Cytogenetics

Question 1

Answer 1

Trisomy 18

Question 2

Overview

Answer 2

Question 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

Answer 3

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

Question 4

Mitosis

Answer 4

Question 5

Meiosis

Answer 5

Question 6

Independent Assortment of Chromosomes

Answer 6

Question 7

Crossing over in Meiosis

Answer 7

Question 8

How many distinct human chromosomes are there?

23

24

46

47

48

Answer 8

24

Question 9

Identify the Karyotype and the logic behind the numbering

Answer 9

Question 10

Terminology

Answer 10

Question 11

Banding patterns of Chromosomes

Answer 11

Question 12

Other banding techniques

Answer 12

Question 13

Autosomal Numbers

Answer 13

1-22

Question 14

X, Y

Answer 14

Sex Chromosomes

Question 15

p

Answer 15

short arm of chromosome, petit

Question 16

q

Answer 16

Long arm of the chromosome

Question 17

del

Answer 17

Deletion of chromosome material

Question 18

der

Answer 18

Derivative, a structurally rearranged chromosome

Question 19

Dup

Answer 19

Duplication of part of a chromosome

Question 20

Ins

Answer 20

Insertion of DNA into a Chromosome

Question 21

Inv

Answer 21

Inversion of DNA within a Chromosome

Question 22

/

Answer 22

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

Question 23

t

Answer 23

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

Question 24

Ter

Answer 24

terminal or (pter, qter)

Question 25

r

Answer 25

Ring Chromosome

Question 26

+ or -

Answer 26

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

Question 27

+ 21 means

Answer 27

+ 21 means a third copy of chromosome 21

Question 28

46, XY

Answer 28

Normal Male Chromosome Constitution

Question 29

47 XX, +21

Answer 29

Female with Trisomy 21

Question 30

47, XY, +21/46 XY

Answer 30

Male who is a moasiac of trisomy 21 and normal cells

Question 31

46, XY, del (4)(p14)

Answer 31

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

Question 32

46, XX, Dup (5p)

Answer 32

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

Question 33

46, XX, inv (3) (p21;q13)

Answer 33

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

Question 34

46, X, r( X)

Answer 34

Female with one normal X chromosome and one X ring

Question 35

Ploidy

Answer 35

Question 36

The only viable monosomy...

Answer 36

X - Chromosome

Question 37

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

Answer 37

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

Question 38

What brings about Polyploidy?

Answer 38

Question 39

What brings about aneuploidy?

Answer 39

Question 40

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

Answer 40

**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)

Question 41

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

Answer 41

Question 42

Non-disjunction occurs more often in

Answer 42

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

Question 43

Which Trisomy's are compatible with life?

Answer 43

Only 13, 18, and 21

Question 44

Which monosomies are compatible with life?

Answer 44

No autosomal monosomies are compatible wiht life X monosomy can be

Question 45

Draw Mitotic Non-Disjunction

Answer 45

Question 46

Answer 46

Question 47

Trisomy and Maternal Age

Answer 47

Question 48

Major Aneuploidy Syndromes Compatible with Live Births

Answer 48

Question 49

Structural Abnormalities in Chromosomes

Answer 49

Question 50

More Structural Abnormalities

Answer 50

Question 51

Translocations

Answer 51

Question 52

Gametes in Recipricol Translocation

Answer 52

Question 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

Answer 53

33

Question 54

Gametes in Reciprocal Translocation Pt. 2

Answer 54

Question 55

Robertsonian Translocation

Answer 55

Question 56

Gametes in Robertsonian Translocation

Answer 56

Question 57

Microdeletions

Answer 57

Question 58

Prenatal Cytogenetics

Answer 58

Question 59

Amniocentesis

Answer 59

Question 60

Chorionic Villus Sampling

Answer 60

Question 61

Cordocentesis

Answer 61

Question 62

Non-Invasive Techniques

Answer 62

Question 63

Quad Test

Answer 63

Question 64

DNA Sequencing -- Cell Free DNA

Answer 64

Question 65

How would you prevent this from happening again?

Answer 65

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.

Question 66

Summary

Answer 66