Final - Lecture 15

Question 1

Gene regulation involves:

Answer 1

mRNA and protein synthesis

Question 2

activator and repressor molecules are:

Answer 2

regulatory proteins that bind to DNA and either activate or repress transcription

Question 3

soluble regulators that act on both copies of the gene are also called:

Answer 3

trans acting

Question 4

regulators that are part of the genetic sequence will only act on that the copy that contains the fragment:

Answer 4

also called cis acting

Question 5

the enzyme __ breaks down lactose

Answer 5

B-galactosidase

Question 6

B-galactosidase is only required when:

Answer 6

lactose is present as a carbon source of energy

Question 7

Jacque Monod observed that bacteria:

Answer 7

would finish all the glucose before resorting to metabolizing lactose

Question 8

The gene for galactosidase only turns PN in the presence of

Answer 8

lactose

Question 9

Lactose acts as a positive/negative regulator in the context of the lac operon.

Answer 9

Positive

Question 10

Lactose-sensing activator will be inhibited by

Answer 10

glucose

Question 11

No activation in presence of
__, only in the presence of ___

Answer 11

No activation in the presence of glucose, only in the presence of lactose

Question 12

repressor is inhibited by:

Answer 12

lactose

Question 13

Presence of lactose and glucose will result in:

Answer 13

An active (i.e non inhibited) repressor

Question 14

If the ___ is inhibited,
lactose will be used for metabolism

Answer 14

repressor

Question 16

In order to assess whether mutations
were dominant or recessive (recall that
the organism is haploid), Monod used

Answer 16

meriploids

Question 17

meriploids

Answer 17

one copy of the operon is in
the bacterial chromosome,and the
other is in an F’ episome.

Question 18

structural genes: Z:

Answer 18

B-galactosidase
An enzyme that cleaves lactose into glucose and galactose

Question 19

structural genes: Y:

Answer 19

lactose permease – facilitates
lactose uptake into the cell

Question 20

Structural genes A:

Answer 20

transacetylase - is not essential to
lactose metabolism

Question 21

How many structural genes?

Answer 21

3:
Z: B galactosidase
Y: lactose permease
A: transacetylase: is not essential to lactose metabolism

Question 22

How many regulatory elements?

Answer 22

4

Question 23

regulatory elements:

Answer 23

Allolactose - inducer
Lacl - repressor
Promoter region
Operator region

Question 24

Lacl :

Answer 24

Binds to the operator site and blocks transcription

Question 25

allolactose is an:

Answer 25

inducer

Question 26

lactose will generate allolactose (inducer), which :

Answer 26

binds to the repressor and prevents binding to the operator region,
This will allow transcription to take place

Question 27

When allolactose binds to the repressor, it does so at a different site than:

Answer 27

its DNA binding site

Question 28

binding with allolactose will cause:

Answer 28

a conformational change in the repressor which will deform the DNA binding site

Question 29

IPTG mimics:

Answer 29

allolactose

Question 30

IPTG is :

Answer 30

a synthetic analog of allolactose used in experimental settings

Question 31

besides IPTF, what are other analogs of allolactose?

Answer 31

other analogs include OPTG, and X-gal

Question 32

What is special about X-gal

Answer 32

it is blue when cleaved, signalling B-galactosidase activity

Question 33

Lacl will bind to:

Answer 33

the operator region

Question 34

lacl mutations are:

Answer 34

transacting

Question 35

I - mutations:

Answer 35

cannot bind to the operator region

Question 36

I+ binds to:

Answer 36

the operator region

Question 37

I+ are __ to I- alleles

Answer 37

I+ alleles are dominant to I- alleles, and they are expressed ONLY when there is lactose in the system

Question 38

Is mutations are

Answer 38

dominant over I+ and I-

Question 39

Is mutations (also called super - repressor mutations):

Answer 39

cannot bind allolactose –> never “off”

Question 40

Lacl binds to :

Answer 40

the operator region: so mutations in the operator region will change binding interactions with the repressor

Question 41

Lacl mutations are __ to operator mutations

Answer 41

Lacl mutations are recessive to operator mutations

Question 42

OC mutations are __ acting

Answer 42

cis

Question 43

OC mutations are __ to I+

Answer 43

OC mutations are dominant to I+

Question 44

RNA polymerase binds to

Answer 44

the promoter
region

Question 45

mutations in the promoter region will
result in

Answer 45

no binding to RNA polymerase,meaning the operon will be functionally off

Question 46

P mutations are

Answer 46

cis-acting