Bio214 Final Exam questions with correct answers

Bio214 Final Exam questions with correct answers "BUT even cooler," you continue, "the molecules are evidence for the 'RNA World Hypothesis!" First, all three molecules are found in all living organisms studied and are involved in the most basic metabolic pathways shared by all organisms, such as glycolysis. Second, inspect the molecules below! What do you see?" How does the information above and your inspection of the molecules support the RNA World Hypothesis? - ANSWERS The RNA World hypothesizes that the first molecule that could self-replicate AND had enzymatic/catalytic activity was an RNA (ribonucleic acid). (1) The three carrier molecules are found in all organisms; the molecules themselves are "ancient" and arose during the early stages of cell evolution. (2) ATP carries energy. But is also a ribonucleotide triphosphate monomer that makes RNA. the other two molecules are derivatives of ATP. All three molecules are ribonucleotide derivatives. (3) This makes sense if the early evolution of cells featured catalytic activity by RNA. RNA World ribozymes could use ribonucleotides common in the RNA world for the basic carrier functions needed in catalysis and metabolism. (4) CDC2 Function - ANSWERS Cdc2 is the CD subunit with kinase activity Central positive regulator of cell cycle If it is missing, cannot promote mitosis DNP is a proton ionophore, a compound that binds protons and carries them through membranes (results in equal concentrations of the ion on both sides of the membrane). explain how DNP affects (1) CO2 production, (2) electron transport chain, (3) ATP synthesis, (4) why DNP was used as a dieting aid? - ANSWERS 1) DNP addition does not affect CO2 production by CO2 is a waste product of the TCA cycle and the loss of the proton gradient does not affect the TCA cycle 2)DNP addition does not affect the ETC. the ETC creates the proton gradient but it is NOT dependent on it 3)DNP addition stops ATP synthesis by it requires a proton gradient 4) DNP was used as a dieting aid by it would stop ATP synthesis and then since ATP is not being produced, the energy of the proton gradient is lost as heat (literally burning fat) each patient has a disease related to a mutation of a cytoskeletal component. explain which component the disease is related to and how the symptoms are caused? 1. beaded hair syndrome and deformed fingernails 2. dystonia (twisting, repetitive movements) 3. chronic respiratory problems, sterile 4. progeria (early aging) - ANSWERS 1. related to intermediate filaments (specifically keratin) which are in charge of structural integrity, strength, protective functions. keratin is found in hair and nails. symptoms stem from incorrect assembly of keratin 2. dystonia-related to actin microfilaments, which are in charge of movement of cells, tissues, and organisms. actin and myosin combine to make contractile bundles and the symptoms of dystonia are related to an inappropriate interaction of actin and myosin or an inability to control contraction. 3. chronic respiratory problems related to microtubules which are important for movement of small things or movement of aqueous layer over cells. movement of cells depends on MT structures found in cilia and flagella. issue with cilia causes mucus to accumulate, issue with flagella causes sperm to not be able to move=sterility 4. early aging-related to intermediate filament mutation. Laminas is a class of intermediate filaments responsible for shape and function of nucleus and the nuclear envelope. the nuclear envelope is important during cell division so symptoms may be due to an issue with cell division that resulted in pre-mature aging. explain the importance of non covalent bonds for the structure and function of macromolecules/proteins. how does heat affect bonds? what is the primary sequence? - ANSWERS they are individually weak, but strong and stable in numbers, can make for specific interactions heat causes denaturing/folding of the protein, and you lose protein function by you lost stability. thermal motion disrupts non covalent interactions primary sequence determines the 3D/tertiary structure and function fluid mosaic model shows that the membrane is not homogeneous. what are some examples of this heterogeneity? - ANSWERS 1. curvature in membranes- fatty acyl chains of phospholipids can have different shapes and there is an uneven distribution of cones and cylinders in the bilayer. want to maximize Van der Waals interactions between cone-shaped lipids to induce curvature in the membrane 2. lipid rafts- different lipids/phospholipids can generate different membrane thicknesses. always trying to maximize van der wails forces and only lipids of the same length (short chain or long chain) will interact to do this same length lipid=max. VDW forces=thicker mem. 3. restricted lipid mobility-lipids are generally free but can become restricted to a specific region of the membrane. this maximizes VDW forces and minimizes hydrophobic exposure 4. tight junctions-restrict movement of proteins, cannot move from cell to cell freely For each case: Which of the cytoskeletal components is affected? What are the general properties and functions of that component? How could changes to that component lead to the symptoms listed? Patient #1 presents with thickened toenails and pain due to planar keratoderma (a horn-like skin condition on the soles of the feet). You diagnose this as pachyonychia congenital. Patient #2 presents with a cancerous tumour. A hallmark of cancerous cells is unregulated cell division. You prescribe chemotherapy that causes stabilization of this type of cytoskeletal filament to block further growth of the tumour. Patient #3 presents with hearing loss. During the interview, he tells you he works as a roadie and sound engineer for a rock and roll band. - ANSWERS 1) Intermediate filaments are a strong, stable member of the cytoskeleton involved in structural integrity of the nucleus, cells and tissues (of animals). They are also used as protective structures outside the cell like hair, nails and horns. In this patient, an intermediate filament subunit (keratin: kerato-) is being made in inappropriate amounts (nails), in inappropriate places (soles of feet) or is assembling inappropriately (both places). Pain may be due to loss of structural integrity of tissue (blisters) or may be more mechanical (callus). 2) Microtubules are relatively weak, very dynamic filaments are often involved in the movement of small objects. In an interphase cell, the microtubules organize the cell; organelles and vesicles move along the microtubules. In a cell undergoing mitosis, they are used to move chromosomes. Microtubule structures are also used to move single cells