Cell Metabolism
Metabolism: Sum of all chemical reactions in an organismEnzymes
- Biological catalysts; speed up the rate of chemical reaction without getting used up in the process
- Folded globular shaped protein
- Can help in either catabolic or anabolic reactions
Catabolic: Amylase breaks down starch into maltose, Catalase braks down H2O2 into water and oxygen
Anabolic: DNA Polymerase helps formation of DNA from its constituent molecules
Enzyme used: Amalase
- Spit in number of test tubes
- Heat each tube at a different temperature using water baths (e.g. 20, 40 and 60 degrees)
- Pour spit of small piece of bread then test for starch using iodide
Effect of pH
-Same as above except instead of changing heat conditions change pH
-Optimum pH for amylase is about 7
Enzyme ImmobilisationEquipment: Yeast(enzyme), Sodium Alginate, Calcium Chloride powder
Drop beads in slowly and leave for 10 minutes to allow to settle.
Application:
- Production of glucose from sucrose
- Use glucose test strip or benedicts solution and heat to test for glucose.
Immobilised Enzymes: Enzymes which are trapped in an inert insoluble material(Sodium Alginate)
Uses: Immobilised lactase to produce lactose free milk
Advantages:
- Gentle, the enzyme is not damaged
- No contamination
- Immobilised enzymes are more stable
Active Site: Area where the substrate(s) enter the enzyme and are changed into a product(s)
Specific: Enzymes will only react with one type of substrate
Bioreactor
Vessel in which a product is formed by a cell/cell component such as enzymesBatch Cultures
- Individual cycles
- Vessel with stirring, heating and cooling system
- The products are usually withdrawn before too many waste products are formed
Continuous Flow
- Have more sensors to test conditions; e.g. temperature, pH
- Nutrients, substrates and medium are continually pumped into bioreactor
- Product continually taken out
Role of Microorganisms in Industrial fermentation
- Used in brewing, producing dairy products, making vinegar
Bioprocessing with Immobilised Enzymes
Uses:
- Industrial fermentation of beer, wine and spirits
- Production of antibiotics such as penicillin
- Detoxify sewage
Photosynthesis
Process of converting light energy into chemical energy by combining water and CO2 to produce O2 and glucose
6CO2 + 6H2O --> C6H12O6 + 6O2
Takes place in the Chloroplasts
Role:
- Food for plants
- Food for animals which eat plants
- Forms oxygen for plants and animals
Process
Stage 1: Light stage
1) Chlorophyll molecule is energised by sunlight and releases an electron
2) Pathway 1 - cyclic pathway - electron passes through a series of electron acceptors, as the elect moves to each acceptor energy is released which is used o combine a phosphate with adenosine diphosphate to become adenosine triphosphate.
ADP + P --> ATP
3)Pathway 2 - Non-cyclic Pathway - Electron instead joins with NADP and Hydrogen to form NADPH
4) Hydrogen comes from the photolysis of water (light splits water) which results in Hydrogen ions, electrons and oxygen. Oxygen is released into the atmosphere. Hydrogen joins NADP and electrons. The electrons go to the chlorophyll molecule which had lost its electron.
5) NADPH and ATP go to the dark stage
Stage 2: Dark Stage
1) Carbon Dioxide enters from the atmosphere and using the energy trapped in ATP Hydrogen ions and electrons from NADPH join with the carbon dioxide to produce glucose. NADP returns to the light stage. Glucose is used to supply energy or is converted into starch to be stored.
Human Intervention
Use of artificial light and carbon dioxide enrichment in crop growth
- To maximise growth of plants and crops
Investigate the influence of light intensity on the rate of photosynthesis
- Vary distance of lamp and measure the number of bubbles produced.
- Cut stem with sharp blade and gentle crush them stem so that oxygen is more easily released.
- Place pondweed upside down so that bubbles are easily seen.
Respiration
Aerobic respiration: Enzyme controlled release of energy using oxygen
C6H12O6 + 6O2 ---> Energy + 6H2O + 6CO2
Anaerobic Respiration: Enzyme controlled release of energy from food without the use of oxygen
Process of Respiration
Stage 1: Glycolysis
- Occurs in the cytosol
- Conversion of a 6 carbon molecule (glucose) to pyruvic acid-3 carbon molecule. Break down of molecule creates energy to form ATP
- When oxygen is not present glucose breaks down to ethanol in yeast or lactic acid in animals.- Conversion of a 6 carbon molecule (glucose) to pyruvic acid-3 carbon molecule. Break down of molecule creates energy to form ATP
Stage 2:
- Occurs in the mitochondria
- Pyruvic acid becomes Acetyl CoA, in the process one molecule of Carbon Dioxide in released.
- As pyruvis acid breaks down electrons and protons are lost and join with NAD+ to become NADH
- Acetyl CoA enters the Krebs Cycle by joining with a 4 carbon molecule
- The 6 Carbon molecule is broken down each time releasing Carbon dioxide. The energy is used to make ATP. Electrons and protons are release to join with NAD+
Electron Transport Chain
Transfer of electrons along a series of enzymes
- NADH dumps the electrons and protons it picked up
- The energy form these particles are used to change ADP into ATP to be used to power metabolic reactions
- After the elecrons and protons have been used they join with Oxygen to for water.
ATP: Adenosine Triphosphate
-High energy molecule responsible for carrying energy and powering metabolic reactions within cells
NAD: Nicotinamide Adenine Dinucleotide
NADP: Nicotinamide Adenine Dinucleotide Phosphate
- Molecules responsible for carrying electrons and hydrogen ions to one reaction in the cell to another
Prepare and Show the Production of Alcohol by Yeast
- Fermentation lock allows gas (CO2) to bubble out but doesn't allow any gases such as Oxygen in.
- Leave solutions overnight in a waterbath at 30 degrees
Test for alchohol;
Add potassium Iodide solution and sodium hypochloride.
Small yellow crystals will appear in the presence of alcohol.
Movement Through Cell Membrane
Selective Permeability: Refers to the cell controlling what substances enter and leave the cell. Controlled by proteins embedded in the cell membrane. 
Osmosis: The movement of water molecule from a region of high concentration to a region of low concentration through a partially permeable membrane.Turgur: Pressure exerted by the cell contents on the cell walls
Application of high sugar or salt content in food
Causes water to move of of the cells therefore any bacteria or fungi present die due to water loss from the cells.
Demonstrate Osmosis
- Water will enter the test tubing because it had a lower concentration of water, by entering the tube the concentration inside and outside the tubing is equal.
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