Biology 2.2

• normal human cells have 46 chromosomes
• These are in Matching pairs one comes form each parent
• You have 23 matching pairs of chromosomes in each cell
• Sex cells have 23 chromosomes (gametes)
• Genes are arranged in a row along a chromosome called liner arrangement
• A single chromosomes has lots of information on how to build your body each bit of information is called a gene
• Chromosomes come in pairs and therefore so do genes
• They are found opposite eachtoehr at the same position
• Chromosomes contain many genes
• Chromosomes and there genes are made up of a molecule called DNA
• Each chromosomes is a very long molecule of tightly coiled DNA
• DNA molecules carry the code that controls what cells are made of and what they do
• What are genes


  Section of dna which codes for a protein
• What is DNA


  A chemical that genes are made from
• What are chromosomes 


  A long strand of DNA which contains lots of genes
• What is mitosis used for

  growth and repair of damaged tissues
• Mitosis produces 2 cells
• Mitosis cells are genetically identical daughter cells
• And mitosis are genetically identical to the parent cells
• Mitosis have the same number of chromosomes as parent cells
• What can uncontrolled mitosis lead to

  Cancer
• How does cancer form

  Tumour cells breaks of and spread to the other tissues forming secondary tumors
• What is meiosis used for

  Sexual reproduction
• Meiosis produced four cells
• Daughter cells in meiosis are geneticaly different
• What does meiosis produce

  Gametes
• What are stem cell’s

  undiffreiented cells that can specialise and are used to repair damadged tissues
• What can stem cells have the potential to use 


  Adult stem cells and embryonic stem cells
• Where are stem cells found in plants

  Meristems
• What are adult stem cells 


  Can only differentiate to become certain cell types
• What is the primary function of adult stem cells

  replacement of dead cells e.g replecment of red blood cells which only live for 120 days
• Positives for adult stem cells

  No donor needed or tissue typing

  no ethical issues

  no rejection
• What are embryonic stem cells

  Stems cells found in very early embryos that are unspecialised and capable of differentating to become any cell type
• Function of embryonic stem cells

  enable the growth and development of tissues in human embryos
• What is the problems with embryonic stem cells

  destruction of a potential life

  cells that are not your own so could be rejected
• Where is genetic information found to

  Nuclear
• stem cells can be used to repair what 2 things

  Spinal cord and brain