Topic 11

Question 1

Operant

Answer 1

Cluster of prokaryotic genes and DNA sequences involved in their regulation

Question 2

3 Prokaryotic Regulatory Sequences

Answer 2

1. Operator
2. Repressor
3. Activator

Question 3

3 lac Operon genes for Lactose Metabolism:

Answer 3

1. lac Z
2. lac Y
3. lac A

Question 4

What and how does it stop lac operon expression?

Answer 4

lac repressor encoded by lac I, binds operator to prevent transcription

Question 5

Allolactose

Answer 5

Isomer of lactose, deactivates repressor protein

Question 6

What enzyme does lac I make?

Answer 6

Repressor protein

Question 7

What happens to an operon when there is no lactose present?

Answer 7

Lac I makes repressor protein that restricts RNA polymerase from making mRNA

Question 8

What happens to an operon when there is lactose present?

Answer 8

Lac I makes repressor protein but it is blocked by allolactose so transcription occurs

Question 9

Positive Regulation of lac Operon

Answer 9

Degree of transcription depends on the concentration of other substrates

Question 10

Where does the repressor bind on a lac operon?

Answer 10

Operator

Question 11

What happens to an operon when there is no glucose present?

Answer 11

Repressor is still inactive, glucose metabolisms stimulates adenylyl cyclase with then make cAMP which then binds to the CAP activating it. CAP binds to promoter and transcription happens.

Question 12

What happens to an operon when there is glucose present?

Answer 12

Repressor is still inactive, no glucose metabolisms keeps adenylyl cyclase from not making cAMP. CAP can not bind to promoter and transcription does not happen.

Question 13

trp Operon Genes

Answer 13

Genes that code for the production of tryptophan

Question 14

Tryptophan (trp)

Answer 14

Amino acid needed for protein synthesis in prokaryotes

Question 15

Corepressor

Answer 15

molecule that represses the expression of genes

Question 16

trp is a type of……

Answer 16

Corepressor

Question 17

What are the genes in a trp operon?

Answer 17

1. trpE
2. trpD
3. trpC
4. trpB
5. trpA

Question 18

What happens to an operon when there is no trp present?

Answer 18

trpR gene makes trp repressor that is not activated so RNA polymerase binds to promoter and transcription happens.

Question 19

What happens to an operon when there is trp present?

Answer 19

trpR gene makes trp repressor that is activated by binding of trp. RNA polymerase can not bind to promoter and transcription does not happen.

Question 20

What does trpR code for?

Answer 20

Trp repressor

Question 21

What do the genes in the trp operon code for?

Answer 21

Trp enzymes

Question 22

Transcription in lac Operon without lactose

Answer 22

No transcription

Question 23

Transcription in lac Operon with lactose

Answer 23

Yes transcription

Question 24

Transcription in lac Operon without glucose

Answer 24

Yes transcription

Question 25

Transcription in lac Operon with glucose

Answer 25

No transcription

Question 26

Transcription in trp Operon without trp

Answer 26

Yes transcription

Question 27

Transcription in trp Operon with trp

Answer 27

No transcription

Question 28

Hererochromatin

Answer 28

Densely packed areas are inactivated

Question 29

Euchromatin

Answer 29

Loosely packed areas are being transcribed

Question 30

Euchromatin

Answer 30

Loosely packed areas are being transcribed

Question 31

Regulatory Points in Eukaryotes

Answer 31

1. Chromatin has his tones 2. Different types of cells 3. Different compartments

Question 32

TATA Box

Answer 32

Kind of promoter needed to begin eukaryotic transcription

Question 33

Enhancers

Answer 33

Tight cluster of regulatory binding sites that can affect long distances at either upstream or down stream of the gene

Question 34

4 Levels of Regulated Expression

Answer 34

1. Transcriptional 2. Post - Transcriptional 3. Translational 4. Post - Translational

Question 35

Activators

Answer 35

Bind to promoter proximal elements and stimulate transcription initiation

Question 36

DNA Methylation

Answer 36

Add -CH3 to cytosine to silence a specific gene

Question 37

Genomic Imprinting

Answer 37

Permanent silencing of a maternal or paternal allele

Question 38

Non-coding RNA (ncRNA)

Answer 38

Functional RNA molecule that is transcribed from DNA, but not translated into proteins

Question 39

What is miRNA? What can it do?

Answer 39

It is ncRNA 1. Degrade mRNA 2. Block ribosomes

Question 40

Protein Degradation

Answer 40

Proteins marked with ubiquitin are broken down by proteasomes

Question 41

Proteasomes

Answer 41

Complex that breaks down protein tagged with ubiquitin