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2 - Brain and behaviour > 4. Genetic disorders > Flashcards

4. Genetic disorders Flashcards

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The Brain flashcards
1
Q

What did Watson et al (1953) discover? (Disorders B&B)

A
  • DNA double helix structure
  • Made of 2 complementary chains of phosphate and deoxyribose
  • 4 nucleotide bases
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2
Q

What are the four nucleotide bases? (Disorders B&B)

A
  • Adenine
  • Thymine
  • Cytosine
  • Guanine
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3
Q

What are genes? (Disorders B&B)

A

Long sequences of base pairs, in the DNA, that code for proteins

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4
Q

What are genes turned on by and what do they do? (Disorders B&B)

A
  • Transcription factors

- Activated during development or by intracellular signalling cascades from other parts of the cell

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5
Q

What is gene expression? (Disorders B&B)

A

When a particular part of the DNA unravels to allow for a transcription fact to bind to the gene

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6
Q

What is transcription? (Disorders B&B)

A

In the nucleus, the DNA sequence is copied onto mRNA

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7
Q

What is translation? (Disorders B&B)

A
  • Ribosome attaches to mRNA and moves long
  • mRNA reads each triplet codon
  • tRNA is used to make a chain out of the amino acids, creating a protein
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8
Q

What are the characteristics of mitosis? (Disorders B&B)

A
  • Somatic cells (daughter cells identical to parents)

- Diploid

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9
Q

What are the characteristics of meiosis? (Disorders B&B)

A
  • Gametes (daughter cells contain half the number of parent chromatids)
  • Haploid
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10
Q

What is homologous recombination? (Disorders B&B)

A
  • Crossing over in meiosis
  • Allows for genetic diversity
  • This is the basis of natural selection
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11
Q

What are the characteristics of Huntington’s Chorea? (Disorders B&B)

A
  • Dominant inheritance
  • Degeneration of the stratum (brain)
  • Deterioration in movement, cognition and temperament
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12
Q

What causes Huntington’s Chorea? (Disorders B&B)

A
  • Autosomal dominant inheritance
  • Single gene disorder on chromosome 4
  • Excessive repeat of CAG bases
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13
Q

What is autosomal dominant inheritance? (Disorders B&B)

A

A single copy will be dominant, leading to the disease i.e. if one parent has hunting tons, 50% chance the offspring will

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14
Q

What are the characteristics of Phenylketonuria? (Disorders B&B)

A
  • Recessive inheritance
  • Mutation on the PAH gene
  • Build up of phenylalanine (toxic) leading to learning difficulties and epilepsy
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15
Q

What is the offspring probability of getting a recessive disorder, if both parents are carriers? (Disorders B&B)

A
  • 25% chance offspring will suffer

- 50% chance offspring are carriers

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16
Q

What are the three types of prenatal chromosomal abnormalities? (Disorders B&B)

A
  • Monosomy
  • Trisomy
  • Downs syndrome
17
Q

What is monosomy? (Disorders B&B)

A

Single copy of a chromosome (one chromosome lacks the matching partner)

18
Q

What is trisomy? (Disorders B&B)

A

Three copies of the chromosome (extra copy present)

19
Q

What is Downs syndrome? (Disorders B&B)

A

Trisomy on chromosome 21, where there is an error in the first meiotic division

20
Q

What is an X-linked condition? (Disorders B&B)

A

The gene causing the condition is located on the X chromosome

21
Q

What is the Y chromosome important for? (Disorders B&B)

A
  • Very few genes

- Mostly govern male sex function

22
Q

What is the X chromosome important for? (Disorders B&B)

A
  • Many genes

- Play a vital role in both sexes

23
Q

What happens in female X-innactivation? (Disorders B&B)

A

One X copy is switched off randomly (allowing the body to function normally)

24
Q

What are the characteristics of RETT syndrome? (Disorders B&B)

A
  • Almost exclusively to females

- Leads to mental impairment

25
Q

What are the causes of RETT syndrome? (Disorders B&B)

A
  • Mutation in the MeCP₂ gene
  • Transcriptional repressor turns off the expression of unwanted genes during synaptic formation
  • Not all the cells express the mutated gene so symptoms vary (due to x-innactivation)

2 - Brain and behaviour (19 decks)

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