Gene Structure And Function

Question 0

MicroRNA (miRNA)

Answer 0

Class of naturally occurring, small non-coding RNA molecules, about 21-25 nucleotides in length. miRNAs are partially complementary to one or more mRNA molecules. Their main function is to down-regulate gene expression through translational repression and or mRNA cleavage

Question 1

Cryptic splice site

Answer 1

Splice sites that are not detectably used in wild-type pre-mRNA. They are only selected as a result of a mutation elsewhere in the gene, most often at the authentic splice site. They can be activated by mutation of nearby authentic or advantageous splice sites

Question 2

RNA interference (RNAi)

Answer 2

Specific type of biological process that uses ds RNA molecules to alter gene expression

Question 3

Short interfering RNA (siRNA)

Answer 3

Class of ds RNA molecules about 20-25 base pairs in length. siRNAs can promote the degradation of target mRNAs

Question 4

Transcriptome

Answer 4

A collection of all the transcripts present in a given cell

Question 5

Histone deacetylases (HDAC)

Answer 5

Whereas HATs add acetylation to histones and cause chromatin opening, HDAC removes acetylation causing gene repression. HDAC inhibitors are being used for cancer therapy by promoting tumor suppressor gene expression

Question 6

Proximal promoter elements

Answer 6

Proximal sequences either overlapping or before transcription start site that are binding sites for the basal transcription factors associated with RNA polymerase II

Question 7

Enhancer

Answer 7

Binding of transcription factor to enhancer causes transcriptional activation

Question 8

Silencer

Answer 8

Binding of transcription factor to a silencer causing transcriptional repression

Question 9

Coactivators

Answer 9

Recruited by transcriptional factors, they alter chromatin structure to make promoter more accessible. Recruit RNA polymerase II and its basal transcription factors

Question 10

Nuclear hormone receptors

Answer 10

Hormone regulated transcriptional activator proteins that bind DNA and activate transcription of target genes. Ex. Steroids

Question 11

Selective estrogen receptor modulators (SERM)

Answer 11

Synthetic compounds that bind to estrogen receptor; each inducing a different shape and causes receptor to activate a different set of genes

Question 12

Spliceosome

Answer 12

RNA protein complexes that mediate mRNA splicing

Question 13

GT-AG rule

Answer 13

There is a 5’ GU splice donor and 3’ AG splice acceptor. These are highly conserved and constitute the GT-AG rule that introns tend to begin and end with these sequences