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Lect 23 Flashcards

1
Q

How many pairs of autosomes are in the human karyotype?

A

22 pairs

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2
Q

How many pairs of sex chromosomes are in the human karyotype?

A

One pair

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3
Q

Fill in the blank: The human karyotype consists of 22 pairs of _______ and one pair of sex chromosomes.

A

autosomes

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4
Q

What is the smallest chromosome?

A

Chromosome 21

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5
Q

Which chromosome is significantly larger, the X chromosome or the Y chromosome?

A

The X chromosome

The X chromosome contains more genes than the Y chromosome, which is important for various biological functions.

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6
Q

How many genes are on the X chromosome?

A

839 genes

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7
Q

What type of genes are included in the X chromosome?

A

Many housekeeping genes

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8
Q

How many genes are on the Y chromosome?

A

48 genes

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9
Q

What is the primary function of the genes on the Y chromosome?

A

Mostly involved in spermatogenesis

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10
Q

What is Klinefelter syndrome?

A

A condition in males characterized by an extra X chromosome (47,XXY)

Occurs in approximately 1 in 1,000 males.

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11
Q

What are the common physical characteristics of Klinefelter syndrome?

A

Poor beard growth, breast development, underdeveloped testes

These features arise due to hormonal imbalances associated with the syndrome.

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12
Q

What is the chromosomal composition of a male with Klinefelter syndrome?

A

47,XXY

This indicates the presence of an extra X chromosome.

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13
Q

True or False: Klinefelter syndrome can occur in females.

A

False

Klinefelter syndrome specifically affects males due to the presence of an extra X chromosome.

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14
Q

Fill in the blank: Klinefelter syndrome is known to affect approximately _______ males.

A

1 in 1,000

This prevalence indicates its rarity among male populations.

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15
Q

What is Turner syndrome’s chromosomal composition?

A

XO or 45,X

Turner syndrome is characterized by the presence of a single X chromosome.

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16
Q

What is the prevalence of female Turner syndrome?

A

Approximately 1 in 2,500 females

This indicates that Turner syndrome is a rare genetic condition.

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17
Q

List common symptoms of Turner syndrome.

A
  • Characteristic facial features
  • Neck webbing
  • Restricted aorta
  • Poor breast development
  • under developed ovaries
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18
Q

What gene is responsible for male determination in individuals with a Y chromosome?

A

SRY gene

The SRY gene is crucial for the development of male characteristics.

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19
Q

What does the SRY gene instruct developing gonads to become?

A

Testes

The development of testes is essential for male sexual characteristics.

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20
Q

What hormone is produced by the testes?

A

Testosterone

Testosterone plays a key role in male sexual development.

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21
Q

What is the primary function of testosterone in male development?

A

Musculonizes the body and gives primary sexual characteristics of a male

Testosterone influences physical traits associated with males.

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22
Q

True or False: The expression of the SRY gene is essential for female development.

A

False

The SRY gene specifically drives male development.

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23
Q

Fill in the blank: The SRY gene tells the developing gonads to become _______.

A

testes

This process is crucial for male sexual differentiation.

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24
Q

What occurs during prophase I of female meiosis?

A

The two X chromosomes pair up and undergo recombination

This pairing is essential for genetic diversity.

