73) The HIV virus that causes AIDS is an RNA retrovirus. A retrovirus 73) A) use

Question

73) The HIV virus that causes AIDS is an RNA retrovirus. A retrovirus 73) A) used reverse transcriptase to make DNA from RNA B) makes proteins directly from RNA C) a cellular virus that uses ribosomes to reproduce inside a living cell 74) Codons are part of the molecular structure of 74) A) tRNA B) a protein C) mRNA 75) The mutation resulting in sickle-cell disease changes one base pair of DNA so that a codon now 75) codes for a different amino acid so it is an example of a A) silent mutation B) missense mutation C) nonsense mutation 76) What is responsible for termination of transcription in eukaryotic protein-coding genes? 76) A) three nonsense mutations in sequence C) a polyadenylation signal or poly(A) B) a sigma factor D) a termination loop composed of guanine 77) Which of the following is the first event to take place in translation in eukaryotes? A) the small subunit of the ribosome recognizes and attaches to the 5' ap of mRNA B) binding of the larger ribosomal subunit to smaller ribosomal subunits C) elongation of the polypeptide D) base pairing of activated methionine-IRNA to AUG of the messenger RNA 78) How does termination of translation take place? 78) A) The poly-A tail is reached. B) The end of the mRNA molecule is reached C) A stop codon is reached 79) During elongation, which site in the ribosome represents the location where a codon is being read? 79) A) P site B) A site C) the small ribosomal subunit 80) Which of the following characteristics determine a viras's host range (vinus host range is the range of cell types and host species a virus is able to infect)? A) whether its nucleic acid is DNA or RNA B) the proteins in the host's cytoplasm C) the proteins on its surface and that of the host D) the enzymes carried by the virus 81) Which of the following statements correctly describes one characteristic of the lytic cycle of viral81) replication? A) Many bacterial cells containing viral DNA are produced. B) Viral DNA is incorporated into the host genome C) The viral genome replicates without destroying the host. D) A large number of phages are released at a time.

Explanation / Answer

Q73:- Option A

Explanation:- Retrovirus is a virus that use reverse transcriptase to produce DNA from RNA.

Q74:- Option C

Explanation:- The codons are part of molecular structure of mRNA.

Q75:- Option B

Explanation:- The sickle cell anaemia is caused due to change in 6th codon that codes for valine amino acid in hemoglobin beta chain ( normal hemoglobin contains glutamic acid) thus this an example missense mutation ( a mutation that results from change in nucleotides sequence in mRNA resulting in changes amio acid in protein.)

Q76:- Option D

Explanation:- In eukaryotes the transcription termination is caused due to termination loop composed of guanine.

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