cell biology (1)

• animal and plant cells are eukaryotic, what do they contain

  cell membrane, cytoplasm , nucleus
• bacteria cells are prokaryotic so the contain...

  cell wall , cell membrane , cytoplasm, plasmids
• function of nucleus

  contains DNA
• function of cytoplasm

  where the chemical reactions occur
• function of cell membrane

  controls what enters and leaves the cell
• function of the mitochondria

  where respiration occurs , provides energy for the cell
• function of ribosomes

  where protein synthesis occurs
• function of chloroplasts

  where photosynthesis takes place and it contains pigment which gives the leaves their green colour
• function of the vacuole

  contains the cell sap , gives the cells support / structure
• function of the cell wall

  provides the structure for the cell
• what are plasmids

  small loops of DNA
• functions of sperm cells

  carrying the males DNA to the egg cell for reproduction
• parts of a sperm cell and their functions

  tail - to aid swimming , lots of mitochondria to supply the energy to allow the cell to move
• what are nerve cells specialised for

  transmit electrical signals quickly from one place in the body to another
• parts of a nerve cells and their functions

  axon - is long, enabling the impulses to be carried long distances. dendrites - lots of extensions meaning the branches can be connected with other nerve cells
• what are muscle cells specialised for

  to contract quickly to move bones
• parts of a muscle cell and their function

  lots of mitochondria to provide lot of energy
• what are root hair cells specialised for

  to take up water by osmosis and mineral ions by active transport
• parts of root hair cells and what they do

  large surface area to absorb more water, mitochondria to provide energy
• what are xylem cells specialised for

  to transport water and mineral ions up the plant from the roots up to the shoots
• what are phloem cells specialised for

  to carry the products of photosynthesis to all the parts of the plants
• how do stem cells turn into specialised cells

  they go through cell differentiation
• equation for magnification

  magnification = image size / object size
• 2 ways to grow microorganisms in the lab

  nutrient broth solution or agar gel plate
• why do Petri dishes need to be sterilised

  it can be contaminated with other microorganisms
• why should inoculating loops be sterilised

  to kill unwanted microorganisms
• how do you sterilise inoculating loops

  passing them through a flame
• why should you seal the petri dish with tape partially 


  to stop airborne microorganisms from contaminating the culture, but should not be fully sealed as then harmful bacteria would grow due to the lack of oxygen entering
• why should the petri dish be stored upside down 


  to prevent condensation from dripping onto the agar and disrupting growth
• why should the culture be incubated at 25 degrees c

  if it was higher e.g. 37degrees it would be more likely to be filled with bacteria that harms humans but if it was incubated at a lower temperature than the culture would be unable to grow
• binary fission


  one cell dividing to produce two
• what is a chromosome 


  DNA structures that are found in the nucleus which are made up of genes
• what is DNA


  the chemical that makes up the genetic material of humans. 
• what is a gene


  a section of DNA in a chromosome that codes for a protein
• how many chromosomes does a human have

  46 and 23 pairs
• what is the cell cycle 


  a series of steps that the cell has to undergo in order to divide
• stage one of the cell cycle

  interphase - the cell grows and increase in number, DNA replicates and energy stores are released
• stage two of the cell cycle

  mitosis - the chromosomes line up at the middle of the cell and are pulled to either side of the cell
• stage 3 of the cell cycle

  cytokinesis - two identical daughter cells form after the cell membrane and cytoplasm has been divided
• mitosis is part of asexual reproduction