B1 - Cell Biology

• Diffusion


  Particles/ molecules move from a high concentration, to a low concentration until an equilibrium is reached. No energy required.

  
• Osmosis


  Movement of water particles from a high concentration to a low concentration across a partially permeable membrane.
• Factors speeding up diffusion & osmosis


  - Higher temperature (particles gain kinetic energy)

  - Thinner membranes (shorter diffusion distance)

  - Higher concentration gradient (takes longer for an equilibrium to be reached)
• Water potential


  Water concentration
• Active transport


  Particles move from a low concentration to a high concentration and requires energy.

  
• Diffusion (Examples)


  - In the lungs (Carbon Dioxide, oxygen, glucose)

  - Carbon dioxide into plants via stomata
• Osmosis (Examples)


  - Distilled water entering a cell

  - Small intestine
• Active transport (Examples)


  - Root hair cells (mineral ions from a low concentration in soil to a high concentration in root hair cell)

  - Small intestine (glucose and amino acids from low concentration in small intestine to a high concentration in the blood using energy)
• Light microscope


  - Low magnification

  - Low resolution

  - Living sample

  - Image in colour (from dye), 2D

  - Image can be blurry

  - Cheaper

  - Used in schools
• Electron microsope


  - High magnification

  - High resolution

  - Dead sample

  - Image in black & white

  - Pass electrons through sample

  - Expensive

  - Uses a vacuum
• Microscope parts


  - Eye piece

  - Arm

  - Objective lenses

  - Stage

  - Focus

  - Light

  - Base

  
• Magnification


  How much bigger an object appears to be than it really is when viewed through a microscope. (Image/ actual)
• Resolution


  The smallest distance that can be seen between two points. (The smaller the distance, the higher the resolving power)
• Metres order


  Kilometres, metres, millimetres, micrometres, nanometres
• Nucleus


  Controls the cell's activities and contains DNA
• Mitochondria


  Site of respiration (Release energy through respiration)
• Cytoplasm


  Site of chemical reactions
• Cell membrane (inside)


  Allows chemicals in and out of the cell
• Cell wall


  Strength and support for the cell
• Ribosomes


  Make proteins
• Vacuole


  Stores cell sap (cell food) and keeps cell turgid (full)
• Chloroplasts


  Site of photosynthesis, contain chlorophyll
• Eukaryotic cells


  - Have a nucleus

  - Bigger

  - Mitochondria

  Plants, animals, yeast
• Prokaryotic cells


  - No nucleus

  - Smaller

  - No mitochondria

  Bacteria
• Sperm cell


  Long tail, pointy head - Help swim and dig into the egg
• Muscle cell


  Overlapping edges - Allows muscles to contract, move
• Nerve cell


  Many branches - Carry more nerve impulses at a time
• Root hair cell


  Elongated shape, tail - Increase surface area to absorb more water
• Phloem


  Little cytoplasm, no nucleus - More room for sugars
• Xylem


  Pits, lignin - Water can move between adjacent cells, stronger walls
• Stem cell


  A cell that hasn't undergone differentiation (all cells start off like this)
• Mitosis


  Cells divide to allow for growth, replace damaged cells (repair)
• Production of new cells - Duplication


  DNA replicated so form two copies of the chromosomes. Increase number of mitochondria, ribosomes, etc.

  
• Production of new cells - Mitosis


  One set of chromosomes is pulled to each side of the nucleus and then the nucleus splits into two.

  
• Production of new cells - Cleaving


  Cytoplasm and cell membranes split and form two genetically identical cells.
• Meristem tissue


  Plant stem cell
• Therapeutic


  Relating to the treatment of a disease
• Therapeutic cloning


  1 - Need two cells; one from the patient and a donated egg cell.

  2 - Remove nucleus from egg, skin cell and replace with patient's nucleus.

  3 - Electric shock is uses to stimulate cell division to develop into an embryo

  
  

  Used to treat cancer, diabetes, heart disease, infertility, regrow tissues, replace faulty organs
• Animal stem cell - Embryonic


  Undifferentiated ( Allow them to develop into a foetus - fertilised egg cell)
• Animal stem cell - Adult


  Differentiated (specialised), used to repair damaged tissues and replace dying cells, found in blood, skin, brain, heart, liver etc.