Eukaryotic Gene Regulation

Question 1

what makes each cell different?

Answer 1

All cells have the same gene but:
Genes can be turned off and on
Genes have special activator molecules to turn on the genes

Question 2

what does the histone tail contain?

Answer 2

lysine and arginine

Question 3

Genome

Answer 3

nucleotide sequence in DNA

Question 4

Epigenome

Answer 4

chemical tags added to histones or DNA

Question 5

do eukaryotes contain operons?

Answer 5

NO

Question 6

what are the basic stages at which gene Expression can be regulated?

Answer 6

packing/unpacking DNA, transcription, mRNA processing, mRNA transport, translation, protein processing, protein degradation

Question 7

Epigenetic modifications:

Answer 7

addition/ removal of chemical tags on either Histones and/or DNA;
Chemical tags determine if the DNA will be tightly wrapped around or loose

Question 8

Acetylation of histone tails

Answer 8

loosens the DNA & activates it - usually increases transcription and gene expression

Question 9

Methylation of tails

Answer 9

can either tighten or loosen

Question 10

DNA methylation of cytosine

Answer 10

(usually silences genes)

Question 11

DNA methylase

Answer 11

add CH3 groups to cytosines to silence the gene

Question 12

Acetylases

Answer 12

add acetyl groups to histone tails, activating the gene

Question 13

Deacetylases

Answer 13

silence the gene

Question 14

Basal transcription rate

Answer 14

regular transcription rate

Question 15

Enhancer Sequence: r

Answer 15

regions of the DNA lie upstream/ downstream from the promoter that interact with cell specific activators or repressor to enhance the basal rate of transcription or decrease it

Question 16

What do activators bind to?

Answer 16

the enhancer sequence

Question 17

role of activators

Answer 17

DNA bending protein Bends molecules→ bringing enhancer region in close proximity to the promoter which enhances RNA polymerase binding & transcription factors binding which increases basal rate of transcription → occurs at transcriptional level

Question 18

what affects which genes are turned on/off?

Answer 18

Types of Activators

Question 19

2 types of post transcriptional regulation

Answer 19

alternative RNA splicing
mRNA degradation

Question 20

Alternative RNA splicing (

Answer 20

variability of exons create a family of proteins

Question 21

mRNA degradation

Answer 21

lifespan of mRNA- determines amount of protein synthesis→ how quickly it gets degrade= stops gene expression → w/o mRNA gene expression stops

Question 22

Ubiquitin

Answer 22

death tag

Question 23

Proteasome

Answer 23

degrades the protein into small enzymes

Question 24

protein processing & degradation

Answer 24

When a protein is tagged with ubiquitin, the protein is to be degraded and it gets sent to the proteasome which degrades it through enzymes

Question 25

what do microRNAs and siRNAs do?

Answer 25

bind to the RISC complex and cleaves mRNA

Question 26

Role of Dicer

Answer 26

cuts dsRNA into small fragments

Question 27

RNA interference results in

Answer 27

either mRNA degradation or blockage of Translation