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25
What happens to the X chromosomes during female meiosis?
They segregate into different gametes (eggs), with each egg receiving one X chromosome ## Footnote This ensures that each gamete has the correct genetic material.
26
In males, what chromosomes pair during meiosis?
The X and Y chromosomes pair during the early stages of meiosis ## Footnote This pairing occurs in a specific region known as the pseudoautosomal region (PAR).
27
Where does recombination occur in male meiosis?
Recombination occurs only at the pseudoautosomal region (PAR) ## Footnote This region allows for homologous sequences to align.
28
What is the outcome of segregation in male meiosis?
The X and Y chromosomes segregate into different gametes, with half receiving X and half receiving Y ## Footnote This results in the production of two types of sperm.
29
What does it mean for males to be heterogametic?
Males produce two types of gametes: half carry the X chromosome and half carry the Y chromosome ## Footnote This is different from females, who are homogametic.
30
What term describes females in terms of gamete production?
Homogametic ## Footnote Females produce only X-bearing eggs.
31
Fill in the blank: Recombination only happens at _____ for males.
PAR
32
How are males represented in human pedigrees?
Males are drawn as squares
33
How are females represented in human pedigrees?
Females are drawn as circles
34
What can human pedigrees help determine?
Non-paternity and assist in ancestry analysis ## Footnote Human pedigrees are useful tools in genetic studies and family history research.
35
What role does the Y chromosome play in understanding human migration?
The Y chromosome is passed down exclusively through the paternal line, allowing it to trace the movement of ancient human populations.
36
Through which line is the Y chromosome inherited?
The paternal line (father to son).
37
True or False: The Y chromosome can be inherited from both parents.
False.
38
Fill in the blank: The Y chromosome is passed down exclusively through the _______.
paternal line.
39
What is the relationship between X-chromosome GENES and the Y-chromosome?
Most X-chromosome genes are absent on the Y-chromosome.
40
Why are males more vulnerable to X-linked genetic disorders?
Males are more vulnerable because there’s no second X to compensate for a defective gene.
41
What does it mean that males have 'one chance' for X-linked traits?
It means males have only one X chromosome, so a defective gene on that X will express the trait.
42
What is hemophilia?
A blood clotting disorder that impairs the body’s ability to stop bleeding ## Footnote Hemophilia can occur from both minor and severe injuries.
43
What processes are activated when an injury occurs in hemophilia?
A complex series of cellular, molecular, and biochemical processes are activated to repair the damage ## Footnote These processes involve several key proteins in blood clotting and wound repair.
44
What causes Hemophilia A?
A deficiency in Factor VIII ## Footnote Factor VIII is essential for normal blood clotting.
45
What causes Hemophilia B?
A lack of Factor IX ## Footnote Factor IX is also crucial for blood clotting.
46
What are the consequences of the deficiencies in hemophilia?
The blood fails to clot properly, leading to uncontrolled bleeding ## Footnote This can occur even from minor injuries.
47
What symptoms can result from hemophilia?
Symptoms include bruising (internal bleeding) and swollen joints ## Footnote These symptoms indicate issues with blood clotting.
48
Why can hemophilia be life-threatening?
Due to the risk of internal bleeding ## Footnote Even minor injuries may lead to severe consequences.
49
Fill in the blank: Hemophilia A is caused by a deficiency in _______.
Factor VIII
50
Fill in the blank: Hemophilia B results from a lack of _______.
Factor IX
51
What is haemophilia associated with?
Loss of function mutations on the X-chromosome
52
What is the inheritance pattern for affected men with haemophilia?
Affected men with haemophilia have unaffected sons and carrier daughters ## Footnote This indicates that the gene for haemophilia is located on the X chromosome.
53
What can carrier females of haemophilia have?
Carrier females of haemophilia can have affected sons and carrier daughters ## Footnote Carrier females pass one of their X chromosomes to their offspring, which may carry the haemophilia gene.
54
What are the parental genetic conditions for affected females of haemophilia?
Affected females of haemophilia have an affected father and a carrier mother ## Footnote Affected females inherit one X chromosome with the haemophilia gene from their father and another X chromosome from their mother, which may be a carrier.
55
What is the treatment plan for Hemophilia A?
Delivering missing clotting factors, such as Factor VIII. ## Footnote Factor VIII is essential for blood clotting and is deficient in Hemophilia A patients.
56
How was Factor VIII historically administered to patients?
Through blood donations from multiple donors. ## Footnote This method raised significant risks of contamination and infection.
57
What was a major health concern for hemophilia patients using historical treatment methods?
Exposure to infections from contaminated blood. ## Footnote Bloodborne diseases such as HIV could be contracted due to multiple donors.
58
True or False: The historical method of obtaining Factor VIII had a low risk of infection.
False. ## Footnote The risk of contracting bloodborne diseases was significantly higher.
59
Fill in the blank: The chances of contracting bloodborne diseases, such as ______, were much higher for hemophilia patients when getting treatments from blood of other donors.
HIV. ## Footnote HIV is one of the serious infections that could be transmitted through contaminated blood.
60
What percentage of males are color blind?
8% ## Footnote This statistic indicates a significant difference in color blindness prevalence between genders.
61
What percentage of females are color blind?
0.64% ## Footnote This shows that color blindness is much rarer in females compared to males.
62
What chromosome contains the genes crucial for distinguishing certain colors related to color vision?
X chromosome
63
What do the genes on the X chromosome encode for in relation to color vision?
Opsin proteins for red and green cones in the retina
64
What are the two colors specifically related to the opsin proteins encoded by the genes on the X chromosome?
Red and green
65
The opsin proteins are associated with which part of the eye?
Retina
66
True or False: The genes on the X chromosome are responsible for encoding opsin proteins for blue cones.
False
67
What is Duchenne muscular dystrophy (DMD)?
DMD is caused by a mutation ( the mutation may be an early stop codon, so they have a shortened version of the protein). DMD is caused by a mutation in the dystrophin gene, leading to a weakened form of the dystrophin protein.
68
What is the primary consequence of the mutation in the dystrophin gene?
It causes progressive muscle weakness.
69
By what age do individuals with DMD often require a wheelchair?
By the teenage years.
70
What other organ can be affected by the lack of functional dystrophin in DMD?
The heart.
71
True or False: Individuals with DMD are not at risk for heart problems.
False.
72
What are potential heart issues that can arise from DMD?
Heart problems, including heart failure and death if left untreated.
73
Fill in the blank: DMD is caused by a mutation in the _______.
dystrophin gene.
74
What is Fragile X syndrome?
A genetic condition that affects brain development, leading to intellectual disabilities and a variety of other symptoms ## Footnote Inherited in an X-linked dominant pattern.
75
How is Fragile X syndrome inherited?
In an X-linked dominant pattern ## Footnote Passed down through the X chromosome.
76
What primarily affects females and is caused by a mutation in the MECP2 gene?
Rett syndrome ## Footnote A dominant condition with varying brain function.
77
What are the consequences of Rett syndrome?
Loss of communication skills and motor abilities over time ## Footnote Some parts of the brain function normally, while others do not.
78
What is Androgen Insensitivity Syndrome (AIS)?
A condition where individuals with one X and one Y chromosome have a mutation in the gene for the testosterone receptor on the X chromosome ## Footnote Prevents the body from responding to testosterone.
79
What results from the mutation in Androgen Insensitivity Syndrome (AIS)?
Development of female characteristics despite having a Y chromosome ## Footnote Individuals have one X and one Y chromosome.
80
list 6 X linked conditions:
• Duchenne muscular dystrophy • Fabry disease • fragile X mental retardation • Lesch-Nyhan syndrome • Rett syndrome • androgen insensitivity disorder

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