This is a summary for the course Genetics, Ecology and Evolution to help you pass the exam. In this summary an overview is given about all the important topics, which were discussed during the lectures. Important concepts from the book can also be find in this summary. (some words are translated t...
Lecture 1 🌱✨
☕️ Introduction
---------------
(1) Genetics
The study of heredity and the variation of inherited characteristics
the study of how certain qualities or traits are passed from parents to offspring as a result of changes
in DNA sequence
branch of biology concerned with the study of genes, genetic variation, and heredity in organism
(2) Ecology
Organisms and their distribution through time and space
The study of the environment
the study of the relationships between living organisms and their physical environment
(3) Evolution
Change in the heritable characteristics of biological populations over successive generations
the theory that organisms have grown and developed from past organisms
the process by which different kinds of living organism are believed to have developed from earlier
forms during the history of the earth
1 → There are changes in the DNA in an organism, because of mutations: genetics
2 → The genetics can change due to the ecology the organism is living in: ecology
3 → The organism will survive with those mutations in the genetics which gives them an adventage
to survive, this will lead to more diversity in the population: evolution
Two ways to think about evolution:
- Some people think it is strictly linear, and that at the ‘end’ there is some kind of superior
animal: for example humans.
- Most likely is branching events, because this shows the same ancestor species shared with
each other in the past. (still around)
Evolution is never done
Some specific genes are undergoing natural selection relatively faster than others:
- smell, reproduction, brain development, skin pigmentation and immunity against pathogens.
- lactose tolerance and sea nomads
Applications
- gene therapy → for genetic disorders
- to identify genes → what the function is of a specific gene
- artificial selection → selective breeding
,Inheritance of genes
- genes are passed on from parents to offspring
- genes have coded information in the form of hereditary units (in DNA)
- there are single-gene traits, but also multi-gene traits (polygenetic)
- DNA is duplicated and packed into reproductive cell (gamete)
- gametes unite during fertilization
- gametes are the vehicles that transmit genes from one generation to the next
- offspring has genetic material from both parents → sexual reproduction
1) sexual reproduction → offspring varies genetically from parents + genetic variation
2) asexual reproduction → offspring are genetic clones of parentsm + no genetic vartiation:
! except for mutations !
Examples asexual reproduction
- animals: it is called parthenogenesis, this is when an unfertilized egg develops into a new
individual.
- facultative → polar cells are vorming besides the egg and when there is no male
around the polar cell is able to fertilize the egg
- obligate → exclusively reproduce through asexual reproduction
- bacteria: through binary fission, a separation of the body into two new bodies. In the
process of binary fission, an organism duplicates its genetic material, or deoxyribonucleic
acid (DNA), and then divides into two parts (cytokinesis), with each new organism receiving
one copy of DNA.
- yeast: budding / vegetative reproduction
- plants: tillering / vegetative reproduction + apomixis, reproduction without fertilization
! always facultative !
Examples sexual reproduction
- animals: fusion of male and female gametes in the process of fertilization
- complex cycle consisting of mitotic and meiotic cell divisions
- plants: similar to animals + occurs after pollination → either self-fertilization or
cross-fertilization
bacteria don’t really have sexual reproduction, but they can exchange genetic information through
conjugation (which is kinda similar)
Chromosome structure
- DNA molecules are packaged into thread-like structures called chromosomes
- you are only able to see chromosomes right before they are going to seperate: cell
division
Localization of Centromeres
- Metacentric → centromere in the middle
- Sub-metacentric → centromere a little of from the middle
- Acrocentric → centromere seperates the chromosome(s) in ⅔ : ⅓
- Telocentric → centromere is on one end
- ! Humans don’t have telocentric chromosomes !
,Chromosomes in a cell
! the chromosome number doesn’t say anything about the complexity of an organism !
Lifecycles
- every organism has a life cycle → from conception until production of their own offspring.
- common feature → alternation (=afwisseling) of meiosis and fertilization.
- meiosis: reduction of chromosome numbers
- interphase: chromosome duplication
- meiosis I: first division of cells
- meiosis II: second division of cells
Genetic variation drives evolution
sexual reproduction:
disadvantages
- easy to make ‘mistakes’
- more expensive energetically
✨ ✨
advantages
- generation of genetic diversity
somatic cells → all cells of the body except the gametes and their precursors (= voorlopers)
karyotype → the resulting ordered display of chromosomes arranged in pairs
The only cells of the human body not produced by mitosis are the gametes, which develop from
specialized cells called germ cells.
sister chromatid cohesion → sister chromatids are two copies of one chromosome, closely associated
all along their lenghts.
, Lecture 2 🌱✨
☕️ Mendelian Genetics
-------------------
✨
A little bit of history ✨
→ Gregor Mendel is the founder of modern genetics, born in 1822 in Heizendorf (CZ).
He wanted to be a teacher, but he failed: so he entered an Augustinian monastery to study physics
and chemistry for two years at the University of Vienna.
He started working with peas in the monastery garden, because peas have:
- multiple varieties
- short generation time
- large number of offspring
character → a heritable feature that varies among individuals
trait → each variant for a character
His experiment:
- naturally, pollen from stamen lands on carpel of same flower and fertilizes eggs
- to prevent peas from self-fertilizing, stamen were removed
- pollen from another plant were dusted onto flowers
- a new seed (pea) develops
typical experiment (7 different traits)
- cross-pollination of two contrasting varieties (parental generation)
- offspring (called filial generation) showed purple trait
- self- or cross-pollination of F1 plants bring white coloration back in F2 plants
- overall ratio = 3 purple : 1 white plants
so purple = dominant trait
so white = recessive trait
1) Alleles account for variation of inherited characters
alleles = alternative versions of a gene
variation of DNA leads to different function of protein → and so for the inherited trait
2) One allele is inherited from each parent
two copies of each gene
3) the dominant allele determines the organism’s appearance
recessive allele has no noticeable effect on the organism’s phenotype (=appearance)
4) two alleles for a heritable character separate from each other → Law of Segregation
only one of the two gene copies is distributed to each gamete (egg or sperm cell)
+ the allocation (= toewijzing) of the gene copies is random
hybridization →crossing of two true-breeding varieties
pleiotrophy → genes have multiple phenotypic effects
epistatis: the phenotypic expression of a gene at one locus alters that of a gene at a second locus
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