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Lec 28 Flashcards

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1
Q

What are the two cell divisions that the human life revolves around?

A

Meiosis ( reduction division to haploid gametes )
& mitosis ( duplication of diploid 46 and divide into 2 cells )

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2
Q

During cell division abnormalities can occur either by ——- or ——-

A

Improper segregation
Duplication of chromosomes

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3
Q

What are the two types of chromosome abnormality?

A

1- numerical abnormality
2- structural abnormality

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4
Q

What is numerical abnormality in chromosomes ?

A

They result when a person has lost one chromosome or gained an extra chromosome

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5
Q

What is structural abnormality in chromosomes?

A

They occur when a large segment of a chromosome is deleted or duplicated

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6
Q

Numerical abnormality in chromosomes is divided into two types what are they?

A

1- aneuploidy
2- polyploidy

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7
Q

What is an aneuploidy ?

A

Gain or loss of a chromosome in a cell

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8
Q

What are examples of aneuploidy :

A
  1. Trisomy ( 46+1 =47 chromosomes )
  2. Monosomy ( 46-1 =45 chromosomes )
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9
Q

What is polyploidy?

A

A cell containing more than diploid ( 2n = 46 ) chromosomes

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10
Q

What are examples of polyploidy?

A
  1. Triploidy ( 3n = 69 )chromosomes
  2. Tetraploidy ( 4n = 92 ) chromosomes
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11
Q

How does aneuploidy result?

A

By nondisjunction

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12
Q

What’s nondisjunction ?

A

The failure of homologous chromosomes to separate properly in meiosis

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13
Q

Aneuploidy can occur in

A

Sex & autosomal chromosomes

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14
Q

What are the mechanisms of aneuploidy in gametogenesis? { the answer includes explanation of the results }

A
  1. Non disjunction in oogensis
    يعني يصير بال egg فبويضة وحدة ما يكون عندها xx و الثانية يكون عندها xx
    Monosomy فلمن يصير إخصاب رح ينتج من اللي ما عندهم
    و اللي عندهم رح يصير لهم trisomy
  2. Non disjunction in spermatogenesis
    يعني يصير بالsperm فمنية يكون عندها xy و المنية الثانية ما عندها
    فلمن يصير إخصاب للبويضة
    اللي عنده xy يصير له trisomy ذكر
    و اللي ما عنده يصير Monosomy أنثى
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15
Q

What is an example for monosomy occurring in sex chromosomes? What does it result from?

A

Turner syndrome
Loss of 1 X chromosome
( 44+XO=45 )

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16
Q

Females of which syndrome are infertile ?

A

Turner syndrome

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17
Q

What is an example for trisomy in sex chromosomes? And what does it result from ?

A

Klinefelter syndrome ( XXY )
Gaining extra X chromosome

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18
Q

Males of which syndrome are commonly infertile ?

Study These Flashcards
A

Klinefelter ( XXY )

19
Q

None dysfunction can occur either in meiosis I or meiosis II of

Study These Flashcards
A

Spermatogenesis

20
Q

What are the offspring of nondisjunction of sex chromosomes during spermatogenesis in the first meiotic division?

Study These Flashcards
A

Klinefelter & Turner

21
Q

What are the offspring of nondisjunction of sex chromosomes during spermatogenesis in the second meiotic division?

Study These Flashcards
A

Super female ( XXX ) , turner

22
Q

Trisomy in which autosomes are humans able to survive with ? The duration of survival depends on ?

Study These Flashcards
A

13,18,21
The complications

23
Q

Monosomy in autosomes

Study These Flashcards
A

cannot survive

24
Q

What are the autosomal trisomy disorders?

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A

1- trisomy 21 ( Down syndrome ) -> reduced IQ , characteristic features
2- trisomy 18 ( Edward’s syndrome ) -> severe disorder of the heart & kidneys, if fetus survived after birth its lifespan is 5 -15 days
3- trisomy 13 ( patau syndrome ) -> severe birth defects including heart and kidney disorders , and malformations ,80% of infants do not survive beyond one year

25
How does trisomy 21 occur in autosomes?
Nondisjunction in meiosis or mitosis
26
What happens during nondisjunction in meiosis I of oogenesis?
One cell receives 23 + extra chromosome 21—> zygote + extra chromosome 21 [ Down syndrome ] 47 XY or 47 XX The other cell receives all chromosomes except 21 —> zygote with only one copy of chromosome 21 ( Monosomy 21 ) and it doesn’t survive
27
What happens during nondisjunction in meiosis II ?
One cell undergoes normal meiosis II The other cell undergoes nondisjunction—> trisomy 21 , Monosomy 21 { non viable gamete }
28
What happens during mitosis mediated mosaicism in sex chromosome?
Nondisjunction in X chromosome during mitosis —> body cells with mixture of both XX and X chromosomes, so individual has body cells with a mixture of both 46XY and 45Y
29
Polyploidy results in ?
Elevated nuclear gene content in the cell without dividing , or endoreduplication
30
Polyploidy can occur in both
Meiosis & mitosis
31
A fetus with polyploidy will
Die within the uterus or after birth
32
In triploid syndrome, the total chromosomes are —
69 either the egg / sperm has 2 full sets of chromosomes
33
In tetraploid syndrome, the chromosomes are —— and the fetus usually dies ——
92 In uterus
34
What are examples of structural abnormality in chromosomes?
1. Deletion 2. Duplication 3. Insertion 4. Inversion 5. Translocation
35
What is deletion? the best example of it ?
A portion of the chromosome is missing or deleted . cri du chat syndrome
36
What is Cri du chat syndrome?
Deletion at the end of short arm of chromosome 5
37
A person with Cri du chat syndrome is ?
Mentally retarded , growth delay, abnormal development of the glottis and Larynx
38
What is duplication?
A portion of the chromosome is duplicated resulting in extra genetic material
39
What is a human disorder of duplication? And what is it caused by?
Charcot- Marie - tooth disease type 1A Duplication of the gene encoding peripheral myelin protein 22 { PMP 22 } on chromosome 17
40
What is insertion? And in which chromosomes does it occur?
A portion of one chromosome has been deleted from its normal place and inserted into another chromosome Usually chromosome 4 chromosome 20
41
What is inversion? What are the types of it ?
Chromosome rearrangement in which a segment of a chromosome is reversed end to end Paracentric ( تحت السنترومير ) & pericentric ( عند السنترومير )
42
What is translocation / reciprocal translocation ?
The mutual exchange of chromosome segments between two non-homologous chromosomes Usually chromosomes 4 & 20
43
What can possibly trigger chromosomal abnormality?
Heat , radiation , chemicals , viruses
44
What are treatments available for chromosomal abnormality?
They are not treated , but we can treat their complications .

Biology (20 decks)

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