Genetics-ⅱ Miscellaneous
- Determine the correctness or otherwise of the following Asertion (a) and the Reason (r)
Assertion : MTT assay is used to determine cell viability based on the principle of colour formation by DNA fragmentation.
Reason : MTT assay is used to determine cell viability based on the colour development by converting tetrazolium soluble salt to insoluble salt.
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The MTT assay is a colorimetric assay which is used for measuring the activity of cellular enzymes that reduce the tetrazolium dye, MTT, to its insoluble formazan dye, giving a purple color. These assays measure cellular metabolic activity via NAD(P)H-dependent cellular oxidoreductase enzymes and may, under defined conditions, reflect the number of viable cells present. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole), is reduced to purple formazan in living cells. A solubilization solution (usually either dimethyl sulfoxide, an acidified ethanol solution, or a solution of the detergent sodium dodecyl sulfate in diluted hydrochloric acid) is added to dissolve the insoluble purple formazan product into a colored solution. Reduction of MTT and other tetrazolium dyes increases with cellular metabolic activity due to elevated NAD(P)H flux.
Correct Option: D
The MTT assay is a colorimetric assay which is used for measuring the activity of cellular enzymes that reduce the tetrazolium dye, MTT, to its insoluble formazan dye, giving a purple color. These assays measure cellular metabolic activity via NAD(P)H-dependent cellular oxidoreductase enzymes and may, under defined conditions, reflect the number of viable cells present. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole), is reduced to purple formazan in living cells. A solubilization solution (usually either dimethyl sulfoxide, an acidified ethanol solution, or a solution of the detergent sodium dodecyl sulfate in diluted hydrochloric acid) is added to dissolve the insoluble purple formazan product into a colored solution. Reduction of MTT and other tetrazolium dyes increases with cellular metabolic activity due to elevated NAD(P)H flux.
- Nuclease-hypersensitive sites in the chromosomes are sites that appear to be
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Region of eukaryotic chromosome DNA that is specifically vulnerable to nuclease attack perhaps because it is not wrapped in histone as nucleosomes are called the nuclease hypersensitive sites in the chromosomes. Thus they are H2 and H4 free, H1 and H2 free, H3 and H4 histone free.
Correct Option: D
Region of eukaryotic chromosome DNA that is specifically vulnerable to nuclease attack perhaps because it is not wrapped in histone as nucleosomes are called the nuclease hypersensitive sites in the chromosomes. Thus they are H2 and H4 free, H1 and H2 free, H3 and H4 histone free.
- Which of the following characteristics with respect to bacterial DNA polymerase III are TRUE?
P. Initiation of chain synthesis
Q. 5′ – 3′ polymerization
R. 3′ – 5′ exonuclease activity
S. 5′ – 3′ exonuclease activity
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NA
Correct Option: B
NA
- Determine the correctness or otherwise of the following Assertion (A) and the Reason (R).
Assertion : Isopropylthiogalactoside (IPTG) is a gratuitous inducer of lactose operon.
Reason : Gratuitous inducers are chemical analogs which behave like natural inducer but they do not serve as substrate for the enzymes that are subsequently synthesized.
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Gratuitous inducer is an analogue of a natural inducer that is capable of inducing an operon while not serving as a substrate for the enzyme being induced. IPTG is a gratuitous inducer. It induces gene expression but itself is not metabolized by the enzyme.
Correct Option: A
Gratuitous inducer is an analogue of a natural inducer that is capable of inducing an operon while not serving as a substrate for the enzyme being induced. IPTG is a gratuitous inducer. It induces gene expression but itself is not metabolized by the enzyme.
- Match the terms in Group I with their associated functions in Group II.
Group I
P. Shine-Dalgarno sequences
Q. Leucine zipper
R. Aminoacyl tRNA synthetase
S. RNA interference (RNAi)
Group II
1. Aminoacylation of tRNA
2. Gene silencing
3. Ribosome binding and facilitation of translation initiation
4. Transcription factors
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The Shine-Dalgarno sequence is a ribosomal binding site in the mRNA. The leucine zipper is a three dimensional structural motif in proteins. These motifs are usually found as part of a DNA-binding domain in various transcription factors, and are involved in regular gene expression. Aminoacyl tRNA synthetase is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl tRNA. RNAi works for the gene silencing (Small interfering RNA is mainly used in gene silencing and Antisense technology).
Correct Option: A
The Shine-Dalgarno sequence is a ribosomal binding site in the mRNA. The leucine zipper is a three dimensional structural motif in proteins. These motifs are usually found as part of a DNA-binding domain in various transcription factors, and are involved in regular gene expression. Aminoacyl tRNA synthetase is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl tRNA. RNAi works for the gene silencing (Small interfering RNA is mainly used in gene silencing and Antisense technology).
