Biological Psychology
Lecture 1 - Evolution and Genes
Life on earth
● 2 million years ago first hominins
● Y-chromosomal Adam and Mitochondrial Eve
● Homo sapiens: one species
○ Y-chromosomal: most recent common ancestor -> from whom all currently living
people descended patrilineally
○ Mitochondrial (named for the matrilineal transmission of mtDNA): most recent
woman from whom all living humans are descended matrilineally
○ Origin Africa, then migrated and mixed with other human species
○ About 200,000 years ago
Human genetic variation
● All humans 99.9% genetically identical
○ 0.1% genetic differences between humans makeup all differences
● The Human Genome Project: identification genetic makeup of humans, completed in 2003
○ In total about 20,000 genes (instructions for making proteins)
○ 3 billion nucleotides or ‘letters’ that make up four-letter DNA alphabet [A-T - C-G]
■ A and T always coupled
■ C and G always coupled
○ < 2% of DNA are functional genes coding for proteins
DNA
● Deoxyribo Nucleic Acid
● Human: about 10 trillion cells
● Single cell: about 5cm of DNA
● Cell -> Nucleus -> Chromosome -> DNA
Charles Darwin
● Voyage of the Beagle 1831-1836
● Barnacles
● Alfred Russle Wallace
● Natural Selection: Traits becoming more common based on:
○ Variation
○ Heritability (e.g. Speckles: dark one will have more dark vv)
○ Struggle for existence (adapting to environment)
○ Survival and reproductive rates
● Mutation creates variation
Human Karyotype
● Karyotype: organised set of chromosomes
● 46 chromosomes
○ 22 identical pairs from mother and father
○ 1 set of sex chromosomes (XX or XY)
DNA in the cell
● Genome: the whole of the genetic information of an organism
● Chromosome: long strand of DNA wound around histones
● Telomere: region at the end of the chromosome, protects the DNA during cell division
● Histones: proteins used to fold the DNA, so it doesn’t become entangled
● Gene: part of DNA with an instruction to make proteins
● Allele: two alternative forms of a gene found at the same place on a chromosome
● Gene loci: position of a gene on a particular chromosome
, Autosomal dominant traits - E.g. Huntingtons X-linked recessive inheritance
● Each parent: inherited a chromosome from mother and ● ‘white’ allele is recessive trait for a condition
father ● Trait is heterozygous in mother, not present on
● Mother homozygous for trait, Father is heterozygous for Y-chromosome -> X-linked
the trait
● When affected allele is inherited by next generation,
person is affected since the trait is dominant
Genotype – Phenotype
● Genotype: genetic makeup of a cell in an organism
● Phenotype: observed trait in organism, based on genes and environment
○ Selection can occur for certain phenotypes
○ Can also be: sensitivity for food reward, becoming depressed, tendency to be persistent,
chance to develop diabetes
● Why do cats have stripes on their fur?
○ Inactivation of parts of DNA, also in women
The theory of evolution via natural selection is supported in different ways. The example of bacteria evolving
resistance against antibiotics is an example of ….
Variation, mutation, heritability, struggle for existence, survival, and reproductive rates
What DNA does
● Double helix, double strand -> double information available
● Long chain of nucleotides which form pairs
○ Basepairs: Nucleotide A opposite T [A – T]
Nucleotide C opposite G [C – G]
● Processes
○ Transcription
■ Location: nucleus
■ Piece of DNA (a gene) is copied (= transcription) into messenger
RNA (mRNA)
○ Translation
■ Location: cytoplasm
■ mRNA of the gene is then translated into a protein at the ribosome
(‘protein factory’)
The genetic code
● A gene contains information for making a protein
● Proteins are made of amino acids
● There are 21 different amino acids
● Three nucleotides together (= triplet code or codon) are the key to which amino acid will be placed in the protein
, The process of making proteins: DNA -> RNA -> mRNA -> chain of amino acids -> protein
STEP 1 - Transcription
● Transcription of a gene from the DNA template to primary RNA
● Comparison RNA and DNA
○ U instead of T nucleotide
○ DNA longer than RNA
○ RNA can leave the cell nucleus
STEP 2 - Splicing RNA into mRNA
● Introns stay “ in” the nucleus (and are recycled)
● Exons “ exit” the nucleus
STEP 3 - Translation of mRNA into a chain of amino acids
● mRNA connects with ribosome
● Each mRNA codon merges with transfer-RNA (tRNA) anticodon
● Each mRNA codon ‘sticks’ to tRNA anticodon
○ Each tRNA molecule has amino acid on one end, anticodon on the other
○ Picture (right): mRNA (UGG) codon combines with tRNA (ACC) anticodon, with amino-acid tryptophan on other end
○ Appropriate codon combinations meet at ribosome, determining order of amino acids in the growing protein chain
● Amino-acid chain at the ribosome: The protein
○ Each new amino-acid combines with the previous one and start to form a chain: the protein
○ When mRNA is finished, the primary protein is complete
○ The mRNA may combine again with a ribosome to repeat the process
STEP 4 - Post-translational protein processing
● Large proteins can be cut into smaller proteins -> creation multiple proteins from one gene
● One can form five different ones
