D2.2 Gene expression

Question 1

transcription

Answer 1

first stage of gene expression

Question 2

Gene expression is required

Answer 2

so that the information carried in the genetic code can be used by the cell

Question 3

Genotype

Answer 3

the total of genes an individual has

Question 4

phenotype

Answer 4

the observable expression of these genes

Question 5

eg the genes controlling eye colour may have

Answer 5

blue, green, brown phenotypes

Question 6

Promoters

Answer 6

Regions of non-coding DNA to which RNA polymerase binds to initiate transcription

Question 7

Enhancers

Answer 7

Activator proteins bind to enhancer sequences of DNA to greatly increase the rate of transcription of a gene

Question 8

Silencers

Answer 8

Repressor proteins bind to non-coding regions of DNA to either block or reduce the transcription of a gene.

Question 9

Gene expression

Answer 9

the process by which genetic information is used to produce RNA and proteins

Question 10

Transcription factors

Answer 10

Proteins that can regulate gene expression by altering the ease with which RNA polymerase binds to a promoter. Ex) activator and repressor proteins

Question 11

The persistence of the mRNA transcript depends on

Answer 11

endonuclease enzymes and stabilising proteins, chemical modifications to the mRNA and oxidative stress

Question 12

All somatic cells within your body have the same genome, but

Answer 12

differences in the environments of the cells lead to differences in gene expression

Question 13

Ex of epigenetic changes

Answer 13

DNA methylation, and histone acetylation and methylation
(does not affect the genome but it does impact the phenotype)

Question 14

Some epigenetic changes can be inherited

Answer 14

-> genetic tags must occur or be maintained in germline cells and passed on to the offspring.

Question 15

genome

Answer 15

the entire set of genes found in a cell

Question 16

transcriptome

Answer 16

all of the mRNA molecules expressed from the genes of an organism

Question 17

proteome

Answer 17

the complete set of proteins expressed from the genes an organism

Question 18

Methylation of DNA

Answer 18

inhibits transcription

Question 20

Processes that inhibit transcription

Answer 20

bind the DNA more tightly to the histone making it less accessible to transcription factors

Question 21

epigenetic tags

Answer 21

Methylation (and acetylation) mark the DNA to affect transcription

Question 22

Environmental factors

Answer 22

such as air pollution, diet and temperature can affect patterns of gene expression

Question 23

Monozygotic twins

Answer 23

useful for studying the effect of the environment on gene expression as they possess the same genome

Question 24

pigments in the fur of Himalayan rabbits

Answer 24

are regulated by temperature.

Question 25

Gene C controls fur pigmentation in Himalayan rabbits. The gene is active when environmental temperatures are between 15 and 25°C

Answer 25

• At higher temperatures the gene is inactive.
• In low temperatures Gene C becomes active in the rabbit’s colder extremities (ears, nose, and feet) and produces a black pigment.
• In the warm weather no pigment is produced and the fur is white

Question 26

morphogens

Answer 26

regulate the production of a transcription factors in a cell

Question 27

Morphogens diffuse across the surfaces of cells from a concentrated source. Therefore different embryonic cells get different concentrations of morphogens

Answer 27

This results in the activation and inhibition of different genes in different cells. This in turn controls how long your fingers should be, where your nose is on your face, and other specifics about body structure.