Flashcards in Exam 3 Deck (133)
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primary gene regulation
transcriptional regulation
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secondary gene regulation
post-transcriptional regulation
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tertiary gene regulation
translational regulation
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quaternary gene regulation
protein modification
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post-transcriptional regulation
secondary-quaternary regulation
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pre-transcriptional regulation
regulate the number of gene copies
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prenatal globin regulation
gamma globin produced instead of beta (expression of beta turned off and expression of gamma turned on)
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postnatal globin regulation
beta globin produced instead of gamma (expression of beta turned on and expression of gamma turned off)
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temporal and spatial regulation of globin
temporal: different globins produced at different times (prenatal vs postnatal)
spatial: gamma gene in liver great 12 weeks post-conception, but nonexistent in bone marrow and spleen
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transcriptional regulation
gene is "on" when it's being transcribed and "off" when transcription is blocked
can also be regulated by controlling how much mRNA is made during transcription
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post-transcriptional regulation
RNA processing
translational control
post-translational control
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weismann germplasm theory
cells destined to become gametes set aside early in development
basic concept correct except theory assumed that once development occurs, the germplasms retains all genetic material while differentiated cells lose genetic material they don't need
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steward 1958
early cloning experiment to determine whether differentiation involves gene loss
determined that since organism could be cloned from a single cell then the cell must not lose any genetic material during differentiation
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exceptions to maintaining genetic material
gene loss
gene gain
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gene loss types
chromatin diminution
chromosome elimination
cancer cells
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chromatin diminution
loss of segments of chromosme but NOT whole chromosome
roundworm ascaris
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roundworm ascaris chromatin diminution
during early development, the somatic cells lose segments of their chromosomes BUT germline cells retain all genetic material
amount of genome lost depends on species
varies from 25%-85%
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chromosome elimination
entire chromosomes lost (not just segments)
sciarid flies
paramecium and tetrahymena
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paramecium and tetrahymena
form 2 nuclei: micronucleus (inactive and only for reproductive purposes) and macronucleus (active nucleus with genes being expressed -- transcription occurring)
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events of macronucleus growth
internal eliminated sequences (IESs) lost and other segments duplicated
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IES removal process
RNA mediated process similar to RNA interference
post-meiotic micronucleus' entire genome transcribed and compared to old macronucleus genome (that was transcribed before disintegration) to determine which sequences to remove
50,000+ segments removed
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repeated replication in macronucleus growth
repeated replication of DNA without cell division produces a giant nucleus with around 800 copies of the remaining segments of DNA
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cancer cells
many chromosomal changes occur in tumors (including chromosome loss) that make them more viable
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gene gain
increase in number of gene copies
repetitive vs single copy genes
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repetitive vs single copy genes
some genes normally present in multiple copies
more copies = more gene product
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3 types of DNA in eykaryotic genomes
single copy DNA
middle-repetitive DNA
highly-repetitive DNA
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single copy (unique sequence) DNA
50% of human genes only present once in each genome (twice in each cell bc 1 from each parent)
mRNA (genes coding for proteins)
hybridizes slowly (high Cot value)
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middle repetitive DNA
around 40% of human genes are moderately repeated with 10-1,000 copies
rRNA and tRNA
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highly repetitive DNA
around 6% of human genes are highly repeated with up to 100,000 copies
segment length of 5-300 nt
aka "satellite DNA" bc it forms a satellite during CsCl centrifugation
transposable elements and repeated segments of centromere and telomere
usually heterochromatin (inactive genes)
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