Lecture 17 Flashcards

1
Q

What do sexually reproduced diploid organisms inherit?

A

1/2 of their DNA from each parent

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2
Q

What is DNA packed onto?

A

Chromosomes

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3
Q

How many sets of each chromosome does a diploid organism have?

A

2, called a homologous pair

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4
Q

What is an allele?

A

An alternative form of a genetic variant located the same place in the gene

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5
Q

What could two different alleles mean?

A

You have two different versions of the same protein

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6
Q

How is genetic variation measured?

A

Through phenotypes

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7
Q

What is a phenotype?

A

The observable characteristic or traits of an individual

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8
Q

What does an individual’s phenotype depend on?

A

Their genotype

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9
Q

What is a genotype?

A

The combination of alleles a person has for a particular genetic variant

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10
Q

What are the simplest form of inheritance to track?

A

Dominant and recessive traits

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11
Q

What is a dominant allele?

A

An organism with at least one dominant allele will show that alleles phenotype

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12
Q

What is a recessive allele?

A

An organism will only show a recessive allele’s trait when both alleles are the same

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13
Q

What is a gain of function variation?

A

It causes the protein to work too well or do something new. They often follow a dominant inheritance patterns

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14
Q

What is a loss of function variation?

A

It causes the protein to no longer work. They often follow a recessive inheritance pattern

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15
Q

What is a monogenic trait?

A

An inherited trait that is controlled by a single gene. They are generally discrete and follow simple inheritance patterns. Environment may influence

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16
Q

What is a polygenic trait?

A

An inherited trait that is controlled by multiple genes. These do not follow obvious inheritance patterns but are common in families and categorised in terms of risk. Environment may influence

17
Q

What is retinitis pigmentosa?

A

A dominant (GOF) retinal degenerative disease caused by variants in the Rhodopsin receptor protein causing night blindness and complete loss of vision over time from overworking the rod cells leading to apoptosis.

18
Q

What is phenylketonuria?

A

A recessive (LOF) inherited inability to metabolise phenylalanine

19
Q

How can we detect genetic variants?

A

Through genotyping

20
Q

What could genotyping help confirm?

A

The specific cause of disease, confirm the inheritance pattern, predict the future health/disease progression

21
Q

What are the three different methods to determine genotype?

A

PCR-RFLP, fluorescence-based methods, genome sequencing

22
Q

What is PCR?

A

The polymerase chain reaction which is a lab-based method to make many copies for a specific segment of DNA

23
Q

What are the reaction components of PCR?

A

DNA sample, primers, polymerase, nucleotides

24
Q

What are the three steps of PCR?

A

Denaturation, annealing, elongation

25
Q

What is denaturing?

A

DNA is separated by heating to a very high temperature

26
Q

What is annealing?

A

Reaction is cooled so DNA primers can attach target sequence

27
Q

What is elongation?

A

Heat is increased slightly so heat-tolerant DNA polymerase can bind primer and replicate DNA

28
Q

What type of growth does PCR enable?

A

Exponential, usually 25-30 cycles

29
Q

What is PCR-RFLP?

A

Polymerase Chain reaction-restriction fragment length polymorphism

30
Q

What does PCR-RFLP use?

A

PCR, restriction enzymes and gel electrophoresis to determine genotype

31
Q

What are the advantages of PCR-RFLP?

A

Quick, simple and scalable

32
Q

What is a restriction enzyme?

A

Proteins isolated from bacteria that cut DNA

33
Q

What does a restriction enzyme recognise?

A

Short and palindromic sequences which it cuts at the same place on both DNA strands

34
Q

What are PCR primers designed to do?

A

Amplify DNA surrounding a genetic variant of interest

35
Q

How are restriction enzymes chosen?

A

The ability to cut one allele of the variant but not the other

36
Q

What is the genotyping fluorescence method?

A

Use different ‘coloured’ probes to detect alleles

37
Q

What are probes designed to do? (in fluorescent method)

A

Specifically anneal to one of the two alleles, each has a different fluorescent dye attached

38
Q

How is the fluorescence method tracked?

A

Through clustering graphs that calculate which alleles are present in a sample

39
Q

What do genotyping ‘chips’ do?

A

Using fluorescence-based methods they assess multiple genetic variants at once