T3M3&4 Review

Question 1

Unlike prokaryotes, eukaryotic genes are not

Answer 1

clustered into operons

Question 2

How are eukaryotic genes regulated?

Answer 2

each gene is regulated by its own promoter and regulatory regions

Question 3

all trans-acting factors have in common

Answer 3

a lot of alpha helices, rich protein structures

Question 4

Where are regulatory regions in eukaryotes?

Answer 4

often quite far away from core promoter region

Question 5

Transcriptional repressors

Answer 5

halt transcription

Question 6

Transcriptional regulators determine

Answer 6

cell types (certain genes are activated, certain are kept off)

Question 7

All cells have the same

Answer 7

DNA blueprint

Question 8

In situ hybridization mostly used in

Answer 8

small organisms, see-through, put under a microscope, tissue sample

Question 9

Cancerous cell

Answer 9

not foreign to body, inappropriate regulation of gene expression

Question 10

Preparing fluorescently labelled cDNA

Answer 10

1. Isolate mRNA
2. reverse transcribe to single stranded cDNA with fluorescent nucleotides (use different colours that can mix together)

Question 11

Microarray chip

Answer 11

as small as a glass slide and contain multiple wells
- each well represents a gene of interest

Question 12

How does microarray chip measure gene expression?

Answer 12

each well is pre-seeded with a single stranded DNA that is anchored to the bottom of the well, each is unique to the gene of interest
- combine equal amounts
- apply mixture to chip
- wash then measure fluorescence

Question 13

Green microarray

Answer 13

more expressed in normal epithelial cells eg kills cells when they malfunction apoptosis

Question 14

Red microarray

Answer 14

more expressed in breast carcinoma cells eg helps cancer cells move

Question 15

Yellow microarray

Answer 15

gene equally expressed in both cell types, maybe housekeeping eg a gene that codes for ribosomes

Question 16

White microarray

Answer 16

other genes, not expressed, eg helps cells become bone

Question 17

Epigenetic regulating eukaryotic gene expression

Answer 17

not DNA sequence, changing how it is expressed by chemical modifications along genome

Question 18

Epigenetic regulating eukaryotic gene expression examples

Answer 18

1. Histone modification
2. DNA methylation

Question 19

Histone modification

Answer 19

regulating amt mRNA transcribed

Question 20

DNA methylation

Answer 20

regulating the amount of mRNA that is transcribed

Question 21

mRNA stability

Answer 21

Regulating the amount of mRNA that is translated into proteins

Question 22

Protein stability

Answer 22

Regulating the amount of mRNA that is translated into proteins

Question 23

Regulating eukaryotic gene expression (4)

Answer 23

1. Histone modification
2. DNA methylation
3. mRNA stability
4. Protein stability

Question 24

Histone modifications

Answer 24

1. Positively charged tails of nucleosomal histone proteins probably interact with negatively charged phosphates of DNA.
2. Acetylation of the tails weakens their interaction
   with DNA and may permit some transcription factors
   to bind to DNA

Question 25

Methylation and acetylation of histone proteins

Answer 25

chemical modification of specific lysine amino acids in the tails of histones protruding from nucleosomes affect transcription

Question 26

Methylation near the promoter of a gene

Answer 26

undermethylation on the cGP island allows transcription, heavy inhibits, in many organisms some cytosine bases in DNA are changed into 5 methyl cytosines

Question 27

Heavily methylated promoters also recruit histone deacetylase because

Answer 27

is able to deacetylate or remove acetyl groups from the
histone proteins tails, inhibiting gene expression at the
transcriptional level

Question 28

Protein degradation

Answer 28

• proteasomes degrade unneeded or damaged proteins
• proteins are removed by marking them for enzymatic degradation, ubiquitins tags (don’t get threaded)