lecture 24 - human genome & disease Flashcards

1
Q

What is the name for mutations that have been inherited and can therefore be passed on to offspring?

A

Germline mutations

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2
Q

What are somatic mutations?

A

Mutations to DNA in somatic cells, meaning they cannot be inherited

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3
Q

What is the name for a mutation that causes a gene to function poorly?

A

Loss of function mutation

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4
Q

Are loss of function mutations typically recessive or dominant, and why?

A

Recessive - if a normal copy of the gene exists on the homologous chromosome pair, then it can perform the genes intended function instead, meaning the mutation has no effect.

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5
Q

What is the name for a mutation that causes a gene to work ‘too well’?

A

Gain of function mutation

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6
Q

Are gain of function mutations typically dominant or recessive, and why?

A

Dominant - an allele that works too well will exceed the smaller effects of the normal allele.

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7
Q

What are monogenic diseases?

A

Disease caused by genetic mutations in single genes, that can be passed down generations

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8
Q

What is haemophilia?

A

A disorder of blood clotting

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9
Q

Are males or females more commonly affected by haemophilia?

A

Males

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10
Q

What mode of inheritance does Haemophilia display?

A

X linked recessive

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11
Q

What is the chance of a male inheriting Haemophilia (X linked recessive) if their mother is a carrier?

A

50%

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12
Q

Are males or females carriers of Haemophilia, an X linked recessive disorder?

A

Females - mutation on X chromosome so all males with mutation will be affected, not just carriers

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13
Q

What mode of inheritance is displayed by Huntington disease?

A

Autosomal dominant

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14
Q

Where is the mutated Huntingtin gene, that causes Huntington’s disease, found?

A

Chromosome 4

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15
Q

What is the mutation to the Huntingtin gene that causes Huntington’s disease?

A

Too many copies of the CAG triplet in the gene.

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16
Q

What is the mode of inheritance of cystic fibrosis?

A

Autosomal recessive

17
Q

What are polygenic disorders?

A

Disorders that appear to have a genetic basis but do not follow clear inheritance patterns - cannot be linked to a specific gene and are instead caused by a combination of mutations of different genes

18
Q

Are the majority of genes probabilistic or deterministic?

A

Probabilistic

19
Q

If a disorder is observed in every generation, is it considered dominant or recessive?

A

Dominant

20
Q

If a disorder is not observed in every generation, is it considered dominant or recessive?

A

Recessive

21
Q

If a dominant condition affects males and females equally, what is the mode of inheritance?

A

Autosomal dominant

22
Q

If a dominant condition affects males and females at different rates, what is the mode of inheritance?

A

X-linked dominant trait.

23
Q

What is the predicted sex ratio of an autosomal dominant condition?

A

1:1

24
Q

In an X-linked dominant condition, why are more females affected than males?

A

Affected males produce 100% affected daughters but no affected sons while affected mothers have a 50% chance of passing on the gene to their offspring, for both males and females.

25
Q

What is the chance that an individual affected by an autosomal dominant condition will pass on their condition to their offspring?

A

50%, regardless of gender, assuming they are heterozygous.

26
Q

If a recessive condition affects males and females equally, what is the mode of inheritance?

A

Autosomal recessive

27
Q

If a recessive condition affects more males than females, what is the mode of inheritance?

A

X-linked recessive

28
Q

If a recessive condition affects only males, what is the mode of inheritance?

A

Y-linked

29
Q

What is the probability that an affected individual with a Y-linked condition will pass on the condition to their offspring?

A

100% chance of passing to male, 0% chance of passing to female.

30
Q

Are males of females carriers in X-linked recessive conditions, and why?

A

Heterozygous females are always carriers, males will always express the gene if they have it.

31
Q

What is the genotype of a female affected by an X-linked recessive condition?

A

homozygous recessive

32
Q

What is the predicted sex ratio of affected individuals with an X-linked recessive condition?

A

More males than females

33
Q

What is the predicted sex ratio of an X-linked dominant condition?

A

More females than males