Science

• YEAR 10 SCIENCE
• WHAT MAKES US WHO WE ARE?
• BRAINSTORM PRIOR KNOWLEDGE
• Unit Objectives


  • Factual
  • Conceptual
  • Debatable
• Factual


  • What is inside a cell and how does it divide?
  • What are genes and DNA?
  • How do we inherit characteristics from our parents?
  • What are some useful applications of genetic information?
• Conceptual


  • Where does life's diversity come from?
  • Can you explore the interconnectedness of DNA, genes, cells, and chromosomes?
• Debatable


  • Are we the sum of our genes?
  • Should undesirable genes ever be eliminated from the population?
• GENETICS GLOSSARY
• GENETICS STATEMENT OF INQUIRY (MYP)
• STUDENT TASK - INTRODUCTION TO GENETICS
• Heredity


  The passing of traits from parents to offspring
• Genetics


  The study of heredity and natural variation
• Hereditary characteristics


  • Features or traits that are inherited and passed from one generation to the next in the form of a genetic code
• DNA (deoxyribonucleic acid)


  The molecule in which the genetic code is written, located within the nucleus of cells
• How DNA (traits) is inherited

  1. Characteristics passed from parents

  2. Chromosomes condense, coil and shorten

  3. DNA molecule = many units of heredity (genes)

  4. Genes are the basic unit of heredity and passed from one generation to the next
• Characteristic chromosome numbers of living things

  • Humans: 46 chromosomes (somatic cells), 23 chromosomes (gametes)
  • Koala: 16 chromosomes
  • Onion: 16 chromosomes
• Autosomes


  The non-sex chromosomes (44 chromosomes or 22 pairs)
• Sex chromosomes


  The 23rd pair, XX - Female, XY - Male
• Mitosis


  1. A single cell divides into two identical daughter cells

  2. For growth and to replace worn out cells
• Meiosis


  1. A single cell divides twice to produce four non-identical daughter cells containing half the original amount of genetic information

  2. Produces sex cells (gametes) - sperm in males, eggs in females

  3. Supports genetic variation
• Mitosis


  DNA replicates/copies, only 1 division occurs, produces 2 identical cells, for growth + repair
• Meiosis


  DNA replicates/copies, 2 separate divisions occur, produces 4 non-identical cells, for sex cell production
• Checkpoints Qu. 1.1 page 5
• CHECKPOINTS 1.1 Extension (OPTIONAL)
• Mitosis


  Cell division for growth and repair in body cells or somatic cells

  
• Meiosis


  Cell division for the production of sex cells (eggs and sperm) needed for sexual reproduction

  
• Importance of cell growth and reproduction

  • For growth, repair, and reproduction
• Mitosis


  1. One cell splits in half to create two new cells

  2. Daughter cells are genetically identical (clones) to each other and the parent cell

  
• Body cells produced in mitosis

  • Diploid (contain 46 chromosomes)

  
• Life cycle of a cell

  1. Interphase (cell grows and carries out normal function)

  2. DNA replication

  3. Mitosis

  
• Stages of mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  
• Before a cell divides, the DNA replicates
• Meiosis produces genetically unique sex cells with only 23 chromosomes (haploid)
• Meiosis involves two cycles of cell division, resulting in four daughter cells

  
• Meiosis is different from mitosis

  
• Differences between mitosis and meiosis

  • Meiosis occurs in sex cells only
  • Meiosis produces cells with half the amount of chromosomes (23 chromosomes - haploid)
  • Meiosis produces different cells to parent cell
  • Meiosis results in 4 daughter cells

  
• Mutation


  When DNA is damaged or changed in such a way as to alter the genetic message carried by that gene

  
• Mutations


  • Can occur naturally during cell division
  • Can be caused by physical damage to the DNA in one or many cells
  • If it happens in a sperm or egg cell, the mutation may be inherited
  • Can include too many or too few chromosomes or incorrect base pair matching

  
• Mutagen


  A substance or factor that causes mutation
• Mutagens


  • X rays
  • UV rays
  • Many kinds of chemicals (mercury, tar, etc.)