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ap bio chp. 17, method of gene expression - transcription/translation -…
ap bio chp. 17
gene expression - the process of DNA synthesizing proteins/sometimes RNA
history of gene expression
Archibald Garrod - one gene-one enzyme hypothesis (genes dictate enzyme production)
proven as one gene-one enzyme hypothesis, genes dictate enzyme production, which causes phenotypic changes via. metabolic pathways
George Beadle
Tatum & Beadle - bread mold
Adrien Srb & Norman Horowitz did more tests
found 3 types of mutants missing different compounds in arginine-synthesis pathway (which is 3 steps)
nutritional mutants (didn't grow) placed in minimal medium + 1 nutrient therefore found that nutritional mutants could not produce arginine therefore were lacking enzyme that synthesized arginine
placed in minimal medium; some grew, some didn't
X-rays cause mutations in complete medium; formed colonies
Neurospora crassa
= haploid bread mold (to disable 1 allele & observe)
Boris & Beadle -
Drosphilia
eye color prediction
speculated that in
Drosophilia
, mutated eye color was caused by preventing production of an enzyme at a specific step, preventing pigment synthesis at that step.
said inherited diseases were caused by an inability to produce a certain enzyme
ex. alkaptonuria (causes black urine) caused by lack of enzymes that catalyze breakdown of alkapton therefore body expels it via. urine
British physician, 1902
one gene-one polypeptide hypothesis
revised to include similar non-enzymatic proteins that genes also regulate
not completely accurate
alternative splicing - one gene = multiple proteins
genes can code for RNA that is not translated into proteins
transcription & translation
translation
transcription
method of gene expression - transcription/translation