DNA and Reproduction

• Deoxyribonucleic acid


  A molecule that describes the characteristics of a living organism
• Watson-Crick model of DNA

  The model used to describe the structure of DNA
• Nucleotides


  Basic units of DNA molecule, composed of a sugar, a phosphate, and one of 4 nitrogen bases
• What is the 4 different nitrogen bases in a DNA

  Adenine (A), Thymine (T), Guanine (G), Cytosine (C)
• Complementary base pairing


  Nitrogen bases pair up in one way as they have different sturctures and shapes that complement each other.
• Base pairing


  A-T

  G-C
• Chromosomes


  Long, thin, thread-like structures in cell nuclei, containing DNA and is wrapped around a protein.
• Chromosome number


  46 in body cells, half from each parent; gametes have half.
• Sex chromosomes


  Determine gender: XX in females, XY in males.
• Homologous chromosome


  Same length

  Has a centromere

  Has genes for particular characteristics at the same location
• Genes


  DNA sections on chromosomes, coding for specific proteins.
• Genetic code


  Order of bases along DNA strand, unique for each gene.
• Proteins


  Create the structure and perform the actions needed for your cells to survive, grow and function.
• Regulatory proteins


  Control cell functions like growth hormone and insulin.
• Enzyme proteins


  Such as amylase which helps digest starch and lactase which helps digest lactose
• Collagen and keratin protein


  Collagen, found in tendons and ligaments and keratin, found in skin, hair and scales.
• DNA Replication


  Process of copying DNA to produce identical molecules
• Zygote


  A single egg cell that has been fertilised by a sperm
• Steps of replication


  1. The parent DNA molecule unzips

  2. Copying of the DNA molecule begins with the complementary bases attaching to both strands of the DNA

  3. Replication results in 2 identical strands of DNA, each one is a double helix

  4. After the chromosome replicates, the 2 copies are joined at the centromere
• Centromere


  The point on a chromosome where the 2 chromatids are joined together.
• Mitosis


  Cell division resulting in two identical daughter cells. Used in the growth and repair of the tissues and the body.
• Meiosis


  Cell division producing sex cells with half the chromosomes
• Gametes


  Sex cells. They are the eggs produced in the ovaries of the female reproductive system and the sperm produced in the testes of the male reproductive system.
• Chromatids


  Identical DNA molecules forming replicated chromosomes
• 1. Interphase


  Stage where chromosomes replicate to form two chromatids
• 2. Prophase


  Stage where replicated chromosomes become visible
• 3. Metaphase


  Stage where replicated chromosomes align along the cell's equator
• 4. Anaphase


  The chromatids separate and move to opposite poles of the cell.
• 5. Telophase


  Two nuclei form, each with the same number of chromosomes as the parent cell.
• 6. Cytokinesis


  Cell membranes form, making two daughter cells, each with a nucleus.
• Cytoplasm Division


  Division of cell contents after nucleus division in mitosis
• Nuclear Membrane


  Membrane surrounding the nucleus of a cell
• Diploid Number


  Total number of chromosomes in body cells (46 in humans), described as 2n.
• Haploid Number


  Half the diploid number of chromosomes, found in gametes (23 in humans).
• Homologous Pair


  Chromosomes that pair up during meiosis, ensuring genetic diversity.
• Metaphase I


  Replicated chromosomes form homologous pairs, attach to spindle fibres and line up in the equator of the cell.
• Anaphase I


  One replicated chromosome of each pair moves to each pole
• Telophase I


  Two cells are formed each with one replicated chromosome
• Metaphase II


  Chromosomes align on the equator
• Anaphase II


  Chromatids separate and move to poles