biology

• Cell


  The basic unit of all living things
• Main types of cells

  • Animal
  • Plant
  • Yeast
  • Bacterial
• Cell organelles


  • Cell membrane
  • Ribosome
  • Cytoplasm
  • Mitochondria
  • Nucleus
  • Cell wall
  • Vacuole
  • Chloroplast
  • Plasmid
• Cell membrane


  • Controls entry and exit of materials in the cell
• Ribosome


  • Site of protein synthesis
• Cytoplasm


  • Site of chemical reactions
• Mitochondria


  • Site of aerobic respiration
• Nucleus


  • Controls the cell's activities
• Cell wall


  • Supports the cell, made of cellulose in plant cells and a different material in yeast and bacterial cells
• Vacuole


  • Contains cell sap
• Chloroplast


  • Site of photosynthesis
• Plasmid


  • Small ring of DNA
• We use a microscope to look at cells and add a stain to the microscope slides so we can see the cell organelles clearly
• Types of cells


  • Yeast cell
  • Animal cell
  • Plant cell
  • Bacterial cell
• Cell membrane


  Made up of proteins and phospholipids
• Passive transport


  Molecules move down a concentration gradient and no energy is required
• Types of passive transport

  • Diffusion
  • Osmosis
• Diffusion


  The movement of molecules down a concentration gradient from a higher to a lower concentration, no energy needed
• Osmosis


  The movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane, no energy needed
• Effects of solutions on cells

  • Animal cell in high water/dilute solution: cell bursts
  • Animal cell in low water/concentrated solution: cell shrinks
  • Plant cell in high water/dilute solution: cell becomes turgid - cell swells and contents push against the cell wall
  • Plant cell in low water/concentrated solution: cell becomes plasmolysed - cell contents shrink and pull away from the cell wall
• Active transport


  Requires energy for membrane proteins to move molecules and ions against the concentration gradient
• DNA


  Carries the genetic information for making proteins and therefore determines characteristics
• Gene


  Codes for a particular protein
• DNA structure


  Made up of 2 strands twisted into a double helix shape, with 4 bases: adenine, thymine, guanine and cytosine
• DNA base pairs


  Adenine-thymine, guanine-cytosine
• Proteins


  Made of amino acids, different amino acids join together in different orders to make different proteins
• mRNA


  Carries a complementary copy of the genetic code from the DNA in the nucleus to the ribosome where the protein is assembled
• Types of proteins


  • Antibodies
  • Hormones
  • Receptors
  • Structural
  • Enzymes
• Enzymes


  Biological catalysts that speed up chemical reactions and are unchanged after it, made of protein and found in all living cells
• Enzyme active site


  Has a shape complementary to only one substrate, enzyme is specific to one substrate
• Types of enzyme reactions

  • Degradation - break down of large molecules into smaller molecules
  • Synthesis - build up of large molecules from smaller molecules
• Enzyme reactions


  • Catalase: hydrogen peroxide -> oxygen + water
  • Potato phosphorylase: glucose-1-phosphate -> starch
• Optimum condition


  The condition at which an enzyme is at its most active
• Enzymes, and other proteins, can be affected by temperature and pH, and can be denatured which changes the shape of the active site and affects the rate of reaction
• Stages of genetic engineering

  1. Identify section of DNA with required gene

  2. Extract required gene from chromosome

  3. Extract plasmid from bacterial cell

  4. Insert required gene into bacterial plasmid

  5. Insert plasmid into host bacterial cell to produce a genetically modified organism

  6. Bacterial cell will produce protein coded for by inserted gene
• Enzymes are used in the genetic engineering process
• Genetic engineering is used to produce human proteins such as insulin and human growth hormone
• Respiration


  The chemical energy stored in glucose must be released by all cells through a series of enzyme-controlled reactions
• ATP


  A molecule containing energy that can be used for cellular activities
• Aerobic respiration


  Glucose + Oxygen -> Carbon dioxide + Water + Energy