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GED L15 Notes Flashcards

1
Q

What is aneuploidy?

A 
•	Aneuploidy:
	Chromosome abnormality -> abnormal number of chromosomes -> no loss / gain of complete chromosome set. 
	Types:
-	Monosomy (Monosomic):
 Loss of single chromosome (2n – 1)
-	Trisomy (Trisomic):
 One extra chromosome (2n + 1)
-	Tetrasomy (Tetrasomic):
 Extra pair of chromosomes (2n + 2)
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2
Q

Name the types of aneuploidy?

A
  • Monosomy (Monosomic):
  • Trisomy (Trisomic):
  • Tetrasomy (Tetrasomic):
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3
Q

Name the process in which there is abnormal chromosome segregation in meiosis?

A

 Non-disjunction

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4
Q

What is Non-disjunction?

A

 Non-disjunction:
 Mistake -> chromosome segregation during meiosis
&raquo_space; Produce aneuploid gametes

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5
Q

Describe Aneuploidy in Autosomes

A

• Aneuploidy -> Autosomes:
 20-50% human conceptions -> aneuploid
- < 0.5% live births
All autosomal monosomies (2n -1) -> Inviable
 Trisomy 13 (Patau Syndrome) & Trisomy 18 (Edwards Syndrome)
Death -> children within few months.

	Down’s Syndrome:
 Charcteristics:
-	Characteristic facial features
-	Short stature
-	Learning disabilities
-	Higher risk -> Heart defects
-	Alzheimers &amp; some cancers -> 1/1000 
 Causes:
	 Trisomy (2n +1):
-	Trisomy 21
	Robertsian Translocation:
-	Chromosome 21 &amp; 14
	Genetic mosaicism:
-	Mix of normal &amp; trisomy 21 cells 
>>Non-disjunction -> early embryonic mitotic divisions
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6
Q

What is a characteristic of autosomal monosomies in autosomes?

A

All autosomal monosomies (2n -1) -> Inviable

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7
Q

Give examples of aneuploidy in autosomes

A

 Trisomy 13 (Patau Syndrome) & Trisomy 18 (Edwards Syndrome)
 Down’s Syndrome:

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8
Q

Name the type of aneuploidy in autosomes which causes death of children within months.

A

 Trisomy 13 (Patau Syndrome) & Trisomy 18 (Edwards Syndrome)
Death -> children within few months.

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9
Q

Describe Down’s Syndrome

A 
	Down’s Syndrome:
 Charcteristics:
-	Characteristic facial features
-	Short stature
-	Learning disabilities
-	Higher risk -> Heart defects
-	Alzheimers &amp; some cancers -> 1/1000 
 Causes:
	 Trisomy (2n +1):
-	Trisomy 21
	Robertsian Translocation:
-	Chromosome 21 &amp; 14
	Genetic mosaicism:
-	Mix of normal &amp; trisomy 21 cells 
>>Non-disjunction -> early embryonic mitotic divisions
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10
Q

What are the characteristics of Down’s Syndrome?

A

Charcteristics:

  • Characteristic facial features
  • Short stature
  • Learning disabilities
  • Higher risk -> Heart defects
  • Alzheimers & some cancers -> 1/1000
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11
Q

What are the causes of Downs Syndrome?

A 
 Causes:
	 Trisomy (2n +1):
-	Trisomy 21
	Robertsian Translocation:
-	Chromosome 21 &amp; 14
	Genetic mosaicism:
-	Mix of normal &amp; trisomy 21 cells 
>>Non-disjunction -> early embryonic mitotic divisions
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12
Q

Describe genetic mosaicism

A

 Genetic mosaicism:
- Mix of normal & trisomy 21 cells
»Non-disjunction -> early embryonic mitotic divisions

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13
Q

What chromosomes does Robertsian Translocation occur on & what disease is this present in?

A

 Robertsian Translocation:

- Chromosome 21 & 14 –> Down’s Syndrome

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14
Q

Describe Trisomy & the chromosome on which it is located

A

 Trisomy (2n +1):

- Trisomy 21

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15
Q

Describe Aneuploidy in sex chromosomes

A 
•	Aneuploidy -> Sex Chromosomes:
	Normal human karyotype
-	46 XY -> Males ; 46 XX -> Females
	Monosomy (2n -1)
 Turner Syndrome (XO) -> (45, X)
-	Sterile females
-	Short stature
-	Some -> learning difficulties
-	1/2500 female births
-	At least 1 X required -> embryonic development
	Trisomy (2n + 1)
Klinefelter Syndrome (47, XXY)
                   Triplo-X (47, XXX)
                   XYY Syndrome (47, XYY)
                   Some individuals -> more than 47 chromosomes -> (48, XXXY / 48, XXYY)
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16
Q

What are the characteristics of the normal human karyotype?

A

 Normal human karyotype

- 46 XY -> Males ; 46 XX -> Females

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17
Q

Name the types of aneuploidy in sex chromosomes

A

 Monosomy (2n -1) Trisomy (2n + 1)

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18
Q

What disease is monosomy found in (Aneuploidy -> sex chromosomes) ?

