Genetics

• Genetics


  The study of genes, heredity and variation in living organisms
• People in the same family look alike


  Because they share genetic information
• Differences in people come from where?
• Why do some diseases run in families?
• Can scientists change the genetic information in an organism?
• Why is the topic of genetic modification so controversial?
• Similarities between Homer and Herb Simpson

  Inherited characteristics
• Marge and Jacqueline have similar hair


  One similarity is inherited, one is due to the way they live their lives
• Patty and Selma are sisters and both have the same hair style

  This is an inherited characteristic
• Bart came back with a tan after the French exchange


  This is an environmental characteristic
• Identical twins separated at birth

  Their development can be influenced by both environmental and genetic factors
• Nature


  Genetic factors
• Nurture


  Environmental factors
• Cell Theory


  • All living things are made of cells.
  • Cells are the basic units of structure and function in living things.
  • All cells are produced from existing cells.
• Drawing an animal cell and a plant cell

  1. Label the parts

  2. Describe what each part does
• All living things contain genetic information in the form of DNA and chromosomes
• Cell interactives


  • Inside a cell
  • Cell Explorers Game
  • Modelling Cell Structure and Function
  • Cell Biology Video Games, Virtual labs and Activities
• DNA


  Deoxyribonucleic acid
• DNA


  • Discovered by James Watson and Francis Crick in 1953
  • Complex molecule
  • It determines the characteristics of living things
• Rosalind Franklin, a female biologist, helped with the discovery of DNA through her X-Ray diffraction photos
• The Discovery of DNA

  1. The Secret of Life - Discovery of DNA Structure

  2. The Discovery of the Structure of DNA

  3. Rosalind Franklin: DNA's unsung hero - Cláudio L. Guerra

  4. TED Talk. James Watson: How we discovered DNA
• DNA is found in the nucleus of cells and is organised into structures called chromosomes
• Structure of DNA


  • Has the same structure in all organisms
  • Made up of smaller molecules called nucleotides
• Nucleotide


  Molecule that has 3 parts: Phosphate group, Deoxyribose sugar, One of four nitrogen-rich bases
• Double helix


  • The shape of DNA, like a twisted rope ladder
  • Uprights = alternating sugar and phosphate groups
  • Rungs = bases
• One strand of DNA

  • The backbone is alternating phosphate and deoxyribose sugar parts
  • The rungs are made up of chemical units called nitrogen bases
• Nucleotide


  • The phosphate, deoxyribose sugar and nitrogen base make up 1 nucleotide
  • They are a repeating unit, only the base changes
• The Bases


  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Chromosomes


  Long thread-like structures found in the nucleus, each one a long strand of DNA coiled up around proteins called histones and then supercoiled
• Complementary base pairing


  • A and T 'fit together'
  • G and C 'fit together'
• The same species always have the same numbers of chromosomes
• Chromosome numbers for different organisms

  • Humans have 46 chromosomes
  • Fruit flies have 8 chromosomes
  • Corn has 20 chromosomes
• If you know the bases on one DNA strand, you can work out the other strand
• Human chromosomes


  We have 46 chromosomes, half (23) from mum and half (23) from dad
• A segment of DNA

  • ACAGGAGCTG
  • TGTCCTCGAC
• Hydrogen bonds


  • Hold the bases together
  • Double bond between A and T
  • Triple bond between C and G
• Gametes


  Sex cells, male gamete = sperm cell (contain 23 chromosomes), female gamete = egg cell (contain 23 chromosomes)
• DNA code


  • Any three of the bases form a triplet code for one amino acid
  • There are 20 amino acids
  • Different sequences of amino acids make up different proteins
  • Proteins can contain less than 12 to more than 50,000 amino acids
  • One DNA molecule can code for thousands of proteins
• Karyotypes


  Chromosomes can be arranged and numbered from largest to smallest
• There are videos provided on WHAT IS DNA?, DNA, What is DNA and how does it work?, and Rosalind Franklin - DNA's unsung hero