Cytogenetics Flashcards Preview

Fundamentals of Molecular Medicine > Cytogenetics > Flashcards

Flashcards in Cytogenetics Deck (66):
1

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Trisomy 18 

2

 

 

 

Overview

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3

Both meiosis and mitosis convert 4n content of DNA to 2n content how are these events different?

 

In mitosis the sister chromatids are identical when the 2 n state is reached

In meiosis the sister chromatids are identical when the 2n state is reached 

The events are not different 

 

 

(But the 2n content in mitosis are from both parents e.g. not identical)

4

 

 

 

Mitosis 

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5

 

 

 

Meiosis 

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6

 

 

 

Independent Assortment of Chromosomes

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7

 

 

 

Crossing over in Meiosis 

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8

 

How many distinct human chromosomes are there?

23

24

46

47

48

 

 

 

24

9

 

 

 

Identify the Karyotype and the logic behind the numbering

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10

 

 

 

Terminology 

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11

 

 

 

Banding patterns of Chromosomes

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12

 

 

 

Other banding techniques

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13

 

 

 

Autosomal Numbers

 

 

 

1-22

14

 

 

 

X, Y 

 

 

 

Sex Chromosomes

15

 

 

 

p

 

 

 

short arm of chromosome, petit 

16

 

 

 

q

 

 

 

Long arm of the chromosome

17

 

 

 

del

 

 

 

Deletion of chromosome material

18

 

 

 

der

 

 

 

Derivative, a structurally rearranged chromosome

19

 

 

 

Dup 

 

 

 

Duplication of part of a chromosome

20

 

 

 

Ins

 

 

 

Insertion of DNA into a Chromosome

21

 

 

 

Inv

 

 

 

 

 

 

Inversion of DNA within a Chromosome

22

 

 

 

/

 

 

 

a designation to indicate mosaicism, two different types of cells within one individual 

23

 

 

 

t

 

 

 

Translocation; the regions which are translocated are described after the t symbol

24

 

 

 

Ter 

 

 

 

terminal or (pter, qter)

25

 

 

 

r

 

 

 

Ring Chromosome

26

 

 

 

+ or -

 

 

 

Placed before the chromosome number, additions or deletions of a whole chromosome

27

 

 

 

+ 21 means 

 

 

 

+ 21 means a third copy of chromosome 21

28

 

 

 

46, XY 

 

 

 

Normal Male Chromosome Constitution

29

 

 

 

47 XX, +21

 

 

 

Female with Trisomy 21

30

 

 

 

47, XY, +21/46 XY 

 

 

 

Male who is a moasiac of trisomy 21 and normal cells

31

 

 

 

46, XY, del (4)(p14)

 

 

 

Male with deletion of short arm of chromosome 4 at the band 14

32

 

 

 

46, XX, Dup (5p) 

 

 

 

A female with a duplication of the short arm of chromosome 5

33

 

 

 

46, XX, inv (3) (p21;q13) 

 

 

 

Female with an inversion of chromosome 3 between band 21 on the short arm and band 13 on the long arm of the chromosome

34

 

 

 

46, X, r( X) 

 

 

 

Female with one normal X chromosome and one X ring

35

 

 

 

Ploidy

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36

 

 

 

The only viable monosomy...

 

 

 

X - Chromosome

37

If too many expressed genes often lead to miscarriage, why do xxx females come to term, often without any symptoms?

There are very few genes on the x chromosome

Different parts of each x chromosome are expressed

Only one x chromosome is expressed 

One x chromosome is inactivated so the individuals are similar to xx women

 

 

 

Only one x chromosome is expressed (Lyon hypothesis) — they get inactivated as barr bodies. 

38

 

 

 

What brings about Polyploidy?

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39

 

 

 

What brings about aneuploidy?

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40

Given the following karyotype: 47,XY, +19/46, XY

 

The patient is a female with down’s syndrome

The patient has Down’s syndrome

Non-dsjunction event occurred in meiosis 

Non-Disjunction event occurred in mitosis 

The patient inherited an extra chromosome from their mother

 

 

Non-Disjunction event occurred in mitosis (Mocaism is usually due to a non-disjunction in mitosis late in development) 

 

Non-dsjunction event occurred in meiosis  (All of the cells would show trisomy)

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Draw out non-disjunction in the first and second meiotic division

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42

 

 

 

Non-disjunction occurs more often in

 

 

 

Non-disjunction occurs more often in the eggs rather than the sperm. 

43

 

 

 

Which Trisomy's are compatible with life?

 

 

 

Only 13, 18, and 21

44

 

 

 

Which monosomies are compatible with life?

 

 

No autosomal monosomies are compatible wiht life

X monosomy can be

45

 

 

 

Draw Mitotic Non-Disjunction

 

 

 

 

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46

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47

 

 

 

Trisomy and Maternal Age

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48

 

 

 

Major Aneuploidy Syndromes Compatible with Live Births

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49

 

 

 

Structural Abnormalities in Chromosomes

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50

 

 

 

More Structural Abnormalities

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51

 

 

 

Translocations

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52

 

 

 

Gametes in Recipricol Translocation

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53

Given a reciprocal translocation between 3 and 21 in one parent, what percentage of conceptions will most likely come to term, assuming all means of segregation have an equal probability? Explain.

100

75

33

67

50

25

0

 

 

 

33

54

 

 

 

Gametes in Reciprocal Translocation Pt. 2

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55

 

 

 

Robertsonian Translocation 

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56

 

 

 

Gametes in Robertsonian Translocation

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57

 

 

 

Microdeletions

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58

 

 

 

Prenatal Cytogenetics 

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59

 

 

 

Amniocentesis 

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60

 

 

 

Chorionic Villus Sampling

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61

 

 

 

Cordocentesis 

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62

 

 

 

Non-Invasive Techniques

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63

 

 

 

Quad Test

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64

 

 

 

DNA Sequencing -- Cell Free DNA

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65

 

 

 

How would you prevent this from happening again?

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The only things she can do to prevent this from reoccurring. Get cytogenetic to look to see if there is a trisomy if not 1% chance of re-occuring. If so there’s a 50% chance of reoccurring. 

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Summary 

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Decks in Fundamentals of Molecular Medicine Class (77):