Year 2 EMS GiM > Cytogenetics - Inheritance > Flashcards

Cytogenetics - Inheritance Flashcards

(54 cards)

Study These Flashcards
1
Q

What is cytogenetics?

A

Study of chromosomes / anything bigger than a gene.

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

Which chromosomes are autosomes?

A

1-22.

23 = X/Y

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

Which chromosomes are acrocentric? (5)

A

13-15, 21, 22.

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

What is conventional cytogenetics?

A

Metaphase chromosome analysis.

-G banding

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

What is molecular cytogenetics?

A

Analysis at all stages of cell cycle.

not just metphase, like conventional

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

What are the main techniques of molecular cytogenetics?

A
  • FISH
  • Microarray CGH
  • Next generation sequencing
  • MLPA
  • QF-PCR
  • qPCR
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

At which stage of the cell cycle are chromosomes most visible?

A

Metaphase.

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

What is G-banding used for?

A

Karyotyping.

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

Which chromosome is generally the largest?

A

Chromosome 1.

-decrease in size from that

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

How many genes does each band contain?

A

~50.

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

What is the short arm of a chromosome called?

A

P.

-p1, p2

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

What is the long arm of a chromosome called?

A

Q.

q1, q2, q3

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

How do cytogenetic abnormalities produce an abnormal phenotype? (5)

A
  • Dosage effect (gain / loss)
  • Disrupt gene
  • Genomic imprinting
  • Position effect
  • Unmask recessive disorder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What generally produces a more severe phenotype; sex chromosome imbalance or autosomal?

A

Autosomal imbalance.

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

What are the main numerical chromosome abnormalities? (4)

A

Diploidy
Aneuploidy
Polyploidy
Mosaicism

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

What is diploidy?

A

2 copies of each chromosome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is aneuploidy?

A

Abnormal number of chromosomes in a cell.

  • gain (trisomy)
  • loss (monosomy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is polyploidy?

A

Gain of whole sets of chromosomes.

-triploidy / tetraploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is mosaicism?

A

Presence of 2+ populations of cells.

-aneuploidy + diploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When do chromosomal abnormalities originate? (3)

A
  • Gametogenesis (meiosis)
  • Fertilsation
  • Early cleavage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the risks of increased maternal and paternal ages?

A

^ maternal age - aneuploidy.

^ paternal age - no significant risk.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is non-disjunction?

Study These Flashcards
A

Failure of chromosome / chromatid to separate.

23
Q

What are the different effects caused by non-disjunction at meiosis I and II?

Study These Flashcards
A

Meiosis I - 2 disomic, 2 nullisomic gametes.

Meiosis II - 1 disomic, 1 nullisomic, 2 normal gametes

24
Q

What are the 3 chromosome that trisomy occurs at, and why?

Study These Flashcards
A

13, 18, 21.

-relatively small chromosomes (can just about cope with extras)

25
What proportion of foetuses with trisomy 21 spontaneously abort?
75%.
26
What effect does trisomy 21 have on fertility?
Females - normal. | Males - usually infertile.
27
What condition does trisomy 18 cause?
Edwards syndrome.
28
What are the main features of Edwards syndrome?
``` Microcephaly Cleft lip Low birth weight Severe mental retardation Heart problems ```
29
What condition does trisomy 13 cause?
Patau syndrome.
30
What are the main feature of Patau syndrome?
``` Small birth weight Microcephaly Sloping forehead Holoposencephaly Cleft lip Polydactyly ```
31
What is holoprosencephaly?
Forebrain fails to develop into two hemispheres.
32
What age does female meiosis begin?
5 months. - the longer the eggs are unfertilised, the more likely they are damaged - male meiosis start at puberty
33
What are the main sex chromosome aneuploidies? (2)
``` Turner's syndrome (45, X) Klinefelter syndrome (47, XXY) ```
34
What are the main features of Turner's syndrome?
Infertility Lymph obstruction (webbed neck, swelling) Short stature Coarctation of aorta
35
What are the main feature of Klinefelter syndrome?
Infertile Hypogonadism Long arm and legs
36
What errors occur at fertilisation? (2)
- Polyploidy (e.g. triploidy) | - Molar pregnancy (double paternal, no maternal)
37
What is the genetic make up of trisomy, and what proportion spontaneously abort?
69, XXY / XYY / XXX. -99.9% spontaneously abort
38
What are the origin of triploidy? (3)
- Digyny (diploid egg fertilised) - Diplospermy (diploid sperm) - Dispermy (2 sperm to one egg)
39
What are the main features of double maternal triploidy?
- Small placenta and foetus - Large head - Growth retardation
40
What are the main features of double paternal triploidy?
- Growth retardation | - Large, cystic placenta
41
What are the conclusions from double maternal / paternal triploidy?
Maternal genome >> foetus. | Paternal genome >> placenta.
42
What is a molar pregnancy?
Placenta develops without a foetus. - empty egg - double paternal genome >> massive cystic placenta
43
What errors occur at early cleavage?
Mosaicism. | -mitotic non-disjunction
44
What are the main consequences of mosaicism?
- Variable phenotype | - Recurrence risk (gonadal)
45
Summarise numerical abnormalities.
MEIOSIS - gain / loss of single chromosomes. FERTILISATION - gain of whole chromosome sets. POST-FERTILISATION - gain / loss during mitosis.
46
What are the 2 types of chromosomal rearrangements?
Balanced | Unbalanced
47
What are the main types of balanced rearrangements? (3)
- Translocation - Inversion - Insertion
48
What are the 2 types of translocation?
- Reciprocal (break and exhange) | - Robertsonian (whole arm fusion, no phenotype risk)
49
Which type of translocation occurs with acrocentric chromosomes?
Robertsonian translocation.
50
What is the process of inversion?
2 breaks, rotation, then rejoining. | - pericentric / paracentric
51
What are unbalanced rearrangements?
Overall loss / gain of chromosomes. - commonest = deletions / duplications - mainly sporadic
52
What is the difference between interstitial and terminal deletions?
INTERSTITIAL - middle of chromosome. 2 breaks >> segment lost. TERMINAL - end of chromosome. 1 break >> segment lost.
53
What are the 2 types of duplications?
- Direct | - Inverted (segment reversed)
54
What causes a ring chromosome?
Breakage then circularisation of a chromosome.
Year 2 EMS GiM
flashcards
Decks in class (12)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions