Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Drew 912 > Block 4 -- Regulation of Gene Expression > Flashcards

Block 4 -- Regulation of Gene Expression Flashcards

1
Q

What is the purpose of gene expression regulation?

A

1) energy conservation
2) environmental adaptation
3) regulation of development & differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 2 control sites?

A

Promoter

Operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the z gene encode in the lac operon?

A

beta-galactosidase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Function of beta-galactosidase?

A

lactose –> glucose + galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the y gene encode in the lac operon?

A

galactosidase permease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of galactosidase permease?

A

allows entry of lactose into cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the a gene encode in the lac operon?

A

Thiogalactosidase transacetylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of thiogalactosidase transacetylase?

A

not sure!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What gene encodes the repressor in the lac operon?

A

lac i

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the inducer in the lac operon?

A

allolactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the function of the regulator gene in the lac operon?

A

encodes the trans-acting factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

define polycistronic mRNA.

A

mRNA that encodes for many proteins, present in eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where does CRP/cAMP complex bind?

A

regulatory region of promoter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the function of CRP/cAMP?

A

stimulate the binding of RNAP by bending DNA to provide an additional site for RNAP interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what does CRP/CAP stand for?

A
    • cAMP repressor protein

- - catabolite activator protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is glucose preferred by prokaryotes?

A

It is the normal carbon source for amino acids, although lactose may be used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

If LacI repressor and CRP/cAMP are both present, what happens?

A

No transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does the trp operon encode?

A

Enzymes for—

chorismate –> tryptophan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What concepts of gene regulation does the trp Operon use?

A

1) co-repression

2) attenuation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What concepts of gene regulation does the lac operon use?

A

Catabolite repression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the components in co-repression for trp operon?

A

1) repressor

2) co-repressor = trp

22
Q

What is the function of the co-repression complex in the trp operon?

A

Works to reduce transcription rate

23
Q

Describe the structure of the trp operon.

A

1) trpR
2) Control (P, O)
3) trpL
4) trpE, D, C, B, A

24
Q

What does trpR encode?

A

The repressor protein

25
What is the function of the leader?
encodes an mRNA leader that controls whether operon is transcribed (includes attenuator)
26
What domains pair under low trp levels? High?
Low--2&3 | High--3-4 (Rho-independent RNAP termination)
27
Define attenuation.
The interruption of transcription
28
What is heterochromatin?
Nonexpressed DNA (e.g. X chromosome in female mammals)
29
What is euchromatin?
Transcriptionally active DNA
30
What are types of gene expression controls in DNA?
1) G/C methylation to silence the TATA box 2) Gene loss or amplification 3) Gene rearrangement
31
Describe deregulation at the DNA level.
Gene rearrangement (e.g. B cell recombination)
32
What DNA sequences encode for a variable antibody chain?
1 D_H, V_H, J_H
33
What regions are present on trans-acting factors?
1) DNA binding domain | 2) Activation domain
34
What is the function of the DNA binding domain in a trans-acting factor?
recognition of DNA sequence
35
What motif(s) are present in the DNA binding domain of trans-acting factors
1) Zn fingers | 2) Helix-turn-helix
36
What is the function of the activation domain in a trans-acting factor?
Allows assembly of transcription complex at the TATA box.
37
What motif(s) are present in the activation domain of trans-acting factors?
1) Leucine Zippers
38
Where are Zinc fingers commonly found?
in the DNA binding domain of steroid hormone receptors
39
Describe the structure of the Zn finger motif.
- - 2 cysteines + 2 histidines chelated to a Zn ion - - 20 residue repeat - - each looks like a finger
40
Describe the structure of the leucine zipper motif.
- - Dimerized helices via hydrophobic interactions form a coiled coil - - 30-40 residue alpha-helix - - Leu every 7th residue - - Portion of dimer grips DNA at **basic** residues
41
How do gene-specific activating proteins work?
1) bind DNA - ----or------ 2) are co-activating proteins with enzymatic activity - - eg histone (de)acetylase - - bind trans-acting factors
42
How do steroid hormones & growth factors increase transcription rate of certain genes?
2nd messenger system - - cAMP - - kinases pass signal from membrane to nucleus
43
Define epigenetic regulation.
Regulation of gene expression without changing DNA sequence
44
What are methods of epigenetic regulation?
1) Cytosine methylation in CpG islands | 2) Histone methylation & acetylation
45
How does methylation of cytosines in CpG islands work, and when is it important?
Reduce transcription - - globin genes in non-RBCs - - gene expression in development
46
Does histone methylation increase or reduce transcription rate?
reduce
47
What is an example of post-transcriptional processing?
B Apoliprotein (liver & intestinal isoforms) - - component of lipoproteins - - intestinal is longer (C --> U) - - Stop codon formed
48
What are types of post-transcriptional processing?
1) RNA editing | 2) mRNA transport
49
Functions of miRNA?
bind dsDNA to tag for degradation | inhibit translation
50
What is the function of the 3' Poly(A) tail?
Increase stability of mRNA | -- reduce effect of nuclease attack
51
How is mRNA protected during transport?
bound to proteins to prevent nuclease degradation
52
How does the transferrin receptor up-regulate when [Fe] is low?
- - IRE-BP binds hairpin loop of mRNA for the receptor at 3' end - - Prevents degradation - - Higher affinity when [Fe] is low

Drew 912 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions