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Pathophys Test 1 > Genetics > Flashcards

Genetics Flashcards

1
Q

How many chromosomes do you have?

A

46

22- 2 somatic copies

Male XY

Female XX

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2
Q

What is transcription?

A

DNA–> mRNA

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3
Q

What is translation?

A

mRNA–> protein

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4
Q

What is RNA polymerase

A

Makes RNA copy

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5
Q

What is DNA polymerase?

A

Makes DNA copies

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6
Q

Difference between RNA and DNA

A
  • RNA single strand- DNA double
  • T on DNA is U on RNA
  • Deoxyribose nucleic backbone on DNA and ribose backbone on RNA
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7
Q

General process for protein synthesis?

A
  • DNA–> mRNA (transcription)
  • mRNA–> cytoplasm and ribosome
  • Ribosome uses mRNA to make protein
  • add amino acid to polypeptide chain, one codon at a time (3 nucleotides at a time)
    • can happen in cytoplasm on free ribosome or on ribosome on rough ER
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8
Q

What is a SNP
?

A

Single nucleotide polymorphisms

single nucleotide changed

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9
Q

What is a frameshift mutation?

A

One base pair deleted or inserted causes all remaining amino acids to be coded wrong

Major implication on protein formation

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10
Q

What are is an X-linked gene disorder?

A
  • Disorder on x chromosome
  • FOr man- every x chormosome affected
  • for women- only one x chromosome affected
  • For dominant diseases- only one needs to be affected
    • in male, most likely die in utero. very rare
  • For recessive diseases- affect men but not really women
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11
Q

What is aneuploidy? Examples?

A

multiple copies of chromosomes or only one

Examples

  • Down syndrome (trisomy 21)
  • Turner (45:X)
  • Klinefelter (47: XXY)

Getting extra copy of chromosome is less of problem than getting one less

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12
Q

What is polyploidy?

A

Having a WHOLE extra set of chormosomes (will have 68 instead of 46)

Real life example- seedless watermelon

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13
Q

What is a locus?

A

location in the genomes

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14
Q

What is an allele

A

one member of a pair of genese

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15
Q

What is genotype?

A

genetic material

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16
Q

What is phenotype

A

physical manifestations of gene

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17
Q

What is penetrance

A

chance that phenotype follows genotype

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18
Q

What is haplotype

A

alleles on single chromosome

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19
Q

What is recombination/corssover?

A

Gene rearrangement between homologous chromosomes

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20
Q

What is the short arm of the chromatid abbreviated as? Long arm?

A

short arm= p

long arm = q

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21
Q

Stages of meiosis? Where does it happen?

A

happens in germ cells

For females

  • In utero (week 9) make oogonia
  • oogonia–> oocytes
  • oocytes start meiosis I- stop around anaphase I
  • When born, no more eggs made
  • when oocyte awakened in puberty–> continue to meiosis II
  • Only when egg meets sperm, will oocyte finish mesosis II
    • other 3 become polar bodies and are thrown away
  • process makes 4 total copies, but only 1 used
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22
Q

What is a nondisjucntion?

A

When chormosomes don’t pull apart after crossover

how we end up with trisomy/monosomy in offspring

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23
Q

What increases risk for disorders of nondisjunction?

A

increased maternal age

24
Q

What is turner syndrome?

A
  • Sex chromosome missing (45:X)
  • Typically infertile
  • characteristics- short stature, female genitalia, webbed neck, shieldlike chest with underdeveloped breasts and widely spaced nipples
  • Tend to have cardiac problems and die around 50
25
Q

What is klinefelter syndrome?

A
  • Extra X chromosome (47, XXY)
  • small testest
  • some development of breasts
  • sparse body hair
  • long limbs
26
Q

What is crossover?

A
  • shuffling and mom and dad’s chromosome 1 prior to splitting during meiosis
27
Q

What are some issues that can occur with chormosome crossover?

A
  • Deletion occurs when chormosome segment is lost
  • generation of duplication and deletion through unequal crossing over
    • ex- cri du chat- deletion of part of 5q
28
Q

What is translocation?

A

Crossover between non-homologous chromsoomes (ie dad chormosome 2 and mom chromosome 3 got together for crossover)

  • Initial off spring (those created with that crossover) will be ok as long as balanced translocation
  • However, that offspring will have trouble producing offspring
    • also more susceptible to Ca
29
Q

What are some dominant single gene disorders?

A
  • Familial hypercholesterolemia
  • retinoblastoma
  • li-fraumeni
  • porphyria
  • huntington dx
  • achondroplasia
  • marfan

Only need one gene affected in order to be affected

30
Q

Example recessive single gene disorder?

A
  • Sickle cell anemia
  • Cystic fibrosis
  • lysosomal storage dx (Tay Sachs- Gaucher- Miemann-pick)
  • Glycogen storage dx (von Gierke, Pompe, McArdle)
  • Phenylketonuria
  • Hemochromatosis
  • Wilson’s disease

Need both genes to be bad to cause a problem

31
Q

Example x-linked recessive dx?

A
  • Duchenne muscular dystorphy
  • hemophilia A (factor VIII) and B (factor IX)
  • Lesch-nyhan syndrome
32
Q

Familal hypercholesterolemia?

