Saturday, 26 July 2014

Regulation of Gene Expression

By Pratiba Muniandy



1.       Decreased binding of histone results in the disruption of nucleosomal structure and physical accessibility of DNA transcription.
2.       Alternative splicing occurs by altering the patterns of exons from a single primary transcript.
3.       Gene promoter sequences which are required for the initiation of transcription are located downstream of the gene.
4.       Operons regulate the expression of genes in bacteria by induction and repression.
5.       Repressor binds to the region of operon and blocks the binding of RNA polymerase to the promoter.
6.       Amplification of gene is involved in the development of tumours, development of drug resistance and synthesis of ribosomal genes.
7.       Regulation of gene expression in eukaryotes occurs at transcriptional, post-transcriptional, translational and post-translational levels.
8.       Degeneracy of the genetic code refers to the fact that
a)codons do not overlap
b) there are more codons than amino acids
c)code is not universal
d)the genetic code is not always a triplet code
      9.  Alternative splicing
                a) allows synthesis of functionally distinct proteins from the primary transcript of a single gene.
b) occurs by altering the patterns of exons from a single primary transcript.
c) occurs during a particular stage during the development of different cell types.
    10. The regulatory genes in lactose operon
                a)lie adjacent to the operon and controls its function
                b) are located adjacent but outside the operon
                c) produce proteins called repressors.
11. Gene regulatory DNA sequences
                a) are also known as the enhancer and silencer sequences
                b) bind to transcription factors that link RNA polymerase II to the promoter to form transcription-initiation complex.
                c) bind to DNA binding molecules to result in either induction or repression of transcription.
                d) are either present upstream or downstream of the structural gene.
12.  Transcription factors
                a)are proteins that recognize and bind to specific sequences in DNA.
                b) are transcriptional units containing clusters of genes comprising regulatory gene and protein encoding genes.
                c) are present in either the major or minor groove of the DNA helix.
                d)  include general transcriptional factors and tissue-specific transcriptional factors.

1.  (TRUE) 2. (TRUE) 3. (FALSE) 4. (TRUE) 5. (TRUE) 6. (TRUE) 7. (TRUE)
8.  (a) (FALSE) (b) (TRUE) (c) (FALSE) (d) (FALSE)
9. (a) (TRUE) (b) (TRUE) (c) (FALSE) 
10. (a) (TRUE) (b) (TRUE) (c) (TRUE)
11. (a) (TRUE) (b) (FALSE) (c) (TRUE)  (d) (TRUE)
12. (a) (TRUE) (b) (FALSE) (c) (TRUE) (d)(TRUE)

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