Cell Biology B1

• Eukaryotic Cells


  Complex

  Include Animal and Plant Cells
• Prokaryotic Cells


  Smaller and Simpler

  Include Bacteria Cells
• Animal Cells


  Include Nucleus, Mitochondria, Cytoplasm, Cell Membrane and Ribosomes.
• Plant Cells


  Include Rigid Cell Wall, Permanent vacuole and Chloroplasts.
• Nucleus


  Contains genetic material that controls activities of the cell.
• Mitochondria


  Where most of reactions for aerobic respiration takes place. Respiration transfers energy that needs that the cell needs to work.
• Cytoplasm


  Gel-like substance where most chemical reactions happen. Contains enzymes that control these chemical reactions.
• Cell membrane


  Holds the cell together and controls what goes in and out.
• Ribosomes

  Where proteins are made in the cell.
• Rigid Cell Wall


  Made of cellulose - supports the cell and strengthens it.
• Chloroplasts 


  Where photosynthesis occurs, which makes food for the plant. Contains a green substance called chlorophyll, which absorbs the light needed for photosynthesis.
• Permanent Vacuole 


  Contains cell sap - a weak solution of sugar and salts.
• Bacterial Cells


  Includes Cell Membrane, Cytoplasm, Circular strand of DNA, Cytoplasm and Plasmids.
• Light Microscopes


  Use light and lenses to form image of specimen and magnify it. Allow us to see individual cells and large sub-cellular structures like nuclei.
• Electron Microscopes


  Use electrons to form an image - have much higher magnification and resolution than light microscopes. Allow us to see smaller things in more detail such as mitochondria and ribosomes.
• Magnification Formula 


  $magnification =$$image size/real size$
• Preparing the Slide


  1. Add a drop of water to the middle of a clean slide

  2. Cut up an onion and separate it out into layers - use tweezers to peel off some epidermal tissue from the bottom of one of the layers

  3. Using the tweezers, place the epidermal tissue into the water on the slide

  4. Add a drop of iodine solution (Stain) - used to highlight objects in a cell by adding colour to them

  5. Place a cover slip on top - stand the cover slip upright on the slide next to the water droplet, then carefully tilt and lower so it covers the specimen. Avoid air bubbles as they will obstruct the view
• Parts of Light Microscope


  Eyepiece

  Coarse and Fine Adjustment Knob

  Light

  Stage

  High and Low power objective lens
• Using a Light Microscope to look at Slide


  1)Clip the slide you've prepared onto the stage

  2) Select the lowest- powered objective lens (one that produces lowest magnification.

  3)Use coarse adjustment knob to move the stage up to below the objective lens.

  4)Look down eyepiece - use coarse knob to move stage downwards until image is roughly focused.

  5) Adjust focus with fine knob until there is a clear image of the slide.

  6) To see slide with higher magnification - swap to higher powered objective lens.
• Differentiation


  Differentiation is the process by which a cell changes to become specialised for its job.
• Animal Cells Differentiation 


  Their ability to differentiate is lost at an early stage after becoming specialised.
• Plant Cells Differentiation 


  Majority of plants don't lose the ability to differentiate.
• Mature Animals


  Cells that differentiate in mature animals are mainly used for repairing and replacing cells - such as skin or blood cells.
• Stem Cells


  They are undifferentiated cells
• Sperm Cells


  -Specialised for reproduction

  -Function is to get male DNA to female DNA

  -Contain lots of mitochondria in the cell to provide energy needed

  -Carries enzymes in the head to digest through the egg cell membrane
• Nerve Cells

  -Specialised for rapid signalling

  -Function is to carry electrical signals from one part of the body to another.

  -Long and have branched connections to connect to other nerve cells and form a network throughout the body.
• Muscle Cells

  -Specialised for contraction

  -Function is to contact quickly.

  -Long and contain lots of mitochondria to generate energy needed for contraction.
• Root Hair Cells

  -Specialised for absorbing water and minerals

  -They are cells on the surface of plant roots - grow into long 'hairs' that stick out into the soil.

  -Gives the plant a big surface area for absorbing water and mineral irons through soil.
• Phloem and Xylem Cells

  -Specialised for transporting substances

  -Form phloem and xylem tubes - transport substances such as food and water around plants

  -To form tubes - cells are long and joined end to end

  -Xylem cells are hollow in centre and Phloem cells have few sub cellular structures - stuff is able to flow through them
• Embryonic Stem Cells

  Can turn into any type of cell
• Undifferentiated Cells (Stem Cells)

  -Can divide to produce more stem cells

  -Differentiate into any type of cell - depending on what instructions they are given
• Stem Cells

  -Found in human embryos

  -Useful for doctors/researchers as have potential to turn into any type of cell

  -Found in adults but only in bone marrow - those can only turn into blood cells.

  -Both can be grown in lab to produce clones - then made to differentiate into specialised cells used in medicine or research
• Stem Cells Uses

  -Adult Stem Cells- Can be used to cure disease

  -Embryonic stem cells - can be used to replace faulty cells in sick people.
• Therapeutic Cloning 


  -Embryo is made to have same genetic info as the patient so stem cells produced would contain same genes - wouldn't be rejected.
• Risks of Stem Cells


  -Stem cells grown in a lab could be contaminated with a virus which could be passed on and make patient sicker.
• Things against stem cells


  -People think human embryos shouldn't be used for experiments - as each one is a potential human life.

  -Embryos used in research are usually the unwanted from fertility clinics - which if weren't used for research would just be destroyed.
• Stem Cells Can Produce Identical Plants


  -In plants - stem cells are found in the meristems.

  -Throughout the plants life the cells in the meristem tissue can differentiate into any type of plant cells.

  -These stem cells can be used to produce clones of whole plants - quickly and cheaply.

  -Used to grow more plants of rare species and farmers use them to grow plants with desired features.
• Chromosomes 


  -Contain genetic information

  -Most cells in the body have a nucleus - nucleus contains genetic material in the form of chromosomes.

  -Each chromosome carries a large number of genes - different genes control the development of different characteristics.
• Cell Cycle 


  -Body cells in multicellular organisms - divided to produce new cells as part of the cell cycle.

  -Mitosis is the stage of the cell cycle when the cell divides.

  -Multicellular organisms use mitosis to grow and develop or replace damaged cells.

  -At the end of the cycle - two identical cells are formed.
• Main stages of cell cycle - Growth + DNA Replication 


  -In a cell that's not dividing - the DNA is spread out in long strings.

  -Before dividing - cell has to grow and increase amount of sub cellular structure such as mitochondria and ribosomes.

  -Then the DNA is duplicated - one copy for each new cell.