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Biology - Genetics > Evolution - Chromosome Abnormaltiies > Flashcards

Evolution - Chromosome Abnormaltiies Flashcards

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1
Q

Trisomy

A

Describes a diploid organism having an extra copy of a chromosome, majorly in autosomes.

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2
Q

Euploidy

A

This is an organism with a chromosome number an exact multiple of the haploid number for the speices.

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3
Q

Types of Euploidy

A

Triploidy or Tetraploidy

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4
Q

Aneuploidy

A

Abnormal amount of chromosomes in a haploid set

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5
Q

Balanced Translocation

A

Occurs when part of one chromosome has moved to another homologous chromosome.

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6
Q

Unbalanced Translocaiton

A

Aneuploidy when some part of the genome is missing

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7
Q

Monosomy

A

Occurs when an organism is missing a copy of an individual chromosome

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8
Q

How does monosomy compare to trisomy?

A

More common, harmful, and more frequent in spontaneous abortions.

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9
Q

What trisomy can result in birth?

A

13, 18 and 21

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10
Q

Down Syndrome

A

This is trisomy 21 affecting intellectual capabilities and heart conditions

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11
Q

What does trisomy 21 result in?

A

Shorter stature due to failure of skeletal system development, poor muscular tone and shortened life span.

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12
Q

What causes trisomy in down syndrome?

A

Non-disjunction

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13
Q

Non-disjunction

A

This is where chromosomes fail to split in meiosis, one gamete containg two copies and the other none.

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14
Q

What does 21 non-disjunction result in?

A

Trisomy 21 and mosomy 21, the progeny depending on fertilisation.

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15
Q

How much trisomy 21 end in spontaneous abortion?

A

3/4.

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16
Q

Amniocentesis

A

Can be used to detect abnormaltiies, where cells are obtained by a needle trough the uterus.

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17
Q

What is meiotic chromosome behaviour dependet on?

A

Chiasmata formation and arm pairing

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18
Q

What happens to meiotic chromosomes in trisomy?

A

Trivalent forms, with two centromeres point to one pole whilst the other to opposing pole

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19
Q

Why do sex chromosome abnormalities have less effect?

A

Because Y contains few functional genes, and most X-linked genes are silenced anyways

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20
Q

Examples of Sex Chromosome Abnormalities?

A

Klinefelter Syndrome(47XX7)
Turner Syndrome (45, x)

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21
Q

Examples of autosomal abnormalities?

A

Cri-du-chat
Prader-Willi Syndrome

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22
Q

Klinefelter Syndrome

A

Seen in males, leading to taller infertile cases, with mental impairment and enlarged breasts

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23
Q

Turner Syndrome

A

Results in no sexual maturation, seen in females, with average mental capabiltiies, heavily selected against(99.9% abortions)

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24
Q

Cri-Du-Chat Syndrome

A

Results from either 5p deletions, being a trisomy condition

25
Q

What might cause Nondisjunction?

A

Variety of envrionmental effects, like smoking, alcohol, fertility drugs, pesticides and radiation.

26
Q

What increases aneuploidy eighfold?

A

Bisphenol A concentrations increases, found in plastics.

27
Q

Deletions

A

Removals of a segment

28
Q

When are deletions most harmful?

A

The larger they are.

29
Q

Small deletions…

A

Viable in normal homologs that are heterozygous, often leath l in homozygous

30
Q

How do deletions form?

A

Breakage and reunion, the broken ends (one contains telomere and one centromere) fuses, where the deleted part is lost

31
Q

Ectopic Recombination

A

Homologous sequence recombination not at the same posiiton on homologous chromosome.

32
Q

Duplications

A

Where a part of a chromosome is duplicated.

33
Q

What causes further repeats of deletions?

A

Unequal Crossing(a type of ectopic recombination)

34
Q

Example of deletions?

A

Hemoglobin

35
Q

What causes RG Colour Blindness?

A

Unequal crossing

36
Q

Where are the blue and red/green pigments found?

A

7q22ter and Xw28( seperated by 5cm)

37
Q

Why are red-green pigments susecpetible to crossover?

A

Similar in amino acid sequence and duplicated togethers.

38
Q

Chimeric Genes

A

This is the joining of two or moe genes, originally coded for seperate or same protines.

39
Q

Postiion effects

A

This results when through rearrangement, genes acquire new neighbouring genes, which affect their expressiion.

40
Q

When might position effect variegation occur?

A

Whne a gene is silence through abnormal juxtaposition with heterochromatin

41
Q

What causes postiion effects?

A

Chromosome aberration moving wild type gene from euchromatin to near the heterochromatin

42
Q

Polyploidy

A

Where in higher plants, a genome in a species is composed of multiple sets of chromosomes

43
Q

Difference between haploid and monoploid?

A

Mono is basic set of chromosome, multiplied in a polyploid species
Haploid is the set present in a gamete regardless of chromosome number in species.

44
Q

Process of meiotic bivalency?

A

Species contains 18 chromoms, 9 bivlaents, gametes recieving one from each bivalent.

45
Q

Sexual Polyploidization

A

This is a meiotic process with formation of unreducedgametes.

46
Q

Asexual Polyploidization

A

Results from endoreplication doubling after mitotic doublig

47
Q

What are the two casues of polyploidy?

A

Asexual and Sexual

48
Q

Two types of polyploidy?

A

Autopolyploidy and Allopolyploidy

49
Q

Autopolyploidy

A

Derived from a single diploid ancestor

50
Q

Allopolyploidy

A

Complete chromosomes sets from different ancestratl species.

51
Q

Chromosome Abnormalities

A

Change in number or structure of a chromsome.

52
Q

How is monosomy and trisomy written?

A

2n-1 and 2n+1 respectively.

53
Q

Why does trisomy often result in spontaneous aboriton?

A

Over expression of genes

54
Q

Non-disjunction in meiosis 1…

A

In meiosis 2 generation, one cell with 6 sister chromatids and one with 2, where the 4 gametes are two trisomy and two monsomy.

54
Q

Non-disjunction in meiosis 2…

A

One homolgoous chromosome fails to split why the second cell is normal, resulting in one trisomy and one monosomy, with two normal gametes.

55
Q

What determines gender?

A

The presence or absence of the Y chromosome.

56
Q

What deletions cause Cri Du Chat and Prader-Willi?

A

chromosome 5 and 15q1.12 deletion.

57
Q

What determines angelman and prader willi syndomre?

A

Impriting.

58
Q

Down syndrome inheritance??

A

Individual carrying translocation between 14 and 21
When have child with norma individuals, the normal produces normal gametes and the translocation carrier abnormal gametes.

Biology - Genetics (14 decks)

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