protein synthesis

• X and Y chromosomes

  there are 23 pairs of chromosomes

  -22 pairs just control characteristics

  -the 23rd pair are labelled XX / XY - these decide the sex:

  • Males have an XY
  • Females have and XX

  There's a 50% chance to get X or Y.

  the original cell has 2 x's - all eggs have one X chromosome
• Mutations - substitutions

  substitution mutations are when a random base in the DNA sequence is changed to a different base

  
• Mutations - deletions

  deletions are when a random base is deleted from the DNA base sequence

  like insertions, they change the way the base sequence is 'read' and has a knock on effect further down the sequence

  
• Mutations - insertions

  insertions are when a new base is inserted into the DNA base sequence where it shouldn't be

  • changes the way the groups of 3 bases are read - therefore changes the amino acids that the code

  they can change more than one amino acid as they have a knock on effect on the bases further on in the sequence