Controlling Gene Expression

Question 1

What is epigenetics?

Answer 1

focuses on changes in gene expression that are not due to changes in DNA sequences, but are either hereditable or have long-term effect

Question 2

What are the three most commonly studied areas in epigenetics?

Answer 2

DNA methylation
chromatin remodeling
RNA interference

Question 3

What is the main function of DNA methylation in prokaryotes?

Answer 3

control gene expression by either promoting or inhibiting transcription

Question 4

What are the two ways DNA methylation turns of gene expression in eukaryotes?

Answer 4

1. methylation physically blocks the gene from transcriptional proteins
2. certain proteins bind methylated CpG groups and recruit chromatin remodeling proteins that change the winding of DNA around histones

Question 5

What is gene dose?

Answer 5

increasing gene expression by gene amplification

Question 6

What is genomic imprinting?

Answer 6

when only one allele of a gene is expressed

Question 7

What is the primary method of regulation of gene expression in prokaryotes?

Answer 7

regulation of transcription

Question 8

What does it mean to be repressible in regards to transcription regulation?

Answer 8

anabolic enzymes whose transcription is inhibited in the presence of excess amount of product

Question 9

What does it mean to be an inducible enzyme in regards to transcription regulation?

Answer 9

catabolic enzymes whose transcription can be stimulated by the abundance of a substrate

Question 10

What are the components of the lac operon?

Answer 10

P region = promotor site
O region = operator site
Z gene = codes for enzyme beta-galactosidase
Y gene = codes for permease
A gene = codes for transacetylase

Question 11

What is the crp gene of the lac operon?

Answer 11

gene codes for a catabolite activator protein and helps couple the lac operon to glucose levels in the cell

Question 12

What is the I gene of the lac operon?

Answer 12

gene codes for the lac repressor protein

Question 13

Where does most of the regulation of gene expression occur in eukaryotes?

Answer 13

initiation of transcription

Question 14

What are UCEs?

Answer 14

upstream control elements; upstream of the initiation site and is a core promoter containing binding sites for the basal transcription complex and RNA poly II and the TATA box

Question 15

What are activator proteins in regards to gene regulation in eukaryotes?

Answer 15

transcriptional regulation; enzymes that bind to enhancer sequences in DNA

Question 16

What are gene repressor proteins in regards to gene regulation in eukaryotes?

Answer 16

inhibit transcription

Question 17

What is RNA transclocation?

Answer 17

process by which mRNA is translationally silent until it has been exported from the nucleus to the its correct location in the cytoplasm

Question 18

What is mRNA surveillance?

Answer 18

cells closely monitor mRNA moelcules to ensure that only high quality mRNA transcripts are read by the ribosome

Question 19

What is RNA interference?

Answer 19

method to silence gene expression after a transcript has been made; mediated by miRNA and siRNA