Cell biology

• Identify the 6 stages of genetic engineering.

  - identify required gene from source chromosome

  - cut out required gene

  - extract plasmid from bacterial cell

  - insert required gene into bacterial plasmid

  - insert plasmid into host cell to produce a genetically modified (GM) organism.
• In genetic engineering, how is an extracted plasmid cut open?

  Using a "cutting" enzyme
• In genetic engineering, how is gene inserted and sealed into a plasmid?

  Using an "sealing" enzyme
• What is genetic engineering?

  The transfer of genetic information from one cell to another.
• What are enzymes?


  Biological catalysts made by all living cells.
• What do enzymes do?

  They...

  - speed up cellular reactions

  - are unchanged in the process.
• How is it that enzymes are specific to one substrate?

  The shape of their active site is complementary to the shape of its specific substrate.
• What is a degradation reaction?


  Then a large, complex substrate is broken down into smaller, simple products.
• What is a synthesis reaction?

  When small, simple substrates are built up into a large, complex product.
• Give an example of a degradation reaction.

  - Starch (substrate) is broken down into maltose (product) by amylase.

  - Hydrogen peroxide (substrate) is broken down into water and oxygen (products)
• What name do we give to the temperature at which an enzyme is most active?

  Optimum temperature.
• What name do we give to the pH at which an enzyme is most active?

  Optimum pH.
• What happens to an enzyme that is heated above its optimum temperature or is put in a solution with an extreme pH?

  It becomes denatured.
• What happens to an enzyme when it becomes denatured?

  It loses its shape.
• What is respiration?


  A series of enzyme-controlled reactions where the chemical energy stored in glucose is released by cells to form ATP.
• What is the name of the high energy molecule that is regenerated during respiration, that can be used for cellular activities such as cell division and protein synthesis?

  ATP
• Give an example of a cell that requires a lot of energy and the reason why it requires a lot of energy transferred by ATP.

  muscle cells - for contraction/movement

  sperm - so that it can travel to the egg

  neuron - for the transmission of nerve impulsesSee an expert-written answer!We have an expert-written solution to this problem!
• Why do certain cell types have more mitochondria than others?

  As they require more energy
• When glucose is first broken down into two molecules of pyruvate, how many molecules of ATP does it yield?

  2 ATP
• What determines whether or not pyruvate is broken down by aerobic respiration or the fermentation pathway?

  The presence of oxygen (aerobic respiration) or absence of oxygen (fermentation).See an expert-written answer!We have an expert-written solution to this problem!
• What is pyruvate broken down into in aerobic respiration?

  carbon dioxide + water
• How much ATP is generated by aerobic respiration?


  A large number of ATP
• What is pyruvate broken down into in fermentation in animal cells?

  lactate
• How many ATP does fermentation yield in total?

  Just 2, from the initial break down of glucose.
• What is pyruvate broken down into in fermentation in plant and yeast cells?

  carbon dioxide + ethanol
• In which part of the cell does aerobic respiration take place?


  It begins in the cytoplasm and is completed in the mitochondria.
• In which part of the cell does fermentation take place?

  In the cytoplasm
• What piece of equipment can be used to measure the rate of respiration?


  A respirometer
• The cell membrane is composed of what two types of molecules?

  Proteins & phospholipids
• The cell membrane is selectively permeable. What does this mean?


  It allows some molecules to pass through but not others.
• What is meant by 'passive' transport.

  1) No energy is required.

  2) Molecules move down a concentration gradient.
• Give an example of a form of passive transport.

  1) diffusion

  2) osmosis
• What is the definition of diffusion?

  Diffusion is the movement of molecules down a concentration gradient from a higher to a lower concentration.
• What is the definition of osmosis?

  Osmosis is the movement of water molecules from a higher water concentration to a lower water concentration, through a selectively permeable membrane.
• Give an example of a molecule that would diffuse into an animal cell.

  1) oxygen

  2) glucose

  3) amino acids
• Give an example of a molecule that would diffuse out of an animal cell.

  carbon dioxide
• What would happen to an animal cell that is placed in pure water?

  Water would move into the cell and the cell would burst.
• What would happen to a plant cell that is placed in pure water?

  Water would move into the cell and the cell would become turgid (the cell wall protects it from bursting).
• What would happen to an animal cell that is placed in a concentrated sugar solution?

  Water would leave the cell and the cell would shrink.
• What would happen to a plant cell that is placed in a concentrated sugar solution?

  Water would leave the cell and the cell would become plasmolysed.