Enzymes
- Enzymes are biological catalysts: this means that they speed up the chemical reactions in living things.
- Enzymes are made of protein; that is why they are sensitive to heat, pH and heavy metal ions and also baking powder to make cakes and exhaust gases from cars.
- Enzymes act as catalysts by lowering the activation energy required for the chemical reaction to occur. However, enzymes can also be denatured due to temperature, pH, and in that case, the chemical reaction that requires that enzyme will not take place.
- The substance that enzymes work on is said to be called substrate.
- The two types of reaction that enzymes can react to are:
- Enzymes work by binding to their reactants and lowering the activation energy required for the two to react.
- Enzyme shape determines enzyme activity. Enzymes have specific shapes that enable them to do their job of making reactions happen faster. Each enzyme has an active site where its reactants fit and are brought together or where a chemical bond is stressed allowing it to be more easily broken. The active site fits only the enzymes reactants just as a key fits only a given lock.
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Increasing temperature increases the energy of molecules. This causes an increase in the rate of reaction due to: a) more frequent collisions being more energetic and therefore more likely to react. The temperature of a chemical reaction states that the rate of reaction will double for each 10°C rise in temperature. In enzyme catalyzed reactions this holds up to a point. After this point (the optimum temperature) increasing energy causes hydrogen bonds and hydrophobic interactions to break. The active site starts to lose its shape and the enzyme denatures.
7B. Changing pH alters the ionic charges on some groups in the protein molecule. This damages ionic bonds, changing the shape of the molecule. Small changes in pH cause reversible damage. Very large changes may irreversibly denature the enzyme.
- The best term to describe the best temperature and PH for enzymes is Optimum condition.
Respiration
- The food that’s used during respiration to give the body energy is called Chemical energy. E.g. it is the way that energy is released from Glucose.
- The food group that Glucose belongs to Kilocalories.
- The energy molecule that’s made from this food is Glucose.
- The substances are ADP and ATP.
5. The first stage of aerobic respiration is , which takes place in the cytosol of cells and also occurs in fermentations and other forms of .
6. Word equation for Aerobic equation:
Glucose + Oxygen = Carbon Dioxide + Water + Energy
7. Waste products from aerobic respiration include carbon dioxide and water, which are released in exhaled air, sweat, and urine in animals, and are exhaled into the air through the many surfaces of plants. The body cannot get rid of lactic acid by breathing it out as it does carbon dioxide, so when the exercise is over lactic acid has to be broken down. This needs oxygen, and the amount of oxygen needed to break down the lactic acid is known as oxygen debt. Even though our leg muscles have stopped working, our heart rate and breathing rate stay high to supply extra oxygen until we paid off the oxygen debt.
8. Aerobic respiration produces CO2 and ATP.
Anaerobic respiration may not necessarily produce ethanol. In humans, it produces lactic acid and ATP.
9. The of respiration that gives the body energy is Aerobic respiration and it produces 38 ATP.
10. Electron Transport Chain - This is the final stage of aerobic respiration. During glycolsis and the Krebs cycle, entire energy was not released from the glucose. In this stage of aerobic respiration, remaining energy from the glucose will be released by the electron transport chain. The network of electrons carrying proteins to the inner membrane of the cell is known as electron transport chain. Eventually, in this stage the electrons along with the protons will be added to oxygen. When electrons and protons are added to oxygen, it produces water and not ATP (energy). Actually, ATP is produced when the protons are moved across the cell membrane.
Photosynthesis
- The raw materials of photosynthesis are water, carbon dioxide, sunlight and chlorophyll.
The main aim of photosynthesis is to form glucose, which is used by the plants to use as food and for storage in the form of starch.
Carbon dioxide acts as a source of carbon and oxygen for the formation of glucose molecule.
Sunlight is used as a source of energy to conduct the process of photosynthesis.
Chlorophyll are the green pigments present in the plants that impart the plants a green color. Chlorophyll molecules are excited in the presence of light and liberate electrons that split water into hydrogen and oxygen. The hydrogen combines with carbon dioxide through various complex processes to form glucose, and the oxygen is liberated out into the atmosphere.
2. 6CO2 + 12H2O + light → C6H12O6 + 6O2 + 6H2O
3. Plants get their energy from sunlight, which energy is used via the chlorophyll, to manufacture food from carbon dioxide from the air, and water and nutrients from the soil.
B. The light energy is converted from the sun is converted to chemical energy as ATP and then to a store of chemical energy in the food.
1ST Stage of Photosynthesis
Sunlight goes into the leaves as well as water. The combination of the sunlight brakes down the water molecules into oxygen. The hydrogen which broke off from the water molecule then gets carried by the NADP molecule (energy storage) into the second stage of photosynthesis
2nd Stage of Photosynthesis
Second stage of photosynthesis where NADP (energy storage molecule) which acquired hydrogen in the first stage, goes to the second stage as NADPH. Hydrogen from this molecule then joins together with carbon dioxide, and through a special process, come together to create glucose.
- The storage substance of plants is Carbohydrate –starch.
- The are 3factors that can limit photosynthesis from going any faster these are:
- Light intensity
- Carbon Dioxide concentration
- Temperature