Genes to ecosystems. Tri 1 Lect 2
- Created by: Loz1669
- Created on: 28-12-19 14:55
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- Genes to Ecosystems
- Evolution and Natural Selection
- Changes in gene frequency
- Ecological change chooses a better selected variant of a population
- Numbers increase of better selected variant.
- Genes that determine the better phenotype is more favoured.
- Numbers increase of better selected variant.
- Ecological change chooses a better selected variant of a population
- Modes of selection
- Stabilising selection
- Directional selection
- Diversifying selection
- Balanced selection
- Sexual selection
- Asexual reproduction:
- Advantages: rapid reproduction
- Disadvantages: limited variability, limited adaptability
- Sexual reproduction
- Advantages: higher variaibility, higher adaptability
- Disadvantages: lower reproductive rate
- Asexual reproduction:
- Speciation: formation of new species. Happens via diversifying selection
- Mechanisms: 1. Geographical isolation 2. Sympatric separation i.e habitat isolation, behavioural isolation, temporal isolation, mechanical isolation (body parts), gametic isolation (sperm and egg incompatibility), hybrid sterility
- Changes in gene frequency
- Genetics: Human and animal development
- Adult -> Gametes -> Fertilised eggs -> Cell multiplication -> Cell differentiation -> Embryo -> Adult
- Genetic material is carried on chromosomes
- Humans has 22 pairs and 1 pair of sex chromosomes
- Karyotype is the arrangement of chromosomes
- Diploid: 2 copies of each chromosome
- Haploid: 1 copy of each chromosome
- Structure of chromosomes: single molecule of DNA, Long so has to be packaged
- DNA is wrapped around nucleosomes. These nuclesomes are compact to form a filamant This filament then coils
- Evolution and Natural Selection
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