded sacs. +Organelles with a double bilayer membranes, organelles without a cell membranes? Double bilayers: Nucleus, mitochondria, chloroplasts. Without membrane: ribosomes, centrosome... + What type of proteins synthesized on the bound or free ribosomes (where to go- trafficking)? When Ribosomes bind to endoplasmic reticulum and when they remain free? Ribosomes bind to endoplasmic reticulum when proteins they are synthesizing contain an N-terminal signal sequence or leader sequence. Proteins destined to function in lysosomes receive a mannose-6- phosphate tag in the Golgi. Proteins secreted from the cell are released either in a constitutive or in a regulated manner. Proteins synthesized on free ribosomes will remain in the cytosol unless they contain a tag to direct them to the nucleus, mitochondria, or peroxisomes. +What are the two types of secretions of proteins from the cells? Proteins secreted from the cell are released either in a constitutive or in a regulated manner. +Why the targeting and phosphorylation of lysosomal proteins are important? Examples of diseases? Phosphorylation is the critical event that removes lysosomal enzymes from the secretion pathway and directs them to lysosomes. Genetic defects affecting this phosphorylation produce I-cell disease in which lysosomal enzymes are released into the extracellular space and inclusion bodies accumulate in the cell, compromising its function. For example; I-cell and Tay-sachs diseases. MEDICAL BIOLOGY LECTURE 4 REVIEW QUESTIONS What is the cell movement and its function? Cell movement refers to the ability of cells to change their position or shape within tissues or in response to external stimuli. Cell movements are essential elements in the growth and differentiation. Why cell movements are important (embryo, Adult,..) Cell movement in multicellular organism are important for ? Ability of cells to migrate is important in evolution in multicellular organisms: – In an embryo, migration of single cells and groups is critical to the development. – In adults, migration is a part of defense against infection. – Uncontrolled cell migration is a sign of cancer. What are two basic mechanisms for cell movement, using ATP? 1) specialized motor proteins (kinesins and dyneins) and microtubules; and 2) actin microfilaments and myosin motor molecules. What is the cytoskeletone is made of? The cytoskeleton of a cell is made up of microtubules, actin filaments and intermediate filaments. What are the microtubulles and their function? Where are they found? Microtubules (MT) are the largest type of filament of the cytoskeleton. Microtubule Functions: involve in mitosis, cell motility, intracellular transport and maintenance of axons and cell shape. They are found in all eukaryotic cells. What is a profilament, and how many of protofilaments compose a singlet microtubule in mammals? Alpha and beta tubulin subunits are assembled into linear protofilaments. Singlet microtubules are 13 protofilaments How microtubules made of tubulin subunits, which one of the subunits minus end and which one of the subunits plus end is exposed? Alpha- end of a tubulin subunits is called minus (-) end and beta plus (+) end. 13 protofilaments are arranged around a hollow core in such a way that all of them have their plus ends (beta (+) end) on the same side. This gives the overall microtubule a directionality. Towards which direction and which end s, microtubules grow (polymerise) or shrink (depolymerise)? Where microtubules start to grow and radiate toward to plasma membrane? Microtubules form by addition of tubulin dimers at the ends. New microtubules form nucleation centres (oligomers) and grow by addition of subunits on either end: elongation. Microtubules tend to grow out from the centrosome to the plasma membrane. What causes vesicles and organelles to move along microtubulles ‘’tracks’’? Molecular Motor Proteins 1. Kinesins and dyneins—two families of molecular motor proteins— move along microtubules, act like tow-trucks, attaching to the cargo and pulling it along the tracks to its destination. Which motor protein to which direction on the microtubulles carry the vesicles (cargo) on the microtubulles? How the vesicles (cargo) are carried on the microtubulles towards to plasma membrane and back to the center? 1. Most kinesins travel away from the center of the cell (+end-directed) 2. Dyneins travel towards the center of the cell (- end-directed) Thus, kinesins function to bring cargoes to the periphery of the cell, while dyneins function to carry cargoes to the center of the cell. What is the importance to have a polarity of a microtubullles/actin filaments? This gives the overall microtubule a directionality. What are MTOC/centrosomes/centrioles and singlet/doublet/ triplet microtubulles? Examples of them? In cells, the minus ends of microtubules are anchored in structures called microtubule organizing centers (MTOCs). Microtubule-organizing centre (MTOC) structure serves as a site for initiation and as an anchor. The primary MTOC in a cell is called the centrosome, and it is usually located adjacent to the nucleus.  