bio p1

• Light microscope

  
  

  • Uses light to form an image
  • Can be used to view live specimens
  • Relatively cheap and easy to use
  • Magnification up to 2,000 times
• Resolution


  The ability to see two things as separate objects
• Light microscope


  • Low resolution with a resolving power of around 200 nanometers
• Electron microscope

  
  

  • Uses electrons to form an image
  • Specimens must be dead
  • Very expensive and has many conditions
  • Magnification up to 2 million times
  • High resolution of 0.2 nanometers
• Permanent vacuole


  Filled with cell sap to help keep the cell rigid
• Cell wall


  Made of cellulose, strengthens and supports the plant cell
• Features of prokaryotic cells

  • Cell membrane
  • Cytoplasm
  • Ribosomes
  • Single loop of DNA (not enclosed in a nucleus)
  • Plasmids
  • Slime layer
  • Flagella
• Prokaryotic cells do not have chloroplasts or mitochondria
• Cell differentiation


  The process by which cells develop different subcellular structures to carry out specialized functions
• Sperm cell

  • Has a tail to help it swim and reach the egg
  • Has many mitochondria in the mid-piece to provide energy for movement
  • Has enzymes to break down the egg
  • Has a large nucleus to contain DNA
• Muscle cell

  • Has many mitochondria to release energy for contraction
  • Contains special proteins that cause contraction by sliding across each other
  • Can store glycogen to be broken down for respiration
• Nerve cell


  • Has a long axon to carry electrical impulses
  • Has dendrites to connect to other nerve cells
  • Has nerve endings that release chemical messengers to transmit impulses
• Root hair cell

  • Has a large surface area projection to absorb water and minerals
  • Has a large permanent vacuole to speed up osmosis
  • Has many mitochondria for active transport of minerals
• Xylem cell


  • Forms long hollow tubes to allow easy movement of water and minerals
  • Has spiral lignin to strengthen the cell walls and support the plant
• Phloem cell

  • Has sieve plates with holes to allow easy movement of dissolved food
  • Has adjacent companion cells with many mitochondria to provide energy for food transport
• Diffusion


  The spreading out of particles in a solution or gas, resulting in a net movement from an area of higher concentration to an area of lower concentration
• Diffusion is a passive process that does not require additional energy
• Factors affecting rate of diffusion


  • Temperature
  • Concentration gradient
  • Surface area
• Osmosis


  The diffusion of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane
• Osmosis is a passive process that occurs down a concentration gradient
• Osmosis is important in maintaining the correct internal environment for animal cells
• Active transport


  Substances move from a low concentration to a high concentration, against the concentration gradient
• Active transport


  • Requires energy from respiration
  • Takes place across a partially permeable membrane, just like osmosis
• Active transport in plant roots

  1. Mineral ions move from the dilute solution in the soil into the more concentrated solution in the root hair cells

  2. Requires energy from respiration in the root hair cells
• Active transport in the small intestines

  1. Glucose is moved from the dilute solution outside the blood vessels to the more concentrated solution inside the blood vessels

  2. Allows the body to absorb as much glucose as possible and transport it to tissues for respiration
• Cell cycle

  1. Stage 1: Cell grows, increases subcellular structures, DNA replicates

  2. Stage 2: Mitosis - one set of chromosomes is pulled to each end of the cell, nucleus divides

  3. Stage 3: Cytoplasm and cell membranes divide to form two identical cells
• Importance of mitosis and the cell cycle

  • Development from a single cell to an organism
  • Growth during childhood and puberty
  • Repair of damaged tissues
• Stem cell

  Undifferentiated cell that can differentiate into specialized cells and regenerate new stem cells
• Embryonic stem cells


  • Found in the early embryo, can differentiate into many cell types, can be cloned
• Adult stem cells


  • Found in some adult tissues, more limited in the cell types they can differentiate into
• Plant stem cells


  • Found in meristem tissue, can differentiate into all plant cell types even in adulthood, used for cloning plants
• Issues with stem cells include risk of viruses, rejection, and ethical concerns
• Binary fission


  Type of simple cell division in bacteria, involves replication of genetic material and splitting into two cells
• Digestion breaks down large insoluble food molecules into smaller soluble molecules that can be absorbed
• Small intestine adaptations


  • Large surface area (villi and microvilli)
  • Good blood supply
  • Short diffusion distance
• Amylase


  Enzyme that breaks down starch into glucose
• Protease


  Enzyme that breaks down proteins into amino acids
• Lipase


  Enzyme that breaks down lipids into fatty acids and glycerol
• Amylase is also produced in the salivary glands and works in the mouth
• Protease is also produced in the stomach and works there