Turning off the Signal

Question 1

Gene expression can be regulated at many times during ______________

Answer 1

protein synthesis

Question 2

At what 6 points can gene expression be regulated?

Answer 2

-transcription initiation
-RNA processing
-Stability of RNA molecule
-Protein synthesis
-Protein modificaition and transport
-Protein degradation

Question 3

How can mRNA be detected when expressing gene expression patterns

Answer 3

Using a complementary probe and a fluorescent tag, the probe will bind in a complementary way to the target mRNA

Question 4

What is in-situ hybridization?

Answer 4

Used to study expression of one or a few genes (ex. fruit fly embryo pictures)

Question 5

What is DNA microarray?

Answer 5

Technique used to analyze thousands of genes at once using base pair interactions of complementary strands in-vitro, usually using glass slides containing DNA

Question 6

What are oligonucleotides

Answer 6

Short fragments of nucleic acids

Question 7

Are all genes active at once?

Answer 7

No

Question 8

If a gene in a microarray is ______ it will produce _________ mRNA, and therefore _______ cDNA molecules will be available after reverse transcription

Answer 8

active, more, more

Question 9

_____________ can indicate how active a gene is

Answer 9

fluorescent intensity

Question 10

Gene expression level can be measured by the quantity of _____ produced

Answer 10

mRNA

Question 11

How is gene expression stopped?

Answer 11

mRNA must be degraded, one way is by length of poly-A tail

Question 12

Why do some genes get transcribed into mRNA but do not get translated?

Answer 12

Activation of RNA interfering machinery by microRNA

Question 13

What is microRNA

Answer 13

Short, noncoding, regulatory double stranded RNA molecules transcribed from protein encoding genes

Question 14

How is microRNA made

Answer 14

Protein encoding genes that form hairpin loops due to complimentary base pairing, which become smaller single stranded mRNA fragments

Question 15

How does microRNA contribute to RNA interference machinery

Answer 15

Activates it by being incorporaated as part of an RNA-induced silencing complex, which can inhibit translation due to complimentary sequences that target mRNA

Question 16

What are siRNAs

Answer 16

Not just exact mRNA complements; they bind to the complementary sequence by association with the RISC and induces cleavage of target RNA, which destabilizes the mRNA causing degradation

Question 17

What is selective degradation?

Answer 17

Limits the length of time a protein functions

Question 18

What are proteasomes?

Answer 18

Large protein complexes that can break peptide bonds and degrade unneeded/damaged proteins

Question 19

How are proteins selected for degradation?

Answer 19

Cells tag proteins with ubiquitin proteins using ATP, and facilitated by ubiquitin activation. Ubiquitin is then conjugated to the target protein.

Question 20

What happens within a proteasome?

Answer 20

The polyubiquitin chain-marked protein is unfolded and cleaved in the proteasome into smaller pieces, and ubiquitin is released