Unit 6, Topic 5: Regulation of Gene Expression

Question 1

a group of genes that can be turned on or off

Answer 1

operons

Question 2

where RNA polymerase can attach

Answer 2

promoter

Question 3

the on/off switch

Answer 3

operator

Question 4

operon that can be activated or repressed depending on cellular needs and the surrounding environment

Answer 4

inducible

Question 5

these affect cell differentiation by determining which regions of an embryo will form what structures.

Answer 5

cytoplasmic determinants

Question 6

substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed (inactive form)

Answer 6

allosteric inhibitor

Question 7

produces a repressor protein that binds to operator to block RNA polymerase from transcribing the gene (reversible)

Answer 7

regulatory gene

Question 8

substrate binds to allosteric site and stabilizes the shape of the enzyme so that the active sites remain open

Answer 8

allosteric activator

Question 9

sections of noncoding DNA that serve as binding sites

Answer 9

Control elements

Question 10

adds acetyl groups to histones, which loosen the DNA

Answer 10

Histone acetylation

Question 11

epigenetic modification that leads to gene silencing; commonly found in cancer cells

Answer 11

DNA methylation

Question 12

chromatin modifications do not alter the nucleotide sequence of the DNA, but they can be heritable to future generations

Answer 12

Epigenetic inheritance

Question 13

code for related enzymes in pathway

Answer 13

Gene

Question 14

cells become specialized in their structure and function

Answer 14

Differentiation

Question 15

the physical process that gives an organism its shape

Answer 15

Morphogenesis

Question 16

cell to cell signals that can cause a change in gene expression

Answer 16

induction

Question 17

map out the body structures

Answer 17

Homeotic genes

Question 18

programmed cell death in cases of harmful mutations

Answer 18

Apoptosis

Answer 19

Pattern Formation

Question 20

What are the three parts of an operon?

Answer 20

Promoter, operator, and the genes

Question 21

Differentiate between a repressible and inducible operon.

Answer 21

Repressible operon: transcription is usually turned on, but can be repressed or stopped.
Inducible operon: transcription is usually off, but can be induces or started.

Question 22

The trp operon is repressible/inducible.

Answer 22

repressible

trp is series of genes necessary to synthesize tryptophan

in prokaryotic cells

Question 23

If a bacterial cell uses up its tryptophan storage, what would happen to the trp operon?

Answer 23

The repressor would leave the operator and transcription can continue. The operon would turn on again and more tryptophan would be produced.

Question 24

If a bacterial cell does not need tryptophan and it builds up inside of the cell, what would happen to the trp operon?

Answer 24

The trp operon would be switched off. This means that tryptophan will bind to the repressor and temporarily shut off transcription of that gene.

Question 25

If a bacterial cell has a mutation to the trp repressor that changes the shape of the active site, how would this affect the production of tryptophan?

Answer 25

The production of tryptophan would be constant. Since the trp repressor has a differentially shaped active site, tryptophan would be unable to it and could not shut off transcription.

Question 26

The lac operon is repressible/inducible.

Answer 26

inducible | lac operon encodes genes required for processing and intake of lactose ## Footnote found in prokaryotes

Question 27

If a bacterial cell is grown in a nutrient rich, lactose free medium, what would you expect to see at the lac operon?

Answer 27

Is is expected that the lac repressor is bound to the operator, making it allosterically active. Transcription is OFF.

Question 28

on to off operon

Answer 28

repressible