Chapter 17

Question 1

Eukaryotic Gene Regulation

Answer 1

• Each gene has its own promoter and is transcribed separately
• DNA MUST unwind from the histone proteins (wrapped around the DNA) before transcription
• transcription and translation are separated in TIME and SPACE

Question 2

DNase I hypersensitivity

Answer 2

Hypersensitive sites: more open chromatin configuration site, upstream of the transcription start
site

Question 3

Histone Modificaiton

Answer 3

− Addition of methyl groups to the histone protein tails
− Depending on which area is methylation – either activation or repression
- Addition of acetyl groups to histone proteins
− Associated with activation
Modifies the expression of the genes

Question 4

DNase 1 function

Answer 4

Unwinds DNA

Question 5

Chromatin remodeling complexes

Answer 5

Remodeling by repositioning the nucleosomes, initiating transcription because physically moving the nucleosome exposes the binding site (promoters) for transcription factors and RNA polymerase to bind

Question 6

Nucleosomes

Answer 6

A length of DNA coiled around a core histone (protein wrapped around DNA)
The structure made up of histone and the DNA wrapped

Question 7

DNA

Answer 7

• electronegative due to phosphate and backbones

Question 8

Histones

Answer 8

Electropositive
Protein that wraps around DNA
Making them MORE electropositive —> tightens DNA around it —> DECREASING TRANSCRIPTION because it is more tightly bound and unable to transcribe (and vise versa)

Question 9

Acetylation of histone proteins

Answer 9

Alters chromatin structure and permits some transcription factors to bind to DNA

Question 10

Chromatin Remodeling

Answer 10

Chromatin-remodeling complexes: bind directly to DNA sites and reposition nucleosomes
DNA methylation

Question 11

DNA Methylation

Answer 11

Methylation of cytosine bases adjacent to guanine nucleotides (CpG) “CpG islands”

Question 12

Chromatin Immunoprecipitation Sequencing

Answer 12

Used to identify DNA binding sites of specific protein and the locations of modified histones proteins

Question 13

Transcription Factors

Answer 13

Stimulate and stabilize basal transcription apparatus at core promoter
Mediator

Question 14

Enhancers

Answer 14

DNA sequence stimulating transcription at a distance away from the promoter
DNA loops over and activating transcriptase apparatus

Question 15

Silencers

Answer 15

DNA sequence with an inhibitory effect on the transcription of distant genes
Position and orientation independent, have binding sites for T.F.s to decrease transcription

Question 16

Insulator

Answer 16

DNA Sequence that blocks or “insulates” the effect of enhancers by looping DNA sequences together
Creates its own neighborhood, pinched off, stopping the effects of other enhancers for

Question 17

Regulation of Transcriptional Stalling and Elongation

Answer 17

RNA polymerase may pause of stall downstream of the promoter: heat shock genes are stall until heat stress is encountered (car in neutral, ready to go, THINK: start box)
Affected by regulatory factors

Question 18

Response Elements

Answer 18

Common regulatory elements upstream of the start sites of a collective group of genes in response to a common environmental stimulus

Question 19

MREs

Answer 19

Multiple response elements
Found in upstream region of the metallothionein in gene

Question 20

Gene Regulation through RNA Splicing

Answer 20

– Eukaryotic genes can be regulated through the
control of mRNA processing.
– The selection of alternative splice sites leads to the production of different proteins.
● Alternative splicing in Drosophila sexual development

Question 21

Alternative splicing of tra pre-mRNA

Answer 21

Two alternative 3’ splice sites are present
A way to regulate gene transcription

Question 22

Degradation of RNA

Answer 22

• 5’ cap removal
• shortening of the polyA tail
• degradation of 5’ UTR coding sequence, and 3’ UTR

Question 23

Small interfering RNAs and micro RNAs

Question 24

Dicer

Answer 24

Cuts up RNA to produce single stranded siRNAs, short, which combine with proteins to form a RISC

Question 25

RISC

Answer 25

Silencing complex, silence mRNA, not allowing mRNA to be translated.

Question 26

Mechanism of gene regulation by RNA inference

Answer 26

RNA cleavage
Inhibition of translation
Transcriptional silencing
Slicer-independent degradation of mRNA

Question 27

RNA Cleavage

Answer 27

RISC containing an si RNA, pair with mRNA molecules and cleave mRNA

Question 28

Inhibition of translation

Answer 28

MiRNAs bind to mRNA, translation not allowed

Question 29

Transcriptional silencing

Answer 29

Altering chromatin structure
STRUCTURE CONTROLS FUNCTION
Methylates attracted to specific histone tails when small RNAs bind to DNA

Question 30

slicer independent degradation of mRNA

Answer 30

MiRNA attract dicer and RISC to cleave mRNA
SLICER AND DICER

Question 31

Factors that impact the rate of translation

Answer 31

• availability of ribosomes
• charged tRNAs
• initiation & elongation factors
  More ribosome binding when there are more initiation factors, there is more translation happening

Question 32

Operon

Answer 32

Several genes controlled by one promoter in bacteria, more complex process in eukaryotes