Transcription

Question 1

Where does transcription occur?

Answer 1

Nucleus

Question 2

How many pairs of chromosomes does the human genome hold?

Answer 2

23 pairs (22 + 1 pair of sex chromosomes)

Question 3

How many protein-coding genomes are there (for humans)?

Answer 3

20,000

Question 4

What is it called if a gene is expressed always in every cell?

Answer 4

Constitutively expressed genes

Question 5

How can constitutively expressed genes be used experimentally?

Answer 5

Can be used as comparisons when investigating how stimuli affect gene expression of other genes

Question 6

What are two examples of constitutively expression genes?

Answer 6

GADPH and beta-actin

Question 7

What does the expression of specifically expressed genes depend on?

Answer 7

Type of cell and specific stimuli

Question 8

What types of stimuli might cause changes in gene expression?

Answer 8

Environment, exercise, hormones, diet

Question 9

How does exercise affect gene expression?

Answer 9

Single bout of exercise significantly changes expression; resistance training causes upregulation of skeletal muscle synthesis; endurance training causes increase in muscle gene expression, particularly genes that are beneficial to aerobic metabolic, e.g. to increased mitochondrial density

Question 10

What synthesises mRNA, and in what direction?

Answer 10

RNA polymerase II; reads fro 3’ to 5’ to synthesise 5’ to 3’

Question 11

How many H bonds between between C and G and A and T?

Answer 11

3 between C and G; 2 between A and T

Question 12

What are promoters and enhances?

Answer 12

Regions of non-coding DNA, which help to regulate and initiate transcription; are control regions that can be acted on by other proteins involved in expression

Question 13

What are promoters?

Answer 13

Region of DNA that initiates transcription; large number of regions; vary between cell and tissue type; essential to every gene; general transcription factors bind to these regions

Question 14

What are the three most common promoters?

Answer 14

TATA, CAAT, and GC box

Question 15

What are transcription factors?

Answer 15

Proteins that alter expression and are involved in activation of promotion of transcription

Question 16

What are general transcription factors?

Answer 16

Assist RNA polymerase II in initiation; are direct activators; directly interact with DNA

Question 17

What are co-activator transcription factors?

Answer 17

Bind to RNA polymerase II or other TFs to increase activity; often altering number of co-activators alters rate of gene expression

Question 18

What causes TFs to activate?

Answer 18

Modification/activation: can be chemical (e.g. phosphorylation) or by direct binding (e.g. hormone binding); changes shape of TF and affects its function. Translocation: to nucleus, as can only do its job unless it’s where the DNA is

Question 19

What effect does exercise have on TFs?

Answer 19

Endurance training boosts levels of PGC-1-alpha: improves mitochondrial efficiency; increases general biogenesis of mitochondria; specifically activates genes essential to aerobic metabolism

Question 20

What are enhancers?

Answer 20

Non-coding, non-essential elements of DNA; are located further from site of initiation than promoter; alter level of response when initiation occurs (amount of mRNA produced)

Question 21

If an enhancer is further in 3’ end, is it upstream or downstream?

Answer 21

Upstream

Question 22

If an enhancer is further in 5’ end, is it upstream or downstream?

Answer 22

Downstream

Question 23

What occurs during elongation?

Answer 23

RNA polymerase II complex moves along DNA strand and replicates coding strand to produce mRNA

Question 24

What occurs during termination?

Answer 24

Occurs when RNA polymerase complex reads a terminator region (poly-A) and complex dissociates from DNA template, release pre-mRNA

Question 25

Outline the basic process of transcription (post DNA unwinding).

Answer 25

Initiation: general TFs bind to promoter regions and assist RNA polymerase II in initiation; co-activators may alter rate of gene expression. Elongation: RNA polymerase II produces mRNA strand complementary to coding strand. Termination: RNA polymerase II reach poly-A and dissociates from DNA template strand, releasing pre-mRNA for splicing

Question 26

What does splicing do?

Answer 26

From pre-mRNA, removes introns (complementary mRNA to non-coding DNA which controls rate/way of transcription) and leaves just extrons (complentary mRNA to coding DNA)

Question 27

How can gene expression be reduced?

Answer 27

Processes which reverse initiation steps (inactivation of TFs, cytoplasmic translocation of factors); directly reduce expression through repressor binding; occurs when stimulus stops or is reduced

Question 28

How can diet affect gene expression?

Answer 28

Enzymes for digestion upregulated following feeding; hormone response in blood upregulates genes involved in metabolism. Responses depend on: fat vs carb intake; micronutrient/supplement response. Diet can also alter exercise/training response.

Question 29

What factors of exercise alter effect on gene expression?

Answer 29

Type/modality, intensity, duration

Question 30

How does exercise affect Type I/Type II prevalence?

Answer 30

Strength athletes see huge increases in Type I and II; endurance athletes see preferential upregulation of Type I

Question 31

How is end response of gene expression determined?

Answer 31

Stimulus combined with genetic background (nature and nurture)