bio paper 1

• Eukaryotic cells


  Cells that contain their genetic material enclosed in a nucleus
• Eukaryotic cells


  • Contain a nucleus
  • Contain a cell membrane
  • Contain cytoplasm
• Prokaryotic cells


  Cells where the genetic material is not enclosed in a nucleus
• Prokaryotic cells


  • Do not have a nucleus
  • Have a cell membrane
  • Have a cell wall
  • Contain cytoplasm
  • May have plasmids
• Prokaryotic cells


  Are much smaller than eukaryotic cells
• You will find plenty of questions on eukaryotic and prokaryotic cells in the revision workbook
• Plant cell


  • Cell membrane - responsible for determining which bits go to in or out of the cell
  • Cell wall - important for structure
  • Vacuole - important for structure
  • Cytoplasm - where most reactions take place
  • Ribosomes - responsible for protein synthesis
  • Chloroplasts
  • Mitochondria - where energy is produced
  • Nucleus
• Animal cell


  • Cell membrane - controlling what goes in and out
  • Mitochondria - where energy is produced
  • Ribosomes - protein synthesis
  • Cytoplasm - where most reactions take place
  • Nucleus - where DNA is held and control center of the cell
• Plant cells have features that animal cells don't share, like cell wall, vacuole, chloroplasts
• There isn't really a typical type of cell because there are a wide range of differentiated specialized cells
• Differentiation


  When various different genes will be turned on and turned off, and that's when cells will start to specialize
• Microscope techniques


  From basic lenses to sophisticated electron microscopes controlled by computer
• Calculating magnification from microscope images

  Magnification = image height / object height
• Metric prefixes


  • Meter (m)
  • Centimeter (cm) - 10^-2 m
  • Millimeter (mm) - 10^-3 m
  • Micrometer (μm) - 10^-6 m
  • Nanometer (nm) - 10^-9 m
  • Picometer (pm) - 10^-12 m
• Enzymes


  • Work with the lock and key mechanism
  • Have a specifically shaped active site
  • Form an enzyme-substrate complex
  • Break apart or join together substrates
  • Release products and remain unchanged
• Temperature affects enzyme activity

  • Low temperatures - not enough energy
  • Optimal temperature
  • High temperatures - enzymes get denatured
• pH affects enzyme activity

  • Optimal pH
  • Too high or too low - active site breaks down, enzyme gets denatured
• Substrate concentration affects enzyme activity

  Increasing substrate concentration increases enzyme activity until active sites are full
• Enzymes as catalysts

  Increase the rate of reaction but don't change the final equilibrium
• Digestive enzymes

  • Lipase - breaks down fats
  • Protease - breaks down proteins
  • Amylase - breaks down starch
• Diffusion

  Movement of particles from high to low concentration
• Osmosis

  Movement of water through a partially permeable membrane from high to low water concentration
• Active transport

  Movement of substances from low to high concentration, against the concentration gradient
• Cancer

  • Uncontrolled cell division leading to lumps (benign or malignant tumors)
  • Malignant tumors are fast growing, aggressive and mobile
• Cancer risk factors


  • Smoking
  • Diet
  • Sun exposure
  • Unprotected sex
• Stem cells


  • Have the potential to turn into any other type of cell
  • Can be used to grow new cells/tissues/organs
• Stem cell production


  Take nucleus from patient cell and insert into empty egg cell, which then develops into an embryo from which stem cells are extracted
• Nervous system


  • Central nervous system (brain and spinal cord)
  • Neurons, receptors and effectors
  • Reflex actions
  • Electrical signals in neurons
  • Slow chemical signals at synapses
• Advantages of sexual reproduction

  • Genetically diverse population
  • Better protection from diseases
• Disadvantages of asexual reproduction

  • Genetically identical population
  • Susceptible to diseases
  • Requires finding a mate
• Advantages of asexual reproduction

  • Only one parent required
  • Energy conserved by focusing on own genes
• Mitosis


  1. DNA condenses into chromosomes

  2. Chromosomes line up in the middle

  3. Chromosomes pulled apart to form two identical daughter cells
• Meiosis


  1. Chromosomes line up and undergo crossing over

  2. Two cell divisions to form four genetically distinct daughter cells
• Selfish gene


  The parent is putting all of its energy into conserving its own genes
• Mitosis


  1. DNA condenses into chromosomes

  2. Chromosomes line up down the middle

  3. Chromosomes pulled apart to either end of the cell

  4. New nuclei form

  5. Two identical daughter cells
• Meiosis


  1. Chromosomes line up

  2. Crossing over occurs

  3. Divide into two

  4. Line up and divide into two again

  5. Four different daughter cells
• Mitosis


  Leads to two identical daughter cells
• Meiosis


  Leads to four different daughter cells
• Gametes


  Eggs in women, sperm in men
• Plant gametes


  Eggs in the stigma, pollen on the stamen