BIOL 2301 TEST Q&A

BIOL 2301 TEST Q&A
transcriptional activators - ANSWER-•recruit transcription complex to promoter or
initiate transcription by an already assembled complex
•can be characterized by DNA binding protein folds

transcription factor - ANSWER-•protein that binds dna
•affects transcription rate of a gene

helix-turn-helix - ANSWER-•2 α helices
•binds to a major groove

zinc finger - ANSWER-•amino acid loop with zinc at the base
•binds to a major groove

leucine zipper - ANSWER-•helix of leucine amino acids
•binds to two major grooves

general transcription factors - ANSWER-•TFIIs (IIA, B, F, E, H)
•TBP (TATA box binding protein
•TAFs (TBF-associated factors)

yeast galactose metabolism - ANSWER-•GAL 1/7/10 are needed to convert
galactose to glucose-1-phosphate
•3 genes are tightly linked, but each has their own promoter, so they make their own
rna
•gene expression is induced when galactose is present
•regulated by GAL80 and GAL4

GAL 4 - ANSWER-•positively regulatory protein
•when not bound to GAL 80 (galactose present), binds to dna and activates
transcription

GAL 80 - ANSWER-•repressor
•binds GAL4 in absence of galactose which blocks transcription
•binds galactose when it's present, changes conformation, so it cannot bind GAL4
and transcription is not blocked

gal4 deletion - ANSWER-uninducible

gal80 deletion - ANSWER-constitutive

gal4 mutant that can't bind gal80 - ANSWER-constitutive

chromatin remodeling - ANSWER-•condensed chromatin need to be loosened for
transcription
•when transcription is activated, but no room for rna polymerase to bind, recruit crcs
or hat which give an open configuration

, crc - ANSWER-•makes binding sites open (accessible) to transcription factors
•repositions nucleosomes which unwinds dna, so gene can be transcribed

hat - ANSWER-•histone acetylase
•positively charged histones, negatively charged dna
•opens histone tails which allows transcription factors to reach dna

dna methylation - ANSWER-turns off genes

dna methylase - ANSWER-•adds methyl group to cytosine
•usually targets CG rich regions
•helps keep genes permanently off
•inactive x is heavily methylated

epigenetic changes - ANSWER-•not mutations
•changes in methylation or chromatin structure that affects gene expression
•can be inherited

genomic imprinting - ANSWER-•parental methylation patterns are passed to
offspring
•changes in maternal germ cells to give correct expression
•female strips paternal methylation pattern which gives them the female pattern
•mammalian

rna stability - ANSWER-•balance between mRNA degradation and transcription of
new messages determine level of individual mRNAs in cells
•5' caps and 3' tails increase it
•varies greatly

quickly degraded mRNAs - ANSWER-•AU rich 3'UTR
•early stop codons

nonsense-mediated mRNA decay - ANSWER-•splicing mistake leaves in an intron
(contains stop codons)
•"surveillance" proteins detect splice junction binding proteins as ribosome stalls
prematurely
•rna is decamped and degraded by nucleases

miRNAs - ANSWER-•prokaryotic and eukaryotic
•regulate gene expression by base pairing with mRNA transcript
•involves anti-sense RNA pairing with mRNA transcripts to be regulate
•can activate or inhibit rna translation

bacteria regulatory rna - ANSWER-•oxyS keeps flhA turned off in times of stress
(hydrogen peroxide present)
•DsrA turns on RpoS (tf that allows e. coli to turn on genes it needs in stationary
phase)

trpL - ANSWER-•codes for a 14 amino acid peptide
•2 trp codons measure trp supply in cell