Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CSF > Block 6 > Flashcards

Block 6 Flashcards

1
Q

Cytogenetics

A

The study of chromosomes, their structure, and inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Centromere

A

Primary constriction of a metaphase chromosome where the kinetochore forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Acrocentric

A

Centromere is located at either end of the chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sub-metacentric

A

Centromere is located closer to one end of the chromosome than the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Metacentric

A

Centromere is located in the middle of the chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Telomeres

A

Chromosome caps located at both ends of sub or metacentric chromosomes and one end of acrocentric chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Subtelomeric regions

A

Gene-rich regions located just above the telomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Chromosome arm

A

Region(s) of the chromosome adjacent to the centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

p arm

A

Smaller chromosome arm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

a arm

A

Longer chromosome arm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which tissues can be used for chromosome analysis?

A

Chromosome analysis requires dividing cells such as lymphocytes from peripheral/cord blood or bone marrow or fibroblasts from solid tissue biopsies, amniotic fluid, or chorionic villi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the procedure for chromosome analyses?

A

Obtain sample, culture and harvest cells, make a band, scan slides for metaphase cells, then analyze, capture, and karyotype the cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cytogenetic nomenclature

A

chromosomes, sex chromosomes, and +/- chromosome if an abnormality is present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Aneuploidy

A

Having a number of chromosomes not equal to a haploid number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Polyploidy

A

Having an abnormal number of chromosomes equal to a multiple of the haploid number, ie having an extra set(s) of chromosomes such as triploidy or tretraploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does triploidy happen?

A

Dispermy or dygyny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Disermy

A

Fertilization of an egg by 2 sperm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Dygyny

A

Fertilization of disomic egg (n=46) by 1 normal sperm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Diandry

A

2 paternally-derived sets of chromosomes that results in a large placenta (often a partial hydatidiform mole) and a small fetus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How does dygyny happen?

A

Usually from a complete meiosis I or II error or retention of a polar body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Mosaicism

A

Presence of 2 or more cell lines in an individual or tissue sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Meiosis in females

A

Oogonia begin division in week 12 and proceed through prophase I until the diplotene stage (~ week 12) and remain in a stage called dichytene until ovulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Meiosis I errors

A

Occur during homolog pairing if both maternal and paternal chromosomes migrate to the same (instead of opposite) poles and then split as per usual; results in 2 disomic gametes and 2 nullisomic gametes (ie there will be 2 or 0 of a certain chromosome in each egg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Meiosis II errors

A

Maternal and paternal chromosomes separate as expected but then the sister chromatids fails to separate so you get 1 disomic gamete,1 nullisomic gamete, and 2 normal gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Down syndrome

A

Trisomy 21; most common autosomal trisomy among liveborns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does trisomy 21 occur?

A

Most cases are d/t errors in maternal meiosis (MI I more so than MI II) and the remaining result from paternal meiosis errors, mitotic errors (mosaicism), or Robertsonian chromosomal translocation (~5%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Mosaic down syndrome

A

Down syndrome w/ the presence of a normal cell line in addition to the trisomy 21 line; the frequency of abnormal cells does not predict the severity of the phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Translocation down syndrome

A

Functional trisomy 21 d/t presence of an extra portion of chromosome 21 attached to chromosome 14; results from an unbalanced Robertsonian translocation involving chromosome 21

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Edward’s syndrome

A

Trisomy 18 characterized by prominent occiput, heart defects, low-set ears, rocker-bottom feet, and characteristic fist clenching; high infant mortality rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Patau syndrome

A

Trisomy 13 characterized by growth retardation, midline defects, micropthalmia, polydactyly; rarer and more severe than trisomy 21 or 18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Turner syndrome

A

Monosomy X (45,X) is very rare and characterized by short stature, broad chest, cubitus vulgus, short webbed neck, congenital lymphedema of hands and feet, sensory motor integration dysfunction, streak ovaries; some cases involve mosaic or have 1 abnormal X chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Klinefelter syndrome

