Neurogenetics Flashcards

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1
Q

How many pairs of chromosomes in the human body?

A

23

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2
Q

The double helix is composed of 2 chains of what?

A

Phosphate and deoxyribose

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3
Q

Watson, Crick, Wilkins and Franklin discovered the double helix in what year?

A

1953

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4
Q

What holds the structure of DNA together?

A

Deoxyribose chains

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5
Q

Name the nucleotide bases

A
  1. Adrenaline and thymine
  2. Cytosine and guanine
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6
Q

What are the natural variations in DNA called?

A

Single nucleotide polymorphisms

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7
Q

What are single nucleotide polymorphisms responsible for?

A

What makes us unique and different from one another

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8
Q

Where does mitosis occur?

A

In somatic cells

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9
Q

Which type of cell division makes identical daughter cells?

A

Mitosis

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10
Q

Where does meiosis occur?

A

In the gametes

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11
Q

What is the term for the swapping and mixing up of DNA in the chromosomes during meiosis?

A

Homologous recombination

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12
Q

How many daughter cells are produced in meiosis?

A

4

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13
Q

In the second division of meiosis what are the resulting cells called?

A

Haploid cells

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14
Q

Homologous recombination allows for what in the population?

A

Genetic diversity

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15
Q

What is a binding sequence and where in the gene is it found?

A
  1. It is a sequence of DNA specific to attract a transcription factor
  2. Found at the top end of a gene
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16
Q

In the first stage of transcription, the transcription factor reads down the gene and produces what?

A

mRNA

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17
Q

After the mRNA is produced it leaves the nucleus and something attaches to it, what is this?

A

Ribosome

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18
Q

What is a triple codon?

A

Three nucleotide base pairs

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19
Q

Describe the process of translation

A
  1. Ribosome reads the triple codon
  2. Using transfer RNAs, the ribosome puts together a chain of amino acids
  3. This chain becomes a protein
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20
Q

Who discovered the inheritance of pea plants in 1865?

A

Gregor Mendel

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21
Q

If genes are identical (TT) what are they called?

A

Homozygous

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22
Q

If the genes are not identical (Ts) what are they called?

A

Heterozygous

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23
Q

What is the difference between the genotype and the phenotype?

A

Genotype = genetic information
Phenotype = how it displays

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24
Q

What is an allele?

A

The variants of the gene

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25
Q

What is a single gene disorder?

A

Where the disorder is caused by a single gene, and can be inherited following either dominant or recessive inheritance

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26
Q

Huntington’s Chorea is inherited through what type of inheritance?

A

Autosomal dominant inheritance

27
Q

What happens to the striatum in patients with Huntington’s chorea?

A

It degenerates

28
Q

What are the three main factors affected in Huntington’s chorea?

A

Movement, temperament, and cognition

29
Q

What does autosomal dominant inheritance mean?

A

A single copy will be dominant and lead to the disease

30
Q

How does the single gene disorder on chromosome 4 causes Huntington’s disease?

A

It causes excessive repeats of CAG bases

31
Q

What does it mean that CAG is an insatiable triplet?

A

The repeats can increase in subsequent generations

32
Q

Name a disorder caused by autosomal single inheritance?

A

PKU (phenylketonuria)

33
Q

PKU is caused by a mutation in what gene?

A

PAH gene

34
Q

What does the mutation of the PAH gene do?

A

Affects the the enzyme that breaks down phenylalanine

35
Q

A build up of phenylalanine can lead to what?

A

Learning disabilities, behavioural difficulties, and epilepsy

36
Q

Name the two types of chromosomal abnormalities

A

Monosomy and Trisomy

37
Q

What causes downs syndrome?

A

Trisomy in chromosome 21 due to an error in the first meiotic division

38
Q

Symptoms of DS include smaller brain size, mid to moderate intellectual ability, and a high risk of early onset alzheimers. Why does the link between DS and alzheimers exist?

A

The amyloid precursor protein gene is found o chromosome 21, and it is known that mutations in the gene can cause alzheimers

39
Q

Why does the error on chromosome 21 seem to be the most common?

A

Because the phenotype for the extra chromosome in 21 is the only one mild enough for people to survive it

40
Q

What does X inactivation do in females?

A

It switches off one copy of the X chromosome during embryogenesis

41
Q

During X-inactivation in females, what % of cells have the maternal X switched off, and what % has the paternal X switched off?

A

It will be 50/50

42
Q

Name 2 X-linked disorders

A

Rett syndrome and Fragile X

42
Q

Name 2 X-linked conditions

A

Rett syndrome and Fragile X

43
Q

The deficits in Rett syndrome are similar to what?

A

Autism

44
Q

Rett syndrome is caused by a mutation in what gene?

A

MePC2

45
Q

What is the MePC2 gene responsible for?

A

Turning off the expression of unwanted genes

46
Q

Why is there variable penetrance of Rett syndrome?

A

Due to X-inactivation, not all cells will express the mutated MePC2 gene

47
Q

What X-linked disorder is the most common inherited form of learning disability?

A

Fragile X

48
Q

What gene is affected in Fragile X?

A

FMR1

49
Q

Briefly, how does maternal licking reduce stress in rat pups?

A
  1. Maternal licking switches on the release of seretonin
  2. Seretonin actions lead to the switching on of the gene that expresses glucocorticoid receptor protein, which is important for regulating stress in the hippocampus
50
Q

What gene becomes permanently methylated in an absence of maternal licking?

A

Nr3C1

51
Q

What is the role of the Nr3C1 gene?

A

Expresses glucocorticoid receptor protein

52
Q

What is transgenerational epigenetics?

A

Environmental influence on parents can affect offspring

53
Q

What can modify histones?

A

Chemicals such as drinking and smoking

54
Q

What are the 2 definitive reasons for alzheimers?

A

Tau microfibrillary tangles and amyloid plaques

55
Q

What is the name for the amyloid precursor protein gene called?

A

PSEN

56
Q

What does it mean if there are mutations in the PSEN1 or 2 gene?

A

Beta amyloid does not get broken down

57
Q

APOE4 is linked with what disease?

A

Alzheimers

58
Q

Why do we use mice in studies? (4)

A
  1. Similarly organised brain
  2. Behavioural traits similar to mammals
  3. Wealth of background on the biological processes
  4. Well defined behavioural tests
59
Q

How can inbred strains be used to study behaviour?

A

Have different genetics and neurobiology and therefore comparison of these strains can show how genes influence behaviour

60
Q

What is the goal of BXD recombinant breeding?

A

To create a population of mice with a mix of traits from each inbred parent strain in order to study how different combinations of genes affect behaviours and traits

61
Q

Name the three types of genetically engineered mice

A
  1. Knock-out mice
  2. Knock in mice
  3. Transgenic mice
62
Q

What happens in transgenic mice?

A

Researchers insert genes from another species in order to study the function of specific genes

63
Q

What did studies of knock-out mice reveal about retts syndrome?

A

Showed that the MePC2 gene is implicated because rats who had the gene removed show similar symptoms