A microtubule is a hollow cylinder of 10 to 15 protofilaments (13 in mammalian cells) around a lumen. Singlet microtubules are 13 protofilaments (A) Doublet microtubules are 13 plus 10 (or 11) protofilaments (A+B) (in cilia or flagella). Triplet microtubules are 13 plus 10 (or 11) plus 10 (veya 11) protofilaments (in basal bodies or centrioles). What is PCM? In the context of the cytoskeleton, PCM stands for "Pericentriolar Material." PCM is a specialized region found near the centrosome, which is a cellular organelle involved in microtubule organization and cell division. The pericentriolar material is a matrix of proteins and other molecules that surrounds the centrioles, which are cylindrical structures at the core of the centrosome. The primary function of PCM is to serve as a microtubule-organizing center. It is responsible for nucleating, anchoring, and regulating microtubules within the cell. What are the actin filaments? Where are actin filaments found? What are the function of actin filaments? Actin microfilaments (MFs or Microfilaments) are smallest element of the cytoskeleton, with a diameter of only about 7-9 nm, made of a protein called actin, twisted two stranded. The protein actin is abundant in all eukaryotic cells. : Muscle contraction (with myosin filaments), cell migration (lamellipodia & filopodia; amoeboid movement; and cytoplasmic streaming). How actin filaments change the cell shape? When cells need to move or engulf particles, the actin network underlying the plasma membrane changes in shape by growth of the actin filaments. The change in the actin filaments leads to the production of protrusions of the cell that help the cell to "crawl" across a surface or engulf particles by phagocytosis. What are the myosin motor proteins? What is the myosin II motor protein functions in muscle cell, which of the cytoskeleton filaments are involved? Myosin motor proteins are a family of proteins involved in various cellular processes, with their primary function being the generation of mechanical force and movement along actin filaments. Myosin proteins are best known for their role in muscle contraction, but they are also important in a wide range of other cellular activities, including intracellular transport, cell division, and cell motility. In skeletal muscle cells, Actin thin filaments and myosin thick filaments are organized into ordered structures called sarcomeres. What are the intermediate filaments, examples of intermediate filaments, where are they found? What are their functions? Intermediate filaments (IFs) are a type of structural protein in the cytoskeleton of eukaryotic cells. They form a network of filaments that provide mechanical support and help maintain cell shape. Unlike microtubules and actin filaments, intermediate filaments are more stable and less dynamic, and they play a critical role in the structural integrity of cells. Keratin, a well known protein, is essential for structures from animal skin (hair, claws and fingernails, horns and beaks, turtle shells, feathers, scales and outermost layer of skin). Main function is, primarily mechanical, to provide mechanical strength to cells, to help with stand stress. As a class, intermediate filaments are less dynamic than actin filaments or microtubules; commonly work in tandem with microtubules, providing strength and support for the fragile tubulin structures. How do cilia and eukaryotic flagella move? What are cilia and eukaryotic flagella made of? Formed from specialized groupings of microtubules called basal bodies. Have a core composed of microtubules connected to the plasma membrane Cilia and flagella move liquid past the surface of the cell (they control the water flow around the main body). In single celled organisms, such as sperm, then it is used to swim  MEDICAL BIOLOGY LECTURE 5 REVIEW QUESTIONS What is ECM? What is ECM composed of? How many type of extracellular matrix proteins are abundant in the extracellular matrix of all tissues ? What other ECM molecules are? (CAM’s) As summarized in Table 19.1, What are the major classes of ECM proteins and their function? What are CAMs and adhesion receptors? What is cell-cell or cell-matrix adhesions? What are their role in cell-cell or cell-matrix adhesion? What are the four major classes of CAMs? As Summarized in Table 19.2: Type of cell junctions and their functions, related adhesion type, principal CAMs adhesion receptors, Related cytoskeletal attachements? What is the plasmodesmata? Study the following components of the extracellular matrix for their function. Collagen forms tough fi bers that impart strength and resistance to shearing forces in tissues that contain it. Elastin is a fi brous protein that imparts rubbery properties to tissues. Fibronectin is a multifunctional adhesive protein. Glycosaminoglycans form hydrated gels and impart resilience to tissues. Laminin, similar in structure to fi bronectin, is an adhesive protein.