A

(47, XXY); relatively common sex chromosome aneuploidy in males causing short stature and long legs, delayed puberty, infertility, small testes, tubular hyanalization, gynecomastia, menetal retardation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

(47, XXX) and (47, XYY)

A

No phenotypic abnormalities or effects no reproductive function because extra X chromosome is inactivated but typically have mental retardation issues

34
Q

SRY

A

Sex determining region of the Y chromosome; deleted or mutated in many XY females and often present (d/t Y translocation) in XX males

35
Q

Robertsonian translocations

A

Rearrangements involving only acrocentric chromosomes (13, 14, 15, 21, 22) caused by fusion of 2 long arms and loss of 1 short arm (which contain only repetitive DNA and ribosomal sequences); benign since all short arms contain the same thing

36
Q

Balanced Robertsonian translocations

A

Involve 2 breakpoints on 2 chromosomes and the swapping of material beyond the breakpoints such that no material is lost or gained, only rearranged

37
Q

Unbalanced Robertsonian translocations

A

Involve formation of a quadrivalent during meiosis and gamete formation with the 2 derivative chromosomes and the 2 normal chromosomes aligning as completely as possible, to allow for homologous recombination however when they segregate during the first meiotic division the 2 derivative chromosomes must go to one pole and the 2 normal chromosomes must go to the other for the gametes to be balanced; risk for a translocation to malsegregate is generally a function of the size of the chromosomes and the size of the translocated segments.

38
Q

Chromosomal deletions

A

Loss of material from a single chromosome; phenotype is dependent on which portion of the genetic material is lost

39
Q

Chromosomal inversions

A

A segment of chromosome breaks and is inverted and inserted back in

40
Q

Paracentric inversion

A

Breakpoints occur on the same arm outside of the centromere

41
Q

Pericentric inversion

A

Breakpoint region includes the centromere

42
Q

FISH (fluorescence in situ hybridization)

A

Technology for IDing chromosomal abnormalities by using fluorescently labeled DNA probes; depending on the probe, can detect specific chromosomal gains, losses, or rearrangements

43
Q

Locus

A

Location of a gene on a chromosome

44
Q

Allele

A

Different forms of a gene that can occupy a single locus

45
Q

Wild type

A

Most common form of a gene

46
Q

Polymorphism

A

2 or more alleles for a given locus, each present in the population at a frequency of at least greater than 1%

47
Q

Compound heterozygote

A

Genotype w/ 2 different mutant alleles at the same locus; ie alleles are different but both are defective

48
Q

The Principle of Dominance

A

Genes come in pairs, one inherited from each parent and individual genes can have different alleles, some of which are expressed over the other

49
Q

Principle of Segregation

A

Organisms inherit 2 alleles for each trait and during gamete formation allele pairs separate so that each cell has a single allele for each trait

50
Q

Principle of Independent Assortment

A

Genes at different loci are transmitted independently and are randomly united at fertilization

51
Q

What are the features of A inheritance?

A

Phenotype is vertically transmitted and equally likely to be transmitted by male or female; each child of an affected parent having a 50% chance of inheriting the trait and phenotypically normal family members do not typically transmit the trait

52
Q

Incomplete dominance

A

One allele is not completely dominant and produces an intermediate phenotype; eg achondroplasia

53
Q

Co-dominance

A

Both alleles are expressed resulting in a phenotype w. features of both alleles; eg ABO blood groups

54
Q

Germline mosaicism

A

2 or more children are born w/ an AD dz when there is no family hx of the dz; theoretically d/t the presence of more than one genetically distinct cell line in the germline of one of the parents

55
Q

Delayed age of onset

A

Some genetic conditions do not manifest until later in life eg Huntington dz and breast CA

56
Q

Penetrance

A

The probability a gene will be expressed; can be all-or-nothing or reduced/variable penetrance eg HNPCC w/ 80% lifetime risk or split-hand deformity w/ 70% penetrance

57
Q

Variable expression

A

Complete penetrance but the severity of the dz varies in people w/ the same genotype

58
Q

Pleitropy

A

One gene produces multiple different effects on physiology or anatomy

59
Q

Locus heterogeneity

A

A single disorder caused by mutations in genes at different loci eg breast CA

60
Q

Allelic heterogeneity

A

A single disorder caused by different mutations in the same gene eg CF

61
Q

Phenotypic heterogeneity

A

Different mutations in the same gene giving rise to different phenotypes eg craniosynostosis syndrome

62
Q

What are the characteristics of autosomal recessive inheritance?

