Inheritance and Evolution

• DNA structure: sugar-phosphate backbone, double helix, specific base pairing
• DNA bases always connect in a specific way: A to T, C to G
• Advantage of asexual reproduction: only one parent needed, no waiting for a mate
• Proteins responsible for various functions in the body including hormones, enzymes, and cell structures
• Mitosis


  Results in diploid cells
• Asexual reproduction common in plants, bacteria, and fungi leading to genetically identical populations
• Only some DNA in cells is useful, some sections may be non-coding or junk
• Advantage of asexual reproduction: energy conservation for gene continuation
• Gene


  Stretch of DNA that codes for a characteristic
• Checklist key practicals and all the keywords available on the website or Amazon
• Meiosis


  Results in haploid cells with half the number of DNA as the original cell
• Meiosis

  • Leads to different daughter cells
  • Used for sexual reproduction
• Genome


  All the genes in a body
• Mitosis


  • Leads to two identical daughter cells
  • Used for growth or repair
• Types of gametes

  • Women: X
  • Men: sperm
  • Plants: eggs (stigma) and pollen (stamen)
• Enzyme-substrate specificity crucial for proper function, mutations can lead to protein dysfunction
• Advantages of sexual reproduction: genetically diverse population, better protection from diseases
• Disadvantages of asexual reproduction: genetically identical population susceptible to diseases affecting all
• Meiosis

  Two divisions, chromosomes line up, sort themselves, crossing over occurs for genetic diversity, divide into two, then divide into two again resulting in cells with half the DNA as the parent cell
• Three-letter DNA sequences code for amino acids which form proteins
• DNA


  There is a massive amount of DNA in each of ourselves and only some of it is useful
• Heterozygous


  Having different alleles for a particular gene
• Dominant


  One gene is needed to express a characteristic
• Recessive

  Two identical recessive genes are needed to express a characteristic
• IVF (In vitro fertilization)


  Embryo screening or pre-implantation genetic diagnosis to select healthy embryos before implantation
• Chromosome

  Bundled up DNA
• Non-coding DNA


  Sections of DNA that are non-functional and are often referred to as junk DNA
• If a family has a known genetic disease, they could opt for IVF to ensure a healthy offspring
• Genetic cross


  Calculating the chances of a disease or phenotype being passed on by crossing the genotypes of parents
• Phenotype


  The collection of characteristics an individual has
• Genetic diseases

  • Polydactyly
  • Cystic fibrosis
• Identical twins have the same genotype but different phenotypes due to environmental influences
• Mutations occur during cell replication, leading to natural selection
• Embryos are created and destroyed in the process of IVF, leading to religious objections for some people
• Humans have 23 pairs of chromosomes, totaling 46, with one copy inherited from each parent
• Alleles


  Different versions of genes
• Cystic fibrosis is a recessive disease
• Genetic females inherit two X chromosomes, while genetic males inherit an X and a Y chromosome
• Homozygous


  Having the same alleles for a particular gene
• Gamete


  A sex cell, such as a sperm or egg