Cell Biology

• Eukaryotic cells


  Contain genetic material (DNA) in a nucleus

  Animal cells

  Plant cells
• Prokaryotes 


  Genetic material is not enclosed in a nucleus

  Much smaller than eukaryotic cells

  Bacteria, loops or wings of DNA (plasmids)
• Micrometre


  1 metre = 1 000 000 micrometers

  
• Human cell


  10-20 micrometers
• Nano metre


  1 nanometre = 1 000 000 000
• Order of magnitude


  1 order of magnitude = 10x

  Every order of magnitude is 10x greater than the one before
• Nucleus (animal cell)


  Where DNA is stored
• Cytoplasm (animal cell)


  Watery solution where chemical reactions take place
• Cell membrane (animal cell)


  Controls what can enter and leave a cell
• Mitochondria (animal cell)


  Aerobic respiration takes place
• Rhibosome (animal cell)


  Electron microscope

  Sites of protein synthesis
• Nucleus (plant cell)


  Contains genetic material
• Cytoplasm (plant cell)

  Chemical reactions take place
• Cell membrane (plant cell)

  Controls what can enter and leave a cell
• Mitochondria (plant cell)


  Can carry out aerobic respiration
• Ribosome (plant cell)


  Site of protein synthesis
• Chloroplasts (plant cell)


  Contain chlorophyll

  Sites of photosynthesis
• Cell wall (plant cell)


  Made from cellulose

  Strengthens the cell
• Permanent vacuole (plant cell)


  Filled with cell sap

  Helps give the plant cell it’s shape
• Animal & Plant cells specialisation

  Have adaptations which help carry out their function

  When a cell is specialised, it’s called differentiation
• Sperm cell (specialised animal)


  Has tail to swim to ovum

  Has enzymes to digest their way through the ovum

  Has mitochondria to provide it with energy to swim
• Nerve cell (specialised animal)

  Job is to carry an electrical impulse around the body

  Long axon, carries impulses

  Myelin insulates the axon and speeds up transition

  Synapses allow the impulse from one nerve to another

  Dendrites increase surface area so more cells can connect easier
• Muscle cells (specialised animal)

  Can get shorter (contract)

  Contain protein fibres to contract

  Mitochondria provides energy for contraction

  Work together to form muscle tissue
• Root hair cells (specialised plant)

  Roots have hairs which increase surface area, and absorb more water

  Contain cell wall, root hair, vacuole, nucleus
• Xylem cells (specialised plant)

  Found in the stem

  Have tubes which carry water and nutrients

  Thick walls with lignin
• Phloem (specialised plant)


  Phloem tubes carry dissolved sugars up and down a plant

  Phloem vessels have sieve plates

  Mitochondria carries energy to the phloem cell
• Electron microscopes 


  Have a larger resolution than light microscope
• Magnification equation 


  Magnification= size of image/size of real object

  
• Binary fission


  One bacterial cell splits into two bacterial cells

  Bacteria can carry out BF once every 20 minutes, as long as the temperature and nutrients is good
• Number of bacteria equation

  1 round every 20 minutes

  write answer in STANDARD FORM

  
• Chromosomes 


  23 pairs in a body

  carry genes, decide a lot of our features
• Mitosis (what happens)


  -DNA replicates to form two copies of each chromosome

  -One set of chromosomes is pulled to each end of a cell, the nucleus also divides

  -The cytoplasm and cell membrane divide to form two identical cells
• Mitosis functions


  Essential for growth of plants and animals

  Mitosis takes place like when a bone repairs

  Asexual reproduction
• Stem cells (animal)


  Undifferentiated cell which can form any type of cell before mitosis

  Found in bone marrow

  Used in therapeutic cloning (won’t be rejected by a human) used for diabetes or paralysis
• Stem cells (plant)


  Meristem tissue (clone any plant)
• Diffusion definition


  The spreading out of particles resulting in movement from an area of high concentrations to low concentrations
• Diffusion examples


  Oxygen- Diffuses into cells to replace CO2 which defuses out of cells

  Urea- Waste product inside cells, diffuses out and into blood plasma
• Rate of diffusion


  -The greater the concentration gradient, the faster diffusion take place

  -The higher the temperature, the greater the rate of diffusion (particles have more energy and move faster)

  -The larger the surface area of cell membran, the greater the rate of diffusion
• Surface area:Volume ratio


  Calculate SA

  Calculate volume

  Divide and create ratio

  As organisms get larger, the ratio decreases
• Multicellular organisms


  Surface area isn’t large enough for their volume

  Not enough oxygen can diffuse into the middle of cells