A

Clinical manifestation is usually only seen in in homozygous individuals and in sibship rather than parents, offspring, or other relatives

63
Q

X-linked inheritance

A

Phenotype is determined by genes on the X chromosome; expressed in males bc they only have 1 X chromosome

64
Q

Hemizygous

A

Having only one member of a chromosome pair or segment instead of 2

65
Q

X-linked recessive

A

A single dose of a mutant allele is dz causing in males and 2 doses is dz causing in females

66
Q

X-linked dominant

A

Phenotype is expressed in both males and females but is usually more severe in males

67
Q

X-inactivation

A

ie Lyon hypothesis which says that one X chromosome is randomly inactivated

68
Q

X-linked dominant lethal

A

X-linked condition that is lethal in the hemizygous state

69
Q

Trinucleotide repeat dosorders

A

Repeated trinucleotide sequences w/i an affected gene that get expanded (ie increased number of trinucelotide repeats) as the gene is passed down through the generations leading to expression of the disorder; all involve neurological disorders

70
Q

Long expansions of trinucleotide repeat disorders)

A

Repeats are usualy ~10x the normal size and are present outside the coding region or associated w/ fragile sites; contain CCG/CGG or CTG coding sequences and are

71
Q

Myotonic dystrophy type I (DMI)

A

AD dz caused by CTG repeat in the 3’ untranslated region of 19q13 myotonin protein kinase characterized by muscle weakness w/ myotonia and muscle wasting, cardiac arrhythmias, cataracts, and male balding and infertility

72
Q

Congenital DM

A

1000’s of repeats causing severe hypotonia, myopathic faces w/ tented mouthes, absent suck and swallow, mental retardation, speech delay, and club feet

73
Q

FMR1-related disorders

A

Fragile X syndrome, Fragile X-associated tremor/ataxia (FXTAS), FMR1-related premature ovarian failure (POF)

74
Q

Fragile X syndrome

A

Results from FMR1 full mutation causing mental retardation in males (less severe in females) and characteristic physical features including long face, macrocephaly, prominent forehead and chin

75
Q

FMR1 gene

A

Normally has ~5-44 repeats of CGG w/ an AGG triplet every 9-10 repeats that anchor the sequence against expansion

76
Q

FMR1 premutation alleles

A

Have ~50-200 repeats but are not associated w/ mental retardation (but can be at increased risk for FXTAS or POF)

77
Q

FMR1 premutation alleles in women

A

Women are at increased risk of having child w/ Fragile X syndrome and may also develop tremors or ataxia

78
Q

FMR1 premutation alleles in men

A

Premutation plus white matter lesion on brain MRI give dx of FXTAS; men w/ FXTAS will transmit premutation to all of their daughters an none of their sons

79
Q

FMR1 full mutation

A

Greater than 200 repeats; about 50% of females will have mental retardation and all males will have Fragile X syndrome; almost all will have abnormal methylation of FMR1 gene

80
Q

Short expansions

A

Characterized by significantly shorter expansions (<100) of repeats w/i protein coding regions; eg CAG sequence forms polyglutamine tracts in the protein product which is a gain if function

81
Q

Huntington’s dz

A

Progressive AD neurodegenerative disorder caused by expansion of 36+ CAGs in HTT; onset is 35-44 years w/ mean survival of 15-18 years after dx

82
Q

Friedreich ataxia

A

AR dz caused by GAA repeats that is characterized by slowly progressive ataxia w/ dysarthria, scoliosis, bladder dysfunction, absent LL reflexes, and loss of position/vibration senses; onset is 10-15 yrs and usually before age 25

CSF (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions