13.3

Question 1

Gene expression 2: post transcriptional gene regulation

Answer 1

occurs during mRNA processing, mRNA transport, and translation
only occurs in eukaryotes

Question 2

export inhibition and regulation of translation initation

Answer 2

-export of mRNA from nucleus can be regulated
-regulation of translation initiation

Question 3

export of mRNA from nucleus can be regulated

Answer 3

-prevents translation of mRNA
-mechanism unknown
-only about 5% of mRNA is exported

Question 4

regulation of translation initation

Answer 4

-limit availability of proteins necessary to translation
-proteins bind to mRNA to prevent translation

Question 5

small RNAs regulate mRNA to knock down gene

Answer 5

micro RNA (miRNA)
small interfering RNA (siRNA)

Question 6

microRNA (miRNA)

Answer 6

single stranded RNA folds to form a small segment of double stranded RNA
-typically encdoed into the organisms genome

Question 7

small interfering RNA (siRNA)

Answer 7

derived from long segments of double stranded RNA
-can be endogenously produced by various mechanisms or introduced exogenously

Question 8

small RNAs regulate gene expression by preventing translation

Answer 8

1. double stranded RNA is processed into 22 nucleotide single stranded RNAs
2. small, single stranded RNAs complex with proteins to form RISC
3. small, single stranded RNA binds to complementary region on target mRNA
4. proteins in RISC block translation or degrade target mRNA

Question 9

RNA interference: small RNAs in research

Answer 9

-RNA interference (RNAi): the introduction of double stranded RNA into a organism to selectively knock down gene expression
-commonly used in:
nematodes
mice
fruit flies
mouse ear cess

Question 10

gene expression 3. post translational gene regulation protein modifcation

Answer 10

-proteins can be modified through addition of certain chemical group
–phosphate
–carbohydrates
–lipids

Question 11

gene expression 3. post translational gene degradtion

Answer 11

-proteins can be targeted for degradation by the addition of ubiquitin proteins
–called uboquitination
-ubiquinated proteins are targeted to the proteasome for degradation
–ubiquitin is not degraded

protien degradation removes unneeded proteins but also removes damaged or misfolded protiens

Question 12

regulation occurs at all stages of gene expression

Answer 12

transcriptional regulation
post transcriptional regulation
post translation regulation

Question 13

transcriptional regulation- what is transcribed

Answer 13

regulation by transcription factors, DNA accessibility

Question 14

post transcriptional regulation-what is translated

Answer 14

regulation by mRNA processing, translation inhibition

Question 15

post translation regulation- how does the protein function

Answer 15

regulation of protein stability, activity