Year 10 Science Revision Semester 1

• Genes/DNA


  They have instructions that tell your cells to make proteins. These proteins can determine your health and your traits.
• Genes


  Sections of DNA that code for the production of a particular protein
• DNA


  Located in the nucleus of animals and plant cells
• Chromatin


  Multiple linear strands of DNA that are partially coiled up
• Chromosome


  DNA condenses and coils further when cells divide
• Organisation from largest to smallest

  • Cell
  • Nucleus
  • Chromosome
  • Gene
  • DNA
• DNA structure


  Double helix shape, sugar and phosphate molecules flipped on the other side, resembles a simple spiralled or twisted ladder when uncoiled
• Nucleotide


  Sugar and phosphate molecules bonded by phosphodiester bonds, with a nitrogenous base attached to every sugar molecule

  
• Nitrogenous bases


  • Adenine
  • Thymine
  • Guanine
  • Cytosine
• Complementary base pairing


  Adenine pairs with thymine, guanine pairs with cytosine
• Chemical bonding between sugar and phosphate molecules

  Phosphodiester bond
• Chemical bonding between nitrogenous bases

  Hydrogen bonds, two bonds between A and T, three bonds between C and G
• Karyotype


  Pictures and scans of a person's chromosomes, showing their complete set and gender
• Autosomes


  Chromosomes that are not sex chromosomes, somatic body cells
• Sex chromosomes


  Chromosomes concerning the sex of an organism
• Homologous chromosomes


  Pairs of chromosomes in diploid organisms that have similar genes
• Male karyotype


  XY chromosome as the 23rd
• Female karyotype


  XX chromosome as the 23rd
• Genetic disorders


  • Down Syndrome - Trisomy 21
  • Turners Syndrome
  • Klinefelter's Syndrome
• Types of cells in the human body

  • Body Cells (somatic)
  • Sex Cells (gametes)
• Mitosis


  The purpose is for the growth, repair and replacement of somatic body cells
• Phases of the cell cycle


  • Mitotic phase
  • Interphase
• Interphase


  The phase where a cell prepares to divide or not, the cell is either performing all its normal functions or preparing for cell division
• Phases of mitosis


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
• Cytokinesis


  The division of the cytoplasm
• Products of somatic cell division


  Two daughter cells that are identical to the parent cell
• Meiosis


  The purpose is the production of sex cells (gametes)
• Interphase in meiosis


  The DNA replicates
• Phases of meiosis


  • Interphase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Products of gamete cell division

  Four daughter cells with genetic variation from the parent cells
• DNA replication happens in interphase
• Helicase


  Breaks the hydrogen bonds
• Primase


  Sets primers and marks where to go
• Polymerase


  DNA polymerase that fills in all the bases
• Ligase


  Glues the DNA together
• DNA replication


  Semi-conservative: half of the original and half is newly created
• Inheritance


  The process of transferring genes from a parent to their offspring
• Gene


  A section of DNA that codes for the production of a specific protein
• Allele


  A different version of a gene, an organism gets one from each parent
• Dominant


  A version of a gene that is expressed when there is only one copy present, a dominant trait appears when at least one allele is present