27. An intron can be a. a region of DNA that is not transcribed b. an integral p
ID: 268932 • Letter: 2
Question
27. An intron can be a. a region of DNA that is not transcribed b. an integral part of a ribosome C. an inverted repeat in a gene's upstream region d. a region of DNA that is not represented by amino acids in a gene's product 28. Sunlight can damage DNA by a. forming pyrimidine dimers b. breaking glycosidic bonds to remove bases c. causing spontaneous deamination of bases d. intercalation of water molecules 29. A mutation is more likely to be silent (have no effect) if it is found in a. an intron b. the region between two genes C, both a and b d. no mutations are silent 30. A mutation that changes the codon GUA to GUG is a a. transversion mutation b. silent mutation c. frameshift mutation d. nonsense mutation 31. Bacteria that have an active lac operon a. can synthesize lactose b. can breakdown lactose c. require lactose to grow d. probably have a mutation in the lac operon 32. The enzyme responsible for the formation of the last phosphodiester bonds in a strand of DNA during DNA replication is a. ligase b. gyrase C. pn mase d. helicase 33. The E coli genome is a. circular, double-stranded DNA b. circular, single-stranded DNA c. linear, double-stranded DNA d. linear, single-stranded DNA 34. During nuclear mRNA splicing, the branchpoint A is unique because it a. base pairs with C instead of T b. forms three phosphodiester bonds instead of two c. d. is located at the 3' splice site is located at the 5' splice siteExplanation / Answer
Answer27= D
Intron is the non coding sequence of DNA which is present in between the exon (coding sequence)
It is removed from exon during post transcriptional modification after transcription and before going to cytoplasm for translation .
Therefore intron are removed before translation and therefore no amino acids represent them.
Answer28= A
DNA directly absorb UV -B light which causes thymine base pair next to each other to bond toghther and form pyrimidines dimers.
Answer29=C
If their is mutation in intron or any part between genes, it remains silent because they are parrt of DNA which doesnt express via proteins therefore doesnt affect the individual.
Answer30=B
coversion of GUA to GUG is a silent muatation becuase both codon codes for same amino acid during translation i.e valine
This is according to wobble hypothesis( i.e 3rd nucleotide i a codon doesnt affect the amino acid coding, 1st two nucleotides decide)
Answer31= B
Lac operon is inducible operon which only gets activated when their is presence of lactose in medium and helps in reanscription of those genes which is involved in BREAKDOWN OF LACTOSE ( i.e beta- glucosidase, permease and acetylase)
Answer32= A
ligase enzyme added the last phosphodieasterase bond.
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