Download Divergent evolution: Same basic structure, different appearance

Divergent evolution: Same basic structure, different appearance, different function, common ancestor
Convergent evolution (analogous structure): Evolved independently for similar purposes
Parallel evolution: Evolved similar features due to similar environments
Taxonomy: Kingdom, phylum, class, order, family, genus, species
Species: Individuals have potential to interbreed & produce fertile offspring
Microevolution: Changes in allele frequencies/genotypes of population
· Genetic Drift: Random changes in certain alleles in small population, reduces genetic variation
· Gene flow: Changes the gene pool within each population
· Mutations: Changes alleles, alters gene pool, original source of genetic variations
· Assortive mating: In breeding, mating with a partner that shares similar phenotypic trait
· Natural selection: Unequal success between individuals in producing, fertile offspring. Acts on phenotypes
o Stabilising selection: Culls extreme phenotypes
o Directional selection: Culls on type of extreme phenotypes
o Diversifying selection: Culls intermediate phenotype, leaves extreme
o Limits: Historical constraints, role of chance in determining gene pool, can’t create new genes
Macroevolution (Speciation)
· Formation of a daughter species from a parent species due to changes in allele frequencies
· Morphological concept: How they look (physical uniqueness)
· Biological concept: Group that is interbreeding & reproductively isolated. Relies on intrinsic factors,
temporal/spatial/behavioural isolation, mechanical barriers. Problems: Species that hybridise, asexual species, fossil species
· Phylogenetic (molecular) concept: Based on genes/genetic uniqueness
· Allopatric: Physical barrier, isolation can be rapid, influenced by differences in environments
· Sympatric: Same country, separated by intrinsic factors, populations evolve separately within range of parent species/same
environment, behavioural differences
Hardy-Weinberg Principle:
· Phenotypic frequencies in a population remain constant at equilibrium, p2 + 2pq + q2 = 1
· Assumptions: Individuals mate at random, population is large & stable, no mutation/migration/natural selection
Pleiotropy: Multiple effects of single genes, affects more than one trait (eg. colour & stem length)
Epistasis: More than one gene acts on characteristic, multiple mutations may not be visible
Environment & phenotypes: Gene expression may require certain environmental conditions to become visible
Epigenetic Regulation: Outside influences control DNA, X chrom. inactivation (equalises expression of genes in both sexes)
Cell Cycle
· Interphase: G1 (growth), G0 (99% of cells exit), S (Duplication of homologous pairs), G2 (Growth)
· Mitosis: Prophase, Metaphase, Anaphase, Telophase - Diploid cells
· Meiosis: Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase/Metaphase 2, Anaphase 2, Telophase 2
Prokaryotes (Bacteria):
· No nucleus, first appeared in fossils 3.5 billion years ago, reproduce asexually, divide every 20 mins
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Gram-positive: Thick, multi-layered, dangerous. Gram-negative: Thinner cell walls, respond less to antibiotics, majority
2 kingdoms: Archaea (First ever, analysis of RNA, extreme environments), Bacteria (Common/infections)
Functions: Nitrogen cycle, oxygenated the earth, DNA handling techniques
Genetic variation: Mutation (resistance), mixing genetic material (transformation, conjunction, transduction)
Cell Membrane: Phospholipid molecules, semi-permeable, 2 non-polar tails (hydrophobic), polar head (hydrophilic), moves
horizontally, not vertically
Properties of water
· High surface tension: Water more attracted to itself than other things, H2 bonding/covalent bonding
· High specific heat: H2 bonds, takes a lot of energy/heat to break bonds
· High heats of vaporisation/condensation: Releases lots of energy as it changes state in opp. direction (latent heat)
Biomolecules/macromolecules
· Carbohydrates: Carbon chains/rings, lots of OH groups, can occur in linear form, monosaccharide = 1 ring, polysaccharide =
chain of rings. Once polys have been built, line them up so they bond to build complex structures
· Lipids: Linear chains of carbons, lots of C and H, single bonds = flexibility/saturated, double bonds = unsaturated.
· Producing a phospholipid: One tail is replaced by a phosphate group linked to a head, whole molecule becomes amphipathic
(polar and non-polar)
· Proteins/Polypeptides: Contains N, infinite amount of variants, -COOH and -NH2 present. Limited number that can be built,
N-C-C backbone (never changes)