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BIOL332 > Anuiploidy + non-disjunction > Flashcards

Anuiploidy + non-disjunction Flashcards

1
Q

Iclicker 1

A

Diploid – have 2 copies of Homologous Chromosomes
- 2 chromosomes (count by # of centromeres)

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2
Q

iclicker 2

A

Still diploid – # of dsDNA strands changes BUT still only 2 chromsomes – still diploid

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3
Q

iclicker 3

A

After anaphase – have 1 copy of HC
- Seperated = haploid

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4
Q

Ploidy in Meiosis

A

Dplioid –> Diploid –> Haploids (during Anaphase)
- Meiosis 2 = get haploid
- After anaphase each cell has 1 copy of HC

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5
Q

Ploidy

A

Number of copies

Example – humans are diploid –> 2 copies of all 23 unique chromosomes

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6
Q

slide 14 - What is the ploidy of this human cell?

A

Triploid – have 3 copies of each chromsome

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7
Q

Polyploid

A

When there is over 2N (over diploid) for every chromosome
- Every cell has same # of chromosomes and its more than normal for that sepcies

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8
Q

Aneuploid

A

An abnormal number of one or more chromosomes
- Have non-typical number at one or more than one but not all

Ex. Trisomy 21 –> Downsyndrome

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9
Q

Polyplodit stability

A

Animals – Polyploidy is lethal in most animals

Fungi – Ploidy is unstable in fungi

Plants – Many plants are tolerant of polyploidy

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10
Q

Polyploidy in plants

A

Polyploidy tends to lead to larger fruits/flowers
- Common in plants because get bigger fruit

Well tolerated in plants

Triploids are usually sterile because 3 chromsomes don’t know how to line up during metaphase

Example – plants were diploid and had seeds that trun balck and now they are triploud and now seeds don’t trun black

Example 2 – Strawberry
Small = wild = diploid
Big = Octoploid

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11
Q

Triploid plants

A

Are usually sterile – because three chromosomes don’t know how to line up during metaphase

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12
Q

How does polyploid occur

A

Ploidy cell typically organinate when spindle fibers don’t form correctley during meiosis
- Arise due to mistake in mitosis or meiosis
- HC alugn on splindle that pulls them apart –> if prevent spindle from forming = won’t be pulled = stay in the middle
- Spindle fibers cam’t form = seperarting chromsomes = stay in teh same cell during cytokenesis

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13
Q

Mutation preventing from spindle from forming

A

The two seperating chromosomes stay in the same cell during cytokensis
- No spindle = chromosomes stay together

One cell = has no DNA
One cell = has double DNA – one cell has extra copy of every chromosome

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14
Q

Disjunction

A

The seperation of chromosomes

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15
Q

When does disjunction occur

A

Mitosis – Anaphase

Meiosis – Anaphase 1 and Anaphase 2

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16
Q

Nondisjuction

A

When chromosomes or sister chromatids fail to seperate

Chromosomes = not seperating –> ALL dragged to one side of the cell

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17
Q

What leads to Annupliody

A

Non-disjuction – mistake in disjunction

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18
Q

When can nondisjunction occur?

A

Mitosis + meiosis 1 + meiosis 2

Can occur in males and females

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19
Q

How many chromosomes does nondisjunction usually affect

A

Typically only affects 1 chromosome

ALL others segragate normally

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20
Q

Result of nondisjunction

A

Results in varaition in chromsome number – ganates with the wrong number of chromosomes

Nondisjunction in M1 – 2N, 2N , 0N , 0N

Nondisjunction in M2 – 2N, 0N, 1N, 1N

***Add in image

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21
Q

How often is nondisjunction

A

Rare event – mistake in meiosis
- More likley in one cell

Even more rare if have nondisjunction in Meiosis 2 that it will occur in both cells in Meiosis 2 – will only occur one cell (because rare)

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22
Q

Slide 22 – iclicker

A

2N + 1N –> get 3N

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23
Q

Slide 23 – iclicker

A

Meiosis 1 – Because 2 gamates with 2N than in Meisosis 2 (have 2 2N in meiosis 1 and 1 2N in meiosis 2) = more likley to get 2N – can the combine to get 3N

