21. RIBOSOMES HAVE QUATERNARY LEVEL OF PROTEIN STRUCTURE. True False 22. A ____
ID: 83220 • Letter: 2
Question
21. RIBOSOMES HAVE QUATERNARY LEVEL OF PROTEIN STRUCTURE.
True
False
22. A ____ mutation results in the conversion of a codon specifying an amino acid to a termination codon.
nonsense
frameshift
chromosomal
missense
silent
23. A mutation that replaces one amino acid in a protein with another is called a ____ mutation.
nonsense
neutral
frameshift
missense
recombinant
24. A ribosome has one binding site for mRNA and two binding sites for tRNAs.
__________________
True
False
25. A(n) nonsense mutation is a base-pair substitution that results in the replacement of one amino acid with another.
__________________
True
False
26. Aminoacyl-tRNA synthetases link ____ to their respective tRNA molecules by ____ bonds.
amino acids; ionic
codons; covalent
amino acids; covalent
amino acids; hydrogen
anticodons; hydrogen
27. Binding of the appropriate aminoacyl-tRNA to the A site requires:
energy supplied by two ATP molecules.
no energy input.
activation of the A site.
energy supplied by GTP.
phosphorylation of the tRNA molecule.
28. During protein synthesis, ribosomes:
translate tRNA into protein.
attach to the mRNA molecule and travel along its length to produce a polypeptide.
transcribe DNA into mRNA.
translate mRNA into tRNA.
attach to the DNA molecule and travel along its length to produce an mRNA molecule.
29. Molecular chaperones assist in the folding of newly synthesized mRNAs.
__________________
True
False
30. Initiation of transcription requires:
Okazaki fragments.
a DNA primer.
a promoter sequence.
an RNA primer.
DNA polymerase.
31. Introns in pre-mRNA:
are spliced out of the message.
code for specific protein domains.
protect pre-mRNA from enzyme degradation.
code for important amino acid sequences.
move within the mRNA, giving rise to new exon combinations.
32. Frameshift mutations result from the:
substitution of one base pair for another.
substitution of a start codon for an amino acid codon.
substitution of a stop codon for an amino acid-specifying codon.
insertion or deletion of one or two base pairs.
substitution of more than one base pair.
33. Following peptide bond formation between the amino acid in the A site on the ribosome and the growing polypeptide chain, the tRNA in the A site:
forms a covalent bond with the P site of the ribosome.
forms a peptide bond with A site of the ribosome.
moves to the P site of the ribosome.
picks up another amino acid to add to the chain.
releases the growing polypeptide chain.
34. RNA is ____ and contains the nitrogenous base ____, which is absent in DNA.
single-stranded; thymine
double-stranded; uracil
single-stranded; uracil
double-stranded; thymine
single-stranded; cytosine
35. RNA polymerase binds to the promoter sequence in RNA.
__________________
True
False
36. RNA synthesis is also known as:
reverse transcription.
transcription.
termination.
elongation.
translation.
37. Ribose differs from deoxyribose by having:
two attached nitrogenous bases.
one less oxygen.
an extra hydroxyl group.
an extra carbon in the ring.
one less carbon in the ring.
38. The process in which RNA is synthesized using a DNA template is called translation.
__________________
True
False
39. The wobble hypothesis states that:
more than one ribosome can bind to an mRNA molecule.
certain tRNA anticodons can pair with more than one codon sequence.
some amino acids are coded for by more than one codon.
there is more than one stop codon in the genetic code.
a particular amino acid may be linked to more than one type of tRNA molecule.
40. Translation is initiated at the ____.
AUG codon
UAG codon
anticodon
promoter
downstream sequence
41. These noncoding sequences located within coding regions of ____ genes are called ____.
only eukaryotic; introns
eukaryotic and prokaryotic; introns
only prokaryotic; introns
only eukaryotic; exons
only prokaryotic; exons
a.nonsense
b.frameshift
c.chromosomal
d.missense
e.silent
Explanation / Answer
22. The correct answer is option A – Nonsense mutation – Mutation in a sense codon which can corresponds to the twenty aminoacids and each aminoacids specified by genetic code is changed to a chain terminating codon.
23. The correct answer is option D – Missense mutation – It is one type of nonsynonymous substitution. The Changes in single nucleotide in codon which can codes for different aminoacid. It is one type of nonsynonymous substitution.
24. False – Multiple binding site present in mRNA and three binding sites for tRNA.
25. True – Changes occurs in the single base pairs and thus creates stop codon.
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