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552 Pathophysiology > Genetics > Flashcards

Genetics Flashcards

1
Q

Transcription

A

mRNA synthesis

in nucleus

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2
Q

How is mRNA different from DNA?

A

single stranded
ribose backbone, not deoxyribose
Us instead of Ts

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3
Q

Translation

A

protein synthesis

in ribosome

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4
Q

codon

A

on mRNA

3 base pairs: code for amino acid

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5
Q

ribosomes

A

protein factory
make protein out of codon from mRNA and anticodon on tRNA
either in cytoplasm or rER

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6
Q

How many nucleotides? amino acids? codons?

A

4 possible nucleotides, each w/ 3 base pairs: 4^3=64 possible codons to code for 20 amino acids
allows for redundancy in translate table

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7
Q

single nucleotide polymorphism (SNP)

A

base pair subsitution
at most only 1 amino acid is changed
very common
allow for no 2 people to look the same

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8
Q

Frame shift mutation w/ one base pair inserted or deleted

A

the rest of the strand will be messed up
protein won’t work
results will be devastating, t/f uncommon

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9
Q

Single gene disorders

A

Dominant
Recessive
X-linked: recessive or dominant

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10
Q

Dominant single gene disorder

A

2 copies of each gene (1 from each parent)
If one bad gene, half of the protein will be bad
If the half bad protein causes a problem, its a dominant disorder

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11
Q

Recessive single gene disorder

A

need 100% problem to cause disease
both genes must be defective
If only 1 gene is bad, it will be overcome by the good proteins

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12
Q

X-linked single gene disorder

A

Recessive: all of the Xs need to be defective (from both parents)
More of a problem for males

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13
Q

Translocations

A

genetic material from 1 chromosome mistakenly put on another chromosome

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14
Q

Deletions

A

genetic material deleted from a chromosome

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15
Q

Nondisjunction

A

abnormal # of chromosomes (aneuploidy)
leads to trisomy or monosomy
incorrect separation of chromosome in Meiosis I or Meiosis II
can occur on any chromosome, but only 21, 18, 13 or X are survivable
usually Trisomy
normal: 44 chromosomes + XX or XY

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16
Q

Down syndrome

A

Down: trisomy 21
maternal age increases chance of trisomy
intellectual disability, facial abnormalities, cardiac problems

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17
Q

Turner syndrome

A 
(45:X)
44 chromosomes + X
only monosomy that survives to term and is consistent with life
infertile females
cardio problems
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18
Q

Klinefelter syndrome

A

47:XXY
infertile males (some are fertile)
slight decrease in IQ

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19
Q

polyploidy

A

chromosome sets that don’t = 2
partial mole: triploid: 2X from dad & 1X from mom
usually 69:XXX or 69:XXY
ocassionally go to term but don’t live long

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20
Q

locus

A

location in the genome

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21
Q

allele

A

one member of a pair of genes (1 allele from mom, 1 from dad)

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22
Q

Genotype

A

genetic material

23
Q

Phenotype

A

physical manifestation

24
Q

Penetrance

A

the chance that phenotype follows genotype

25
Q

Haplotype

A

alleles on a single chromosome

26
Q

Recombination/crossover

A

gene rearrangement btw homologous chromosomes
occurs during prophase I of meiosis
allows for new arrangement of maternal and paternal alleles on same somatic chromosome

27
Q

Structure of chromosomes

A

2 chromatids attached at the middle by centromere
2 short arms and 2 long arms
P: petite arm
Q: long arm

28
Q

SNP

A

single nucleotide polymorphism

29
Q

somatic cell

A

body cells; not sex cells
reproduced by mitosis
46 (2 pairs of 23) chromosomes in each cell: 22 autosomal and 1 pair sex chromosomes
diploid cell

30
Q

gamete

A

sex cells: egg or sperm
only 1 copy of each chromosome
haploid cell

31
Q

karyotype

A

chart that places homologous chromosomes in size order matching shape and banding patterns

32
Q

euploid cells

A

balanced set of chromosomes (in relation to haploid #

33
Q

aneuploid cell

A

abnormal # of chromosomes (in relation to haploid #)

34
Q

meiosis

A

how a diploid cell divides for sexual reproduction into 4 haploids
2 fissions occur of the nucleus
4 gametes created: each have 1/2 the # chromosomes as original cell
mixing of chromosomes occur

35
Q

What happens if nondisjunction occurs during meiosis I?

