Popular topic of debate

Francis Galton

• Intelligence testing
• Hereditary Genius (1869)
• Twin studies
• View point: Nature vs. Nurture

Richard Mulcaster

• Introduced terms
• View point: Nature and Nurture

Nature and Nurture interact!

Nature

• Genetics
  • Blame your ancestors...

Nurture

• Environment
  • From the womb to the tomb

Chromosomes

Strands of DNA

Humans have 23 pairs of chromosomes:

• 22 pairs of autosomes
• 1 pair of sex chromosomes

Genes

Genes are:

• Segments of your DNA
• Responsible for controlling what proteins are produced

Proteins are:

• Molecules that make (almost) everything in you
• Made up of amino acids
• Capable of affecting your behaviour

Physiology & behaviour: can not separate

Chromosome Replication

Mitosis

• In all cells except germ line
  • You are a pile of clones: precise replication
  • Cell differences due to genes

Meiosis

• In germ line: eggs and sperm
  • Drop to half a chromosome
  • Egg and sperm each contribute half chromosome to get full set of genes
  • 50% genetic material from each parent

How many combinations can you make?

• 23 chromosomes
  • 100,000 genes in genome
  • 3,500,000,000 base pairs
• Mutation
• Crossing over
• Infinite possibilities (theoretically)

Genetic diversity!

Important for a "healthy" population

Mutations

• Fatal (most)
• No apparent affect
• Beneficial

When the environment changes, genetically diverse species survive

• "Fatal, but not serious."

How diverse are humans?

• Any two people: 3 x 10^6 base pairs (3,000,000)

Genotype and Phenotype

Genotype

• The genes that you have
• What you have the potential to be

Phenotype

• The genes that are physically manifest
• What you appear to be

Twins

Monozygotic

• Identical twins
• Fertilized egg cleaves apart
  • Genotypically identical
  • Phenotype different

Dizygotic

• Fraternal twins
• Two egss fertilized by two sperm at same time
  • Genotype different
  • Phenotype different

Dominant and Recessive Genes

Locus

• Site of a gene
• Can have slightly different genes at same locus

Homozygous

• Same gene

Heterozygous

• Different gene

Dominant Genes

• Takes precedence: always expressed as phenotype
• Represented with capital letter

Recessive Genes

• Only expressed if as phenotype if homozygous
• Represented with lower case letter

Mendel

Is It All in the Jeans?

What is the difference between your genotype and your phenotype?

Should there be more genetic counselling for expecting parents?

Why is genetic diversity necessary in a population?

How can the expense of the Human Genome Project be justified?