cell biology

• Nucleas

  • contains genetic material that controls the activities of the cell
• cytoplasm

  • a gel like substance where chemical reactions happen
• cell membrane

  • holds the cell together
  • controls what goes in and out of it
• mitochondria

  • provide cells with energy they need to function for aerobic respiration
• Ribosomes

  • the site of protein synthesis
• cell wall

  • made of cellulose
  • strengthens the cell
• permanent vacuole

  • contains cell sap
  • a weak solution of sugar and salts
• chloroplasts

  • this is where photosynthesis occurs which makes food for the plant
  • contains green substance called chlorophyll which absorbs light
• plasmids

  • small rings of DNA
• what is diffusion?

  •  the spreading out of the particles from an area of higher concentration to an area of lower concentration
  • happens in any in solution or a gas
• what is osmosis?

  •  the movement of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane.
• how does active transport happen in root hair cell?

  • active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil against a concentration gradient
  • this is essential for growth but needs a lot of energy
• why is active transport used in guts?

  • when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood
  • active transport allows nutrients and glucose to be taken into the blood and transported to cells where it is used for respiration
• whats the difference of differentiation in animals and plants?

  • animals- occurs early in development, embryo
  • plants- retain the ability to differentiate constantly
• is a eukaryotic cell bigger than a prokaryotic cell?

  yes
• cell differentiation

  • determines the development of specific organelles
• is starch preset in plants?

  • yes
  • glucose is stored as starch
  • energy released from glucose in respiration
  • is required for growth
• sperm cell

  • nucleus in the head
  • tail to swim to the ovum
  • mitochondria for energy for swimming
  • acrosome, penetrates the egg
  • 23 chromosomes
• nerve cell

  • axon to carry electrical impuses
  • myline to insulate the axon, which speeds up transmission
  • synapses are junctions which allow impulses to pass from each nerve
• Binary fission

  • Bacteria carrys out binary fission every 20 mis
  • with enough nutrients
  • suitable temperature
• describe the process of mitosis

  • the chromosomes are duplicated which makes an x chain
  • they line up in the centre
  • cell fibres pull away the chromosomes in half to opposite sides of the cell
  • nuclear membranes form around each set of chromosomes
  • cell membrane and cytoplasm pull apart to form two identical daughter cells
• name the type of cell division that occurs in a meristem cell

  • mitosis
• light microscope

  • magnifies 1500 X
  • uses a glass lens to magnify
  • low resolution
  • low magnification
  • cheap
  • light and lenses forms an image
• Electron microscope

  • magnifies 500000 X
  • expensive
  • higher resolution
  • higher magnification
  • beams of electrons form image
  • see organelles in finer detail - ribosome
• Red blood cells

  • large surface area so large amounts of oxygen are able to diffuse
  • no nucleus, which means more haemoglobin
  • flexible, allows them to squeeze through narrow capillaries
  • biconcave disc
• stem cells

  • hasn't undergone differentiation
• Binary fission cycle

  • the circular DNA and plasmids replicate
  • the cell gets bigger
  • the circular DNA strands move to the opposite poles
  • cytoplasm begins to divide and new cells form
  • the cytoplasm divides to produce two daughter cells
  • each one with the copy circular DNA
  • with variable number of copies of plasmids
• concerns of stem cells

  • lab grown stem cells may be contaminated with viruses which can spread to patients
  • loss of potential human life