Ch 12 Control of Gene Expression

Question 1

gene regulation

Answer 1

encompasses the mechanisms and systems that control the expression of genes, is critical for the control of numerous life processes in all organisms

Question 2

structural genes

Answer 2

encode proteins that are used in metabolism or biosynthesis or that play a structural role in the cell

Question 3

regulatory genes

Answer 3

the products of these, either RNA or proteins, interact with other DNA sequences and affect the transcription or translation of those sequences

Question 4

constitutive

Answer 4

a few structural genes, particularly those that encode essential cellular functions are expressed continually
these are not regulated

Question 5

regulatory elements

Answer 5

DNA sequences that are not transcribed at all
affect the expression of DNA sequences to which they are physically linked
common in both bacterial and eukaryotic cells and much of gene regulation in both types of organisms takes place through the action of proteins produced by regulatory genes that recognize and bind to regulatory elements

Question 6

two processes play a role in gene regulation

Answer 6

DNA methylation and changes in chromatin

Question 7

operon

Answer 7

a group of bacterial structural genes that are transcribed together, along with their promoter and additional sequences that control their transcription

Question 8

regulator gene

Answer 8

helps to control the expression of the structural genes of the operon by increasing or decreasing their transcription

Question 9

regulator protein

Answer 9

the regulator gene has its own promoter and is transcribed into a short mRNA which binds to a region of the operon called the operator and affect whether transcription can take place

Question 10

negative control

Answer 10

a regulatory protein is a repressor, binding to DNA and inhibiting transcription

Question 11

positive control

Answer 11

a regulatory protein is an activator, stimulating transcription

Question 12

inducible operons

Answer 12

those in which transcription is normally off (not taking place)

Question 13

repressible operons

Answer 13

those in which transcription is normally on (taking place)

Question 14

inducer

Answer 14

transcription is turned on when a small molecule binds to the repressor

Question 15

allosteric proteins

Answer 15

proteins which change shape upon binding to another molecule

Question 16

corepressor

Answer 16

a small molecule that binds to the repressor and makes it capable of binding to the operator

Question 17

coordinate induction

Answer 17

stimulation of the simultaneous synthesis of several proteins by a specific molecule, the inducer

Question 18

lacZ gene

Answer 18

encodes B-galactosidase

Question 19

lacY gene

Answer 19

encodes permease

Question 20

lacA gene

Answer 20

encodes thiogalactoside transacetylase

Question 21

partial diploid

Answer 21

the cells of these strains possessed two different DNA molecules: the full bacterial chromosome and an extra piece of DNA

Question 22

constitutive mutations

Answer 22

causing the lac proteins to be produced all the time, whether lactose was present or not

Question 23

superrepressors

Answer 23

mutations that produced defective repressors that could not be inactivated by an inducer

Question 24

catabolite repression

Answer 24

when glucose is available, genes that participate in the metabolism of other sugars are repressed through a process known as this
results from positive control in response to glucose

Question 25

catabolite activator protein (CAP)

Answer 25

positive control is accomplished through the binding of this protein to a site about 22 nucleotides long that is located within or slightly upstream of the promoter of the lac genes

Question 26

adenosine-3’,5’-cyclic monophosphate (cyclic AMP, or cAMP)

Answer 26

before CAP can bind to DNA, it must form a complex with this modified nucleotide which is important in cellular signaling processes in both bacterial and eukaryotic cells