2 - MUTATIONS Flashcards

1
Q
  • Heritable changes in the nucleotide sequence of a given DNA
  • Substitution, deletion or insertion of one or more nucleotides
  • Could affect or not a given phenotype
  • The major basis of diversity among organisms
  • The raw material of evolution
A

Mutations

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2
Q

Caused (mostly) by

A

mutagens

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3
Q

UV radiation, ionizing radiation (e.g., gamma rays, X-rays), byproducts (e.g., reactive oxygen species such as superoxides, hydroxyl radicals)

A

DNA damage

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4
Q

(e.g., base analogs: 5-bromouracil (5-BU), 2-amino-purine; alkylating
agents: ethylmethane sulfonate (EMS); intercalating agents: proflavine, acridine orange, ethidium bromide)

A

mutagens

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5
Q

(e.g., base excision repair, nucleotide excision repair, mismatch-repair system)

A

Can be repaired by the body in normal conditions

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6
Q

Classifications of Mutations

A

Based on nature of occurrence
Based on cell type where it occurs

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7
Q

Based on nature of occurrence

A

Spontaneous
Induced

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8
Q

arise in the absence of known mutagen

A

Spontaneous

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9
Q

presence of mutagens or environmental agents

A

Induced

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10
Q

Based on cell type where it occurs

A

Somatic
Gametic

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11
Q

originates in mitosis and affects subset of cells

A

Somatic

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12
Q

originates in meiosis and affects all cells of an individual

A

Gametic

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13
Q

Gametic

A

Autosomal
X-linked

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14
Q

change in the sense of information (missense)

A

Substitution

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15
Q

purine to purine or pyrimidine to pyrimidine

A

Transition

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16
Q

purine to pyrimidine or vice versa

A

Transversion

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17
Q

deletion or insertion of one base

A

Frameshift

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18
Q

change of one letter

A

point mutation

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19
Q

loss of one letter

A

deletion (frameshift mutation)

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20
Q

gain of one letter

A

insertion (frameshift mutation)

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21
Q

mutation changes 1 codon for an amino acid into another codon for that same amino acid

A

Silent

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22
Q

codon for 1 amino acid is replaced by a codon for another amino acid

A

Missense

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23
Q
  • codon specifies chemically similar amino acid
  • Does not alter protein function in many cases
A

Synonymous missense

24
Q

codon specifies chemically dissimilar amino acid

A

Nonsynonymous missense

25
Q

Phenylalanine

A

non-polar, hydrophobic

26
Q

Serine

A

polar, hydrophilic

27
Q

Point mutations and multiple variants in the “a determinant” region can destroy
the ? of HBV

A

antigenicity and immunogenicity

28
Q

codon for 1 amino acid is replaced by a translation termination codon

A

Nonsense

29
Q

A region from one chromosome is aberrantly attached to another chromosome

A

Translocation

30
Q

examples of translocation

A

Burkitts Lymphoma
Chronic Myelogenous Leukemia (bcr-abl gene)

31
Q
  • 20% of all leukemia cases
  • characterized by an overproduction of cells of granulocytic and occasionally monocytic series
  • presence of Philadelphia chromosome in >90% of patients
A

Chronic Myelogenous Leukemia

32
Q
  • short-term lymphocyte culture
  • lymphocyte harvest
  • slide preparation and staining
  • slide analysis
A

routine chromosomal analysis

33
Q
  • standard media composed of RPMI 1640, fetal bovine serum and penicillin-streptomycin
  • addition of phytohemagglutinin –> induces mitotic activity
  • 72-hour culture
A

short-term lymphocyte culture

34
Q
  • addition of colcemid –> prevents formation of spindle fibers
  • centrifugation
  • hypotonic solution –> disrupts cytoplasmic material in cells
  • fixation
A

lymphocyte harvest

35
Q
  • 24-hour slide aging
  • GTG-banding technique (G-bands by Trypsin using Giemsa)
A

slide preparation and staining

36
Q
  • based on International System of Human Cytogenetic Nomenclature (ISCN)
  • chromosomes are arranged according to size and banding pattern
  • Cytovision by Applied Imaging Inc
  • Ikaros by Metasystems Inc
A

slide analysis

37
Q
  • numerical abnormalities –> deviation from the normal chromosome number (46)
  • structural abnormalities –> change in structure and morphology
A

slide analysis

38
Q
  • treat metaphase spread with trypsin that digests part of chromosomal protein.
  • Stain with Giemsa and observe under light microscope.
A

Giemsa G-banding

39
Q

fluorescent staining method which uses quinacrine to identify chromosomes and their structural anomalies

A

Quinacrine Q-banding

40
Q

involves denaturing in hot acidic saline followed by Giemsa staining

A

Reverse R-banding

41
Q

used in identifying heterochromatin by denaturing chromosomes in a saturated alkaline solution followed by Giemsa staining

A

Centromere C-banding

42
Q

Numerical chromosome
abnormalities

A
  • Trisomy 21 (47, + 21)
  • Trisomy 18 (47, + 18)
  • Trisomy 13 (47, + 13)
43
Q

Sex chromosome abnormalities

A
  • Turner syndrome (45, X)
  • Klinefelter syndrome (47, XXY)
44
Q

Structural chromosome
abnormalities

A
  • Deletion
  • Duplication
  • Translocation
  • Inversion
45
Q

Trisomy 21

A

Down Syndrome (47, + 21)

46
Q

Trisomy 18

A

Edward Syndrome (47, + 18)

47
Q

Trisomy 13

A

Patau Syndrome (47,+ 13)

48
Q
  • A laboratory technique for detecting and locating a specific DNA sequence on a chromosome.
  • The technique relies on exposing chromosomes to a small DNA sequence called a probe that has a fluorescent molecule attached to it.
  • The probe sequence binds to its corresponding sequence on the chromosome.
  • Useful in disorders with very small aberrations or samples with no metaphase cells available.
A

Fluorescence in situ hybridization (FISH)

49
Q

Steps in FISH

A
  • Denaturation of the sample
  • Hybridization of probe to target cells
  • Washing
  • Detection (fluorescent microscopy)
50
Q

Detection of BCR-ABL (Breakpoint Cluster Region-Abelson) gene fusion by FISH using

A

bone marrow aspirate or peripheral blood

51
Q

Detection of AML-ETO (Acute Myeloid Leukemia) gene fusion by FISH using

A

bone marrow aspirate or peripheral blood

52
Q

Detection of PML-RAR (ProMyelocytic Leukemia-Retinoic Acid Receptor) gene fusion by FISH using

A

bone marrow aspirate

53
Q

Detection of Y-Chromosome for sex-mismatched bone marrow transplantation by FISH using

A

bone marrow aspirate

54
Q

BCR-ABL

A

Breakpoint Cluster Region-Abelson

55
Q

AML-ETO

A

Acute Myeloid Leukemia

56
Q

PML-RAR

A

ProMyelocytic Leukemia-Retinoic Acid Receptor