Topic 3: The Chemistry of Life 3.6 Enzymes 3.6.1 Define enzyme and active site Definition enzymes are globular proteins that work as catalysts. A catalyst speeds up chemical reactions. The enzyme converts a substrate into a product Enzymes are found in all living cells and are secreted by some to work outside the cell Enzymes can be used again and again without altering its shape/structure Definition the active site is the location on an enzyme where a substrate binds 3.6.2 Explain enzyme-substrate specificity Living organisms produce thousands of enzymes because most enzymes only catalyze one biochemical reaction. Enzyme Specificity An enzyme will only work with a specific substrate for a specific reaction The enzymes 3-dimensional structure results in a specific shape that only a specific substrate will fit Called the lock and key model home.mira.net 3.6.3 Explain the effect of temperature, pH and substrate concentration on enzyme activity The speed of the reaction can be measured in two ways: a)The rate the substrate disappears b)How fast the product is formed biowithberkeley.blogspot.com 3.6.3 Explain the effect of temperature, pH and substrate concentration on enzyme activity Temperature Temperature affects enzymes in two ways: 1.When a liquid is heated their molecules have more kinetic energy. The enzyme and substrate will move at a greater speed and will more likely collide. 2.When enzymes are heated, the bonds in the enzymes vibrate and there is more of a chance of the bonds breaking. When the bonds break, the structure of the enzyme changes shape. No more bonding can occur and enzyme activity decreases This is called denaturation Almost every enzyme will denature at 60C Every enzyme has an optimum temperature where activity is the highest (most enzymes have an optimum temperature of 37C) 3.6.3 Explain the effect of temperature, pH and substrate concentration on enzyme activity Relationship between enzyme activity and temperature 3.6.3 Explain the effect of temperature, pH and substrate concentration on enzyme activity pH Acidity vs. alkalinity the lower the pH the higher the acidity Acidity is due to the presence of H ions Enzymes are sensitive to pH. If the pH is too high or too low the enzyme can become denatured Not all enzymes have the same pH. There is quite a variance. 3.6.3 Explain the effect of temperature, pH and substrate concentration on enzyme activity Substrate concentration Simply, if there is more substrate, the reaction will be quicker Another substrate cannot bind to the binding site until the product has been Produced, so eventually the reaction rate will slow down. 3.6.4 Define denaturation Definition the structural change of a protein resulting in its loss of its biological properties Caused by high temperatures and extreme pH 3.6.5 Explain the use of lactase in the production of lactose-free milk Lactose is the sugar that is naturally present in milk It is converted into glucose and galactose by the enzyme lactase 70% of humans in the world are lactose intolerant because the gene that produces the enzyme, lactase, is turned off. The enzyme can be obtained from yeast, purified and then added to the milk. The lactose is broken down into glucose and galactose to allow lactose intolerant people to drink milk, eat ice cream, etc 3.6.5 Explain the use of lactase in the production of lactose-free milk A more effective way to convert lactose into glucose + galactose is called enzyme immobilization Procedure: First the enzyme (lactase) is immobilized in alginate beads. Next the beads are placed in a container over which milk can be passed. The milk is collected and re-circulated (pumped) to convert any remaining lactose to glucose and galactose. The circulation is maintained until all lactose has been converted. This procedure is cheaper and more efficient 3.6.5 Explain the use of lactase in the production of lactose-free milk Percentage of the world population that is lactose intolerant. Are you part of the majority in your country? 3.7.1 Define cell respiration. (1) State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP.(1) Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and carbon dioxide, with no further yield of ATP.