Topic 6 - Inheritance, Variation and Evaluation

• Types of reproduction include the fusion of male and female gametes, as seen in animals like sperm and egg, and the fusion of pollen and egg, as seen in flowering plants.
• One parent reproduction, also known as asexual reproduction, does not involve the fusion of gametes and does not mix genetic information, producing clones.
• Advantages of sexual reproduction include the mixing of genetic information, which creates variation and allows natural selection to increase the chances of surviving environmental changes.
• Sexual reproduction is also time and energy efficient and produces a large number of offspring.
• Disadvantages of sexual reproduction include the need for a mate and can be slower than asexual reproduction.
• Asexual reproduction in malarial parasites involves sexual reproduction in mosquitos and asexual reproduction in humans.
• Certain plants and fungi halve the number of chromosomes to produce gametes and fertilisation restores the full number of chromosomes.
• Mitosis is a process where a cell divides by mitosis then differentiates.
• Meiosis is a process where a cell divides twice to produce 4 gametes.
• Gametes produced by meiosis are genetically different.
• DNA is a polymer made of 2 strands that form a double helix and is organised into chromosomes.
• There are 4 types of repeated nucleotides in DNA: A to T, G to C.
• Nucleotides are made of sugar, phosphate and base (A, T, G, or C).
• A sequence of 3 nucleotides codes for an amino acid in a protein.
• Change in structure of DNA may lead to a change in the protein.
• Genome is the entire genetic material in an organism.
• Gene is a section of DNA that codes for a sequence of amino acids to make a protein.
• Non-coding DNA controls expression of gene.
• Allele: different form of a gene.
• Identification of genes linked to diseases and inherited disorders is important.
• Tracing past human migration patterns is also important.
• Polydactyly and cystic fibrosis are examples of inherited disorders.
• Sex can be determined by genotype, for example, male XY and female XX.
• Genotype contributes to the phenotype, for example, altered shape or function.