A
  • Dominant single gene d/o
  • defect in cholesterol receptor–> high cholesterol
  • If get one gene from mom/dad–> only 1/2 good receptors on cell, liver gets message to increase cholesterol
    • liver begins to make more cholesterol (double)
  • If both genes bad–> no good receptors and usually die in utero
    • if somehow you survive utero–> typically first MI very young (1yo or so)
33
Q

What is porphyria?

A
  • defect in porphyrin enzyme–> buildup of intermediat product
  • dominant- single gene
  • Anemia, people look like they should be dead
34
Q

Huntington disease?

A
  • Dominant
  • increase in repeating CAG count (triple nucleotide repeat, longer the repeat, the more problems) –> neuro-degeneration similar to parkinson’s
35
Q

Achondroplasia?

A
  • Dominant single gene
  • FGFR 3 mutation–> decreases bone growth
36
Q

Cystic fibrosis?

A
  • Recessive gene
  • defect in Cl transporter
    • 1 bad transporter- still move chloride, just at half rate
    • 2 bad- then get cystic fibrosis
37
Q

Lysosomal storage dx?

A
  • Defect in lysosomal enzyme–> cells fill with debris
38
Q

Phenylketonuria?

A
  • Recessive
  • Defect in enzyme that converts phenylalanine to tyrosine
    • again, 1 bad gene, ok, just convert slower
    • 2 bad genes- problems with buildup of intermediate products
39
Q

Hemochromatosis?

A
  • Dysregulation of iron uptake–> iron overload
  • txmt- blood transfusion
40
Q

Wilson’s disease?

A
  • defective copper transporter for biliary excretion–> copper overload
  • Recessive gene
41
Q

Who is more affected by x-linked recessive diseases?

A

men

women tend to be carriers

  • women have 2 copies X, so if one bad, usually fine, just carriers
  • men- only have one copy of X. Takes one defective gene to not work

Dominant x-linked genes typically die in utero

42
Q

Do you have to inherit trait for achondroplasia?

A

no, can be spontaneously mutates, but rare.

43
Q

What is likelihood of offspring having disease when 2 affected parents have a dominant disease?

A

3/4 children will have disease

1/4 unaffected

44
Q

What is likelihood of offspring being affected with dominant disease when one parent has a disease and one does not?

A

1/2 affected

1/2 unaffected

45
Q

In a recessive disease, how many would be affected if both parents carriers?

A

1/4 potentially affected (homozygous affected)

2/4 heterozygous carriers

1/4 normal (homozygous normal)

46
Q

What is the X-inactivation process?

A
  • In zygote and early embryonic cells, maternal and paternal X chromosomes are botha ctive
  • X inactivation takes place in uterine development
    • all cells individually flip a coin, and turn off one of the x’s
    • so, women are mosaics with either mom or dad’s x chormosome working
      *
47
Q

What is example of a system affected by X inactivation process?

A
  • hepatocytes- gene for clotting factors carried on x-chromosome
    • if female and inherited faulty x from mom- half of hepatocytes have functioning chromsome, half dont
      • make 1/2 clotting factors, can generally be ok
    • if male and inherited faulty x from mom- that’s the only x you have and ALL hepatocytes incorrectly make coag factors- screwed
48
Q

What is a barr body?

A
  • Inactive x chromsome in female
  • not fully inactive, but about 99% inactive
49
Q

What is likelihood of offspring having x-linked dx if mom is carrier and father is normal?

A

2/4 unaffected

1/4 carrier

1/4 affected

50
Q

What is likelihoood of offsping having x-linked diseaes if mom is unaffected and not carrier and dad is affected?

A

1/2 are carriers

1/2 normal

51
Q

What is likelihood of offsping having x-linked disease if mother is carrier and father affected?

A

1/2 have the disease

1/4 carrier

1/4 normal

52
Q

What is duchenne muscular dystophy?

A

defect in sarcolemma–> muscle damage and wasting

recessive

53
Q

What is hemophilia A and B?

A

lack of factor VIII (A) or IX (B)

Recessive

54
Q

What is lesch-nyhan syndrome?

A

lack of purine production–> uric acid overproduction

55
Q

What is epigenetics?

A
  • Summary- how we can have genes skip a generation
  • When you make gametes, disable some of the gene (via methylation)
    • there’s a male and female pattern for doing this
    • female will disable certain genes
      • egg with gene turned off (every female does this)
      • kid made with egg, kid has 2 copies of every gene but mom’s copy turned off, only dad’s copy active
    • Men have diff pattern activation
      • turn off diff genes than female
      • kid has some of mom’s genes turned off, some dad’s gene turned off
        • won’t affect kid BUT when daughter goes to make egg, takes gene from one or other using cross over
        • can take gene in dad active in her, put it in egg and turn it off
          • can have gene from father but not express characteristic
56
Q

What happens if environment changes suddenly?

A
  • We want kids that are adaptive to environment
  • we can change DNA, turning on and off genes based on our environment
    • if famine- make epigenetic modification to turn off hunger gene
  • bascially, we can immediately affect our genes to affect future generation
    • ex with fetal alcohol syndrome, animal in swamp that make alcohol

Pathophys Test 1 (7 decks)

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