Lecture IV - Control of Gene Expression

Question 1

What are Structural genes?

Answer 1

encoding proteins

Question 2

What are regulatory genes?

Answer 2

encoding products that interact with other sequences and affect the transcription and translation of these sequences

Question 3

What are regulatory elements?

Answer 3

DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences.

Question 4

What is Constitutive expression?

Answer 4

continuously expressed under normal cellular conditions

Question 5

What is positive control?

Answer 5

stimulate gene expression

Question 6

What is negative control?

Answer 6

Inhibit gene expression

Question 7

What are domains?

Answer 7

60-90 amino acids long, responsible for binding to DNA, forming hydrogen bonds with DNA.

Question 8

What is a Motif?

Answer 8

Within the binding domain, a simple structure that fits into the major groove of the DNA. There are distinctive types of DNA-binding proteins based on the motif. Examples include Helix-turn-helix, Zinc finger, leucine zipper, etc.

Question 9

How do amino acids in DNA-binding proteins interact with DNA?
A. By forming covalent bonds with DNA base
B. BY forming hydrogen bonds with DNA base
C. BY forming covalent bonds with sugars

Answer 9

B. By forming hydrogen bonds with DNA base

Question 10

What is an Operon? What does it consist of?

Answer 10

Consists of a.. promoter + additional sequences that control transcription (operator) + structural genes.. it is thought to regulate genes that control protein synthesis.

Question 11

What is a Regulator gene?

Answer 11

DNA sequence encoding products that affect the operon function but are not part of the operon. So they help to regulate the operon

Question 12

What is the difference between a structural gene and a regulator gene?
A. Structural genes are transcribed into mRNA, but regulator genes are not.
B. Structural genes have complex structures; regulator genes have simple functions
C. Structural genes encode proteins that function in the structure of the cell; regulator genes carry out control transcription of other genes.

Answer 12

C. Structural genes encode proteins that function in the structure of the cell; regulator genes control transcription of other genes.

Question 13

What are the three important ways that eukaryotic cells differ in gene regulation in comparison to bacterial cell?

Answer 13

1) Each structural gene has its own promoter and is transcribed separately
2) DNA must unwind from the histone proteins before transcription
3) Transcription and translation are separated in time and space.

Question 14

What is DNase I hypersensitivity?

Answer 14

DNase I hypersensitive sites have a more open chromatin configuration site, upstream of the transcription start site. Making them more sensitive to cleavage by the DNase I enzyme.

Question 15

What is histone modification?

Answer 15

Addition of methyl or acetyl groups to histone protein tails/histone proteins… This disrupts structure and allows some transcription factors to bind to DNA.

Question 16

What is Chromatin remodeling? Who carries out chromatin remodeling?

Answer 16

Done by chromatin-remodeling complexes that bind directly to DNA sites to reposition the nucleosome.

Question 17

What is CHIP?

Answer 17

Used to identify DNA-binding sites of a specific protein and the locations of modified histone proteins… Done by cross-linked DNA fragments associated with the proteins of interest. These proteins are selectively immunoprecipitated from the cell debris using an appropriate protein-specific antibody.

Question 18

These proteins bind to sites on DNA and stimulate transcription.

Answer 18

Transcriptional activator proteins

Question 19

Transcription is activated by GAL4 in response to what?

Answer 19

Galactose.

Question 20

Enhancers stimulate transcription and are blocked by?

Answer 20

Insulators

Question 21

(T/F) Transcription stimulation of a specific gene may require various proteins to bind upstream of the transcription start box. Including MREs, GREs, Enhancers, Etc

Answer 21

True

Question 22

Most transcription activator proteins affect transcription by interacting with? 
A. Introns
B. the basal transcription apparatus 
C. DNA polymerase
D. Nucleosomes

Answer 22

B. Basal transcription apparatus.

Usually located in the TATA box

Question 23

Alternative splicing can regulate?? This is significant because?

Answer 23

Gene function.

It can causes cancer, heart defects, developmental defects, etc.

Question 24

What is the function of microRNA (miRNA)?

Answer 24

RNA silencing and post-transcriptional regulation of gene expression.

Question 25

What can RNA silencing lead to?

Answer 25

degradation of mRNA or inhibition of translation or transcription.

Question 26

In RNA silencing, siRNAs and miRNAs usually bind to which part of the mRNA molecules that they control?
A. 5' UTR
B. the segment that encodes amino acids
C. 3' Poly (A) tail
D. 3; UTR

Answer 26

D. 3’ UTR

Question 27

If there is a lack of certain components required for translation what can happen to certain eukaryotic genes?

Answer 27

They will not be expressed.