cell biology

• eukaryote cells have a nucleus
• prokaryotes are bacteria
• mitochondria where anaerobic respiration happens

  ribosomes where the proteins are made in the cell

  Vacuole contains cell sap - were weak solution and sugar and salts
• microscopy

  light microscope use light and lenses to form image of and magnify it let us see individual cells and large sub cellular structures.
• electron microscope uses electrons to form image - higher magnification, higher resolution, see smaller thing in more detail like (mitochondria and chloroplasts)
• differentiation is the process by which a cell changes to become specialised for its job
• allows them to carry out specific functions
• undifferentiated cells are called stem cells
• • sperm cells - long tail and streamlined head help it swim to the egg
  • lots of mitochondria for energy
• Nerve cells - carry electrical signals

  • cells are long
  • branched connections to connect to other nerve cells to form a network throughout the body
• Muscle - contraction

  • long so have space to contract
  • contain lots of mitochondria to generate energy
• root hair cells - absorbing water and minerals

  • surface of plant roots which grow into long "hairs"
  • gives plant big surface area to absorb water and minerals from soil
• phloem and xylem

  • tubes
  • hollow
  • stuff can flow through
• stem cells are found in the bone marrow and can differentiate into any type of cell
• adult stem cells cannot turn into ant type of cell type at all
• stem cells from embryos and bone marrow can be grown in lab to produce clones and made to differentiate for medicine or research
• adult stem cells cure disease
• stem cells from healthy person replace faulty blood cells
• embryonic cells for diabetic, nerve cells for paralysed by spinal injuries
• therapeutic cloning, embryo made to have same genetic information as patient
• stem cells same genes would not get rejected
• risks - contaminated with a virus which could be passed on to make patient sicker
• against cell research shouldn't be used on potential human life
• embryos used in research are unwanted ones - against
• some countries banned stem cell research
• stem cells can produce identical plants
• produces clone quickly
• grow more rare species (plants)
• nucleus contains genetic material in for of chromosomes
• body cell 2 copies of each chromosomes - mother and father
• each chromosomes carrie large number of genes different genes control the development of characteristics
• 23 pairs of chromosomes
• cell cycle makes cells for growth, development and repair
• body cells, multicellular organisms divide and produce new cells
• cell dividing mitosis
• mitosis is to grow or replace cells that ave been damaged
• growth and DNA replication

  • not dividing, DNA spread out in long strings
  • before, cell grows + increases mitochondria and ribosomes
  • duplicates DNA so one copy from each new cell. copied in x - shapes and is exact duplicates
• mitosis

  • chromosomes lined up in centre of cell
  • cell fibres pull apart two arms go to opposite side of cell
  • membranes for around sets of chromosomes. they become nuclei of the two new cells - nucleus has been divided
  • cytoplasm and cell membrane divide
  • 2 new daughter cells - contain the same DNA identical - DNA also identical to parent cell
• prokaryotic cells replicate by binary fission

  1. circular DNA and plasmid replicate
  2. circular DNA strands move to opposite ends of the cell
  3. cytoplasm divides and new cell walls form
  4. cytoplasm divides two daughter cells produced. each one has one copy of the circular DNA but has a variable number of plasmids.
• diffusion is the spreading out of particles from an area of high concentration to low concentration