Chapter 4: Gene Function Flashcards
Disruptions of biochemical processes by genes can cause a build up of what?
- intermediate
L> how much and what kind of build up depends on where the disruption occurs.
L> disruptions occur via enzyme activity.
Genes regulate ____.
Genetic Diseases affect _____.
- chemical events
- biochemical processes
Who provided the first evidence of a relationship between genes and enzymes?
-What was it? (3)
- Garrod
- a step in the metabolic pathway may be blocked
- intermediate chemical accumulates
- inborn error of metabolism ( aka born with the genetic disorder)
Phenylalanine hydroxylase is the enzyme that is rendered inactive with what genetic disorder?
L> recessive or dominant?
L> sex chromosome or not?
- Phenylkentonuria (PKU)
L> autosomal recessive(2 copies of a defective gene)
L> not sex chromosome related
With PKU aside from getting the defective gene from both parents how else can one get this disorder.
- spontaneous mutation of one allele and the inheritance of another mutated allele.
Symptoms of PKU?
L> low mental capabilities…hypotonia, skin, rashes, musty odor, fairer complexion
Albinism is caused by the defect in what enzyme?
- Tyrosinase
L> normally breaks down tyrosine into DOPA which produces melanin ( pigment)
Homogentisic Acid Oxidase enzyme is defective in what disorder?
L> causes?
L> recessive, not?
L> sex chromosome, not?
-Alkaptonuria
L> black urine disease
L> autosomal recessive
Beadle and Tatum created what hypothesis?(1942)
L> describe it
- One gene- one enzyme
- gene mutation may result in loss of enzyme activity
L> absence of end product and accumulation of precursors
What was corrected about the one gene one enzyme hypothesis?
- its actually one gene- one polypeptide
Phenylketonuria (PKU)
- ______mutation on what chromosome?
- What enzyme is involved, what does it normally produce?
- Excessive amounts of PHE are ____.
- it has ___ effects
- Chromsome 12 , recessive
- Phenylalanine hydroxylase
- tyrosine production
- harmful
- pleiotropic effects
What are pleiotropic effects?
- when one gene influences multiple phenotypic traits (ex: PKU)
L> that whole intermediate build up via enzyme not working concept.
Phenylalanine hydroxylase comes from?
- dietary source
Symptoms of PKU?
- severe delayed mental development
- slow growth rate
- early death
L> can be teratogenic (cause malformations of an embryo or fetus )
Screening for PKU: - What is the Guthrie Test? L> what is put on filter paper? L> its incubated with \_\_\_\_ and \_\_\_\_. L> Growth of the above is promoted by \_\_\_. L> whose it done on?
- blood drop on filter paper
- incubates with bacillus subtillis and B-2-thienylalanine
L> growth is promoted by PHE (test comes up positive if present) - new borns