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24
Q

Result of fertalization after annuploidy

A

Meiosis 1 – 2N –> 3N
0N –> 1N

2N + 2N + 0N + 0N —> 3N + 3N + 1N + 1N

***3N = trisomy
End = get trisomy

Meiosis 2 – 2N + 0N + 1N + 1N –> 3N + 1N + 2N + 2N

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25
Q

iclicker

A

XXX, XXX, XO, XO

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26
Q

Affect of most anueplodies in humans

A

Are lethal

27
Q

Viable human autosomal Anuploides

A
  1. Trisomy 21 – Downs syndrome
  2. trisomy 13 – Patau Syndrome
  3. trisomy 18 – edwards syndrome

***trisomies 9 and 8 are very rare

28
Q

Liklihood of NJ in one chromosome vs. another

A

There is nothing specieal about NJ in one chromosome or othr –> Chromsome 21 is NOT more likley to have NJ its just that most are not viable so we do not see results of NJ in other chromsomes

Seeing trimosy 21 is NOT because 21 is more likley to have NJ its that the other NJ are not going to be viable = won’t see others

29
Q

Affect of Annuploidy + Miscarrige

A

10-20% of preganacey end through miscarige –> 35% of fetuses in a miscarrige have anuiploides

30
Q

How common is NDJ

A

NDJ leading to annuplodies is common

10-20% of preganacey end through miscarige –> 35% of fetuses in a miscarrige have anuiploides

31
Q

Sex chromosome anuploides

A

Humans are very tolerant to sex chromosome aneuploides

Ex. XXY – Kleinfelter synderome

Ex 2. XO – Turner syndrome (viable but more of phenotype than Kleinfelter synderome)

32
Q

Kleinfelter synderome

A

Lots of phenotypic varaition – many XXY males will never know unless a karyotype is preformed

Taller + might have femanized characteristics BUT might have no real phenotype

Very viable

33
Q

Example Sex chromosome anuploides

A

XO – truners Syndrome

XXY – Kleinfelter synderome

XXX – Triple X syndrome (phenotypically normal – sometimes developmental delays and sometimes low fertility)

XXXX – Tetrasomy X (phenotypically normal – sometimes developmental delays and sometimes low fertility)

XXXXX – pentasomy (phenotypically normal – sometimes developmental delays and sometimes low fertility)

XYY – Jacobs syndrome

34
Q

XXY – Jacobs syndrome Misconception

A

Phenotypes can (but most often do not) include developmental delays + delayed speech + poor muscle tone + taller and thinner than average)

MISCONCEPTION – They are hyperagressive

XYY males are NOT hyperaggressive (the first reprots of XYY karyotypes were from federal prisomners with no “general popultion” controls and small sample sizes)

35
Q

Why are X inactivation so tolerant to anueplodies

A

X inactiveation and dosage compensation

36
Q

Lyonization

A

X-inactivation

37
Q

Mary Lyon

A

Determines that 1 X chrosmomes could be inactived to prevent gene expression from both X chrosmomes

38
Q

X-inactivation

A

1 X chrosmomes could be inactived to prevent gene expression from both X chrosmomes

One X chromosome is randomly inactivated during embryonic development through chromatin condensing (lyonizatioon) forming Barr bodies

39
Q

X chrosmome expression in females

A

Females (XX) do NOT express twice as many X-linked genes than males (XY) –> One X chromosome is randomly inactivated during embryonic development through chromatin condensing (lyonizatioon) forming Barr bodies
- One of the X chromsomes is selected for X inactivation –> condensed to form Barr Body

40
Q

X-inactivation process

A

Done through chromatin condensing (forms Barr body(

41
Q

X inactivation in marsupials

A

In some Marsupials the X chromosome in the sperm is inactivated

42
Q

Example of X inactivation

A

Seen in female cat – all cells have XB and XO BUT only one is expressed
- One cell - have only active organge
- some cells - have only active Black

Makes some cells organge phneotype and some cells black phenotype = get calico cat –> NOT having one cell that is half orange and half black

get mosaic of cells

***Add in slide 33 image)

43
Q

Dominance on organismal vs. cellular level

A

SHOWS that dominace relationships are contexual

XB and XO are codominant (See both orange and black fully) at the organismal level BUT At the cell level there is no relationship because they are both hemizygous (because only 1 of the X chromosomes is actually active)
- Only one is expressed NOT black and organge in one cell

