Lecture 1

Question 1

genotype:

Answer 1

• genetic constitution of an organism, inhereted in genes
  -from parents(diploid)/parent(haploid)
  the specific allelic constitution of an organism, either of the entire organism or for a certain set of genes or a certain gene.

Question 2

phenotype:

Answer 2

-morphological, biochemical, behavioural properties of an organism resulting from a specific genotype (includes what happens in cells)

Question 3

genome:

Answer 3

total amount of genetic material in a chromosome set

• includes genes and other non coding sequences of DNA
• The genetic complement in a set of chromosomes

Question 4

transcriptome

Answer 4

DNA sequence that is being transcribed

Question 5

epigenome

Answer 5

sequence of DNA that can be altered by an external factor

Question 6

promoter

Answer 6

switches genes on/off

Question 7

glucocorticoid

Answer 7

hormone, role in regulating response to stress

Question 8

What is methylation and what are its effects on gene expression?

Answer 8

addition of CH3 (methyl) groups to C or G, preventing gene expression

• methylated gene won’t be expressed
• epigenetic event
• changes to gene expression, not the sequence of the gene

Question 9

What is sequencing a genome?

Answer 9

• working out the base sequence of the DNA (doesn’t include function of the bases)
• human genome mapped in 2001, 1mm between each nucleotide
• haploid human genome is 3 000 000 000 bases pairs
• salamander genome is 81 300 000 000- so number doesn’t equal complexity

Question 10

Give an example of an environmental factor affecting variation in genome?

Answer 10

e. g. fetal alcohol syndrome (FAS) –mother drinking at pregnancy
- results=growth retardation, characteristic facial features, CNS anomalies(intellectual impairment)
- can’t predict if a drinking woman will have FAS offspring
- have to look at the whole picture-maternal age, diet, medication

Depends on mother’s ability to metabolise alcohol=so partly genetic partly environmental- blurring of the lines .

Question 11

Give an example of a genetic factor affecting variation in genome?

Answer 11

e. g. Huntington’s disease (HD)
- mutation on chromosome no.4, everyone has two copies of no. 4, producing huntingtin protein- normally the sequence CAG is repeated up to 35 times, normal range= 18-20, if more than 42 repeats in one copy of the chromosome- HD
- degeneration of the brain, late onset
- purely genetic
- experiments with mice= more active mice show delayed onset of HD

Question 12

Give an example of a combination (genetic and environmental) factor affecting variation in genome?

Answer 12

• most are a combination of both
• Drosphilas with the same genotype- eggs in hot or cold temp-hot=curled wing/cold=no curled wing
  
  • curled wing gene influenced in expression by temperature
• hydrangeas-same genotype-acidic soil=blue/alkaline soil=pink
  - pH is influencing the colour gene expression
• fox-same genotype-summer=brown fur/ winter= white fur
  
  • gene influenced by temp

Question 13

What is epigenetics?

Answer 13

(epi means on top of)- genes influenced by environment

Changes in gene expression without changes in DNA sequence

Question 14

Give an example of epigenetics!

Answer 14

• pregnancy-stressed=baby more behavioural problems
• calm= baby fewer behavioural problems
• physical abuse on mother= baby higher methylation in the promoter of the gene for glucocorticoid receptor
• child abuse leaves epigenetic marks
• PTSD patients= different pattern of DNA methylation plus gene expression

Question 15

gene

Answer 15

the fundamental physical and functional unit of heredity, which carries information from one generation to the next; a segment of DNA.