DNA replication and mitosis

• DNA


  A DNA molecule is made up of 2 strands of repeated nucleotides (building blocks)

  
• Nucleotide


  Consists of a sugar unit, a phosphate group, and a base unit
• Bases


  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
• Base pair rule


  • Adenine always bonds with Thymine (A-T)
  • Cytosine always bonds with Guanine (C-G)

  
• Triplet


  A set of 3 bases that codes for one amino acid
• Gene


  All the triplets that code for one complete protein
• Alleles


  Different forms of the same gene
• Cell cycle


  Series of events that take place in a cell leading to its division and replication

  
• Interphase


  Consists of the G1, S and G2 phase
• DNA replication


  The process of making new copies of DNA
• DNA replication


  • Semi-conservative - the new strand is made up of one original (old) strand and one new strand
  • Happens before cell division (mitosis and meiosis)
  • Specifically during the "S phase" of interphase

  
• Antiparallel


  The two parent strands of DNA run in opposite directions
• Template


  The two parent strands act as a template to ensure the two new strands of DNA molecule are identical to the original copy

  
• Semi-conservative


  Half of the new DNA molecule comes from the old (parent) DNA
• Purpose of DNA replication

  To replicate the cells' DNA in preparation for cell division, so the new daughter cells carry out the same function as parent cells

  
• Mitosis


  The process of cell division that produces 2 genetically identical daughter cells
• Mitosis


  • Occurs in active cells that require growth and constant renewal
  • The rate of mitosis can be affected by factors which affect enzymes (temperature, pH, substrate concentration) and mutagens

  
• Karyotype


  Shows a picture of all the chromosomes of an organism

  
• Chromatid


  Identifies different stages of the chromosome during cell division

  
• Chromosome


  Identifies different stages of the chromosome during cell division
• Phases of mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  
• Cytoplasmic division


  • In animal cells, a furrow develops between the two nuclei pinching the cytoplasm into two
  • In plant cells, a new cell wall develops between the two nuclei
• Cell division is essential for growth and repair


  Cells constantly die and are replaced by identical cells
• The rate of mitosis varies depending on the cell/tissue type

  
• Intestinal lining, skin cells, liver cells, intestinal muscle

  Have different rates of mitosis due to different exposure to wear and tear
• Tumour


  An irregular mass of cells (often have irregular shapes/appearance) caused by uncontrolled mitosis
• Mutation


  Any permanent change to the sequence of DNA within a gene

  
• Oncogene


  A mutated gene that causes cancer
• Most cancers occur as the result of a series of genetic mutations
• A typical tumour contains about 1,000,000,000 cells by the time it is detected
• Factors that affect the rate of mitosis

  • Availability of nutrients and energy
  • Location of cells
  • Environmental factors (temperature, pH, salt levels)
• Mitosis and DNA replication involve enzymes