A

 Turner Syndrome (XO) -> (45, X)

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19
Q

What is the chromosomal no. in monosomy?

A

 Monosomy (2n -1)

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20
Q

Describe the characteristics of Turner Syndrome

A

 Turner Syndrome (XO) -> (45, X)

  • Sterile females
  • Short stature
  • Some -> learning difficulties
  • 1/2500 female births
  • At least 1 X required -> embryonic development
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21
Q

Name the diseases in which Trisomy is found (Aneuploidy -> sex chromosomes)?

A

Klinefelter Syndrome (47, XXY)
 Triplo-X (47, XXX)
 XYY Syndrome (47, XYY)
 Some individuals -> more than 47 chromosomes -> (48, XXXY / 48, XXYY)

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22
Q

What is the chromosome number & conformation in normal human karyotype?

A

 Normal human karyotype

- 46 XY -> Males ; 46 XX -> Females

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23
Q

What is the chromosome number & conformation in Turner Syndrome?

A

 Turner Syndrome (XO) -> (45, X)

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24
Q

What is the chromosome number & conformation in Klinefelter Syndrome?

A

Klinefelter Syndrome (47, XXY)

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25
What is the chromosome number & conformation in Triplo-X?
 Triplo-X (47, XXX)
26
What is the chromosome number & conformation in XYY Syndrome?
 XYY Syndrome (47, XYY)
27
What is the chromosome number & conformation in individuals with more than 47 chromosomes?
 Some individuals -> more than 47 chromosomes -> (48, XXXY / 48, XXYY)
28
What does X chromosome inactivation cause?
• X chromosome inactivation switches off all but one X chromosome
29
Describe maternal age & trisomy
• Maternal Age & Trisomy  Incr. trisomy  Responsible for incr. miscarriage -> older women.  95% -> trisomy 21  Maternal non-disjunction -> meiosis 1  Human oocytes  Paused -> late meiotic prophase I (diplotene) >> Alongside paired, replicated chromosomes  Begins before birth >> Maintained -> decades -> Until egg matures -> menstrual cycle  Loss of cohesion -> Prophase I  Aneuploidy -> older women >> Premature loss -> cohesion ->> 2 univalents -> segregate independently > Aneuploid (n +1) gametes
30
What is a result of incr. trisomy?
 Incr. trisomy |  Responsible for incr. miscarriage -> older women
31
What process is trisomy 21 responsible for & what percentage does it occur?
 95% -> trisomy 21 |  Maternal non-disjunction -> meiosis 1
32
Describe maternal age & trisomy in terms of human oocytes
 Human oocytes  Paused -> late meiotic prophase I (diplotene) >> Alongside paired, replicated chromosomes  Begins before birth >> Maintained -> decades -> Until egg matures -> menstrual cycle
33
Describe the pause of human oocytes in meiosis
 Human oocytes  Paused -> late meiotic prophase I (diplotene) >> Alongside paired, replicated chromosomes  Begins before birth >> Maintained -> decades -> Until egg matures -> menstrual cycle
34
Describe loss of cohesion in prophase I
```  Loss of cohesion -> Prophase I  Aneuploidy -> older women >> Premature loss -> cohesion ->> 2 univalents -> segregate independently > Aneuploid (n +1) gametes ```
35
Describe extranuclear genomes of mitochondria & chloroplasts
• Extranuclear genomes -> mitochondria & chloroplasts: - Circular dsDNA genomes - Ribosomes -> mitochondria & chloroplasts >> Different -> cytoplasmic ribosomes >> Sensitive -> Bacterial antibiotics  Mitochondrial Genomes / DNA: - Components -> Translation Eg. tRNAs & rRNAs - Structural genes -> proteins involved -> oxidative phosphorylation Eg. Cytochrome oxidase, NADH-dehydrogenase, ATPase  Chloroplast Genomes / DNA: - Genes encoding tRNAs & rRNAs involved -> translation - Structural genes -> proteins involved -> photosynthesis Eg. Biphosphate decarboxylase • Transmission -> Extranuclear Genomes:
36
Describe ribosomes of mitochondria & chloroplasts & the type of genomes they contain
• Extranuclear genomes -> mitochondria & chloroplasts: - Circular dsDNA genomes - Ribosomes -> mitochondria & chloroplasts >> Different -> cytoplasmic ribosomes >> Sensitive -> Bacterial antibiotics
37
Describe mitochondrial Genomes / DNA
 Mitochondrial Genomes / DNA: - Components -> Translation Eg. tRNAs & rRNAs - Structural genes -> proteins involved -> oxidative phosphorylation Eg. Cytochrome oxidase, NADH-dehydrogenase, ATPase
38
Describe chloroplast genomes / DNA
 Chloroplast Genomes / DNA: - Genes encoding tRNAs & rRNAs involved -> translation - Structural genes -> proteins involved -> photosynthesis Eg. Biphosphate decarboxylase
