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Question 1

Structural genes encode the enzymes themselves. The structural genes of an operon usually lie adjacent to one another, and RNA polymerase moves from one to the next, transcribing all of the genes into a single mRNA. An mRNA containing information for more than one polypeptide is called a polycistronic mRNA. The polycistronic mRNA is then translated into the various individual enzymes of the metabolic pathway.

Question 2

The operator typically resides adjacent to or overlaps with the _______________ (see Figure 12.4) and serves as the ____________ for a protein, usually a ____________.

Answer 2

promoter, binding site, repressor

Question 3

The promoter is the site where the

Answer 3

RNA polymerase binds to the DNA prior to beginning transcription (discussed in Section 11.1).

Question 4

The regulatory gene encodes the

Answer 4

repressor protein

Question 5

What type of gene codes for a repressor?

Answer 5

Regulatory

Question 6

The key to operon expression lies in the sequence of the

Answer 6

Operator and presense/absence of repressor

Question 7

What is an inducible operon’s default state?

Answer 7

Off

Question 8

What is a repressible operon’s default state?

Answer 8

On

Question 9

n a repressible operon, such as the tryptophan (or trp) operon, the repressor is unable to bind to the operator DNA by itself. Instead, the repressor is active as a DNA-binding protein only when complexed with a specific factor, such as tryptophan (Figure 12.3a), which functions as a corepressor.

Question 10

z gene, which encodes β-galactosidase;

Question 11

the y gene, which encodes galactoside permease, a protein that promotes entry of lactose into the cell; and

Question 12

the a gene, which encodes thiogalactoside transacetylase, an enzyme with a physiologic role that is unclear.

Question 13

Negative control

Answer 13

Inhibits gene expression

Question 14

Is the lac operon under - or + control?

Answer 14

Both- + is that glucose will be preferentially metabolized, and represses beta-gal production

Question 15

How does cAMP overcome effects of glucose (How does + control of lac operon work?)

Answer 15

Binds to CRP, which binds to control region of lac operon. DNA changes conformation, which means RNA pol can transcribe lac operon

Question 16

Attenuation

Answer 16

A feedback mechanism that controls transcription termination that controls the level of protein transcribed in accordance with the environment

Question 17

Riboswitches

Answer 17

mRNAs that undergo changes in folded conformations that let them alter gene expression involved in their own production

Question 18

What do histones do?

Answer 18

Package eukaryotic dna

Question 19

What are histones made of?

Answer 19

Arginine and lysine

Question 20

What types of histones are there?

Answer 20

H1, H2A/B, H3, H4

Question 21

Nucleosome structure

Answer 21

146 BP around 8 histones (2 of each except for 1 H1 on the outside

Question 22

Is hetero or euchromatin compacted during interphase?

Answer 22

Hetero

Question 23

Constitutive heterochromatin

Answer 23

Always compacted, never expressed (Like ends of telomeres)

Question 24

Facultative heterochromatin

Answer 24

Deactivated under certain circumstances

Question 25

Are all proteins expressed in the body at any given time?

Answer 25

No

Question 26

Transcriptional control mechanisms determine

Answer 26

if/when a gene can be transcribed

Question 27

Processing control mechanisms determine the path by which the primary mRNA transcript (pre-mRNA) is processed into a messenger RNA that can be translated into a polypeptide.

Question 28

Translational control mechanisms determine

Answer 28

if/how often/how long a particular mRNA actually translated

Question 29

Posttranslational control mechanisms regulate the

Answer 29

protein activity/stability

Question 30

differential gene transcription is a key mechanism by which

Answer 30

eukaryotic cells activate or repress gene expression

Question 31

Transcription factors

Answer 31

Proteins that control transcription of nearby genes

Question 32

general transcription factors that bind at core promoter sites in association with RNA polymerase (Section 11.4)

Question 33

sequence-specific transcription factors that bind to various regulatory sites of particular genes

Question 34

transcriptional activators that stimulate transcription of the adjacent gene or as

Question 35

transcriptional repressors that inhibit transcription of anadjacent gene

Question 36

How many transcription factors can a gene be controlled by? How many places can a transcription factor work?

Answer 36

Many, many

Question 37

What domains are present in transcription factors?

Answer 37

DNA binding and activation (regulates transcription by acting with other proteins

Question 38

Is there one or multiple shapes a DNA binding region can take?

Answer 38

Multiple

Question 39

What are some shapes a DNA binding region can take?

Answer 39

Zinc finger (Zinc ion between 2 cysteines and histidines), helix loop helix (helixes separated by alpha loop)

Question 40

enhancer

Answer 40

Regulatory site that lies up/downstream to promoter, usually with multiple binding sites that work with transcriptional factors to control transcription

Question 41

How do enhancers stimulate transcription?

Answer 41

Influencing core promoter eventsh

Question 42

How do we know promoters work with correct enhancers?

Answer 42

Insulators

Question 43

How do activators bound to enhancers stimulate transcription at promoter?

Answer 43

Coactivators

Question 44

What do coactivators do?

Answer 44

Interact with components of basal transcription machinery (gen transcription factors/RNA polymerase) or chromatin- turn it from inaccessible to something that can be transcribed

Question 45

How do nonhistone proteins interact with DNA wrapped around core histones

Answer 45

Histones are acylated by histone acetyltransferases and moved away from active genes

Question 46

Chromatin remodelling complex

Answer 46

Alter/move nucleosomes by energy from ATP hydrolysis

Question 47

Histone deacetylases

Answer 47

Remove histones, repressing transcription

Question 48

How do lncRNAs repress transcription?

Answer 48

act as scaffolds to hold protein complexes in close association to specific target sites in the genome, where they can carry out their chromatin-modifying function, which can be affected if they're deactivated