cell biology

• what does the nucleus do?

  Controls the cell and contains genetic material.
• what does the cytoplasm do?

  most of the chemical reactions take place here
• what does the cell membrane do?

  Controls the movement of substances in and out of the cell.
• what does the mitochondria do?

  Produces energy, where aerobic respiration takes place.
• what do ribosomes do?


  Protein synthesis
• what three sub-cellular structures are in a plant call but not an animal cell?

  cell wall, permanent vacuole and chloroplast.
• what is the cell wall and its function?

  made of cellulose, outside the cell membrane, strengthens the cell.
• whats the vacuole and its function?

  filled with cell sap which supports the plant (keep its shape)
• what are choloroplasts and their function?

  they absorb light to make food (glucose) by photosynthesis
• why will some plant cells contain chloroplasts?

  because the plant needs to make its own food
• how do we investigate cells? (required practical)

  using a light microscope to observe, draw and label a selection of plant and animal cells
• whats the objective lense?

  3 or 4 lenses with different magnifications
• whats the stage?


  a platform that holds the slide for observation.
• whats the slide?

  a thin piece of glass that holds the specimen.
• whats the lamp for?

  provides light to illuminate specimen, sometimes used with a mirror.
• whats the eyepiece lense?


  part of the microscope that you look through
• whats the coarse focus wheel for?


  To quickly bring the specimen into rough focus.
• whats the fine focus wheel for?

  To sharpen the quality of image.
• whats the base for?

  supports the microscope
• whats the method for investigating cells?

  1. place a tissue sample on a slide
  2. add a few drops of suitable stain
  3. lower a coverslip onto the tissue
  4. place the slide on the microscope stage and focus on the cells using low power
  5. change to high power and refocus
  6. draw any types of cells that can be seen
  7. add a scale line to the diagram
• what stain do we use on animal cells?

  methylene blue
• how do w stain plant cells?

  iodine
• what a eukaryotic cells?

  eukaryotic cells contain their genetic material (DNA) within a nucleus e.g. plant and animal cells
• what are prokaryotic cells?

  in prokaryotic cells, the genetic material (DNA) is not enclosed in a nucleus e.g. bacterial cells
• are eukaryotic cells or prokaryotic cells smaller?

  prokaryotic cells are much smaller
• why is there no ribosome or mitochondria in bacterial cells/prokaryotic cells?


  because their roles are taken over by the cytoplasm
• what are plasmid DNA in bacterial cells?


  a small, commonly circular, section of DNA that can replicate independently of chromosomal DNA. Plasmids allow bacterial cells to move genes from one cell to another
• what is chromosomal DNA in bacterial cells?

  the DNA of bacteria is not found within a nucleus and is usually found as one circular chromosome
• whats the flagella in bacterial cells?

  tail-like structures that rotate to help bacteria move
• whats the cell wall in bacterial cells?

  provides structural support to the bacteria (not made of cellulose)
• what are chromosomes and where are they found?

  they are long molecules made from DNA, found in the nucleus
• what does each chromosome carry?

  hundreds to thousands of genes
• what are genes?

  part of a chromosome, made of DNA, which codes to make different proteins and so control the development of characteristics
• how many pairs of chromosomes do humans have?

  23 pairs (46 single chromosomes), one from each parent
• size of a plant cell in mm?

  0.1 mm in diameter
• size of animal cell in mm?

  0.02 mm in diameter
• size of prokaryotic cells in mm?

  0.002 mm long
• whats the magnification formula?

  magnification = size of image/size of real image
• how many cm in a metre?

  100 , 1 x 10^2
• how many mm in a metre?

  1000 , 1 x 10^3