cell biology

• Animal cells and plant cells are eukaryotes
• Animal cells and plant cells are eukaryote cells are they both have a nucleus which contains the genetic material of the cells (DNA)
• in a eukaryotes cell there is a nucleus with DNA enclosed inside, cell membrane and the cytoplasm
• a bacteria cell is an example of a prokaryotes cell. the genetic material is not enclosed in a nucleus. they are much smaller than the other type of cell
• In a prokaryotes cell, the dna is in a loop and also may have small rings of DNA called plasmids. They have a cell membrane, cell wall and cytoplasms
• Prokaryotic cells are much smaller than eukaryotic cells
• 1. 1 m is 100 cm
  2. 1 cm is 10 mm
  3. 1 m is 1 000 mm
  4. 1m is 1 000 000 hm
  5. 1 nm is 1 000 000 000 nm
• 1 order of magnitude means 10 times
• every order of magnitude is 10 times greater than the one before
• 1. count the zeros
  2. 10 times = one order of magnitude
  3. 100 times = two orders of magnitude
  4. 1000 times = three orders of magnitude
• The cytoplasm is a watery solution where chemical reactions take place
• the cell membrane controls the molecules that can enter and leave the cell
• the mitochondria is the site of aerobic respiration and is where most of the energy is released
• ribosomes are the sites of protein synthesis
• list what is in a animal cell

  1. ribosomes
  2. mitochondria
  3. nucleus
  4. cytoplasm
  5. cell membrane.
• Chloroplasts contain chlorophyl and are the sites of photosyntheis
• the cell wall strengthens the cell with a chemicals called cellulose
• the vacuole is filled with cell sap which helps give the plant cell its shape
• what do plant cells contain?

  1. chloroplasts
  2. cell wall
  3. vacuole
  4. cell membrane
  5. mitochondria
  6. ribosomes
  7. cytoplasm
  8. nucleus
• The job of a nerve cell is to send electrical impulses around the body. They have axons to do this which are covered in insulates it and speeds up the transmission of nerve impulses. They also have synapses which allow the impulse to pass from one nerve cell to another. their dendrites increase the surface area so that other nerve cels can connect more easily.
• muscle cells can contract, they can do this because they contain protein fibres which can change their length by shortening. they have a lot of mitochondria to provide energy for muscle contraction.
• Root hair cells contain hairs to increase the surface area of the root so it can absorb water and dissolved minerals more effectively. They do not contain chloroplasts as they are underground.
• Xylem cells are found in the plant stems and they form long tubes which carry water and dissolved minerals from the roots to the leaves. They have thick walls containing lignin which provides support to the plant. Because the cell walls are sealed with lignin this causes the xylem cells to die. The end walls between the cells have broken down which means they form a long tube so water and minerals can flow easily. They have no nucleus, cytoplasm, vacuole or chloroplast.
• phloem tubes carry dissolved sugars up and down the plant. phloem vessel cells which have no nucleus and limited cytoplasms and the end walls of the vessel cells have pores called sieve plates. both these features allow dissolved sugars to move through the interior. each cell has a companion cell connected by pores which contain mitochondria to provide energy.
• Describe a microscope

  At the centre is a stage where we place the microscope slide and the stage had clips to hold it in place. Below the stage is a lamp. There are 3 objective lenses. At the top is an eyepiece which we look through which has an eye piece lense which has a magnification of 10x.
• How do you use a optical microscope to view a prepared slide

  1. Place slide on the stage and use clips to hold in place
  2. select the lowest power objective lens and position until it almost touches the slide by slowly turning the coarse focussing dial
  3. whilst doing that look at the microscope from the side to minimise damage caused
  4. look down through the eye piece and slowly turn the coarse focussing dial to increase the distance between the objective lense and the slide to bring the cells into focus
  5. use the fine focussing dial to bring them to a more clear focus
• to calculate the total magnification multiply the magnification of the eyepiece lens by the magnification of the objective lens
• Why do light microscopes have limited magnification

  Light microscopes have a limited magnification this is because the magnification is not powerful enough
• 
  

  electron microscopes have a much greater magnification and resolution than light microscopes
• how do you calculate the magnification

  magnification = size of image divided by size of the real object
• 
  

  Human body cells contain 23 pairs of chromosomes
• chromosomes carry a large number of genes which determine many of our features
• what are the stages of mitosis

  • the DNA replicated to form two copies of each chromosome
  • the cell grows and copies its internal structures
  • one set of chromosomes is pulled to each end of the cell. the nucleus’s also divides
  • the cytoplasm and the cell membrane divide to form two identical cells
• functions of mitosis

  1. essential to the growth and development of multicellular organisms
  2. when a organism repairs itself
  3. during asexual reproduction
• When cells specialise, it is called differentiation
• a stem cell is a undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells
• stem cells can be found in bone marrow
• bone marrow stem cells can only differentiate into cells found in our blood
• leukaemia is a cancer of the bone marrow, to treat this the existing bone marrow must be destroyed using radiation. they then receive a transplant of bone marrow from a donor. the stem cells in the bone marrow divide and form new bone marrow. they also differentiate and form new blood cells.
• what are some Robles with bone marrow transplant

  • donor has to be compatible with the patient otherwise the white blood cells produced by the donated bone marrow could attack the patients body
  • risk of viruses being passed on