Ch 15 Regulation Of Gene Expression

Question 1

In operon, where does RNA polymerase bind

Answer 1

Promoter Regino of the DNA

Question 2

What does the lac operon produce when the repressor is inactive

Answer 2

Lactase

Question 3

The Trp operon is a ____ operon and is example of ___ genes

Answer 3

Repressible, negative

Question 4

What is the natural state of Trp operon and in what from is its repressor synthesized

Answer 4

ON, inactive

Question 5

When does cAMP accumulate in the cell?

Answer 5

When glucose is scarce

Question 6

The on off switch is a segment of DNA called

Answer 6

Operator

Question 7

Genes whose expression is turned off in response to a substance in the environment are

Answer 7

Repressible genes ( on by default)

Question 8

Genes whose expression is turned on in response to a substance in the environment are known as

Answer 8

Inducible genes (off by default)

Question 9

What is the name of the stethoscope of DNA where RNA polymerase binds?

Answer 9

Promoter

Question 10

What is the name given to a protein that binds to the operator and blocks RNA polymerase

Answer 10

Repressor

Question 11

In addition to responding to the presence or the absence of lactose, the lac operon is also sensitive to glucose levels. In the presence of high amounts of glucose

Answer 11

cAMP is produced and attaches to the CAP protein allowing it to bind to the CAP site resulting in high levels of gene expression

Question 12

In addition to responding to the presence or absence of lactose, the lac operon is also sensitive to glucose levels in the presence of low amounts of glucose

Answer 12

No cAMP is made an the CAP protein will not bind to the CAP site, leading to low levels of gene expression

Question 13

A geneticist isolates a gene for the trait X in mice. He also isolates the corresponding mRNA derived from this mouse gene. He notices that the mRNA contains 1,535 less nucleotide bases than the DNA isolate. Did the geneticist isolate the wrong segment of DNA?

Answer 13

No the final mRNA contains only exons. The introns were removed during mRNA splicing

Question 14

Key components of an operon

Answer 14

-promoter: site where RNA pol can bind
* Operator : repressor proteins bind to regulate transcription
* structural genes: genes within the operon that code for the desired proteins

Question 15

Guide RNA

Answer 15

Guide RNA: sequence which acts as a GPS guiding Cas9 enzyme to specific location. Change an organisms DNA: first select which DNA sequence you’d like to modify, synthesize guide RNA with a sequence complements to the target DNA, take guide RNA and Cas9 into organisms cells, Cas9 then uses guide RNA to find where its needed to cut into the DNA sequence which then the enzyme cuts the DNA at specific site creating a double strand break - this process is called CRISPR - Cas9 gene editing

Question 16

What’s cas9, its function, how its used for cell defense

Answer 16

Produced by CRISPR, Cas 9 is a type of enzyme which binds to the DNA and after cuts off the specific regions of DNA. It’s useful bc it can create a site specific DNA which helps develop an adaptive immune resistance to viruses.

Question 17

Difference between prokaryotes and eukaryotes gene regulation

Answer 17

Eukaryotes have a nucleus whch makes the processes of transcription and translation separate, resulting in control of gene expression at multiple levels when prokaryotes where regulation mostly happens at transcription level bc lack of nucleus and free floating DNA in cytoplasm

Question 18

Transcription factors in prokaryotes and eukaryotes

Answer 18

Transcription factors - Prokaryotes: use sigma factors ( specific proteins that guide RNA pol to promoter) regulations involve repressors and activators that bind near the promoter. Lacks general transcription factors. Eukaryotes: use general transcription factors like TFID, TFIIB to assemble at promoter and form the transcription initiation complex

Question 19

Co -Activators andd mediators

Answer 19

Co -Activators andd mediators - prokaryotes: rarely use it, transcription regulation is relatively direct, with proteins interacting closely with RNA polymerase
Eukaryotes: Involve co activators and the mediator complex, which bridge specific transcription factors and RNA pol2 facilitating transcription initiation