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CMMB 413 MT 1 > Clinical Cytogenetics > Flashcards

Clinical Cytogenetics Flashcards

1
Q

Mitochondrial DNA (MtDNA) Properties

A

-circular and lacks introns
-is exclusively maternally inherited
-is 16.5 kb and encodes 37 genes
-mitochondrial-specific transcription and translation

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2
Q

MtDNA Organization

A

-heavy and light strands
-D-loop contains the control region
-replication is variable between cells
-between 1000-10, 000 mtDNA copies within the inner mitochondrial compartment in a cell

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3
Q

7S DNA Strand

A

-causes D-loop in MtDNA due to being triple stranded
-short third strand in MtDNA
-can pair with the the L-strand=displacement of the H-strand + D-loop formation

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4
Q

Maternally Inherited Diabetes and Deafness (MIDD)

A

-1% of diabetic patients and most common in the Japanese population
-mutations in mitochondrial genes, MT-TL1, MT-TK, or MT-TE by reducing tRNA activities

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5
Q

Human Genome Project (HGP)

A

-an international ,collaborative research program aimed to map and understand all the genes (genome) of human beings.
-intron-exon structure distinguishes eukaryotes from prokaryotes.
-introns are spliced out of mRNA before they leave the nucleus
-3.1Gb of DNA (,1.5% encodes proteins, 45% is unique or single-copy, rest is repetitive)

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6
Q

Alpha-satellite

A

-171-bp sequence that can extend to several million base pairs or longer
-near the centromeres of chromosomes

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7
Q

Minisatellites

A

-blocks of tandem repeats (each 11 bplong or greater)
-total length is a few thousand base pairs

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8
Q

Microsatellites

A

-the repeat units are 1-10 bp long
-total length less then a few hundred base pairs

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9
Q

SINE (short interspersed elements) family

A

-10% of the genome (>1 million members)
-member is 300bp in length
ex. Alu family

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10
Q

LINE (long interspersed Nuclear Element or L1) family

A

~20% of the genome (~850,000 members) members could be as long as 6 kb in length

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11
Q

Segmental duplication family

A

->5% of the genome
can span hundreds of kb

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12
Q

Nucleosome

A

the basic repeating structural subunit of the packed chromatin inside the cell’s nucleus
(DNA wrapped around 8 histones)

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13
Q

Solenoid

A

includes 6 nucleosomes
organized into chromatin loops

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14
Q

Ploidy

A

refers to the number of different copies of each chromosome present in a cell
the number of chromatids within a cell is indicated by the letter c

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15
Q

1n 1c

A

one haploid chromosome that is unreplicated

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16
Q

2n 2c

A

two homolog (diploid) unreplicated chromosomes (two chromatids)

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17
Q

1n 2c

A

one single chromosome (haploid) in which DNA has been duplicated

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18
Q

2n 4c

A

two homolog chromosomes (diploid) consisting each of two sister chromatids (two yellow and two blue), thus 4 c in total

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19
Q

Meiosis

A

-is responsible for the production of gametes

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20
Q

genetic consequences of meiosis

A

-shuffling of the genetic materials by recombination
-additional shuffling of genetic material by random assortment of the homologous
-reduction of the chromosome number from diploid (2n) to haploid (n)
-segregation of alleles

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21
Q

Meiotic Nondisjunction

A

the homologous chromosomes or the sister chromatids of a chromosome failed to separate from one another to travel to the opposite poles, resulting in cells that do not have normal number of chromosomes

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22
Q

clinical cytogenetics

A

is the practice of medical genetics by studying the structure and number of chromosomes to identify chromosome abnormalities

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23
Q

Aneuplodiy

A

one or more extra or missing chromosome. instead of 46 chromosomes in a diploid cell

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24
Q

Trisomy

A

extra copy of one chromosome

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25
Q

Triploidy

A

when you have an entire extra set of chromosomes

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26
Q

Tetrasomy

A

when you have two extra copies of the same chromosome

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27
Q

Tetraploidy

A

when you have two extra sets of chromosomes

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28
Q

Chromosomal Abnormalities

A

-leading cause of pregnancy loss
`10-20% ocytes have an extra or missing chromosome
-2% of pregnancies in women >35 years

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29
Q

autosomal disorder and unbalanced rearrangments

A

1/230

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30
Q

Balanced rearrangements

A

1/500

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31
Q

Indicators- early growth/development

A

-developmental delay
-physical malformations
-ambiguous genitalia
mental retardation

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32
Q

Indicators- Stillbirth

A

10% stillbirth/neonatal death

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33
Q

fertility problems

A

-amenorrhea
-recurrent miscarriage
-history of infertility

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34
Q

Karotyping

A

-determine abnormal chromosomal numbers
-determine abnormal chromosomal structures caused by rearrangements

35
Q

insertion/deletions

A

-autosomal deletions occurs at 1/7000 live births

36
Q

translocation

A

the transfer of a segment of one chromosome to another chromosome

37
Q

Robertsonian translocation

A

is a translocation between 2 acrocentruc chromosomes by fusion at or near the centromere, with the loss of short arms

38
Q

Routine Karotyping

A

-cells must be easy to obtain
-able to grow rapidly in culture

39
Q

Giemsa banding (G)

A

-staining with Giemsa stain
-light (GC-rich regions) and dark (AT-rich regions)
-most common

40
Q

Giemsa stain

A

nucleic acid, methylene blue, eosin, and Azure B

41
Q

metacentric chromosomes

A

-more or less central centromere
-arms of approximately equal length
-1,2,3

42
Q

submetacentric chromosomes

A

-off-center centromere
-arms of different length
-4,5

43
Q

acrocentric chromosomes

A

-centromere near one end
-13,14,15, 21,22

44
Q

Quinacrine banding

A

-staining with quinacrine mustard
-detects heteromorphism (homologous pair which are not morphologically identical)

