Regulation of Gene Expression

Question 1

Operon

Answer 1

entire stretch of DNA that includes the operator (switch), the promoter, and the gens they control

Question 2

Repressor

Answer 2

protein that binds to operator - blocks RNA polymerase attachement

Question 3

Trytophan

Answer 3

corepressor activates the repressor
the activated repressor binds to the operator, turns of transcription
so: no tryptophan = the repressor is inactive and the RNA polymerase moves through the operator

Question 4

Repressible

Answer 4

can turn it off to regulate

Question 5

Inducible

Answer 5

can turn it on to regulate

Question 6

inducer enzymes usually function in…

Answer 6

catabolic pathways, their synthesis is induced by a chemical signal

Question 7

repressible enzymes usually found in…

Answer 7

anabolic pathways, their synthesis is repressed by high levels of the end product

Question 8

trp

Answer 8

repressible: need to produce tryptophan, presence of the thing needing to be made represses production of enzymes

Question 9

lac

Answer 9

inducible: need to breakdown lactose, presence of thing needing to be broken down induces product of enzymes

Question 10

altering the availability of DNA for transcription

Answer 10

improve access:
- add acetyl group (histone acetylation promotes transcription)
decrease access:
- Methylation ( blocks access)

Question 11

epigenetic inheritance

Answer 11

the inheritance of traits transmitted by mechanisms not directly involving nucleotide sequences

Question 12

Control Elements

Answer 12

segments of noncoding DNA that serve as binding sites for transcription factors that help regulate transcription

Question 13

RNA interference (RNAi)

Answer 13

small noncoding RNA segments block expressions, turning off genes

Question 14

Small interfering RNAs (siRNA)

Answer 14

attach to mRNA, block expression, turning off genes specifically - very specific

Question 15

MicroRNAs (miRNA)

Answer 15

small single stranded RNA molecules that can bind to complementary mRNA sequences (can block its translations or cause degradation of DNA)

Question 16

Reverse Transcriptase

Answer 16

an enzyme that adds nucleotides complementary to an RNA parent strand -> results in cDNA

Question 17

In situ hybridization

Answer 17

in the living organism

Question 18

nucleic acid hybridization

Answer 18

the base pairing of a strand of nucleic acid to its complementary sequence

Question 19

nucleic acid probe

Answer 19

complementary molecule in this case is short single-stranded DNA or RNA