cell biology

• What is a cell?


  Basic unit of life that can replicate independently
• What are eukaryotic cells?

  plant and animal cells
• Our animal and plant cells uni or multicellular?

  multicellular
• Our Bactria cell uni or multicellular?

  unicellular
• Animal cell sub cellular structures

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

  
• Plant cell sub cellular structures

  Nucleus, cytoplasm, cell membrane, ribosomes, mitochondria, cell wall (made of cellulose), permanent vacuole (with cell sap) and chloroplasts

  
• What do plant cells have that animal cells don't?

  cell wall, chloroplasts, vacuole
• What is the function of the nucleus?

  Contains the cell's genetic material that controls the activities of the cell
• What is the function of the mitochondria?

  aerobic respiration and gives energy to the cell
• What is the function of the cell membrane?


  to control what enters and leaves the cell
• What is the function of the cytoplasm?

  Gel like substance, site of chemical reactions, contains enzymes that control these chemical reaction
• what the function of ribosomes?

  protein synthesis take place and are made
• what is the function of a cell wall?

  made of cellulose so will strengthen the cell and give it extra support
• What the function of the vacuole?

  cell sap, solution of sugar and salts
• what the functions of chloroplasts?

  Chloroplasts carry out the process of photosynthesis, which involves using light energy from the sun to make glucose.

  The green pigment that absorbs the light energy is called chlorophyll. This is what makes plants green.
• What is a prokaryotic cell?


  A cell without a nucleus eg bacteria
• What do bacterial cells contain?


  Cytoplasm, cell membrane, cell wall, flagella, ribosomes, mitochondria,plasmids (small rings of DNA) and a single circular strand of DNA that floats freely in the cytoplasm

  
• what the function of plasmids?


  small ring of dna
• what is the function of the flagella?

  movement
• What is differentiation?


  The process by which a cell differentiates developing different sub-cellular structure to become specialised for its job
• what are animal specialised cell?

  sperm cell , nerve cell , muscle cells
• Plant specialised cells?


  xylem , phloem and root hair cells
• What are adaptations of a sperm cell?

  - streamlined body and flagella for easy movement

  - digestive enzymes for penetrating the egg

  - lots of mitochondria for energy
• what are the adaptations of nerve cells?

  - Elongated cells carry impulses over long distances.

  - Dendrites can make connections with many other neurones

  - Myelin sheath insulates one axon from another.
• adaptations of muscle cells?

  - Adapted to contraction quickly

  - Long so have space to contract

  - Contain lots of mitochondria to generate energy needed for contraction
• adaptations of xylem ?

  Dead, hollow cells; cell wall contains lignin; contain pits
• Adaptation of phloem tissue ?

  1. Sieve plates

  2. Companion cell

  3. No nucleus, thin layer of cytoplasm, few organelles

  4. Many plasmodesmata in walls

  5. made up of living cells
• Adaptation of root hair cell?

  hair provides a large surface area so more water and minerals absorbed
• What are undifferentiated cells called?

  stem cells, they are not specialised cells this means that they can divide by mitosis to make different types of cells
• magnification


  How many times larger the image is than the actual size of the object being viewed
• Resolution


  distinguish between two points so how detailed the image is
• what is the equation for magnification ?


  Magnification = image size / actual(real) size
• describe features of a light microscope?

  
• Conversion of um --> mm

  divide by 1000
• electron mircoscope


  - very expensive

  - hard to use only use by scientist

  - use electron instead of light

  - -better resolution can see more sub-cellular structures eg nucleus
• Light Mircoscope


  - easy to use

  - cheap

  -rely on light

  - resultion is limeted
• How do you work out magnification?

  Image size/actual size
• Microscopy Practical - Preparing the Slide

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

  2) Cut up an onion & 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 - a 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 & lower it so it covers the specimen. Try not to get any air bubbles under there - there'll obstruct your view
• Microscopy Practical - Using a Light Microscope

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

  2) Select the lowest-powered objective lens

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

  4) Look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus

  5) Adjust the focus with the fine adjustment knob, until you get a clear image of what's on the slide
• Microscopy Practical - Drawing Observations

  1) Draw what you see under the microscope using a pencil with a sharp point

  2) Make sure your drawing takes up at least half of the space available & that it is drawn with clear, unbroken lines

  3) Your drawing should not include any colouring or shading

  4) If you are drawing cells, the subcellular structures should be drawn in proportion

  5) Include a title & write down the magnification that it was observed under

  6) Label the important features of your drawing using straight, uncrossed lines