PRACTICE EXAM 4 Cell Biology Spring 2017 MULTIPLE CHOICE (15 questions, 100 poin

Question

PRACTICE EXAM 4 Cell Biology Spring 2017 MULTIPLE CHOICE (15 questions, 100 points total). Choose the one alternative that best completes the statement or answers the question. 1) HIV Protease inhibitors work by: a) inhibiting binding of the HIV virus to CD4 on the surface of the helper T-cell b) inhibiting reverse transcription of the viral RNA c) inhibiting insertion (integration) of viral DNA into the human genome d) inhibiting transcription of the viral DNA into mRNA e) inhibiting cleavage of the viral polyprotein into individual functional proteins 2) Anti-influenza drugs such as Tamiflu work by: a) inhibiting entry of the influenza virus into host cells b) inhibiting exit of the influenza virus from host cells c) inhibiting replication of the influenza virus genome once infection has occurred d) enhancing the host (human) immune system response to influenza virus e) inhibiting insertion of the influenza genome into the human DNA 3) In terms of molecular biology, a gene is best defined as: a) a heritable unit of function b) a region of DNA sequence that codes for a protein c) a nucleotide sequence that codes for a functional product d) a region of DNA sequence that contains the information necessary for transcription of a functional RNA product e) a region of DNA sequence that can exist as different alleles 4) Initiation of eukaryotic transcription requires a large assembly of "general transcription factors" binding at the promoter to assist in recruitment of RNA polymerase to the site. The first of these general transcription factors to bind atthe promoter are: a) Sigma factor b) TATA box c) TBP, TFIID d) TFIIH e) RNA Polymerase C-terminal domain Cell Bio Practice Exam 4 Page 1

Explanation / Answer

Please find the answers below:

Part 1: Choice E (An HIV protease inhibitor directly prevents accumulation of viral poly-protein synthesized in the infected host cell and thus prevents synthesis of a complete and active viral particle inside the host cell. This powerful strategy has been very successful in controlling viral replication rates)

Part 2: Choice B (Tamiflu is an viral neuraminidase inhibitor by nature. This enzyme is necesary for the pathogen to aid its exit from the cell by breakdown of cell membrane glycoprotein mediated by sialic acid. Thus, once the pathogen has entered one cell and tamiflu is taken, it will prevent the exit of these intracellular pathogens and thus consequently prevent the infection of other host cells)

Part 3: Choice D (Since an mRNA trascript can give rise to more than one kind of proteins followed by post-transcriptional modifications, a gene can be best described as a sequence of DNA which can give rise to a functional sequence of mRNA)

Part 4: Choice A (The Sigma factor identifies the promoter region based upon its conserved sequences such as TATA box and binds to it. Binding of Sigma factor recruits RNA polymerase and consequently other enhancers which promote transcription)

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