Ch 18 Genetic and Epigenetic Regulation

Question 1

What is Epigenetics?

Answer 1

Changes in expression in a gene or get of genes without a change in the DNA sequence

Question 2

DNA Methylation of Cytosine

Answer 2

CPG islands if CG sequences (found in promoter sequences). When the C is methylated it inactivates transcription. Unmethylated is when transcription is on.

Question 3

What is a promoter?

Answer 3

Sequence of DNA where DNA polymerase binds at the 5’ end.

Question 4

What are the effects of DNA Methylation?

Answer 4

The methylated DNA attracts repressor proteins that inhibits translation. Mis-regulation is cancerous and in oncogenes and tumor suppressors

Question 5

Chromatin remodeling

Answer 5

Acetylation of histones modifies nucleosomes to make DNA more accessible and increase transcription. When de- acylated transcription is blocked as dna is less accessible.

Question 6

Why does x-Chromosome inactivation occur in females?

Answer 6

They have the ability to produce twice as much protein for x-linked genes. So to regulate this an X chromosome is inactivated allowing equal dosage of expressed X chromosome in males and females

Question 7

Xist in X chromosome inactivation center

Answer 7

1. The list gene is transcribed and spliced and exist noncoding RNA bings with the x-chromosome INACTIVATION center.Transcription is then allowed to continue and the x-chromosome becomes coated with Xist RNA-the presence of this triggers dna methylation to reduce transcription

Question 8

Random x chromosome inactivation

Answer 8

Will turn one allele off so only one shows

Question 9

Regulatory transcription factors

Answer 9

Promoter sequences and enhancer/silencer sequences

Question 10

Why are transcription factors and polymerase needed in transcription?

Answer 10

to recognize promoter sequences

Question 11

What is a common example of a promoter sequence?

Answer 11

The TATA box

Question 12

WHY the TATA box?

Answer 12

Dna denaturation begins here, and T and A are easier to pull apart because only they only have two bonds

Question 13

What must assemble on the chromosome before RNA polymerase can bind to the promoter?

Answer 13

General Transcription factors

Question 14

What three things form the Transcription complex

Answer 14

TFIID binding to the TATA box and other transcription factors

Question 15

What is the point in the transcription complex?

Answer 15

to bring in RNA polymerase

Question 16

What is the point in the promoters, Tata box, TFIID?

Answer 16

To initiate transcription in Eukaryotes

Question 17

An enhancer is what type of regulator?

Answer 17

Positive

Question 18

An silencer is what type of regulator?

Answer 18

Negative

Question 19

When can multiple genes be regulated at the same time?

Answer 19

When the genes share the same regulatory sequences which bind to the same transcription factor.

Question 20

What is an example of multiple genes being regulated at the same time?

Answer 20

The SRE stressor gene- a stressor activates transcription of regulatory protein producing stress proteins instead of normal ones

Question 21

What is RNA editing?

Answer 21

When RNA made in the cell is changed by an enzyme. The enzyme changes the base sequence of the primary therefore changing the protein it encodes for. Ex- C to U

Question 22

What regulated transcription?

Answer 22

Promoters, T.F, enhancers, and silencers

Question 23

what regulates Translations?

Answer 23

Micro Rnas (MiRNA) which are regulator RNA

Question 24

What does miRNA do?

Answer 24

Binds to 3’ UTR to target mRNA and translation is inhibited

Question 25

what is a risk complex?

Answer 25

RNA induced silencer complex

Question 26

How does miRNA and the RISC complex regulate translation?

Answer 26

miRNA binds to the RISC complex and targets mRNA sequences to inhibit translation (regulating it)

Question 27

What does a repressor do?

Answer 27

Whenever the repressor is bound it prevents translation

Question 28

What are proteins tagged for breakdown tagged with?

Answer 28

A small protein called Ubiquitin that bind to a proteasome complex or where the protein is digested

Question 29

What two ways can the rate of metabolic pathways be regulated?

Answer 29

Time and amount

Question 30

Negative feedback is when…

Answer 30

there is more than enough so the pathway is shut off so their is no more enzyme creation

Question 31

What does proper gene expression depend on?

Answer 31

promoter and transcription factors binding to enhancers

Question 32

What is expression from one specific gene is prokaryotes controlled by?

Answer 32

One repressor protein (when the gene is transcribed but not translated due to binding of the repressor) or activator protein (when the gene is not even transcribed until the activator protein binds)

Question 33

Positive Transcription

Answer 33

Transcription only occurs when the activator binds

Question 34

Negative transcription

Answer 34

Stops transcription when bound an example is the LAC Operon

Question 35

What is an Operon?

Answer 35

a cluster of genes with a single promoter

Question 36

What does a typical operon consist of?

Answer 36

consists of a promoter, coding genes, and an operator which binds a repressor protein to block transcription

Question 37

In the absence of Lactose

Answer 37

repressor binds to operator and prevents transcription

Question 38

In the presence of Lactose

Answer 38

the repressor changes shape and transcription can occur