FINAL EXAM 2017, questions PDF

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BIO282-Section II Sample questions for the Final Exam Gene Regulation 1. In prokaryotes, genes are usually organized in operons so that the genes involved in a particular function can be controlled coordinately. Answer all questionsA. Show an operon using a schematic diagram labelling structural and regulatory genes, promoter, operator and terminator. B. Differentiate between inducible and repressible operons. C. Differentiate between positive and negative regulators. D. Using figures, describe an inducible operon that is controlled by a negative regulator. E. Using figures, describe a repressible operon that is controlled by a positive regulator. 2. A regulated operon is turned on in the presence of a small molecule ‘X’. A mutation that stops the synthesis of regulatory protein makes the operon permanently turned off. Answer both questionsA. Which type of regulator is the regulatory protein? B. Is the operon an example of induction or repression? Explain your answer. Using figures show the operon expression in presence and absence of regulator and also in presence and absence of the small molecule ‘X’ 3. Bacteria use a number of ways to control gene expression. The enzymes required for the biosynthesis of the amino acid tryptophan are synthesized only if tryptophan is not available in the growth medium, i.e. trp operon is expressed only in the absence of tryptophan. The trp operon of E. coli is not only controlled through a regulatory protein but also by transcription attenuation. Answer all questionsA. What is gene expression? Show steps of gene expression using a figure. B. List different methods that bacteria can use to regulate gene expression at the transcription step. C. Describe the regulation of trp operon by attenuating transcription. 4. Different cells of an organism can have the same genetic complement. However, products from only a small number of genes are required by a cell at a particular time and in a particular condition. To produce the right type and amount of required proteins, cells regulate gene expression at different levels. Answer all questionsA. What is gene expression? Show steps of gene expression using a figure. B. List different methods cells can use to regulate gene expression at the translation step. C. How do protein factors involved in translation regulate gene expression? Describe using an example. D. How do translational repressors control gene expression? Describe using an example.

5. Iron is transported to the cells using transferrin receptors. If the level of iron inside cells increases then it gets stored by ferritin. So these proteins play an important role in iron metabolism. Answer all questionsA. What is gene expression? Show steps of gene expression using a figure. B. List different methods cells can use to regulate gene expression at the translation step. C. How do cells regulate the synthesis of ferritin and transferrin receptors in response to iron? Describe using figures.

Signal Transduction 6. Signal transduction is a fundamental process where a signal from outside the cell brings chemical changes within the cell. A number of pathways are used for transmitting the signals. Answer all questions A. What do you understand by signal transduction? List major signal transduction pathways operating in eukaryotes. B. What are G proteins and how do they function in signal transduction? C. Some signal transduction events leading to an increased level of cAMP inside the cell. How does a level of cAMP regulate gene expression? 7. Challenged by fluctuations in their environment, bacteria employ sophisticated signal transduction systems to overcome abiotic stresses. A. What do you understand by signal transduction? List three different signal transduction systems used by bacteria. B. Describe a two-component signal transduction system operating in these organisms.

DNA Replication 8. In a Meselson-Stahl type experiment, bacterial cells grown in 15N medium for many generations were washed and then allowed to grow in 14N medium. DNA was extracted just after transfer (0 generation) and then after 1 and 2 generations. All these samples were analyzed by CsCl gradient centrifugation. From DNA isolated from generations 0, 1 and 2 show A. Position of bands in the centrifuge tubes (10 marks) and B. 14N and 15N labelled DNA strands (10 marks) Answer both questions for each mode of replication ie semiconservative, conservative and dispersive mode of replication 9. Replication of the E. coli chromosome starts at a particular point, the origin of chromosomal replication (oriC) and proceeds bidirectionally around the circular chromosome. A. Describe how the strands at oriC are separated to allow replication of the chromosome. B. Once the replication is initiated the process of bidirectional semi-discontinuous DNA replication occurs. Describe this process.

10. Answer both parts A. Draw a molecule undergoing theta replication. On your drawing identify i .Or i g i no fr e p l i c a t i o n i i .Th ep o l a r i t yo fa l lt e mp l a t es t r a n dsa n dn e wl ys yn t h e s i z e ds t r a n d s i i i .Le a d i n ga ndl a g g i n gs t r a n d s i v .Oka z a kif r a g me n t s v. Lo cations of primers B. List different proteins and enzymes taking part in bacterial replication. Give the function of each in the replication process. 11. The ends of linear chromosomes are difficult to replicate. A. Describe the problems associated with replicating the ends. B.Toa v o i dt h el o s so ft e r mi n a ls e q u e n c e sd i ffe r e nto r g a n i s msu s ed i ffe r e n t s t r a t e g i e st or e p l i c a t et h e i rDNA. i . Wh a tf e a t u r e so ft hec h r o mo s o medo e sE. c o l i h a v et oc i r c u mv e n tt hi s pr o b l e m?Pr o v i d ead e t a i l e da n s we r . i i . Wh a ts t r a t e gyd op r o k a r y ot e su s et or e p l i c a t el i n e a rc h r o mo s o me st o c i r c umv e n tt hi sp r o b l e m?Pr o v i d ead e t a i l e da n s we r . i i i . Wh a ts t r a t e g yd oe uk a r y o t eus et or e p l i c a t ec h r o mo s o me st o c i r c umv e n tt hi sp r o b l e m?Pr o vi d ead e t a i l e da n s we r .

Development and Apoptosis 12. A group of proteins control embryo development in Drosophila. Answer both parts of this question A. What are Hox proteins and how do they work in the development of Drosophila embryos. B. Describe the regulation of hox gene expression in embryo development of the Drosophila. 13. Apoptosis is the process of programmed cell death. It is an integral part of development in multi-cellular organisms. Answer both questionsA. Describe the role of Ced proteins for apoptosis in C. elegans. B. Describe the mechanism of apoptosis regulation by the BAD protein.

Mutagenesis The question(s) from this section will be discussed in the lecture...