Dear student,
This is a thorough and detailed summary of the lectures, obligatory textbook, articles,
and videos provided for the course of Biological Psychology at Tilburg University. I have
tried my best to provide you with all the necessary information for passing the exam and
I hope you find this summary helpful. Please do remember that this is a SUMMARY and
it may be the case that some minor topics have not been covered.
I hope you all the best in your studying and that you SMASH those exams :)
Best of luck,
Jana
Lecture 1 - Evolution & Genes
Can you inherit depression?
No one simply inherits depression from their mother or father. Each person inherits a unique
combination of genes from their mother and father, and certain combinations can predispose to
a particular illness.
Y-chromosomal Adam and Mitochondrial Eve
The story of how humans came to be → similarity with some of our ancestral human male and
female form via chromosomes and mitochondria.
Y-Chromosomal Adam → Most recent common ancestor from whom all currently living
people are descended patrilineally. Get your Y chromosome from father.
Mitochondrial Eve → The most recent woman from whom all living humans are
descended matrilineally (via the mother) through transmission of mitochondrial DNA. All
eggs contain mitochondria and so already exist before the sperm even reaches the egg,
so mitochondria exists within the female.
*Men have XY chromosomes, females have XX chromosomes*
Human Genetic Variation
➔ All humans are 99.9% genetically identical
➔ The 0.1% genetic differences between humans make up all the differences
,The Human Genome Project Identified the genetic makeup of humans, completed in 2003.
➔ In total about 20000 genes.
➔ Genes are a small part of your DNA which is basically an instruction for how to make
proteins.
◆ 3 billion nucleotides or “letters” that make up the four letter DNA alphabet
◆ A-T and C-G
Amazing DNA
Each cell contains about 5cm of DNA and we have about
10 trillion cells :)
Charles Darwin
Proposed that all organisms are related and share a
common ancestor.
Natural Selection
Certain characteristics of the organism are more beneficial within a particular environment.
Some will help the organism survive longer, therefore these organisms have the opportunity to
live and reproduce, passing on those traits. Thus, these traits become more common based on
➔ Variation
➔ Heritability
➔ Struggle for existence
➔ Survival and reproductive rates
,Selective breeding → creating an organism with specific genes and traits
Evolution & Genes
From an evolutionary perspective, humankind has evolved from its progenitor species.
Out of Africa hypothesis → If we go back in time, we discover that our ancestors were African.
But going back even further in time, suggests we came about in Asia.
In behavioural genetics there are 2 subtypes of heritable characteristics or traits;
➔ Qualitative traits are often influenced by a single gene and follow a simple pattern of
inheritance. It is typically unaffected by environmental factors.
➔ Quantitative traits do not follow simple patterns of inheritance. They are more variable
and less predictable.
Attention Deficit Hyperactivity Disorder (ADHD)
ADHD is a neurodevelopmental disorder, of which the symptoms include extreme impulsivity,
hyperactivity, lack of attention. It is believed to most likely be genetic although evidence cannot
be regarded conclusive because there are also potential environmental factors. ADHD is
caused by an imbalance of the neurotransmitter dopamine.
Mendelian Genetics
Gregor Mendel was a monk who was working on inheritance at the same time as Darwin was
explaining evolution. Mendel was able to account for differences in conspecifics and for the
inheritance of behavioural as well as physical and anatomical characteristics.
He examined dichotomous traits → characteristics that are in one form or another, for
example a pea plant seed can be either yellow or green. This variation in colour is known as a
trait, if a yellow seeded plant inbred with another yellow seeded plant, the offspring plant would
also have a yellow seed. Traits arise from alleles → two alternative forms of a gene.
He believed that we have dominant and recessive traits.
Human Karyotype → An organised set of chromosomes.
,The karyotype of a human:
➔ 46 chromosomes
➔ 22 identical pairs from mother and father (autosomes → the first 22 pairs do not differ
between genders.)
➔ 1 set of sex chromosomes: Female XX, Male XY
➔ Mitosis → To obtain a multicellular organism, the cellular division that takes place is an
ongoing process called mitosis. During mitosis, the cell doubles its chromosomes before
subsequent division.
DNA in the cell
Genome → the whole of the genetic information of an organism
Chromosome → a long strand of DNA wound around histones. We inherit half of our
chromosomes from our father and half from our mother.
Telomere → Region at the end of the chromosome, protects the DNA during cell division
Histones → are proteins used to fold the DNA, so that it doesn't become entangled
Gene → part of DNA with an instruction to make proteins
Allele → the two alternative forms of a gene found at the same place on chromosome
Chromosome → DNA → Gene → Protein
,Autosomal Dominant Trait
Each parent inherited a chromosome from their mother and
father.
Mother is homozygous for the trait
Father is heterozygous for the trait
When the affected allele is inherited by the next generation, this
person is affected since the trait is dominant
Example: Huntington’s Disease
Huntington’s disease is a progressive disorder characterised by motor disturbances and
subsequent cognitive decline. First symptoms that tend to appear are a lack of emotions,
alternating periods of aggression, excitement, depression, difficulty concentrating, short-term
memory lapses, and problems with orientation. Further, there are slight uncontrollable
movements of the face, and jerking or fidgety movements of the body. This eventually leads to
death. The Huntington allele is dominant and therefore if one parent has it, there is a high
chance that it can be passed onto the offspring.
Genotype vs Phenotype
The genotype is the genetic makeup of a cell in an organism whilst the phenotype is an
observed trait in the organism, based on genes and environment.
➔ Phenotype could also be sensitivity for food reward, becoming depressed, tendency to
be persistent, chance to develop diabetes, etc.
What does DNA do?