(3) Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondrion into carbon dioxide and water with a large yield of ATP. (3) 3.7.1 Define cell respiration Cell respiration is - the controlled release of energy from organic compounds in cells to form ATP Living things require energy to: repair body structures maintain activities of life (movement, reproduction, nutrition, excretion, etc...) protein synthesis active transport across membranes 3.7.1 Define cell respiration 3.7.2 State that, in cell respiration, glucose in the cytoplasm is broken down by glycolysis into pyruvate, with a small yield of ATP Glycolysis The first step in cell respiration the breakdown of one molecule of glucose into two molecules of pyruvate and a small net yield of ATP This occurs in the cytoplasm ATP adenosine triphosphate the energy is stored in its bonds requires steps to release energy, so that the amount of energy released can be controlled intranet.canacad.ac.jp 3.7.3 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and CO2, with no further yield of ATP If there is no oxygen, the cell needs to use anaerobic respiration (no oxygen) to get its energy 3.7.3 Explain that, during anaerobic cell respiration, pyruvate can be converted in the cytoplasm into lactate, or ethanol and CO2, with no further yield of ATP 3.7.4 Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondria into CO2 and water, with a large yield of ATP If oxygen is present, the pyruvate that is produced in the cytoplasm moves to the mitochondria and it is broken down into CO2 and water, and lots of ATP 3.7.4 Explain that, during aerobic cell respiration, pyruvate can be broken down in the mitochondria into CO2 and water, with a large yield of ATP 3.8.1 State that photosynthesis involves the conversion of light energy into chemical energy.(1) State that light from the Sun is composed of a range of wavelengths (colours).(1) State that chlorophyll is the main photosynthetic pigment.(1) Outline the differences in absorption of red, blue and green light by chlorophyll.(2) State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen.(1) State that ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make organic molecules.(1) Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass.(3) Outline the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis.(2) 3.8.1 State that photosynthesis involves the conversion of light energy into chemical energy. Location: chloroplast Reaction: Traps light energy (photons) and converts it into chemical energy. Organisms: Prokaryotic and Eukaryotic Substrate: Inorganic CO 2 and H 2 O Products: Organic compounds (sugars) and O 2 3.8.2 State that light from the Sun is composed of a range of wavelengths (colours). Light from the sun is composed of a range of wavelengths (colours). The visible spectrum illustrates the wavelengths and associated colour of light. The shortest wavelengths are the 'blues' which have more energy. The longer wavelengths are the 'reds' which have less energy. kollewin.com 3.8.3 State that chlorophyll is the main photosynthetic pigment. Chlorophyll is the main photosynthetic pigment. This is where light energy is trapped and turned into chemical energy. 3.8.4 Outline the differences in absorption of red, blue and green light by chlorophyll. The main colour of light absorbed by chlorophyll is red and blue. The main colour reflected (not absorbed) is green. Hence why so many plants are seen as green, the light is reflected from the chlorophyll to your eye. 3.8.5 State that light energy is used to produce ATP, and to split water molecules (photolysis) to form oxygen and hydrogen. Photolysis 2H 2 O + 4 photons (light) 4e - + 4H+ + O 2 Hydrogen ions from photolysis of water accumulate inside the thylakoid compartment of chloroplasts to set up concentration and electric gradients As the hydrogen ions flow out through channels into the stroma, enzyme action links Pi to ADP to form ATP.This mechanism is called the chemiosmotic theory of ATP formation. 3.8.6 State that ATP and hydrogen (derived from the photolysis of water) are used to fix carbon dioxide to make organic molecules. H + from the splitting of water are combined with carbon dioxide to form organic compounds like sugar. The H + created during photolysis are used to produce ATP ATP is used to form bonds between the carbon, hydrogen and oxygen C, H, O are enough to form lipids and carbohydrates. With a Nitrogen source amino acids and therefore proteins can be made. bealbio.wikispaces.com 3.8.7 Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass. Processes like photosynthesis and respiration can be measured by either: 1.Depletion of substrate. 2.Accumulation of products Carbon dioxide + water ----> Organic molecule + Oxygen measuring how much carbon dioxide has been used or how much water is used measuring how much oxygen is produced or organic molecules (biomass) produced 3.8.7 Explain that the rate of photosynthesis can be measured directly by the production of oxygen or the uptake of carbon dioxide, or indirectly by an increase in biomass. Indirect or direct? 3.8.8 Outline the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis.