BIO P1 1. Cell Biology

• Eukaryotes

  Animal and plant cells

  • have a cell membrane
  • genetic material in enclosed in a nucleus
• Animal cell


  • Nucleus - contains DNA and controls all the cell's activities
  • Cytoplasm - jelly-like liquid where chemical reactions take place
  • Cell membrane - outer layer that controls which substances can pass into and out of it
  • Mitochondria - where respiration occurs, releasing energy
  • Ribosome - creates protein (in charge of protein synthesis)
• Plant cell


  • Nucleus - contains DNA, controls all cell activities
  • Cytoplasm _ where chemical reactions take place
  • Cell membrane - controls what substances can pass into and out of it
  • Cell wall made of cellulose - strengthens the cell and provides support
  • Sap vacuole - keeps cell firm and maintains water balance
  • Chloroplast - contains chlorophyll, a pigment, and is where photosynthesis occurs
• Prokaryotes


  Bacterial cells with no nucleus or subcellular structures
• Approximate sizes: Animal cell 10 micrometers, Plant cell 50 micrometers, Prokaryote 5 micrometers
• Nerve cell


  • Cell body
  • Dendrites
  • Axon
  • Insulating sheath
  • Axon terminals
• Sperm cell


  • Mid piece with mitochondria
  • Tail
  • Acrosome
• Muscle cell


  • Fibers for contraction
  • High density of Mitochondria - more respiration to occur to release more energy for muscle contractions
  • Glycogen store
• Xylem cell


  • No end plates
  • No cytoplasm
  • Lignin rings for support
• Phloem cell


  • Little cytoplasm
  • End plates with pores
  • Companion cells
• Root hair cell


  • Large surface area - to absorb more minerals and water
  • Many mitochondria
  • No chloroplasts - is underground
  • Long projection - to increase surface area
• Microscopes


  Simple microscopes have low magnification and resolving power

  Electron microscopes have high magnification and resolving power
• Calculating magnification


  Magnification = Size of image / Size of real object
• Magnification calculations


  • Root hair cell image 5 mm, real size 20 μm, magnification 250x

  Sperm cell image 10 mm, magnification 2000x, real size 5 μm
• Culturing microorganisms


  Binary fission for rapid division

  Provide nutrients like glucose and amino acids

  Incubate at 25°C to encourage growth
• Growing uncontaminated cultures


  Sterilise equipment and work area

  Inoculate agar plate with loop

  Seal plate to prevent contamination

  Incubate at 25°C
• Testing antibiotics/antiseptics


  Place antibiotic/antiseptic discs on agar with bacteria

  Measure area of dead bacteria around discs

  Control variables: disc area, concentration, volume
• Cell cycle and mitosis

  Stage 1: Cell grows, number of sub-cellular structures doubles and DNA replicates to form two copies of each chromosome

  Stage 2: one set of chromosomes is pulled apart to each end of the cell, forming two nuclei

  Stage 3: Cytoplasm and cell membrane divide, forming two identical cells
• Stem cells


  • Embryonic stem cells are undifferentiated

  Adult stem cells can differentiate into limited cell types
• Mitosis


  The process of cell division
• Embryonic stem cells


  • Undifferentiated, can be cloned, can differentiate into most other cell types
• Adult stem cells


  • Found in bone marrow, can differentiate into many cell types, mainly blood cells
• Plant stem cells


  • Found in meristem tissue in root and shoot tips, can differentiate into any plant cell
• Therapeutic cloning


  1. Patient body cell nucleus inserted into empty human egg cell

  2. Cloned to produce stem cells

  3. Stem cells differentiated to make specialized cells/tissues for treatment
• Diffusion


  Spreading out of particles in a solution or gas, with net movement from higher to lower concentration
• Factors affecting rate of diffusion

  • Concentration gradient
  • Temperature
  • Surface area
• Active transport

  Movement of particles from lower to higher concentration, requires energy
• Active transport examples


  • Sugar absorption in small intestine
  • Mineral ion absorption in plant root hair cells
• Surface area to volume ratio

  Ratio of surface area to volume, smaller in larger organisms
• Adaptations for exchange systems

  • Villi and microvilli in small intestine
  • Alveoli in lungs
  • Stomata in leaves
  • Gill filaments in fish
• Osmosis


  Diffusion of water from dilute to concentrated solution through partially permeable membrane
• Investigating effect of solutions on plant tissue mass

  1. Prepare solutions of different concentrations

  2. Cut equal-sized plant tissue samples

  3. Immerse samples in solutions

  4. Measure mass change after time
• Potato loses mass


  Solution outside more concentrated than inside, water moves out by osmosis
• Potato gains mass


  Solution inside more concentrated than outside, water moves in by osmosis
• Stem Cells

  • are undifferentiated, meaning it can give rise to more cells of the same type