D2.2 Gene Expression Flashcards
phenotype, regulating transcription, epigenesis, twins, factors
gene expression
process of reading gene and building protein, contributing to phenotype
promoter region
sequence of DNA upstream from gene, indicating start point and controlling transcription
transcription factors
proteins that bind to promoter/enhancer regions and regulate transcription
promoter protein
binds to promoter region and encourages RNA polymerase, which is in charge of transcription, to attach
enhancer region
further upstream than promoter, activator proteins attach to encourage transcription
describe mRNA circulation
mRNA circulates for a period of time (mins/days) for ribosome use, destroyed when cell stops producing protein
what structures does mRNA have to protect it?
cap at beginning and polyA tail at end
what enzymes work to degrade mRNA?
decapping and deadenylase complexes remove cap and tail, exonucleases remove nucleotides 1 by 1
epigenesis vs epigenetics
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
layers of cells in embryo
ectoderm (forms skin/brain), mesoderm (forms skeleton/circulatory), endoderm (forms lung/liver)
methylation of cytosine
methyl attaches, flagging part of genome as epigenetic tag; prevents RNA polymerase from attaching to promoter region, resulting in transcriptional silencing
methylation of histones
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
transcriptome
all RNA in cell, different in different cell types based on gene expression
proteome
all proteins able to be synthesized by cell, different in different cell types and organisms
what are RNA transcripts and how and why are they studied?
transcribed strands, quantities studied/identified by RNA sequencing to learn how cells differentiate
benefit to knowing someone’s proteome
can develop personalized medicine, predict how a person would react
three key facts about epigenetic modifications
reversable, mostly erased, DNA code not modified
what are epigenetic modifications a result of and what are their effects?
result of parent experiences and experiences right after birth; affects susceptibility to diseases, behaviours, allows adaptation
environmental factors influencing epigenetic changes and their effects
air pollutants (ozone, nitrogen oxides, particulate matter, polycyclic aromatic hydrocarbons) add/remove methyl tags, diet, cigarette smoke; causes asthma, cancer, heart disease
what cells do sperm and egg cells come from?
primordial germ cells, formed when developing into foetus
epigenetic reprogramming
epigenetic tags on primordial germ cells removed, but some remethylated before fully developing into gamete to produce viable zygote
imprinted genes
one of the two (paternal or maternal) copies silenced; bypass reprogramming
why can’t two sperm or two eggs form an embryo?
they’re imprinted differently
liger
male lion and female tiger, grows bigger than parents because dominant male growth gene
