Lecture 1 Flashcards

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1
Q

genotype:

A
  • 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.
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2
Q

phenotype:

A

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

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3
Q

genome:

A

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
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4
Q

transcriptome

A

DNA sequence that is being transcribed

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5
Q

epigenome

A

sequence of DNA that can be altered by an external factor

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6
Q

promoter

A

switches genes on/off

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7
Q

glucocorticoid

A

hormone, role in regulating response to stress

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8
Q

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

A

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
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9
Q

What is sequencing a genome?

A
  • 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
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10
Q

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

A

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 .

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11
Q

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

A

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

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12
Q

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

A
  • 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
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13
Q

What is epigenetics?

A

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

Changes in gene expression without changes in DNA sequence

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14
Q

Give an example of epigenetics!

A
  • 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
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15
Q

gene

A

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

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