44
Q

Women as mosaic

A

Woemn have some cells that expressed one X from mom and some cells that expresses X from dad

Males = just express the X from mom

45
Q

Result of X inactivation

A

Have one X chromsome that is active and all other sare condensed to Barr bodies

46
Q

Counting number of Barr bodies

A

of bar bodies = # of X xhromsomes - 1)

XXY = 2-1 = 1
XXX = 3-1 = 2

47
Q

Iclicker page 36

A

2, 0, 0

XXX = 3-1 = 2
XY = 1 - 1 = 0
XYY = 1 - 1 = 0

48
Q

Why are there any phenotypes for sex chromosome anuplodies?

A

Reason why think this = because shouldn’t X-inactivation balance out the extra X chromsomes

Reasons why have phenotypes:
1. Sometimes need expresison for both X then one is silenced

  1. Sometimes get some gene expression –> Sometimes too much is a bad thing
    • Some gene expression occurs from the condensed X chromosome
  2. Chromosome structure is dynamic
  3. X-inactivation may not be complete

Example – what Xlinked genes contributeds to the short stature and congintive abnoramalutes of someone with Turner syndrome – Maybe SHOX (Short-stature homebox containing gene) maybe otehrs too

49
Q

Haploinsufficiencey

A

When 1 copy of a gene is not enough to produce the wild-type phenotype

50
Q

Mechanism of X-inactivation

A
  1. Initiation – A specific RNA binds to one of the 2Xic genes at random
  2. Spreading – This intiates a cascade to coat the rest of the chromosome
  3. The X-chromosome that is coated condesed into a Barr body
51
Q

What is associated with human anuploidies

A

Human aneuploides are associated with maternal age – pribability of annuploidy increases in age

52
Q

Spematogenetsis

A

Occurs in adults all of the time – smaller than eggs

53
Q

Division in Oogensis

A

There is an unequal division of cytoplasmic componenets – The cells that don’t get “the goods” become polar bodies

Keeps all of the proteins and resources to make egg that will be used to give to fetus – cells w/o the goods = polar bodies

54
Q

Polar bodies

A

The cells that don’t get “the goods” during Oogensis

Contain DNA but not realy anything else

55
Q

Result of Oogensis

A

1 cells + 3 polar bodies

***Add in imaghe on slide 41

56
Q

Oogensis

A

Begins in Utero and finsihes at menapause

begins in Utero – THEN the primary oocytes are paused in prophase 1 –> meiosis restarts in puberty
- Have oogensis restart one cell at a time monlthy until menapause

57
Q

Where are oocytes pasued in?

A

Prophase 1

58
Q

Older cells in Oogensis

A

Older cells have trouble seperating the cohesion proteins in the synaptonemal complex that hold the HC togetehr = REASON HAVE MORE NDJ WHEN HAVE OLDER WOMEN
- Proteins that hold chromsomes togetehr in prophase get older = degrade = more likley to make mistakes and not seperate chromosomes

59
Q

Oogensis (MINE)

A

Before puberty – egg cells initiate meisois —> stay in prophase of meiosis 1 until ouberty –> once a month one will finish meiosis – it doesn’t go to meiosis to until fertlized
- Seperate teh goods to one egg cell and teh rest become polar bodies

60
Q

NDJ in mitosis

A

MDJ can occur in mitosis –> leads to chromosomal Mosaism – NDJ during anaphase of mitosis can cause some cells (liek cancer cells) to have different karyotype than other cells

Mitosis = can lead to annueploidy TOO

61
Q

JDJ in mitosis + bilateral development

A

NDJ in mitosis with bilateral development can leave one side of the body to develope as male and the other side as female –> Some cells male on one side of body and some cells female on the other side of the body
- Mitsosi = can lead to aneuploidy
Result: Gyandromorphes

62
Q

Gynadromoprhs

A

Organisms made up of half male and half female tissues

63
Q

Development of Hyandromoprhs

A

Mitosis NDJ for sex chromsomes in species with bilateral development can leave one side of the body to develop as male and the other side female

ex. A cardinal was spotted in PA

64
Q

Preclass

A

Look at pre-class notes

BIOL332 (25 decks)

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