45
Q

Reverse Banding

A

-Europe
-heated before staining
-dark and light bands are the revese of the Q and G banding methods
-used to analyze distal ends of chromosomes that stain poorly with the other methods

46
Q

C-banding

A

-method involving Xylene substitute, for staining:
-centromeric regions (1q, 9q,16q, distal Yq
-regions containing constitutive heterochromatin, and staining darkly at interphase cells

47
Q

Constitutive heterochromatin

A

hyper-condensed, late replicating, and C-banding positive genomic region, usually consisting of highly repetitive DNA

48
Q

Fluorescence In Situ Hybridization

A

-uses fluorescent labelled ssDNA probes to hybridize with chromosomes immobilized on microscope slides to identify chromosomal aberrations
-gene specific or locus specific probes used to detect chromosomes

49
Q

Spectral Karyotyping

A

-24 probes of human chromosomes are combined and used for FISH of metaphase chromosomes
-each chromosome-specific probe emits it’s own signal

49
Q

Spectral Karyotyping

A

-24 probes of human chromosomes are combined and used for FISH of metaphase chromosomes
-each chromosome-specific probe emits it’s own signal

50
Q

Plasmid

A
  • an extra-chromosomal DNA molecule found in bacteria and can be replicated independently from the the microoorganism’s own chromosomes
51
Q

Vector

A

-plasmid that is engineered for the applications in molecular biology
ex. BAC specially designed

52
Q

Library

A

collection of clones, which carry vector molecule into which a different fragment of DNA derived from the total DNA or RNA is inserted

53
Q

Genomic DNA

A

complete or fragment of a gene including introns and exons

54
Q

Genomic library

A

a collection of total genomic DNA from an organism

55
Q

cDNA

A

is a coding DNA fragment synthesizexd from a mRNA template using reverse transcription

56
Q

cDNA library

A

is a combination of caDNA fragments inserted into a collection of host cells, which together constitute the “transcriptome” of the organism

57
Q

Nucleic Acid Hybridization

A

is a process establishing a sequence-specific interaction between 2 or more complementary strands of nucleic acids into a single complex

58
Q

Comparative Genome Hybridization (CGH)

A

-used to determine the copy number (or dosage) differences between two distinct DNA samples
-useful for detecting deletions and duplications that <1 Mb
eg. copy number polymorphism

59
Q

CGH Limitation

A

when used with metaphase chromosomes deletions/duplications smaller than 5-10 Mb cannot be detected microscopically.
enter aCGH

60
Q

DNA Microarray

A

-collection of microscopic DNA spotted onto a solid surface for measuring the expression levels of large number of genes simultaneously or to genotype multiple regions of a genome

61
Q

Rett Syndrom Microarray

A

-x-linked dominant affects motor skills and language
-loss of function of the MECP2 gene which encodes a nuclear protein that binds methylated DNA and recruits histone deacetylase to methylated DNA; or in over expression as in MECP2 duplication syndrome

62
Q

Genomic Hybridization Techniques

A

FISH
SKY
CGH
Microarray

63
Q

Whole Genome Sequencing

A

-alignment of sequence reads from a patient’s genome to the reference sequence

64
Q

Clastogens

A

chromosome breaking agents

65
Q

mosaicism

A

mutation occurs in one cell of the developing embryo

66
Q

Duplication

A

can be caused by unequal crossing over between misaligned homologous chromosomes or sister chromatids

67
Q

Haploinsufficiency

A

the inability if a single copy of a gene to carry out the function normally performed by two copies

68
Q

Pallister-Killian Syndrome

A

craniofacial, retardation
duplication of chromosome 12p

69
Q

Marker Chromosome

A

-very small chromosome annot be identified
-1/2500
-likely to be ring

70
Q

Ring chromosomes

A

formed by two breaks and the broken ends of the chromosome reunite in ring stucture

71
Q

Isochromosome

A

chromosome in which one arm is missing (partial monosomy) and the other duplicated (partial trisomy)

72
Q

Mechanisms for isochromosome formation

A

-mis-division through centromere
-defective meiotic crossover

73
Q

pseudodicentric

A

dicentric chromosomes that are
-mitotically table due to one of the two centromeres in inactivated
-both centromeres always coordinate their movement to one of the mitotic pole during segregation

74
Q

Dicentric chromosomes

A

chromosomes that have 2 centromeres

75
Q

Balanced rearrangements

A

no phenotypic effect for carrier
-chromosomal inversions
paracentric, pericentric
-chromosomal translocations
reciprocal, Robertsonian, insertion

76
Q

Chromosomal inversion

A

occurs when a single chromosome undergoes 2 breaks and is reconstituted with the segment between the break inverted

77
Q

Paracentric inversion

A

-no centromer
-both breaks occur in one arm
-arm ratio is not altered
-determined with banding or FISH (locus probes)

78
Q

Pericentric incersion

A

-includes centromere
-break in each arm
-easier to be identified due to changes in banding patterns

79
Q

Chromosomal translocation

A

involves the exchange of chromosome segments between 2 non-homologous chromosomes

80
Q

Reciprocal Translocation

A

-total genetic material remains the same
-chromosome number is unchanged

81
Q

Robertsonian translocation

A

-deletion of short arms (acrocentric chromosomes)
-one less chromosome

82
Q

Chromatid

A

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

83
Q

Chromatin

A

mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms

CMMB 413 MT 1 (1 decks)

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