Inheritance, Variation and evolution

    Cards (59)

    • Meiosis
      The formation of four non-identical cells from one cell
    • Mitosis
      The formation of two identical cells from one cell
    • Sexual reproduction
      1. Joining of male and female gametes, each containing genetic information from the mother or father
      2. Sperm and egg cells in animals
      3. Pollen and egg cells in flowering plants
    • Gametes are formed by meiosis, as they are non identical
    • Normal cell
      Has 46 chromosomes, two sets of 23 chromosomes (one from each parent)
    • Gamete
      Has 23 chromosomes, fuses in fertilisation
    • The genetic information from each parent is mixed, producing variation in the offspring
    • Asexual reproduction
      1. One parent with no gametes joining
      2. Happens using the process of mitosis, where two identical cells are formed from one cell
      3. No mixing of genetic information
      4. Leads to clones, which are genetically identical to each other and the parent
    • Meiosis
      The formation of four non-identical cells from one cell. Cells in the reproductive organs divide by meiosis to form gametes. Gametes only have one copy of each chromosome.
    • Meiosis
      1. Cell makes copies of its chromosomes, so it has double the amount of genetic information
      2. Cell divides into two cells, each with half the amount of chromosomes (46)
      3. Cell divides again producing four cells, each with a quarter the amount of chromosomes (23)
      4. These cells are called gametes and they are all genetically different from each other because the chromosomes are shuffled during the process, resulting in random chromosomes ending up in each of the four cells
    • Gametes with 23 chromosomes join at fertilisation to produce a cell with 46 chromosomes, the normal number
    • After fertilisation
      1. Cell divides by mitosis to produce many copies
      2. More and more cells are produced, and an embryo forms
      3. The cells begin to take on different roles after this stage (differentiation)
    • Advantages of sexual reproduction
      • Produces variation in offspring
      • Allows for selective breeding
    • Advantages of asexual reproduction
      • Only one parent is needed
      • Uses less energy and is faster as organisms do not need to find a mate
      • In favorable conditions lots of identical offspring can be produced
    • Organisms that use both sexual and asexual reproduction
      • Malarial parasites
      • Some fungi
      • Some plants
    • Sexual reproduction
      Involves two parents and fusion of gametes, offspring are not genetically identical, produces variation and leads to evolution
    • Asexual reproduction
      Requires a single parent, no fusion of gametes, offspring are clones and genetically identical, no variation and evolution
    • Meiosis
      1. One parent cell divides to form four daughter cells
      2. Chromosome number is halved
      3. Crossing over occurs, producing variation
    • Meiosis takes place in sex cells, is involved in production of gametes, and leads to evolution
    • Formation of offspring
      1. Male and female parents have 23 pairs of 46 chromosomes
      2. Meiosis forms male and female gametes
      3. Fertilization of gametes produces zygote
    • Asexual reproduction in fungi
      1. Releases spores which germinate to form fungal hyphae
      2. Sexual reproduction involves fusion of two nuclei, meiosis to form spores
    • Asexual reproduction in plants
      1. Runners, stolons, tubers produce genetically identical plants
      2. Sexual reproduction involves pollination, fusion of gametes, seed formation
    • Malaria life cycle
      1. Asexual reproduction in liver and blood cells
      2. Sexual reproduction in mosquito, fusion of male and female gametes
    • Nucleus
      Contains chromosomes
    • Chromosome
      Contains DNA
    • DNA
      Double helix structure with phosphate, deoxyribose, and nitrogenous bases
    • Gene
      Segment of DNA that codes for a protein
    • Human genome project sequenced around 3 billion DNA base pairs and over 20,000 genes
    • Protein synthesis
      1. DNA transcribed to mRNA in nucleus
      2. mRNA transported to ribosomes
      3. Ribosomes read mRNA codons and synthesize polypeptide chain
    • Mutation
      Change in DNA sequence, can be silent, harmful, or beneficial
    • Mutation can change amino acid sequence, leading to non-functional proteins
    • Chromosome
      Structure in nucleus that holds DNA
    • Gene
      Section of DNA that codes for a protein
    • Allele
      Alternative form of a gene
    • Dominant allele
      Allele that is always expressed
    • Recessive allele
      Allele that is only expressed when present in both copies
    • Homozygous
      Both alleles are the same
    • Heterozygous
      Alleles are different
    • Genotype
      Genetic makeup
    • Phenotype
      Physical characteristics expressed by genotype