Enzymes

• Enzymes are important to a living cell as they increase the speed of chemical reactions without being used up in the process.
• Enzymes are large proteins made up of long chains of amino acids that can fold up to form different shapes, each unique enzyme catalyzing a particular chemical reaction.
• Enzymes have a special region called an active site which is a part of the enzyme with a unique shape that's complementary to the substrates of the reaction.
• If the substrate doesn't fit the active site of the enzyme, the reaction won't be catalyzed, allowing the enzymes to be specific about which reactions they speed up.
• The original lock and key model of enzyme action suggested that the substrate had to fit perfectly into the active site like a key into a lock.
• The more realistic induced fit model of enzyme action suggests that the enzyme changes shape slightly as it binds to the substrate, allowing them to fit together more perfectly.
• The rate of an enzyme-controlled reaction changes with temperature, increasing as the temperature increases due to more kinetic energy in the particles, and dropping after about 37 degrees as the high temperatures start to break some of the bonds holding the enzymes together and change the shape of the active site.
• The optimum temperature is the temperature at which the rate of reaction is highest, which for most enzymes is 37 degrees.
• All enzymes have an optimal temperature, but different enzymes have different optimal temperatures.
• The rate of reaction can be affected by pH, which is a measure of acidity, as seen in the graph where the rate of reaction drops if the pH gets too high or too low due to some of the bonds holding the enzyme together breaking and the active site changing shape.
• The pH at which the enzyme works best is called its optimal pH and it depends on where the enzyme normally works, for example, most enzymes in our body work best at neutral pHs of around seven, while those that work in the stomach, like pepsin, have an optimal pH of around two because they need to be able to function in the stomach's acidic environment.
• Carbohydrates are found most in starchy foods like bread, pasta, and potatoes, as well as in fruits and vegetables.
• The main reason we need carbohydrates is as an energy source, providing us with most of the energy we need to carry out chemical reactions and move around.
• Lipids, also known as fats, are found in oily fish, nuts, and seeds, dairy products, and avocados.
• The main role of lipids is to provide energy, but they also act as a longer-term store of energy because we can store lots of fat for use later.
• Lipids also do other useful things like keeping us warm by insulating us and protecting our organs.
• Proteins are found in nuts, seeds, meat, and fish, as well as in legumes like lentils and beans.
• Proteins can be thought of as building blocks, as we need them to grow and to repair damaged tissue.
• Proteins can also be used for energy, but only really in emergencies if we don't have enough carbohydrates or lipids.
• Vitamins are organic molecules, made by living organisms, and are needed in very small amounts.
• Vitamin A can be gained from foods like liver or leafy vegetables and is needed for good vision and to keep the skin and hair healthy.
• Vitamin C can be obtained from fruit and vegetables, particularly citrus fruits like oranges, and is needed to prevent scurvy.
• Vitamin D can be produced by the body itself using sunlight, but can also be obtained in foods like eggs and oily fish, and its main purpose is to help you absorb calcium.
• Calcium is a mineral found in dairy products like milk and leafy vegetables, and is needed for strong bones.
• Iron is a component of hemoglobin which helps red blood cells transport oxygen around the body, and if you don't get enough iron, you can develop a condition called anemia where you can't transport as much oxygen to your tissues anymore.
• Fiber is a type of carbohydrate that is not absorbed into the body, and is found in wholemeal foods like wholemeal bread and brown rice as well as in fruits and vegetables, helping food move through the intestines properly.
• Water is normal water that we get from our drinks and also from most foods, and is needed for various bodily functions including chemical reactions, with most of our body being made of water and continuously losing water by breathing, sweating, and urinating, necessitating constant replacement.
• Minerals are inorganic molecules, not made by living organisms, and are also needed in very small amounts.
• Enzymes play a crucial role in digestion by breaking down the large molecules we eat into smaller soluble molecules that can be absorbed through our intestinal lining.
• The three main groups of nutrients that need to be broken down are carbohydrates, proteins, and fats.
• Carbohydrates are found mainly in foods like pasta, potatoes, and rice, and our body uses them mainly as an energy source.
• The main type of carbohydrate is starch, which is broken down by an enzyme called amylase into smaller sugars such as maltose.
• Amylase is made in three different places: the salivary glands of the mouth, the pancreas, and the small intestine.
• Amylase is an enzyme that breaks down starches, which are found in foods like nuts, meats, and beans.
• Protease enzymes break down proteins into amino acids.
• Protease enzymes are made in the stomach, where they are called peptin.
• Amylase enzymes are also made in the stomach.
• Proteases are also made in the pancreas and the small intestine.
• Fats, also known as lipids, are found in foods like cheese, oils, and chocolate, and they are broken down by lipases into both glitteral and fatty acids.
• Lipase enzymes are only produced in the pancreas and small intestine.