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Genetics > Chapter 4: Gene Function > Flashcards

Chapter 4: Gene Function Flashcards

0
Q

Disruptions of biochemical processes by genes can cause a build up of what?

A
  • intermediate
    L> how much and what kind of build up depends on where the disruption occurs.
    L> disruptions occur via enzyme activity.
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1
Q

Genes regulate ____.

Genetic Diseases affect _____.

A
  • chemical events

- biochemical processes

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2
Q

Who provided the first evidence of a relationship between genes and enzymes?
-What was it? (3)

A
  • Garrod
  • a step in the metabolic pathway may be blocked
  • intermediate chemical accumulates
  • inborn error of metabolism ( aka born with the genetic disorder)
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3
Q

Phenylalanine hydroxylase is the enzyme that is rendered inactive with what genetic disorder?
L> recessive or dominant?
L> sex chromosome or not?

A
  • Phenylkentonuria (PKU)
    L> autosomal recessive(2 copies of a defective gene)
    L> not sex chromosome related
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4
Q

With PKU aside from getting the defective gene from both parents how else can one get this disorder.

A
  • spontaneous mutation of one allele and the inheritance of another mutated allele.
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5
Q

Symptoms of PKU?

A

L> low mental capabilities…hypotonia, skin, rashes, musty odor, fairer complexion

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6
Q

Albinism is caused by the defect in what enzyme?

A
  • Tyrosinase

L> normally breaks down tyrosine into DOPA which produces melanin ( pigment)

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7
Q

Homogentisic Acid Oxidase enzyme is defective in what disorder?
L> causes?
L> recessive, not?
L> sex chromosome, not?

A

-Alkaptonuria
L> black urine disease
L> autosomal recessive

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8
Q

Beadle and Tatum created what hypothesis?(1942)

L> describe it

A
  • One gene- one enzyme
  • gene mutation may result in loss of enzyme activity
    L> absence of end product and accumulation of precursors
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9
Q

What was corrected about the one gene one enzyme hypothesis?

A
  • its actually one gene- one polypeptide
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10
Q

Phenylketonuria (PKU)

  • ______mutation on what chromosome?
  • What enzyme is involved, what does it normally produce?
  • Excessive amounts of PHE are ____.
  • it has ___ effects
A
  • Chromsome 12 , recessive
  • Phenylalanine hydroxylase
  • tyrosine production
  • harmful
  • pleiotropic effects
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11
Q

What are pleiotropic effects?

A
  • when one gene influences multiple phenotypic traits (ex: PKU)
    L> that whole intermediate build up via enzyme not working concept.
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12
Q

Phenylalanine hydroxylase comes from?

A
  • dietary source
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13
Q

Symptoms of PKU?

A
  • severe delayed mental development
  • slow growth rate
  • early death
    L> can be teratogenic (cause malformations of an embryo or fetus )
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14
Q 
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?
A
  • 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
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15
Q

What is KUVAN?

A
  • medication used to lower PHE levels for those with PKU
16
Q

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 ____.
A
  • 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)
17
Q

Kartagener Syndrome:
- autosomal or sex mutation?
L> recessive or dominant?

A
  • autosomal recessive
18
Q

Kartagener Syndrome:

- what are the three characterizations!

A
  • sinus and lung abnormalities
  • sterility
  • dextrocardia (organs are mirror images of what they should be)
19
Q

Kartagener Syndrome:

- mutation is on what chromosome?

A
  • chromosome 9
20
Q

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?

A
  • 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.
21
Q

Cystic Fibrosis:
- autosomal or sex related?
L> recessive or dominant?

A
  • autosomal recessive
22
Q

Cystic Fibrosis:

- located on what chromosome

A
  • 7q31.2-q31.3
23
Q

Cystic Fibrosis:

  • 1/ ___ births have this
  • estimated carriers to be 1/__ people
A
  • 2000

- 23

24
Q

Cystic Fibrosis:

-life expectancy??

A
  • ~40 years
25
Q

Cystic Fibrosis:

- characterizations? (3)

A
  • pancreatic, pulmonary, and digestive dysfunction in children and young adults!
26
Q

Cystic Fibrosis:

- Deletion of ____, a single __ is missing, affecting a ____.

A
  • delta F508
  • amino acid (3bases)
  • chloride channel M- protein
27
Q

Cystic Fibrosis:

- _/3 mutations are delta F508 but the rest are of the other ___ mutations that can cause it.

A
  • 2/3

- 999

28
Q

Cystic Fibrosis:
-Where is the most common site of the CF mutation delta F508?
( think Cystic Fibrosis transmembrane conductance regulator diagram (CFTR) )
L> what does this cause?

A
  • Most common site site affected by the deletion of the delta F508 sequence is a nucleotide binding fold (NBF) region that binds ATP
    L> the mutation causes excess Cl- to not be taken back and the sweat gland releases more in the sweat (aka higher Cl- concentration in sweat than normal person)
29
Q

What are the two types of genetic counselling?( fetal analysis)

A
  • Amniocentesis

- Chorionic villus sampling

30
Q 
Genetic Counselling: 
- Chorionic villus sampling ?
L> time period?
L> reliable?
L> issues?
L> results, fast?slow?
A 
- sampling of placental tissue!
L>10-12 weeks it can be done 
L>not very reliable 
L> due to cell mosaicism : presence of two or more populations of cells with different genotypes in one individual   ( cells from mom and baby together) 
- results are made quick!
31
Q 
Genetic Counselling: 
- Amniocentesis ?
L> reliable, yes or no?
L> time frame of use? 
L> results waiting period? 
L> safe?
A
  • amniotic fluid is sampled which contains fetal tissue to culture.
    L> yes
    L> 16 weeks
    L> long waiting period…cells need to be cultured
    L> not 100%… 1/300 babies are lost via this

Genetics (14 decks)

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