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
What is KUVAN?
- medication used to lower PHE levels for those with PKU
Lesch-Nyhan Syndrome :
- Is the mutation on a sex Chromosome or not?
- recessive, dominant?
- What enzyme deficiency is linked to it?
- What is excessively produced?
- This disease is ultimately ____.
- It’s on the X Chromosome… recessive
- HGPRT: hypoxanthine guanine phosphotibosyl transferase : essential to purine usage
- purine is produced excessively…and converted to uric acid which accumulates
- fatal (before 20)
Kartagener Syndrome:
- autosomal or sex mutation?
L> recessive or dominant?
- autosomal recessive
Kartagener Syndrome:
- what are the three characterizations!
- sinus and lung abnormalities
- sterility
- dextrocardia (organs are mirror images of what they should be)
Kartagener Syndrome:
- mutation is on what chromosome?
- chromosome 9
Kartagener Syndrome:
-Genes affected code for proteins of the dynein motors of ___ and ___.
L> What does this have to do with the three characterizations of the disorder?
- cilia and flagella
- Lungs and sinus: mucous etc will not be moved properly etc
- Sterility: sperm cannot move…eggs don’t move
- Dextrocardia: normally cilia motion cells in embryo to the correct spot during development…but not in this syndrome. The embryonic fluid moves randomly instead of to the right.
Cystic Fibrosis:
- autosomal or sex related?
L> recessive or dominant?
- autosomal recessive
Cystic Fibrosis:
- located on what chromosome
- 7q31.2-q31.3
Cystic Fibrosis:
- 1/ ___ births have this
- estimated carriers to be 1/__ people
- 2000
- 23
