DNA and genes

• DNA


  Deoxyribonucleic acid, the chemical that all of our genetic material is made of
• DNA


  • It's a polymer made up of lots of similar units stuck together
  • It has two strands which are stuck together to form a double helix
• If you unraveled all the DNA in a single cell, the strand would be over two meters long</b>
• Chromosome


  A really tight coil of DNA, of which each cell has 46 (23 pairs)
• The 23rd pair of chromosomes are the sex chromosomes, with females having two X chromosomes and males having one X and one Y chromosome
• Gene


  A small section of DNA that codes for a particular type of protein
• There are only 20 different types of amino acids, but they can be combined in many different sequences to form thousands of different proteins
• Genome


  The entire set of genetic material in an organism
• Scientists have now worked out the complete human genome, which allows them to identify genes linked to certain diseases and develop better treatments
• Genomes can also be used to trace the migrations of human ancestors
• DNA


  Two strands wrapped around each other in a double helix
• Structure of DNA


  1. Nucleotides

  2. Complementary base pairing

  3. How a gene codes for a protein
• Nucleotide


  Monomer that makes up DNA, consisting of a phosphate, sugar, and base
• Bases in DNA


  • Adenine
  • Thymine
  • Cytosine
  • Guanine
• DNA


  • Polymer made up of many nucleotides
  • Phosphate and sugar form a backbone
  • Bases stick out and pair up between strands
• Complementary base pairing


  A pairs with T, C pairs with G
• How to determine complementary DNA strand

  1. Look at sequence of one strand

  2. Determine complementary bases for each base
• Genetic code


  Sequence of DNA bases
• Gene


  Specific sequence of bases that codes for a protein
• How a gene codes for a protein

  1. DNA sequence read in triplets

  2. Triplets code for specific amino acids

  3. Amino acids combine in order to form a protein

  4. Protein folds into unique shape to perform function
• Main uses of proteins

  • Enzymes (biological catalysts)
  • Hormones (carry messages)
  • Structural proteins (add strength to cells and tissues)