Each chromosome is made up of two strands of DNA. If we unravel a chromosome we can see
strands of DNA stretched out. The DNA molecule is along the length of each chromosome. DNA
has 2 functions:
➔ Replicate itself to make new cells
➔ Make proteins and determine functions of the cell.
The Nucleic acid is a large molecule made up of smaller components, the most important of
which are the nucleotides. The nucleotide bases are attached to a sugar phosphate support or
backbone. The 2 strands of DNA are held together by a mutual attraction of the nucleotides
using a carbon bond as the glue. The double stranded structure is known as the double helix.
,Nucleotides form pairs → The base pairs include:
➔ Nucleotide A opposite T (A-T)
➔ Nucleotide C opposite G (C-G)
➔ A = Adenine
➔ T = Thymine
➔ C = Cytosine
➔ G = Guanine
Where do these processes take place?
Nucleus → Transcription: a piece of DNA, a gene, is copied into messenger RNA (mRNA)
Cytoplasm → Translation: mRNA of the gene is then translated into a protein at the ribosome:
protein factory.
Protein Synthesis
The nucleotide bases are the basic elements of a code. They are a code that permits the
construction of amino acids → a series of amino acids can then make up enzymes, proteins,
and polypeptide chains.
Proteins are made from amino acids → there are 21 different amino acids → Three nucleotides
together (codon) are the key to which amino acid will be placed in the protein.
The code from DNA has to be transported outside the nucleus before the amino acid can be
formed. The process of reading the DNA code is called transcription
So...Step 1: Transcription → DNA to RNA
During transcription, a strand of DNA acts as a template for the creation of messenger RNA
(mRNA) which carries the code from the nucleus to the cytoplasm of the cell.
*The difference between RNA and DNA = U is used instead of T nucleotide, RNA is shorter than
DNA, and RNA can leave the nucleus*
If this process goes wrong and an incorrect amino acid is used, this can have serious effects
like sickle cell disease.
,Looking closely at transcription and the message coded in the DNA, we can see areas within
the sequence called exons and introns.
So...Step 2: Splicing RNA into mRNA
Exons refer to base sequences that code for proteins, whilst introns are non-coding
sequences. The primary transcript RNA reads the DNA, including the introns. However, the
mRNA spices the exons together, removing the introns.
The mRNA is then transported out of the nucleus into the cytoplasm where translation will
occur.
So…Step 3: Translation of mRNA into a chain of amino acids
Ribosomes are the translators of the sequence of nucleotide bases contained in mRNA.
Ribosomes read the sequence and add amino acids as the codons instruct. The translation
starts with a start codon and then the amino acids are taken to the ribosome by transfer
ribonucleic acid (tRNA). As the ribosome reads the codons, each specific tRNA molecule adds
amino acid after amino acid. Eventually the ribosome reaches a codon that indicates that the
protein is complete - stop the codon.
,Amino-acid chain at the ribosome: the protein
Each new amino-acid combines with the previous one and starts to form a chain: a protein.
When the 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, creating multiple proteins from one gene
Proteins
What do proteins do?
➔ Building blocks of body
➔ Can become part of cell membrane to form receptors for neurotransmission.
➔ Are part of the cell structure and function e.g. cytoskeleton, muscle contraction,
connecting cells
➔ Combines with other proteins and iron to transport oxygen (haemoglobin) in red blood
cells
➔ Form ribosomes in order to create new proteins
➔ Products of the immune system to kill invaders
➔ Some function as hormones or even neurotransmitter
➔ Can serve as fuel for energy and heat production
➔ Can be an ENZYME to metabolize chemical reactions (cellular glue or scissors)
Genetic variation
A particular type of variation, often referred to in the context of the genetics of disease and
disorder, is polymorphism → the differences in DNA sequences among individuals that are
present at a frequency greater than 1% of the population.
Unlike polymorphism, a Mutation is a change in a single gene that is rare, random, and often
independent of the needs of the organism.
What is the difference? A mutation can directly lead to disorder and often follows mendial
pattern of inheritance, whilst a polymorphism is a gene that confers an increased risk of the
disorder but does not directly cause the disorder itself.
, Down’s Syndrome
Down Syndrome is a disorder characterized by decreased muscle tone at birth, flattened nose,
separated joints between skull bones, small earths and mouth, impulsive behaviour, poor
judgement, short attention span and slow learning. Down syndrome is caused by an extra
chromosome in the 21st chromosome. This occurs at random and is caused by non-disjunction
of the 21st chromosome during meiosis.
Lecture 2 - Communication & The Endocrine System
Epigenetics → The study of heritable phenotype changes that do not involve alterations in the
DNA sequence.
● Phenotypic changes other than the DNA sequence in response to environment can
involve stress, food, smoking, radiation.
Twin studies examining differences in monozygotic and dizygotic twins can shed more light on
heritable vs environmental factors
➔ Monozygotic → identical DNA and shared environment
➔ Dizygotic → DNA same as regular brother or sister, but with shared environment during
gestation, birth, and development.
Heritability is a statistical estimate of the contribution of genetic differences to phenotypic
differences in traits.
Turkheimer states that there are three laws of behavioural genetics:
1. All human behavioural traits are heritable
2. The effect of being raised in the same family is smaller than the effect of genes
3. A substantial portion of the variation in complex human behavioural traits is not
accounted for by the effects of genes ir families.
The Endophenotype
Not all disorders have simple Mendelian transmission, many are complex polygenic disorders.
An endophenotype is an intermediate account of genes and environment that was adapted for
filling the gap between available descriptors and between the gene and the elusive disease
processes’ . Thus, between the genes that are more likely to cause a disorder and the
symptoms is a theoretical account of the disorder that links the physical gene to the behavioural.