Lecture 1 - Evolution and Genes
Life on earth
● 2 million years ago first hominins
● Y-chromosomal Adam and Mitochondrial Eve
● Homo sapiens: one species
○ Y-chromosomal: most recent common ancestor -> from whom all currently living
people descended patrilineally
○ Mitochondrial (named for the matrilineal transmission of mtDNA): most recent
woman from whom all living humans are descended matrilineally
○ Origin Africa, then migrated and mixed with other human species
○ About 200,000 years ago
Human genetic variation
● All humans 99.9% genetically identical
○ 0.1% genetic differences between humans makeup all differences
● The Human Genome Project: identification genetic makeup of humans, completed in 2003
○ In total about 20,000 genes (instructions for making proteins)
○ 3 billion nucleotides or ‘letters’ that make up four-letter DNA alphabet [A-T - C-G]
■ A and T always coupled
■ C and G always coupled
○ < 2% of DNA are functional genes coding for proteins
DNA
● Deoxyribo Nucleic Acid
● Human: about 10 trillion cells
● Single cell: about 5cm of DNA
● Cell -> Nucleus -> Chromosome -> DNA
Charles Darwin
● Voyage of the Beagle 1831-1836
● Barnacles
● Alfred Russle Wallace
● Natural Selection: Traits becoming more common based on:
○ Variation
○ Heritability (e.g. Speckles: dark one will have more dark vv)
○ Struggle for existence (adapting to environment)
○ Survival and reproductive rates
● Mutation creates variation
Human Karyotype
● Karyotype: organised set of chromosomes
● 46 chromosomes
○ 22 identical pairs from mother and father
○ 1 set of sex chromosomes (XX or XY)
DNA in the cell
● Genome: the whole of the genetic information of an organism
● Chromosome: long strand of DNA wound around histones
● Telomere: region at the end of the chromosome, protects the DNA during cell division
● Histones: proteins used to fold the DNA, so it doesn’t become entangled
● Gene: part of DNA with an instruction to make proteins
● Allele: two alternative forms of a gene found at the same place on a chromosome
● Gene loci: position of a gene on a particular chromosome
, Autosomal dominant traits - E.g. Huntingtons X-linked recessive inheritance
● Each parent: inherited a chromosome from mother and ● ‘white’ allele is recessive trait for a condition
father ● Trait is heterozygous in mother, not present on
● Mother homozygous for trait, Father is heterozygous for Y-chromosome -> X-linked
the trait
● When affected allele is inherited by next generation,
person is affected since the trait is dominant
Genotype – Phenotype
● Genotype: genetic makeup of a cell in an organism
● Phenotype: observed trait in organism, based on genes and environment
○ Selection can occur for certain phenotypes
○ Can also be: sensitivity for food reward, becoming depressed, tendency to be persistent,
chance to develop diabetes
● Why do cats have stripes on their fur?
○ Inactivation of parts of DNA, also in women
The theory of evolution via natural selection is supported in different ways. The example of bacteria evolving
resistance against antibiotics is an example of ….
Variation, mutation, heritability, struggle for existence, survival, and reproductive rates
What DNA does
● Double helix, double strand -> double information available
● Long chain of nucleotides which form pairs
○ Basepairs: Nucleotide A opposite T [A – T]
Nucleotide C opposite G [C – G]
● Processes
○ Transcription
■ Location: nucleus
■ Piece of DNA (a gene) is copied (= transcription) into messenger
RNA (mRNA)
○ Translation
■ Location: cytoplasm
■ mRNA of the gene is then translated into a protein at the ribosome
(‘protein factory’)
The genetic code
● A gene contains information for making a protein
● Proteins are made of amino acids
● There are 21 different amino acids
● Three nucleotides together (= triplet code or codon) are the key to which amino acid will be placed in the protein
, The process of making proteins: DNA -> RNA -> mRNA -> chain of amino acids -> protein
STEP 1 - Transcription
● Transcription of a gene from the DNA template to primary RNA
● Comparison RNA and DNA
○ U instead of T nucleotide
○ DNA longer than RNA
○ RNA can leave the cell nucleus
STEP 2 - Splicing RNA into mRNA
● Introns stay “ in” the nucleus (and are recycled)
● Exons “ exit” the nucleus
STEP 3 - Translation of mRNA into a chain of amino acids
● mRNA connects with ribosome
● Each mRNA codon merges with transfer-RNA (tRNA) anticodon
● Each mRNA codon ‘sticks’ to tRNA anticodon
○ Each tRNA molecule has amino acid on one end, anticodon on the other
○ Picture (right): mRNA (UGG) codon combines with tRNA (ACC) anticodon, with amino-acid tryptophan on other end
○ Appropriate codon combinations meet at ribosome, determining order of amino acids in the growing protein chain
● Amino-acid chain at the ribosome: The protein
○ Each new amino-acid combines with the previous one and start to form a chain: the protein
○ When mRNA is finished, the primary protein is complete
○ The mRNA may combine again with a ribosome to repeat the process
STEP 4 - Post-translational protein processing
● Large proteins can be cut into smaller proteins -> creation multiple proteins from one gene
● One can form five different ones
