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Block 1 Week 1 > Genetic Contributions to Common Disease > Flashcards

Genetic Contributions to Common Disease Flashcards

1
Q

What is genetic drift?

A

variation in the relative frequency of different genotypes in a small population

  • due to the chance disappearance of particular genes as individuals die or do not reproduce
  • REDUCE GENETIC DIVERSITY
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2
Q

Why is loosing alleles in a population due to genetic drift bad?

A

-at first, those alleles may not have a huge role, but if an old pathogen is RE-INTRODUCED, that the allele had previously protected for, now you have a population at risk for wipe out due to lacking the protective allele.

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3
Q

Individual vs. population when it comes to protective allele loss?

A
  • in a population, some members will lack a protective allele for certain pathogens due to genetic diversity. BUT herd immunity will protect them, the disease won’t be as widespread or endemic
  • also individual death is not as traumatic as pop death
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4
Q

what is herd immunity?

A
  • when individuals are protected by the resistance of the population to a certain disease or pathogen
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5
Q

Generally speaking why is loosing genetic diversity bad?

A
  • because genetic diversity incase population’s ability to fight new/ recurrent diseases
  • no genetic diversity= one bad pathogen could potentially wipe out entire population
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6
Q

What is Hybrid Vigor?

A

-populations with more allelic diversity will outgrown/outbreed the populations with less allelic diversity since diversity leads to increased resistance to pathogen & better adaptability to env changes

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7
Q

Different types of mutations and their consequences?

A
  • phenotypes (severity of disease) depends on whichmuatted alleles person gets and where those alleles have mutations
  • can be at any point of DNA synthesis, repair, trxn, translation, splicing UTR region; ANYWHERE ON THE GENE
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8
Q

Chromosomal disorder and their affect on pregnancy?

A
  • many chromosomal disorders are too severe to survive

- 50% of first trimester miscarriages, 5% still births

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9
Q

How can we tell WHEN the chromosomal abnormality occurred?

A
  • if in 100% of individuals cells, came from the parents germ cells (meiosis)
  • if only in a small subset of cells, then could have occurred anytime after fertilization (mitosis)
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10
Q

What is it called when have 3 of each chromosome in genome?

A

Triploidy= 3 complete copies of the genome

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11
Q

What is it called when have 3 chromosomes at ONE location in a genome?

A

-trisomy (most common chromosome abnormality)

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12
Q

Numerical chromosome abnormalities? Structural abnormalities?

A

1) Euploid or Aneuploid

2) deletions, duplications, translocations, inversions rings

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13
Q

What is euploid? Aneuploid?

A

1) multiple number of haploid number (N)
- triploid, diploid, tetraploid
2) unbalanced number of chromosomes (too many/few)
- trisomy, monosomy

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14
Q

Most common chromosomal abnormality?

A

-Trisomy (Down syndrome, Trisomy 21)

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15
Q

What is nondisjunction? When can it occur?

A
  • the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during meiosis
  • occur in meiosis 1 OR 2
  • can lead to trisomy or monosomy
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16
Q

What happens during nondisjunction in meiosis 1?

A
  • the tetrad (duplicated mom & dad chromosomes) are not evenly separated into daughter cells
  • have one cell w/ both mom &dad; one daughter cell with ZERO genetic material
17
Q

What happens during nondisjunction in meiosis 2?

A
  • the sister chromatids fail to separate into distinct daughter cells
  • one cell gets, BOTH sets of chromosomes from mom/dad, other daughter cell gets none
18
Q

Is nondisjunction occurring with all the chromosomes?

A
  • No. This is just a single chromosome, the rest of chromosomes may separate equally & correctly.
  • each chromosome separates independently, not reliant on what the number chromosomes are doing
19
Q

If took genotype of trisomic kid, can you see where the nondisjunction occurred?

A

Yes. Because each grandparent tparent has a unique genotype. Will be able to see if they have chromosomes from ONLY one grandparent (meiosis 2) or from BOTH grandparents (meiosis 1)

20
Q

Which parent is usually the problem w/ nondisjunction? Why?

A
  • typically the mother, risk is proportional to mothers age
  • because women are doing meiosis every month at ovulation until menopause
  • means eggs are more likely to have disfunction in meiosis than sperm which undergo mitosis
21
Q

Female reproduction outline?

A
  • start meiosis 1 at 20 weeks fetal
  • arrest in prophase until puberty, then complete meiosis 1 every ovulation
  • complete meiosis 2 upon fertilization w/ sperm
  • therefore cells are arrested & performing meiosis throughout women’s fertile life
22
Q

1) chromosomal deletions

2) chromosomal duplications

A

1) a portion of the chromosome is missing/deleted

2) a portion of the chromosome is duplicated creating extra genomic material

23
Q

chromosomal translocations? The two types? Why are they so bad?

A
  • when a portion of one chromosome is transferred to another chromosome
    1) robertsonian translocation
    2) reciprocal translocation
    • BOTH can lead to balanced/unbalanced*

-are bad when have an unbalanced translocation and are missing segments of genetic material

24
Q

What is a Robertsonian translocation?

A
  • when an entire chromosome gets placed on top of another chromosome at the centromere (usually head-head)
  • usually attaches to the p arm
  • can be balanced or unbalanced
25
Q

What are chromosomal inversions?

A

when a portion of the chromosome has broken off, turned upside down, and reattached
-genetic material is now inverted

26
Q

What are chromosomal rings?

A
  • a portion of a chromosome has broken off and formed a circle or ring
  • this can happen with/without loss of genetic material
27
Q

What are isochromosomes?

A

-chromosomes supposed to split down the middle, but instead they separated

28
Q

effect of meiotic recombination on homologous chromosomes?

A
  • can be balanced, when no genetic material is lost (usually symptomless) or unbalanced (devastating)
  • leads to patchwork inheritance due to crossing over between homologous chromosomes
  • occurs during meiosis , increases genetic diversity & heterogeneity
29
Q

What is an unbalanced translocation?

A
  • when a parent had a translation as a result of their parents egg+ sperm combo
  • parent has equal amount fo genetic material none is missing
  • when have child though, can pass on extended chromosomes or nearly deleted chromosomes therefore creating an imbalance and a gain/loss of genetic material (monosomy or trisomy) which leads to genetic disorders
30
Q

What is an unbalanced translocation?

A
  • when a parent had a translation as a result of their parents egg+ sperm combo
  • parent has equal amount fo genetic material none is missing
  • when have child though, can pass on extended chromosomes or nearly deleted chromosomes therefore creating an imbalance and a gain/loss of genetic material (monosomy or trisomy) which leads to genetic disorders
31
Q

How use FISH to detect chromosomal abnormalities?

A
  • we can paint chromosomes unique colors and see them in interphase or metaphase
  • see if all chromosomes are present (2 of each color) and see if they are translocated onto other chromosomes or not
32
Q

Different kind of FISH techniques?

A

1) entire chromosome
2) locus specific (with DNA specific fluorescent probe)
3) centromere repeat probe

33
Q

1) 3q29 mean?

A

chromosome 3, q arm, band 29

34
Q

What is anticipation mean?

A
  • involved in alzeihmers & other disorders
  • means that each generation has a higher risk of having more severe disease since triplet repeats increase with each generation
  • saying symptom gets worse with each generation
35
Q

CAG repeats in healthy person? CAG repeats for Alzeihmers? reduced penetrance range?

A

1) 1-34 you are healthy
2) 35-39 decreased penetrance, have a range
3) 40 and above have disease
- more repeats you have is correlated to earlier onset of disease symptoms

Block 1 Week 1 (9 decks)

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