Lecture 2- Neurogenetics

Question 1

How many pairs of chromosomes are there in humans

Answer 1

23

Question 2

Chromosomes are present in

Answer 2

Every cell in the body

Question 3

Natural variation in our DNA are known as

Answer 3

Single Nucleotide Polymorphisms

SNPs

Question 4

How much of DNA is shared with others

Answer 4

99.9%

Question 5

Mitosis produces

Answer 5

Somatic cells

Identical

Question 6

Meiosis produces

Answer 6

Gametes

Half the number of chromosomes

Question 7

What is homologous recombination

Answer 7

“Crossing over” of chromosomes

Question 8

How many genes on human chromosomes

Answer 8

Approx 23000

Question 9

Genes encode

Answer 9

Proteins

Question 10

Genes are turned on by

Answer 10

Transcription factors

Question 11

Transcription factors are activated during

Answer 11

Development or by intracellular signalling cascades from other parts of the cell

Question 12

What is transcription

Answer 12

In the nucleus genes DNA sequence is copied into mRNA

Question 13

What is translation

Answer 13

A ribosome attaches to the mRNA and moves along the mRNA reading each triplet codon and using tRNA to put together the amino acid chain to make a protein

Question 14

What are alleles

Answer 14

Variants of a gene

Question 15

What is Huntington’s Chorea

Answer 15

• Degeneration of the brain leading to progressive deterioration of movement, temperament and cognition
• Excessive repeat of CAG bases
• Dominant inheritance

Question 16

What is autosomal dominant inheritance

Answer 16

Single copy will be dominant and lead to the disease

Question 17

What is Phenylketonuria

Answer 17

• Mutation in the PAH gene
• Affects the enzyme that breaks down phenylalanine
• Recessive inheritance
• Can cause learning difficulties, epilepsy

Question 18

What is monosomy

Answer 18

Single copy of a chromosome, embryonic lethal

Question 19

What is trisomy

Answer 19

Three copies of a chromosome, very high rate of embryonic lethality

Question 20

What causes Down’s syndrome

Answer 20

Trisomy in chromosome 21

Question 21

What are the symptoms of Downs syndrome

Answer 21

• Smaller brain size frontal lobes and cerebellum
• Mild to moderate intellectual ability
• High risk of early onset Alzheimer’s Disease

Question 22

Characteristics of Y Chromosomes

Answer 22

• Very few genes (smaller)

- Mostly governing make sexual function

Question 23

X inactivation ensures

Answer 23

That the dosage of active genes is maintained in all individuals

Question 24

Mutation in the gene MeCP2 turns off

Answer 24

The expression of unwanted genes during synapse formation

Question 25

Rett Syndrome is

Answer 25

- X linked - Affects exclusively females - Mutation in the gene MeCP2

Question 26

The FMR1 gene encodes the FMR protein which is thought to

Answer 26

Shuttle select mRNAs between the cytosol and nucleus

Question 27

Fragile X is

Answer 27

- Most common inherited form of learning disability | - Milder penetrance to females as mosaic pattern of genes

Question 28

Epigenetics

Answer 28

- Inherited change in phenotype - Not due to changes in genotype - Not a mutation in the gene but in how the gene is read

Question 29

What happens without GR loss of feedback inHPA axis

Answer 29

Increased stress hormones, increased anxiety/ depression

Question 30

Disrupted histones in sperm cells showed

Answer 30

Altered RNA profile in offspring

Question 31

Causative genes for Alzheimer’s Disease

Answer 31

- APP - PSEN1 - PSEN1

Question 32

One SNP difference between APOE3 and APOE4 which

Answer 32

Changes an amino acid in the protein

Question 33

What is concordance

Answer 33

The degree to which a trait is seen in 2 individuals

Question 34

What genes are associated with schizophrenia

Answer 34

- Synaptic transmission - Glutamate - Dopamine

Question 35

What are the difficulties in studying genes affecting behaviour

Answer 35

- Defining genetic and non-genetic factors - Understanding interactions among factors - Following steps of gene expression to behaviour - Allowing for individual differences

Question 36

Pros of animal models

Answer 36

- Similarity of genes - Can breed genetically identical strains - Control environmental conditions - Manipulate genes by removal or mutate

Question 37

Why are mice used

Answer 37

- 99% same genes - Similarly organised brains - Lots of background info on biological processes - Targeted mutagenesis - Short life cycle

Question 38

Inbred strains allow

Answer 38

Comparison of these strains can tell us about how genetics influence behaviour

Question 39

What is transgenic mice

Answer 39

- Reporter constructs to tag cells | - Constructs to target cell specific or time specific gene manipulations

Question 40

What are knock-in mice

Answer 40

- Introduce a specific mutation | - Humanised mice

Question 41

What are knockout mice

Answer 41

-Absence of specific gene