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- 1MitosisProphase: Chromatid strands form recognisable chromosomes. centrioles move to opposite sides of cell. spindle fibres form from one pole to another.
Metaphase: Condensed chromosomes move to the equator and attach to spindle fibres by centromeres. In late metaphase each chromosome splits as DNA is replicated.
Anaphase: Centromeres complete DNA replication. Chromatids move towards poles.
Telophase: Two daughter cells are formed - 2MeiosisThe creation of sex cells. Specialised pair of cell divisions that reduces chromosome number from diploid to haploid.
- 3GametogenisisProcess of creating gametes (a sexual reproductive cell - egg/sperm)
- 4ZygoteFertalized egg. diploid cell.
- 5Mendel's LawsLaw of dominance: One allele is dominant and the other is recessive (when two alleles are in an organism)
Law of segregation: When gametes are formed, the alleles that control two different traits separate from each other & retain individuality.
Law of Independent assortment: If two different genes are separate chromosomes, where one allele goes is not affected by the other. - 6GenomeDiploid or haploid number of chromosomes in a cell.
- 7Codominancewhen alleles are neither dominant nor recessive. This causes a heterozygous individual (both alleles show up in the phenotype).
- 8Incomplete DominanceLack of dominant relationships between alleles. Causes heterozygous offspring with an intermediate phenotype (red + white = pink)
- 9Multiple AllelesEg. Blood type - more than two alleles for one trait. AB = co-dominance. A & B are dominant over O.
- 10Polygenic InheritancePhenotypic characteristics determined by the interaction of genes on different locations on chromosomes or several locations on one chromosome.
eg. skin colour. - 11PleiotropyA single gene that produces one product but multiple effects on the phenotype.
Eg. Marfan Syndrome - 12Environmental influenceCan include internal and external influence.
External = diet, sunlight etc. Freckles do not express themselves unless the person is exposed to sunlight.
Internal = hormones released during puberty. - 13Mutagenic agentsSuspected causes of DNA damage
Eg. certain viruses, v-rays, tobacco. - 14Chromosomal AberrationsMajor changes in DNA. Inversions, duplications, deletions & Translocations
- 15InversionChromosome is broken. Broken piece reattaches in reverse order
- 16TranslocationBroken segment integrates into another chromosome.
- 17DuplicationPortion of chromosome is replicated and attached to original section in the sequence
- 18DeletionBroken piece is lost or destroyed before it can reattach
- 19Point MutationA single nucleotide of the gene is changed
Eg. Haemoglobin Molecule :
Val - His - Leu- Thr- Pro - Glu - Glu - Lys
/
Val - His - Leu - Thr - Pro - Val - Glu - Lys
Can cause brain damage, possible death.
worse if it happens in sex cells. - 20Stem CellsUsing Somatic cell nucleus transfer. Involves transferring a nucleus from the patients cell to a human egg (with the nucleus already removed). Human egg would develop embryonic stem cells.
No organ rejection. Immunologically compatible. - 21Genetic fingerprintingShowing the Nucleotide differences between individuals.
- 22Anti-CodonA triplet nucleotide sequence on tRNA that is complementary to a codon on mRNA.
- 23RNASingle strand copies of DNA
- 24mRNAMessenger RNA. straight copy of gene that describes the sequence of amino acids.
- 25tRNATransfer RNA. molecules responsible for picking up specific amino acids and transferring hem to the ribosome.
- 26Complementary basesAdenine - Thymine/Uracil
Cytosine - Guanine - 27Epigeneticsthe study of changes in gene expression by factors other than alterations in cell DNA.
- 28Recombinant DNAEnzymes manipulate DNA to create complimentary bases - new DNA called recombinant DNA can produce different products
eg. Enzymes. - 29Telomere'caps' on chromosomes that contain nucleotides called a telomere. Required for chromosome replication
- 30The Hardy - Weinberg ConceptUsing the genes in a population to determine evolution. An unchanging gene pool over several generations would indicate that evolution is not taking place.
- 31The Hardy - Weinberg ConceptUsing the genes in a population to determine evolution. An unchanging gene pool over several generations would indicate that evolution is not taking place.
- 32Conditions required for evolution to not occur:Mating must be random: unlikely. In animal population the female selects a male.
Mutations must not occur: Mutations alter genetic diversity by changing one genetic message or introducing a new one.
Migration in & out of population must not occur: as this introduces new genes or removes genes from a gene pool.
The population cannot be too large: small populations have less genetic diversity.
Natural selection must not occur: Natural selection filters some genes out of the population. (death rates, reproductive rates) - 33SpeciesOrganisms who's members can interbreed naturally to produce fertile offspring but do not breed with other groups.
- 34Gene FlowThe movement of genes from one generation to the next
- 35Biological Species ConceptSpecies can be distinguished from one another by heir inability to produce fertile offspring.
- 36Morphological Species ConceptUsing physical characteristics to determine a species (physical, chemical, behavioural)
- 37Artificial SelectionHuman beings consciously or unconsciously choosing the specific individual organisms (plants/animals) for reproduction
- 38Horizontal Gene TransferGenetic exchanges between unrelated organisms.
Eg. Endo-symbiosis which resulted in the development of chloroplasts and mitochondria. - 39Genetic DriftAccidental events that greatly effect the frequency of a gene in a population (NOT natural selection)
- 40Reproductive IsolationGenetic differences that accumulate when species are separated and result in 'sub-species'.
Speciation has only occurred if gene flow between isolated populations does not occur even with the barriers removed. - 41Speciation without Isolationsome individuals may breed or flower at a different time than others. courtship and mating could effectively separate one species into two. In plants genetically determined incompatibility of pollen between the species could lead to separate species.
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