39
Describe transmission of extranuclear genomes
``` • Transmission -> Extranuclear Genomes:  Egg  Diameter -> ~100um  > 100,000 copies mitochondrial DNA  Sperm  Diameter -> ~5um  < 1000 copies mitochondrial DNA  Transmission -> mitochondrial & chloroplast genomes  Uniparental pattern >> Usually maternal inheritance ->> Females transmit -> All children ->> Males never transmit  Paternal mammalian mitochondria & sperm components (excl. nucleus) destroyed after fertilisation.  Plants:  Maternal inheritance common  Paternal & Biparental inheritance also found ```
40
Describe characteristics of the egg in terms of mitochondrial DNA
 Egg  Diameter -> ~100um  > 100,000 copies mitochondrial DNA
41
Describe the characteristics of the sperm in terms of mitochondrial DNA
 Sperm  Diameter -> ~5um  < 1000 copies mitochondrial DNA
42
Describe transmission of mitochondrial & chloroplast genomes
```  Transmission -> mitochondrial & chloroplast genomes  Uniparental pattern >> Usually maternal inheritance ->> Females transmit -> All children ->> Males never transmit ```
43
Describe what happens to paternal mammalian mitochondria & sperm components after fertilisation
 Paternal mammalian mitochondria & sperm components (excl. nucleus) destroyed after fertilisation.
44
What is destroyed after fertilisation?
 Paternal mammalian mitochondria & sperm components (excl. nucleus) destroyed after fertilisation.
45
Name the types of inheritance found in plants -> Extranuclear genome transmission
 Plants:  Maternal inheritance common  Paternal & Biparental inheritance also found
46
Describe mitochondrial DNA disease
• Mitochondrial DNA Disease: - ~1/200 healthy individuals -> pathological mtDNA mutation - ~ 1/10,000 adults -> mtDNA disease - > 1000 mitochondrial proteins encoded -> nuclear genome  Mutations here can cause mitochondrial disease - Signs & symptoms Highly variable -> Even within family - Same mtDNA mutation  Different signs & symptoms -> diff individuals
47
Describe characteristics of mitochondrial DNA disease
• Mitochondrial DNA Disease: - ~1/200 healthy individuals -> pathological mtDNA mutation - ~ 1/10,000 adults -> mtDNA disease - > 1000 mitochondrial proteins encoded -> nuclear genome  Mutations here can cause mitochondrial disease
48
What are the signs & symptoms of mitochondrial DNA disease
Highly variable -> Even within family - Same mtDNA mutation  Different signs & symptoms -> diff individuals
49
Describe heteroplasmy
• Heteroplasmy:  Mutation -> mitochondrial genome Mixture -> normal & mutant mitochondria >> Passive segregation -> mitochondria -> cell division  Proportion -> mutant mitochondria -> affects severity >> Varies between ->> Individuals ->> Tissues -> single individual
50
What affects the severity of heteroplasmy?
 Proportion -> mutant mitochondria -> affects severity
51
What does the severity of heteroplasmy vary in?
 Proportion -> mutant mitochondria -> affects severity >> Varies between ->> Individuals ->> Tissues -> single individual
52
What is heteroplasmy and how is it caused?
• Heteroplasmy:  Mutation -> mitochondrial genome Mixture -> normal & mutant mitochondria >> Passive segregation -> mitochondria -> cell division
53
Describe mitochondrial Replacement therapy
• Mitochondrial Replacement Therapy:  Maternal Spindle Transfer:  Repair -> egg -> before fertilisation  Metaphase II spindle & associated chromosomes -> mother’s egg >> Transplanted -> donor egg ->> Nucleus removed Some unhealthy mitochondria possibly transferred alongside mother’s nucleus.
54
Name the process in which mitochondrial replacement therapy occurs
 Maternal Spindle Transfer:
55
Describe the process of mitotic spindle transfer
 Maternal Spindle Transfer:  Repair -> egg -> before fertilisation  Metaphase II spindle & associated chromosomes -> mother’s egg >> Transplanted -> donor egg ->> Nucleus removed Some unhealthy mitochondria possibly transferred alongside mother’s nucleus.
56
Describe monosomy
- Monosomy (Monosomic): |  Loss of single chromosome (2n – 1)
57
What is monosomy?
- Monosomy (Monosomic): |  Loss of single chromosome (2n – 1)
58
Describe Trisonomy?
- Trisomy (Trisomic): |  One extra chromosome (2n + 1)
59
What is Trisonomy?
- Trisomy (Trisomic): |  One extra chromosome (2n + 1)
60
Describe Tetrasomy?
- Tetrasomy (Tetrasomic): |  Extra pair of chromosomes (2n + 2)
61
What is Tetrasomy?
- Tetrasomy (Tetrasomic): |  Extra pair of chromosomes (2n + 2)

Genes Evo & Dev Y1 (23 decks)

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