Chromosomes and Chromosomal Abnormalities Flashcards Preview

Molecules to Cells > Chromosomes and Chromosomal Abnormalities > Flashcards

Flashcards in Chromosomes and Chromosomal Abnormalities Deck (37):
1

What is the name for the short arm of a chromosome?

p

2

What is the name for the long arm of a chromosome?

q

3

What is a metacentric chromosome?

Centromere at mid point

4

What is a submetacentric chromosome?

Smaller p than q arm

5

What is an acrocentric chromosome?

Virtually no p arm

6

What is the difference between dark bands and light bands on karyotypes?

Dark bands = gene poor heterochromatin

Light bands = gene rich euchromatin

7

How many genes can be in a single band?

As many as 50+!

8

What characteristics are used to identify chromosomes?

1. Size
2. Centromere position
3. Banding pattern

9

What are 2 ways in which you can get double copies of chromosomes (tetraploidy)?

1. Furrow recession during cytokinesis
2. Multiple fertilization

10

Nondisjunction tends to be associated with _________.

Advanced maternal age oocytes

11

As many as ___% of spontaneous abortions are due to chromosomal abnormalities.

50%

12

Noninvasive prenatal screening is helpful for detecting what?

Trisomy 13, 18, 21

13

The majority of nondisjunction events occur in _____.

Meiosis I

14

How does FISH work?

Make a probe complementary to a known unique sequence to identify aneuploidy.

15

How do microarrays work?

Probes are fixed to a slide in unique positions and you wash the sample over the slide.

Make a hybrid of green (control) and red (fetal)

Measures the quantity of DNA...every spot SHOULD be yellow (red + green)

Red or green shows excess or loss of a gene

16

What is another name for Trisomy 18?

Edwards Syndrome

17

What are classic Trisomy 18 symptoms?

Rockerbottom feet
Clenched first 2nd and 3rd digits overlapping
Mental retardation, cardiac malformations

18

What is another name for Trisomy 13?

Patau syndrome

19

What are classic Trisomy 13 symptoms?

Body patterning is off:

Bilateral cleft lip
Mental retardation
Midline defects: cyclopia, absence of eyes
Congenital heart and urogenital defects

20

what does t(14;21) indicate in a karyotype?

translocation between chromosomes 14 and 21

21

What is a Robertsonian translocation?

Translocation involving acrocentric chromosomes

22

What are common Trisomy 21 symptoms?

Hypotonia
Short stature
Flat nose
Palmar crease
Mental retardation
Congenital heart defects
Early onset Alzheimers

23

What are common symptoms of Turner syndrome?

Webbed neck
Short stature
Amenhorrea
Gonadal dysgenesis
Infertility

24

What is the genotype of patients with Turner syndrome?

45, X

25

What are symptoms of Kleinfelter Syndrome?

Long limbs
Hypogonadism
Gynecomastia
Behavioral problems

26

What is a parAcentric inversion?

A block of DNA on a chromosome that moves AWAY from the centromer

27

What is a perIcentric inversion?

A block of DNA that moves INVOLVING the centromere

28

What is a consequence of paracentric inversion?

Unbalanced offspring and genomic instability

29

What is a consequence of pericentric inversion?

Unbalanced offspring

30

What is spectral karyotyping (SKY)?

Individual probe sets labelled in 24 different colors--makes it easy to determine origin of extra DNA and for translocations

31

What test is especially useful for detecting translocations?

Spectral karyotyping

32

What is a Philadelphia chromosome?

bcr-abl fusion protein formed due to a reciprocal translocation between chromosomes 9 and 22

33

What disease develops from the formation of a Philadelphia Translocation

Chronic Myelogenous Leukemia

34

In the case of defective x chromosomes, what are the priorities for inactivation/preservation?

1. Preserving activity of one x-chromosome equivalent
2. Preserving autosomal sequences

35

Can some genes escape X inactivation?

Yes

36

What is cri du chat?

5p 15 deletion

37

What are the symptoms of Cri du chat?

Cat cry
Mental retardation
Microcephaly
Epicanthal folds
Low set ears
Heart defects