Cell bio & transport

• eukaryotic cells are both animal and plant cells which contain genetic information (DNA) that is contained in the nucleus
• Animal cells have a nucleus, mitrochondria, cell membrane, ribosomes and cytoplasm
• Cell membrane controls the movement

  of substances in and of the cell
• Nucleus contains DNA
• Mitrochondria is where energy is released through respiration
• Ribosomes is the site of protein synthesis
• Cytoplasm is a jelly-like substance, where chemical reactions take place
• Plant cells have everything a animal cell has with a perm vacuole, chloroplast and a cell wall
• Perm vacuole contains cell sap
• Chloroplast contain chlorophyll to absorb light energy for photosynthesis
• Cell wall made of cellulose, which strengthens the cell
• Prokaryotic cells characteristics:

  • single celled
  • no nucleus- single loop of dna
  • smaller that eukaryotic
  • small rings of dna called plasmids
• bacteria cells have a cellwall, cellmembrane, plasmids, cytoplasm, bacterial dna loop and flagellum
• Features of a light microscope

  • use light to form images
  • living samples can be viewed
  • relatively cheap
  • low magnification
  • low resolution
• Features of a electron microscope

  • use elector beams to form images
  • living samples cannot be viewed
  • relatively expensive
  • high magnification
  • high resolution
• Electron microscopes allow you to see sub-cellular structures, such as ribosomes, that are too small to be seen with a light microscope.
• magnification = image size / actual size
• Cells in animals and plants differentiate to form different types of cells. Most animal cells differentiate at an early stage of development, whereas a plant’s cells differentiate throughout it lifetime.
• the function of a sperm cell is to fertilise a ovum (egg)
• red blood cells transport oxygen around the body
• muscle cells contract and relax to allow movement
• nerve cells carry electrical impulses around the body
• root hair cells absorb mineral ions and water from the soil
• palisade cells enable photosynthesis in the leaf
• adaptions sperm cell:

  • tail to swim to the ovum and fertilise it
  • lots of mitochondria to release energy from respiration, enabling the sperm to swim to the ovum
• adaptions red blood cell:

  • no nucleus so more room to carry oxygen
  • contains a red pigment called haemoglobin that binds to oxygen molecules
  • flat bi-concave disc shape to increase surface area- to volume ratio
• adaptions muscle cell:

  • contains protein fibres, which can contract to makethe cells shorter
  • contains lots of mitochondria to release energy from respiration, allowing the muscles to contract
• nerve cell adaptations:

  • branched endings, called dendrites, to make connections with other neurones or effectors
  • myelin sheath insulates the axon to increase the transmission speed of the electrical impulses
• Adaptations of root hair cell:

  • long projection speeds up the absorption of water and mineral ions by increasing the surface area of the cell
  • lots of mitochondria to release energy for the active transport of mineral ions from the soil
• adapations palisade cells:

  • lots of chloroplasts containing chlorophyll to absorb light energy
  • located at the top surface of the leaf where it can absorb the most light energy
• diffusion is the spreading out of particles, resulting in a net

  movement from an area of higher concentration to an

  area of lower concentration
• Factors which affect the rate of diffusion: difference in

  concentration, temperature, and surface area of the membrane
• osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• active transport is movement of particles from a more

  dilute solution to a more concentrated solution using energy from respiration
• In diffusion particles move down the concentration gradient –

  from an area of high concentration to an area of low concentration
• In osmosis water moves from an area of lower

  solute concentration to an area of higher solute concentration
• In active transport particles move against the concentration

  gradient – from an area of low concentration to an area of highe concentration
• in diffusion energy is not required (passive process)
• In osmosis energy is not required (passive process)
• In active transport energy released by respiration is required