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Module 5 Week 1 > Cytogenetics > Flashcards

Cytogenetics Flashcards

1
Q

What is cytogenetics

A

The study of chromosomes and chromosomal abnormalities

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2
Q

A lot of fertility issues linked to…

A

Chromosomal abnormalities

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3
Q

Most chromosomal abnormalities are…

A

Not compatible with. Survival

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4
Q

Chromosomal abnormalities related to… (3)

A

– Infertility
– Embryonic loss
– Growth and developmental abnormalities

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5
Q

What is a karyotype

A

general appearance of the complete set of chromosomes in an animal

(Anki shows what it looks like)

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6
Q

Chromosomes made up of…

A

Proteins, DNA wrapped. Around histone octamers to form nucleosides which are compacted into chromatin fibre

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7
Q

What are autosomes & what do they determine

A

Non sex chromosomes
Determine somatic characteristics

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8
Q

What are allosomes
-role

A

Sex chromosomes
-sex determination

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9
Q

-Female sex chromosomes
-Male sex chromosomes
-Birds/moths/butterflies male and female

A

XX
XY
ZW female, ZZ male

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10
Q

How are karyotype images ordered

A

Largest to smallest & sex chromosomes at the end

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11
Q

Describe process of preparation of Karyotypes

A

• Nucleated cells are isolated from animal e.g. White blood cells, amniotic fluid
• Cells are grown in culture -mitogens to stimulate cell division
• Cells are ‘arrested’ in metaphase-disruption of the mitotic spindle
• Cells are dropped onto slides and stained- dropping from a short height allows chromosomes to spread; ‘chromosome spreads’

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12
Q

Name staining technique used to view chromosomes

A

Fluorescent/light microscopy

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13
Q

Staining patterns are unique for each chromosome which aids in…

A

Chromosome identification

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14
Q

Why are chromosomes arrested in metaphase in karyotype preparation

A

During metaphase they are most replicated and condensed

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15
Q

Sister chromatid is…

A

An arm of a chromosome

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16
Q

Name each component of chromosome.

A

On anki

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17
Q

position of the centromere also aids identification of chromosomes. Name the 3 different positions that exist

A

Acrocentric- just off centre (common in cows)
Metacentric- in the middle
Telocentric- at edge

18
Q

What is chromosomal painting
-probes can be…
-advantage

A

Use of fluorescent probes to help identify specific chromosomes
-can be specific to specific chromosome eg X specific probe paints the X chromosome a different colour
-doesn’t rely on position of centromere and rapid way of identifying

19
Q

2 Types of chromosomal abnormalities

A
  1. Numerical- Changes in chromosomal number
  2. Structural
20
Q

Changes in chromosomal number
—aneuploidy
-definition
-usually affects…

A

Presence or absence of one or more chromosomes
-X chromosome

21
Q

Euploidy meaning

A

Normal diploid set of chromosomes

22
Q

-Trisomy
-Monosomy

A

-47XXX—> 1 extra X ch.
-45XO—> only 1 X ch.

23
Q

What type of chromosomal abnormality causes Down syndrome

A

47XX + 21–> 1 extra ch. 21

24
Q

Gene dosage effect meaning

A

3 sets or 1 set of chronometer expressed (abnormal amount)

25
Q

The less that gene is disrupted by chromosomal abnormalities, the more likely it is…

A

To be compatible with animal

26
Q

What are numerical chromosome abnormalities caused by?

A

Failure of chromosomes to separate properly

27
Q

Name a type of chromosome failure to separate properly

A

Nondisjunction

28
Q

Describe what occurs in nondisjunction

A

Either: abnormality in meiosis 1 causing both chromosomes to stay together and not divide or abnormality in meiosis II

(Diagram on anki)

29
Q

What types of aneuploidy occurs in end product during nondisjunction of meiosis I & meiosis II

A

-Trisomy and monosomy
-trisomy, monosomy & diploid

30
Q

Animals with two or more cells derived from a single zygote (2 different Karyotypes that exist within animal)

A

Mosaic

31
Q

What are Chimeras

A

Animals with 2 or more cell lines derived from 2 zygotes (fusion of 2 different Karyotypes)

32
Q

What is placental anastomosis

A

Fusion of placenta

33
Q

How can a vet check whether an animal is chimera?

A

Looks for XX and XY Karyotypes present in karyotype image

34
Q

What is the most common chromosomal disorder in horses?

A

Monosomy ch.63 (XO)

35
Q

What does monosomy X ch. 63 cause in horses?

A

Infertility

36
Q

What is male to female sex reversal syndrome: what causes is

A

Female XY
Animals have a male karyotype; can display external genitlalia; usually have no uterus, US often shows testicles in abdomen
Causes infertility

-caused by lack of SRY gene on Y chromosome; this means they lack processes that cause a foetus to develop male gonads and prevent development of female reproductive structures

37
Q

XXY chromosomal abnormalities in animals
-affected animals show…
-causes…

A

-males with extra X chromosome
-show male phenotype; underdeveloped male sexual characteristics
-causes infertility

38
Q

Changes in chromosome structure arises when… -2 types and their meeanings

A

chromosomes break and are not restored to the original structure

-genetically balanced- All genetic information retained but in different order
-genetically unbalanced- Some genetic information missing or present in more than one copy

39
Q

Main types of chromosome structural abnormalities

A

Deletion
Duplication
Inversion- reverses segment within chromosome
Translocation- moves segment from one chromosome to another

40
Q

What is the robertsonian translocation
-what does this mean for cell
-what does it cause in cell

A

Centromere of two acrocentric chromosomes fuse together to give one large metacentric chromosome
-can’t undergo mitosis
-embryonic loss

41
Q

Causes of structural chromosomal abnormalities

A

• Some may be inherited
• Others occur as random events in the formation of reproductive cells
– Unequal crossing over in meiosis
– Breakage of chromosomes (e.g. Chemical mutagens, Radiation)

Module 5 Week 1 (14 decks)

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