Edexcel B2.1 Building Blocks of Cells

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Edexcel B2.1 Building Blocks of Cells
2013-05-15 03:06:02
Edexcel Unit2 Cells DNA

Edexcel Additional Science
Show Answers:

  1. What is the function of a Mitochondrion?
    Where respiration takes place (releases energy)
  2. Name 3 cell organelles which are present in plant cells but not animal cells. What are their functions?
    • Cell Wall - Provides support for the cell
    • Vacuole - contains cell sap
    • Chloroplasts - where photosynthesis occurs. (Contains chlorophyl)
  3. Which part of the cell controls what goes in and out?
    Cell membrane
  4. Which type of cell would you find a plasmid?
    Bacteria! Plasmids are small loops of DNA
  5. Which part of a  bacterial cell rotates and helps movement?
  6. Which type of cell has NO nucleus?
  7. What piece of equipment is used to see things which are too small to see with the naked eye?
    A Microscope
  8. Which type of microscope is the most powerful? Light or Electron?
    • Electron Microscopes.
    • They can see very small things in lots of detail.
  9. Give the equation for magnification.
    Magnification = Length of image/Length of Specimen
  10. What is the role of the focusing wheel?
    To make the image clearer
  11. Name 4 DNA bases.
    Adenine (A), Thymine (T), Cytosine (C), Guanine (G).
  12. Which bases pair together?
    • A and T
    • C and G
  13. Bases are linked by which type of Bond?
    Hydrogen Bonds
  14. Define a gene.
    A gene is short section of DNA which encodes a protein.
  15. Why is detergent used in DNA extraction?
    To break down cell membranes.
  16. How many bases encode one amino acid?
  17. What are proteins made of?
    Amino Acids
  18. Why is the amino acid sequence of a protein important?
    The sequence of amino acids determines the shape of the proteins and the shape determines their functions.
  19. What is a mutation?
    A mutation is a change in a DNA sequence.

    Mutations can be beneficial, harmuful or have no effect.
  20. What is an enzyme?
    An enzyme is a catalyst in living things.
  21. What is the name for the part of the enzyme that binds to the substrate?
    Active Site

    This has a specific shape so it only fits one substrate.
  22. Enzymes speed up reactions such as........
    Digestion, DNA Replication and Protein Synthesis
  23. What is the loack and key mechanism?
    That an enzyme is specific to just one sustrate.

    Just like only one key fits a lock.
  24. What does denature mean?
    When an enzyme has changed shap and can no longer bind to the substrate. The enzyme can no longer catalyse reactions.
  25. Which 3 factors affect the rate of an enzyme reaction?
    • Temperature
    • pH
    • Substrate Concentration
  26. What do we call the temperature at which enzymes work best?
    • Optimum Temperature.
    • Optimum temperature in humans is often 37 degrees Celcius.
  27. What is genetic engineering?
    Changing an organisms genes/DNA
  28. During genetic engineering what is used to cut genes from chromosomes?
    An enzyme
  29. Which type of cell division produces two new genetically identical cells?
  30. Why is mitosis needed?
    Growth and repair
  31. What name is given to cells which contain two copies of chromosomes?
  32. What type of cell division produces sex cells?
  33. What does haploid mean?
    Only one copy of each chromosome (half the DNA of a non-sex cell)
  34. Mitosis is what type of reproduction?
  35. What happens to DNA before a cell divides?
    The DNA is copied/ replicated.
  36. What is cloning?
    Cloning produces cells which are genetically identical to the original.
  37. What is a stem cell?
    A stem cell is an undifferentiated cell (it does not yet have a function).
  38. Other than adult stem cells name another type of stem cells.
    Embryonic stem cells.
  39. Give an advantage of embryonic stem cells over adult stem cells.
    Can differentiate into any type of cell/
  40. What are the disadvantages of using adult stem cells?
    • Can be hard to find or in small numbers.
    • They can only differentiate into a small number of different cell types.