Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medicine Year 1 - Semester 2 - Part 2 > Chromosomes and Chromosomal Abnormalities > Flashcards

Chromosomes and Chromosomal Abnormalities Flashcards

1
Q

Explain basic chromosomal organisation

A

Telomere (end portions)
Short arm (p)
Centromere (spindle connects here in mitosis)
Long arm (q)
Telomere (end portions)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is a chromosome recognised ?

A

Banding pattern with specific stains
Length
Position of centromere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Acrocentric chromosomes

A
  • the short arm doesn’t really matter
  • mainly observe long arm

You see:

  • centromere
  • long arm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

State some acrocentric chromosomes

A

Chromsomes:

-13
-14
-15
-21
-22

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Chromosome changes that cause disease

A

Balanced chromosome rearrangement
Unbalanced chromosome rearrangement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Balanced chromosome rearrangement

A

All chromosome material is present
- physical change in location effectively

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Unbalanced chromosome rearrangement

A

Extra or missing chromosomal material.

Usually 1 or 3 copies of some of the genome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Aneuploidy

A

Whole extra or missing chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Translocation

A

Rearrangement of chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

State some chromosome changes

A

Insertions
Deletions
Duplications
Inversions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Aneuploidy and Non-disjunction in meiosis

A

Genome doesn’t develop correctly
Occurs prior to fertilisation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Non-disjunction

A

When chromosomes fail to separate normally, resulting in a gain or loss of chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Down Syndrome

A

47 XY + 21

Trisomy 21 (additional chromosome 21)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Edward Syndrome

A

47 XY + 18

Trisomy 18 (additional chromosome 18)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Patau Syndrome

A

47 XY + 13

Trisomy 13 (additional chromosome 13)
- associated with cleft palate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are trisomy diagnoses picked up ?

A

Rapid prenatal diagnosis
- Interphase chromosome counting using FISH (fluorescence in situ hybridisation)

  • Array CGH
17
Q

FISH

A

Fluorescence In Situ Hybridisation

18
Q

45 X

A

Turner Syndrome

Lack of one sex chromosome
Females with only one X chromosome

18
Q

Array CGH

A

Mix 2 types of genomic DNA together.

Label one with green and one with red.

If equal numbers of both –> yellow signal

If non-equal numbers –> you would see the predominant colour come through.

Use computer software and a data plot.

Anything above the zero reference = gain of chromosomal info

Below zero reference = loss of chromosomal info

19
Q

Why is X chromosome aneuploidy better tolerated ?

A

Due to X chromosome inactivation

20
Q

47 XXY

A

Klinefelter syndrome

21
Q

47 XXX

A

Triple X

22
Q

State the 2 major chromosome mutations

A
  1. Chromosomal Insertion
  2. Chromosomal Translocation
23
Q

Robertsonian Translocation

A

2 Acrocentric chromosomes (only Q arm) stuck end to end.

End-end fusions around the centromeres.

24
Q

Results of Robertsonian translocation

A

Increased risk of trisomy in a pregnancy

25
Q

Trisomy 14

A

Miscarriage

26
Q

Reciprocal translocation

A

Exchange of information between the different chromosome pairs.
(acentric and centric fragments)

27
Q

Results of Reciprocal translocations

A

Reproductive risks

  • For most translocations, ~50% of conceptions will have either normal chromosomes or the balanced translocations

Unbalanced products result in
- miscarriage (large segments)
- dysmorphic delayed child (small segments)

28
Q

What do unbalanced products result in ?

A
  • miscarriage (large segments)
  • dysmorphic delayed child (small segments)
29
Q

Clinical effects of chromosomal abnormalities

A

Cancer

30
Q

Cancer - Philadelphia chromosome

A

Break between 2 segments
Chromosome 9 and chromosome 22

Balanced translocation effect.
Movement of ABL fuses with BCR.

ALTERED CHROMOSOME 22

31
Q

Philadelphia chromsome

A

Chromsome 22

32
Q

Single Chromosome Mutations

A

Deletion
Duplication
Inversion

32
Q

Philadelphia chromosome FISH

A

bar-abl is a chimeric oncogene

95% of CML patients have Ph Ch

33
Q

Chromosomal Deletion example

A

X-linked Ichthyosis

34
Q

Chromosomal Duplication example

A

Charcot Marie Tooth disease

35
Q

Charcot Marie Tooth disease

A

Damage to myelin sheath in peripheral nerves - progressive loss of muscle tissue and touch sensation

Mutations in 39 genes can cause CMT

Commonest form - CMT1A

70-80% cases have a large duplication of 17p11.2

36
Q

Chromosomal Inversion

A

Rare

Most common inversion (2%) - inversion on chromosome 9

Medicine Year 1 - Semester 2 - Part 2 (53 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions