D2.2 Gene Expression

Question 1

Define gene expression (2)

Answer 1

process where genetic instructions are encoded to create a functional product

mechanism where genetic instructions give rise to observable characteristics

Question 2

Define genome

Answer 2

entire set of genetic instructions for that organism

Question 3

Define transcriptomes

Answer 3

genetic instructions that hav been transcribed into RNA molecules (tRNA, mRNA, rRNA)

Question 4

Define proteomes

Answer 4

all proteins expressed within a cell, tissue or organism

Question 5

Define epigenetics (2)

Answer 5

study of how chemical + environmental triggers change gene expression patterns

do not alter DNA sequences + potentially reversible

Question 6

Define epigenesis

Answer 6

development of an orginism from an undifferentiated egg into an multicellular organism

Question 7

Define epigenetic tags

Answer 7

controls gene expression by switching genes on (active) or off (inactive)

Question 8

DNA methylation (4)

Answer 8

methyl groups bond to cytosine bases

most genes have cytosine bases in their promoter areas

methyl groups impede action of RNA polymerase

DNA methylation reduces transcriptional activity

Question 9

Histone methylation for acetyl group (3)

Answer 9

histone proteins have positively charged tails allowing association with negative DNA

acetyl group neutralises charge on tails –> DNA is less tightly coiled

transcription increases as RNA polymerase can more easily access the genes

Question 10

Histone methylation for methyl groups (2)

Answer 10

methyl groups amplifies the positive charge –> DNA becomes more tightly coiled

transcription decreases as RNA polymerase can less easily access the genes

Question 11

Define condensed heterochromatin

Answer 11

tightly packed DNA not available for transcription

Question 12

Define euchromatin

Answer 12

loosely packed DNA available for transcription

Question 13

External conditions that contribute to epigenetics (4)

Answer 13

air pollutants (e.g nitrogen oxides) can change DNA methylation

air pollution affects methylation of immunoregulatory gene –> increased inflammation, altered immune system

can cause cancer

can increase blood pressure + cause respiratiory conditions

Question 14

Purpose of transcription factors (2)

Answer 14

allow for RNA polymerase to bind to promoters

increase probability of transcription

Question 15

Activators in gene expression (2)

Answer 15

proteins that bind to enhancer sites on DNA

can recruit other transcription factors that allow for RNA polymerase to bind to promotor region

or can directly have RNA polymerase bind to the promotor region

Question 16

Repressors in gene expression

Answer 16

bind to promotor regions

prevent RNA polymerase from binding to the promotor region