D2.2 Gene Expression

Question 1

gene expression

Answer 1

process of reading gene and building protein, contributing to phenotype

Question 2

promoter region

Answer 2

sequence of DNA upstream from gene, indicating start point and controlling transcription

Question 3

transcription factors

Answer 3

proteins that bind to promoter/enhancer regions and regulate transcription

Question 4

promoter protein

Answer 4

binds to promoter region and encourages RNA polymerase, which is in charge of transcription, to attach

Question 5

enhancer region

Answer 5

further upstream than promoter, activator proteins attach to encourage transcription

Question 6

describe mRNA circulation

Answer 6

mRNA circulates for a period of time (mins/days) for ribosome use, destroyed when cell stops producing protein

Question 7

what structures does mRNA have to protect it?

Answer 7

cap at beginning and polyA tail at end

Question 8

what enzymes work to degrade mRNA?

Answer 8

decapping and deadenylase complexes remove cap and tail, exonucleases remove nucleotides 1 by 1

Question 9

epigenesis vs epigenetics

Answer 9

process of undifferentiated to specialized (zygote to multicellular), interaction of genes and environment during development, phenotypic changes always passed down vs study of activation/silencing of genes, gene expression

Question 10

layers of cells in embryo

Answer 10

ectoderm (forms skin/brain), mesoderm (forms skeleton/circulatory), endoderm (forms lung/liver)

Question 11

methylation of cytosine

Answer 11

methyl attaches, flagging part of genome as epigenetic tag; prevents RNA polymerase from attaching to promoter region, resulting in transcriptional silencing

Question 12

methylation of histones

Answer 12

attaches to lysine in histone tails of histone 3; if attached to lysine 4, DNA around histone loosened, gene activated; if 9/27, tightened, silenced

Question 13

transcriptome

Answer 13

all RNA in cell, different in different cell types based on gene expression

Question 14

proteome

Answer 14

all proteins able to be synthesized by cell, different in different cell types and organisms

Question 15

what are RNA transcripts and how and why are they studied?

Answer 15

transcribed strands, quantities studied/identified by RNA sequencing to learn how cells differentiate

Question 16

benefit to knowing someone’s proteome

Answer 16

can develop personalized medicine, predict how a person would react

Question 17

three key facts about epigenetic modifications

Answer 17

reversable, mostly erased, DNA code not modified

Question 18

what are epigenetic modifications a result of and what are their effects?

Answer 18

result of parent experiences and experiences right after birth; affects susceptibility to diseases, behaviours, allows adaptation

Question 19

environmental factors influencing epigenetic changes and their effects

Answer 19

air pollutants (ozone, nitrogen oxides, particulate matter, polycyclic aromatic hydrocarbons) add/remove methyl tags, diet, cigarette smoke; causes asthma, cancer, heart disease

Question 20

what cells do sperm and egg cells come from?

Answer 20

primordial germ cells, formed when developing into foetus

Question 21

epigenetic reprogramming

Answer 21

epigenetic tags on primordial germ cells removed, but some remethylated before fully developing into gamete to produce viable zygote

Question 22

imprinted genes

Answer 22

one of the two (paternal or maternal) copies silenced; bypass reprogramming

Question 23

why can’t two sperm or two eggs form an embryo?

Answer 23

they’re imprinted differently

Question 24

liger

Answer 24

male lion and female tiger, grows bigger than parents because dominant male growth gene

Question 25

tigon

Answer 25

male tiger and female lion

Question 26

heterozygotic twins

Answer 26

when 2 sperm fertilize 2 eggs, non-identical

Question 27

monozygotic twins

Answer 27

when same zygote forms 2 embryos, identical

Question 28

what gene is transcribed into insulin, and how is it stimulated?

Answer 28

INS transcribes insulin when blood sugar levels too high; insulin signals cells to let glucose in, decreasing sugar levels, stop transcription

Question 29

how does e coli control digestion of lactose?

Answer 29

lac repressor binds to operator between promoter region and genes, stops RNA polymerase binding and transcription for lactase enzyme stops; lactose deactivates repressor and allows lactase digest lactose

Question 30

lac operon

Answer 30

3 genes for lactase, promoter, operator; lactase regulator

Question 31

androgen response element

Answer 31

DNA sequence where androgen receptors (transcription factors for male sex hormones) bind

Question 32

what is a way that translation is stopped?

Answer 32

translation repressor proteins remove nucleotides