os Multiple-Choice. (16 questions, 1.5 points each, 24 points for this section)
ID: 212350 • Letter: O
Question
os Multiple-Choice. (16 questions, 1.5 points each, 24 points for this section) 1. The poly(A) tail of an mRNA A. is where the start codon is located B. is where ri C. protects the mRNA from attack by RNA-digesting enzymes in the cytoplasm D. covers the stop codon until it is needed attach at the start of translation Pm Sm A. has only recently started to be used in scientific research (beginning in about 2005) B. is a dangerous viral infection C. replicates slowly, reproducing only once per year D. can be infected by Viruses that kill bacterial host cells during each cycle of infection are called Np P viruses 3. B. enveloped viruses C. lysogenic bacteriophages 4. Small loops of DNA that occur in bacteria, in addition to the main circular chromosomal DNA molecule are called D. plastids 5. During translation, tRNAs bind to mRNA (pairing between anticodons and codons) through A. ionic bonds C. nonpolar covalent bonds D. polar covalent bonds 6. What is the natural function of restriction endonucleases? A. research applications B. defense against viruses that infect bacteria C. regulating bacterial gene expression D. DNA manipulation in vitro (that is, in the test tube) 7. Which genes encode proteins that regulate the cell cycle in normal cells? A. B. proto-oncogenes D. tumor suppressor genes and proto-oncogenes tumor suppressor genes C. oncogenes 8. PCR (the polymerase chain reaction) is- A. repeated DNA replication cycles of a small, specific region of a DNA molecule B. DNA replication in which DNA polymerase replicates an entire chromosome C. a reaction in which restriction enzymes cut a gene of interest from the chromosome D. transcription during which only a portion of the cell's DNA is expressed 9. Which bases are found in RNA? A. adenine and uracil only B. adenine, thymine, and cytosine only C. adenine, uracil, guanine, and cytosine D. adenine, thymine, guanine, and cytosine 10. You leave your house on a cold morning, and walk down the street. To your shock, you find a man lying on the sidewalk, possibly injured or dead. You shout at and shake him, but he does not move or attempt to speak. He is also very cold to the touch. Strictly from these observations, two of the ordinary aspects of life that you decide are no longer present are A. inheritance of DNA, and response to environmental stimuli B. response to environmental stimuli, and C. maintenance of homeostasis, and complex structure composed of cells. of homeostasis (constant internal conditions). D. complex structure composed of cells, and inheritance of DNAExplanation / Answer
1) c it protects the mRNA molecule from enzymatic degradation
2)d can be infected by bacteriophage viruses( eg T4 is one of the bacteriophages which is known to infect E coli)
3)a virulent bacteriophages.
These infect the bacteria and kill them by lysis. That is why they replicate via lytic cycle
4)b plasmids
the DNA carried by these circular plasmids is distinct from the chromosomal DNA. It functions to provide the bacteria with certian advantages such as antibiotic resistance
kindly ask the questions separately
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