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Genetics 2133 > Chromosomal Instability > Flashcards

Chromosomal Instability Flashcards

(50 cards)

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1
Q

What is chromosomal instability?

A

A distribution of chromosomes deviating from the modal number, or an elevated frequency of chromosome gains/losses

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2
Q

What is CIN?

A

Chromosomal instability

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3
Q

What do CIN cells and cancer cells have in common? (4)

A
  1. Microsatellite instabilities
  2. Aneuploidy
  3. Polyploidy
  4. Chromosomal rearrangements
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4
Q

What is a microsatellite instability?

A

DNA mismatch repair in inhibited in microsatellite (repeating) areas

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5
Q

What are the two ways a CIN can arise?

A

Spontaneously or in response to carcinogens

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6
Q

What are CINs caused by?

A

Defects in proteins or enzymes essential for DNA repair and chromosomal maintenance

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7
Q

What does diagnosis of a CIN compose of?

A
  1. Genetic testing
  2. Evaluation of chromosomal breakage
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8
Q

What are 4 well known CIN examples?

A
  1. Louis Bar - Lack of coordination/dilated blood vessels
  2. Bloom Syndrome - skin changes/immune deficiency/cancer
  3. Fanconi Anemia - genomic instability/cancer
  4. Nijmegen breakage syndrome - microcephaly, growth retardation
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9
Q

What is a microsatellite?

A

A short repetitive DNA sequence (1-9 base pairs)

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10
Q

What are the 3 major uses of microsatellites?

A
  1. Genetic Mapping
  2. Population genetics - study diversity/relationships
  3. Forensic analysis - DNA fingerprinting
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11
Q

How many human microsatellites are sequenced?

A

1.4 million

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12
Q

What are the minimum length requirements in repeats for a mononucleotide? Dinucleotide? Other?

A

12 repeats - 6 repeats - 4 for others

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13
Q

How do microsatellites evolve?

A

Duplication errors in mitosis

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14
Q

What can be said about the mutation of DNA satellites?

A

They have a higher mutation rate through insertions/deletions

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15
Q

When are microsatellites more important for genetic diversity and evolution?

A

In viral genomes

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16
Q

What are the roles of microsatellites?

A

Modulation of:
1. Transcription Factor Binding
2. Spacing between promotor regions
3. Cytosine methylation
4. Alternative splicing
5. mRNA stability
6. Selection of transcription sites in alternative splicing
7. Nucleosome/chromatin structure
8. Noncoding RNA
9. Meiotic recombination hotspots

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17
Q

How much of the human genome is variable and used for forensics? What are these sequences called?

A

0.5% - polymorphic sequences

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18
Q

What is the STR?

A

A short tandem repeats do not control known traits and have no known functions

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19
Q

What is the TH01 STR? How does it present/vary in people?

A

TCAT has a different number of repeats in different alleles

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20
Q

What are the numerical number of chromosomes in an aneuploid vs euploid individual?

A

Aneuploid:
2n-1
2n
2n + 1
etc

Euploidy
2n
3n
4n
etc

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21
Q

What is the role of colchicine?

Study These Flashcards
A

It is an antimitotic plant metabolite and inhibits the microtubule formation -> mitotic spindle

22
Q

How does colchicine contribute to plant polyploidy?

Study These Flashcards
A

It arrests cells in anaphase

23
Q

What is a clinical use of colchicine?

Study These Flashcards
A

It prevents the proliferation of tumor cells

24
Q

What is trisomy?

Study These Flashcards
A

2n+1 chromosomes

25
What is the most well known trisomy?
trisomy 21 - down syndrome
26
What is the process to analyze a fetus?
Karyotyping protocol is the sampling of chorionic villus in the placenta
27
What stage of cell division are cells in when they are harvested for karyotyping?
Metaphase
28
What are the common targets of trisomy screening?
Chromosomes 21, 18, 13
29
Karyotyping finds abnormalities in what percent of pregnancies?
2-3%
30
What are the two types of staining for the karyotype screening?
Classic FISH SKY - labelling - different colors for different targets
31
What is the FISH protocol?
Fluorescence In Situ Hybridization: - Designing of complementary fluorescent probes -Denaturing the sample -Hybridizing probes to samples -fluorescence microscope
32
What are the 5 variations in chromosome structure?
1. Deletion 2. Duplication 3. Inversion 4. Non reciprocal translocation 5. Reciprocal translocation
33
What could duplications lead to?
Gene redundancy and CNV (copy number variations)
34
What is an UFB?
An ultrafine bridge is an under replicated DNA that is not resolved before mitosis
35
What is a one ended DSB? What can it give rise to?
A one ended double strand break can give rise to an acentric fragment which can lead to a micronuclei
36
When could a fully duplicated chromosome lead to a micronuclei formation?
When there is lagging chromosomes from kinetochore or microtubule problems
37
What are the three mechanisms of polyploidy/polyteny?
1. Cytokinesis failure 2. Mitotic slippage 3. endocycling
38
What stages of cell division fail in mitotic slippage and endocycling?
Slippage - metaphase Endocycling - Ends after G2 phase
39
What are CIN cells called in their first stage after being normal tissue
tumorigenic
40
What are some characteristics that tumorigenic cells can acquire as their CIN increases?
Drug Resistance and Metastasis
41
What happens to metastatic cells after they undergo more severe CIN?
Cell death
42
What are most solid human tumors attributed to?
Chromosomal instability
43
What are the three impacts of genomic/chomosomal instability?
Cancer, telomere dysfunction, aneuploidy hypothesis
44
What are the controversial aspects of chromosomal instability and carcinogenesis?
1. Genomic instability early or late event? 2. Genomic = driving force? 3. Genomic = necessary for tumors?
45
How many antibodies are in adult blood?
3-9 million
46
How do lymphocytes vary so much?
Genesplicing system called translocation that takes genes and puts them in different genes along the chromsome
47
Will antibody alleles of the mother or father be expressed?
Both, each b lymphocyte expresses one parent at a time
48
What are the VDJ genes?
V = variable D = diversity J = joining
49
What are the forms of antibody diversity?
1. Combinatorial diversity - Each B cell randomly selects a V, D, or J cell 2. Junctional diversity - addition or deletion of nucleotides at junctions of VDJ 3. Somatic Hypermutation: After antigen exposure, immune cells undergo point mutation at a high rate -> affinity maturation
50
How many VDJ segments does a heavy chain have to choose from?
V = 38-46 D = 23 J = 6

Genetics 2133 (17 decks)

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