A

all gametes are affected
2 have 1 extra chromosome
2 have 1 less chromosomes

36
Q

What happens if nondisjunction occurs during meiosis II?

A

half of the gametes are affected
2 normal
1 has 1 extra chromosome
1 has 1 less chromosome

37
Q

At the end of meiosis, how many of the 4 haploids become sex cells in males?
Females?

A

males: keep all 4: 4 sperm cells
females: 1 ova, and 3 polar bodies

38
Q

When does meiosis occur in females?

Males?

A

Females: all in fetal ovary
males: after puberty

39
Q

What does crossover allow for?

A

genetic diversity

40
Q

What are some errors of crossover?

A

uneven crossover: 2 copies of a gene
deletion of a gene: cri du chat
* we tolerate additional DNA better then missing DNA

41
Q

What is chromosome translocation?

A

cross over btw non-homologous chromosomes (i.e. chromosome 1 from mom and chromosome 2 from dad mix together)

42
Q

If a child has balanced translocation how will this affect them?

A

They will have the right amount of DNA but when they go to have kids, the chances of combining DNA in the correct amounts is very low: alot of spontaneous abortions
Also…problems at the edges w/ mutated proteins: increased risk of Ca

43
Q

What are some examples of Dominant single gene disorders?

A 
Familial hypercholesterolemia
Huntington
Achondroplasia
Marfan
Retinoblastoma
Li-Fraumeni
44
Q

What are some examples of Recessive single gene disorders?

A 
sickle cell anemia
cystic fibrosis
lysosomal storage diseases (Tay-Sachs, Gaucher, Nieman-Pick)
Phenylketouria
Glycogen storage disease
45
Q

What are some examples of X-linked recessive single gene disorders?

A 
Duchenne muscular dystrophy
Hemophilia A (factor VIII) or B (IX)
46
Q 
In a pedigree, what does each symbol mean?
empty circle
empty square
empty diamond
darkened square or circle
square or circle w/ line through it
A

empty circle: unaffected female
empty square: unaffected male
empty diamond: unknown sex
darkened square or circle: affected male or female
square or circle w/ line through it: dead

47
Q

If 2 people have a dominant disease (Dd), how likely is it that they will have a:
homozygous affected
heterozygous affected
homozygous normal

A

homozygous affected: 25% (rare)
heterozygous affected: 50%
homozygous normal: 25%

48
Q

If 1 person has a dominant single gene disorder (Dd) mates with a normal person (dd), how likely is it that they will have a:
homozygous affected
heterozygous affected
homozygous normal

A

homozygous affected: 0
heterozygous affected: 50%
homozygous normal: 50%

49
Q

If 2 people are carriers of a recessive single gene disorder, what is the likelyhood they will have a
homozygous affected
heterozygous carrier
homozygous normal

A

homozygous affected: 25%
heterozygous carrier: 50%
homozygous normal: 25%

50
Q

How does X inactivation work?

A

occurs in embroyo of female: inactivation occurs and cells will either have an active paternal X or maternal X
“X chromosome mosaics”

51
Q

If a normal male mates w/ a female carrier of an X-linked recessive gene, what is the likelyhood that there will be a
normal daughter/ son
carrier daughter/son
affected daughter/son

A

normal daughter: 25%; son: 25%
carrier daughter: 25%; males: 0
affected son: 25%; females: 0

52
Q

If a normal female mates w a male affected by an X-linked recessive disease, what is the likely hood they will have a
normal daughter/ son
carrier daughter/son
affected daughter/son

A

normal daughter: 0 son: 50%
carrier daughter: 50% son: 0
affected daughter/son: 0

53
Q

if a carrier female mates w/ a male w/ a recessive gene disease, what is the likely hood they will have:
normal daughter/ son
carrier daughter/son
affected daughter/son

A

normal daughter: 0 son: 25%
carrier daughter: 25% son: 0
affected daughter: 25% : 25%

54
Q

What are epigenetic modifcations?

A

we can actually turn off some genes

  • generation skipping phenomena
  • genes that are methylated can’t be expressed but can be passed to your offspring

552 Pathophysiology (5 decks)

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