B1 - cell biology

• The cells that differentiate in mature animals are mainly used for repairing and replacing cells, such as skin or blood cells
• Most differentiation occurs as an organism develops
• Some cells are undifferentiated cells called stem cells
• In most animal cells, the ability to differentiate is then lost at an early stage, after they become specialised
• You Need To Know These Examples of Specialised Cells
• The function of nerve cells


  Is to carry electrical signals from one part of the body to another
• Cells Differentiate to Become Specialised
• The function of a sperm

  Is to get the male DNA to the female DNA
• Lots of plant cells don't ever lose this ability
• Sperm Cells are Specialised for Reproduction
• Nerve Cells are Specialised for Rapid Signalling
• Nerve cells are long and have branched connections at their ends


  To connect to other nerve cells and form a network throughout the body
• This allows cells to carry out specific functions
• Cell Differentiation and Specialisation


  Differentiation is the process by which a cell changes to become specialised for its job
• Cells don't all look the same. They have different structures to suit their different functions
• As cells change

  They develop different subcellular structures and turn into different types of cells
• Mitochondria


  Where most of the reactions for aerobic respiration take place
• Eukaryotic cells


  Cells that are more complex and larger than prokaryotic cells
• Plant and Animal Cells have Similarities and Differences
• A pokann is a prokaryotic cell
• Animal cells


  • Nucleus
  • Mitochondria
  • Cytoplasm
  • Cell membrane
  • Ribosomes
• Ribosomes


  Where proteins are made in the cell
• Nucleus


  Contains genetic material that controls the activities of the cell
• Cell membrane


  Holds the cell together and controls what goes in and out
• Cytoplasm

  Gel-like substance where most of the chemical reactions happen
• Cells can be either prokaryotic or eukaryotic
• Organisms can be prokaryotic or eukaryotic
• Organisms

  • Prokaryotes
  • Eukaryotes
• Cells

  • Prokaryotic
  • Eukaryotic
• Examples of prokaryotic cells

  • Bacteria
• Prokaryotic cells

  Single-celled organisms
• Cells are Studied Using Microscopes
• Electron microscopes use electrons instead of light to form an image
• Microscopes can see things that we cannot see with the naked eye
• Resolution is the ability to distinguish between two points, so a higher resolution gives a sharper image
• A mitochondrion is approximately 0.0025 mm long, written in standard form as 2.5 x 10^-3 mm
• Standard form is used to write very big or small numbers with lots of zeros into a more manageable format
• Electron microscopes have a much higher magnification and resolution than light microscopes
• Light microscopes use light and lenses to form an image of a specimen and magnify it to make it appear bigger
• Bacterial cells may contain one or more small rings of DNA called plasmids