Chromosomes

• Where are chromosomes found

  • Chromosomes are found in the nucleus of cells 
  • Chromosomes contain the molecule DNA

  
• What is DNA

  • Scientists say that DNA is the genetic material 
  • This is because our DNA determines our inherited features
• Structure of DNA

  • DNA consists of 2 strands, and each strand is a polymer 
  • In other words, each strand is made by joining together lots of smaller molecules 
  • In DNA, the 2 strands wrap around each other to form a double helix - this is the structure of a DNA

  
• What is a gene

  • Each chromosome carries hundreds to thousands of genes 
  • A gene is a small section of DNA on a chromosome 
  • Different genes contain the code to make different proteins 
  • So different genes control the development of different characteristics 
  • E.g. the gene that determines blood type is found on chromosome 9

  
• How do genes make proteins

  • Proteins are made by joining together amino acids 
  • Each gene encodes for a specific sequence of amino acids to make a specific protein 
  • For example, the blood type gene encodes the sequence of amino acids for the protein that determines blood type

  
• Chromosomes in pairs

  • Humans have thousands of genes - for example, chromosome 9 has well over 700 different genes 
  • In body cells, chromosomes are found in pairs , with one chromosome coming from each parent  
  • Both chromosomes in a pair have the same genes (So e.g. the pair of 2 chromosome 9’s have the same gene for blood type)

  
• What is the human genome

  • The genome is the entire genetic material of an organism 
  • The human genome is the entire genetic material that makes a human 
  • Scientists have now studied the entire human genome
• Benefits of understanding the human genome

  • Understanding the human genome will help us to search for genes that are linked to a disease (e.g. genes that increase the risk of developing cancer or Alzheimer’s disease) 
  • Understanding the human genome will help us to understand and treat inherited disorders (e.g. cystic fibrosis) 
  • We can use the human genome to trace human migration patterns from the past - this helps people to discover their ancestry