General (1) Flashcards

1
Q

What step of the cell cycle is the most error-prone?

A

anaphase I

chromosomes separate at centromere

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2
Q

At what phase do oocytes pause from formation until ovulation?

A

prophase I

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3
Q

Where is the polyA tail located?

A

the 3’ UTR

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4
Q

What is the TATA box?

A

a promoter sequence upstream of the transcription start site

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5
Q

What is the CAT box?

A

a region upstream of the TATA box ; important for transcription, normal gene expression

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6
Q

What is the start codon?

A

AUG

methionine

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7
Q

What are the 3 stop codons?

A

UAA, UGA, UAG

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8
Q

How many kb are in the mitochondrial genome?

How many genes?

A

16kb

37 genes

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9
Q

What is the difference between a proband and a consultand?

A

proband: first affected person who brings an issue to attention
consultand: first person who seeks genetic counseling

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10
Q

What does “sex-limited” mean?

A

a defect is inherited in an autosomal fashion, but affects only one sex
ex: HBOC

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11
Q

What is a missense mutation?

A

a mutation leading to a different amino acid

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12
Q

What is a nonsense mutation?

A

a single base substitution leading to a premature stop codon; yields a shortened and usually nonfunctional protein

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13
Q

What is an example of a dinucleotide mutation hotspot?

A

CG

methylated Cs can spontaneously deaminate to form T

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14
Q

What percentage of sperm contain a new deleterious mutation?

A

10%

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15
Q

What are tested in a paternity test?

A

microsatellites

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16
Q

What is a linkage analysis?

A

a determination of the distance between 2 genes based on frequency with which they remain together through meiosis

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17
Q

What is the most common chromosome rearrangement?

A

13q14q Robertsonian translocation

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18
Q

What is the incidence of chromosome abnormalities in newborns?

A

0.7%

1/160

19
Q

What is the incidence of chromosome abnormalities in miscarriages?

A

40-50%

20% of them are 45,X

20
Q

What is a complete mole?

A

paternal chromosomes only

no fetus, abnormal placenta

21
Q

What is a partial mole?

A

triploid (2/3 of cases have 2 paternal sets and 1 maternal set of chromosomes)
atrophic fetus, remnants of a placenta

22
Q

What syndrome is the most common cause of mental retardation?

A

Down syndrome, T21

23
Q

How many genes are on the Y chromosome?

A

50

24
Q

At what point in embryonic development are the gonads bipotential? What happens then?

A

6th week

if TDF is present it acts as switch to stop ovarian development

25
Q

What percentage of genes are inactivated during X-inactivation?

A

85% - 90%

26
Q

What is the function of hemoglobin?

A

to carry oxygen in red blood cells

27
Q

In what regions of a gene does nonsense mediated decay occur?

A

when the nonsense mutations are more than 50bp 5’ to the end

28
Q

What is allelic heterogeneity?

A

when there can be multiple mutations (leading to multiple alleles) at a specific locus which lead to the same phenotype

29
Q

What is locus heterogeneity?

A

when there are multiple loci associated with the same disease

30
Q

What is the most common indication for prenatal diagnosis?

A

advanced maternal age

31
Q

If an amniocentesis is performed too early, what risks are present?

A

miscarriage, club feet

32
Q

What percentage of neural tube defects occur with a positive family history?

A

5%

33
Q

How long do fetal lymphocytes remain present in maternal blood?

A

years - may confound fetal cell sampling in future pregnancies

34
Q

If a neural tube defect occurs in a pregnancy, what is the risk that it will happen in a subsequent pregnancy between that couple?

A

4%

35
Q

What are the criteria for effective newborn screening programs? (6)

A

1) treatment is available
2) starting treatment early can reduce or eliminate severity of disease
3) there is no other way (exam) to notice the disorder in a newborn
4) rapid and economical testing is available with high sensitivity (no false negatives) and somewhat specific (few false positives)
5) condition is relatively common such that the screening is worth the cost
6) societal infrastructure is in place to inform parents/doctors and begin treatment

36
Q

What are the 3 cardinal principles of medical ethics?

A
  • beneficence
  • respect for individual autonomy
  • justice
37
Q

What teratogenic substance can lead to heart defects?

A

lithium

38
Q

What 3 congenital phenotypes have a 30% syndromic, 70% nonsyndromic breakdown?

A
  • hearing loss
  • heart defects
  • cleft lip
39
Q

What 4 congenital phenotypes have a prevalence of approx. 1/1000?

A
  • hearing loss
  • NTDs
  • clefting
  • congenital heart defects
40
Q

What are 5 phenotypes which should make you consider chromosome abnormalities?

A
  • global DD, MR
  • major malformations
  • multiple minor anomalies
  • growth retardation
  • hearing loss
41
Q

Other than a neurologist, what two types of specialists are especially important for patients with neuromuscular disorders?

A
  • cardiologist

- respiratory therapist

42
Q

What is the carrier frequency of CF in caucasians, blacks, asians?

A

caucasian: 1/28
black: 1/61
asian: 1/87

43
Q

What is the most common molecular cause of overgrowth?

A

hypomethylation

44
Q

What is another term for anomaly?

A

malformation