Biopsychology
Video Lecture 1.1 Evolution and genes
- Can you inherit depression? Is there something like a
No one simply inherits depression from their mother or their father. Each person inherits
a unique combination of genes from their mother and father, and certain combinations
can predispose to a particular illness.
- The earth was formed about 4.5 quadrillion years ago. The first forms of life began to emerge
4 quadrillion years ago. The first hominims only appeared 2 million years ago. We’re just
here.
Blauw is bacteriën, groen is archeota en wij vallen onder de dieren (rood), tussen de schimmels en slijmdieren in.
Ancestors
Y-chromosomal Adam: Most common ancestor from whom all currently living people are
descended patrilineally.
Mitochondrial Eve: The most recent woman from whom all living humans are descended
matrilineally (via the mother), through transmission of mitochondrial DNA.
Y-chromosomal Adam & Mitochondrial Eve are tracable to an area where the country of
Congo (Africa) is right now. (Out of Africa hypothesis)
There is also an hypothesis that people emerged from Eurasia.
,Human genetic variation
- All humans are 99.9% genetically identical. The 0,1% is what makes up all the differences
between humans.
The human genome project identified the genetic make-up of humans, completed in
2003.
Our DNA contains about 20.000 genes.
3 billion letters of nucleotide: - A-T - C-G
<2% of the DNA are functional genes coding for proteins.
DNA
Cel -> Nucleus -> Chromosome -> DNA
Een chromosome is just rolled up DNA. Every cell contains about 5cm in
The body contains about 10 trillion cells.
Charles Darwin
- Traveled around the world and brought out a book between 1831 and 1836 – Voyage of the
beagle.
- Written in his notebook in 1837 how he thought about the evolution of creatures – as a tree
with branches that could be further apart or closer apart, depending on the ancestor.
- In 1858 Alfred Russell Wallace (an animal taxidermist) brought out a book: ‘On the tendency
of varieties to depart indefinitely from the original type’
- Darwin recognized his own work and brought out his book: ‘On the origin of species by
means of natural selection’.
There was more than 20 years between Darwins idea and the book. This was because of
the religious climate at the time.
Natuurlijke selectie
Traits become more common based on these steps: variation, heritability, struggle for existence and
survival and reproductive rates.
Video Lecture 1.2 Evolution and genes
Karyotype
The human karyotupe contains 46 chromosomes. 22 identical paires of mother and father and the
23rd pair are the sex-chromosomes.
- When someone has Downs syndrome, there are 3 chromosomes on the 21st pair.
,DNA in de cel
Histones are proteins around which the DNA is neatly coiled, so that the DNA does not get confused.
Telomere is a repeat of nucleotides at the end of DNA, is necessary for cell division. With each cell
division the telomere is needed and a piece of it is removed.
.
Nucleotides -> T&A - C&G
A gene is a piece of DNA that codes for a protein.
Not all DNA is genes!
Each chromosome consists of alleles -> the information of the 1 and the other (for example the color
of the flower. One allele contains the gene for a white flower and the other allele on the other
chromosome contains the gene for a purple flower)
An allele is a gene location that can occur in different variants.
You have dominant and recessive alleles (B-b). If you have two different alleles it is
heterozygous, if you have 2 same alleles it is homozygous.
Verschillende aandoeningen:
- Autosomal dominant
o You get the disease if you carry it. It doesn't matter if you get 1 or 2 copies of it (e.g.
huntington).
o As a result, in half of the cases, children will develop the condition if 1 parent has 1 defective
allele. The gene for huntington is dominant.
-X-linked recessive inheritant
o A certain trait that is on an x chromosome = x-linked
o The mother is a carrier, but is not affected, because she still has an x chromosome and it is a
recessive gene.
o When a daughter is born, she will also be a carrier, because she also has a second x
chromosome. The chance of being a carrier is therefore 25% and the chance that the person
has it is also 25%. Only a son can really get it, because it does not contain 2 x chromosomes.
, Genotype en fenotype
- Genotype is the genetic makeup of a cell in an organism. (Bijvoorbeeld AA)
- Phenotype is that which is expressed, that which you can observe. This is based on genes but
sometimes also on the environment. (For example dark)
- Phenotype can also be hypersensitivity to certain foods, reward, risk of becoming depressed,
tendency to be persistent or to develop diabetes (not just in appearance!)
Video Lecture 1.3 Evolution and genes
About DNA
- Remember A-T & C-G
- On the outside, there are sugarphosphate molecules and on the inside are the base pairs.
- 1 nucleotide consists of one letter and one sugarphosphate backbone.
- DNA is basically one long chain of nucleotides.
- Transcription of the DNA only happens to a small piece of DNA. The mRNA leaves the nucleus
and gets into the cytoplasma where translation takes place.
The genetic code
The conversion of DNA into a protein is based on the genetic code.
3 letters together (3 nucleotides) (= codon) form the code for which amino acid must
ultimately be produced and linked to form a protein.
mRNA can leave the nucleus and the T is replaced by a U.
Translation of mRNA into a chain of amino acids:
You have a process in which the mRNA is pulled through the ribosome, each time a new tRNA is
produced with an anticodon on one side and an amino acid on the other. These amino acids together
form a long chain of amino acids and this is the beginning of a protein.
Sometimes the mRNA links again with a ribosome to repeat the process.
The primary protein is not always finished. Sometimes it still needs to be cut/split, resulting in
multiple proteins being created from 1 gene.
Protein, enzymes and what can go wrong.
Enzyme example
- Serotonin is a neurotransmitter.
- Created from the amino-acid L-tryptophan.
- Two enzymes are needed to convert tryptophan to serotonin.
- Serotonin is NOT a protein from your DNA, but the enzymes which make it are.
- DNA via enzymes can control serotonin production.
SNP (single nucleotide polymorphism) = one letter is different in the DNA. Can lead to disease (sickle
cell) or increased susceptibility to disease.
Mutation example: crossover – Crossover of a set of chromosomes, exchange of alleles -> creates
offspring with recombined genes.
Epigenetics
= the study of heritable phenotype changes that do not involve alterations in the DNA sequence.
Like environmental factors, smoking, stress.
Studied with twin studies.
