Biology 20: Enzymes, Nutrients, Digestion Study Guide

• Biology 20: Enzymes, Nutrients and Digestion is covered in this study guide

Enzymes and Catalysts

• Catalysts are chemicals that increase the rate of chemical reactions.
• Catalysts allow reactions to occur at lower temperatures and/or energy.
• Catalysts are not used up in the process.
• Catalysts provide an alternate reaction pathway.
• Catalysts decrease the energy required for a reaction to take place.
• Enzymes are protein catalysts found within living organisms.
• Enzymes have an active site, or area where the substrate binds to the enzyme.
• The substrate is the substance being reacted on.
• Sucrose, a substrate consisting of glucose and fructose molecules bonded together, binds to the enzyme.
• This forms an enzyme-substrate complex.
• The binding of the substrate and enzyme places stress on the glucose-fructose bond, causing it to break.
• Products, glucose and fructose, are released, and the enzyme is then free to bind other substrates.

Factors Affecting Enzyme Reactions

• Specific enzymes function best within a specific range of pH.
• Enzymes in the blood function best at a pH of 7.2-7.4.
• Enzymes in the stomach function best at a pH of 1.0-2.0
• Enzymes denature if the pH is too low or high
• Denaturing destroys the characteristic properties of a protein or other biological macromolecule.
• Denaturing is caused by heat, acidity, or other effects that disrupt its molecular conformation.
• Increasing the substrate concentration increases enzyme activity until all of the active sites are occupied up to saturation point.
• Increased temperatures increase enzyme activity until the enzyme begins to denature.
• Very high temperatures break down proteins, rendering the enzymes ineffective. molecules have a shape similar to the
• Competitive inhibitors bind to the active site of an enzyme, preventing the desired reaction.
• Carbon monoxide is a competitive inhibitor to the binding of oxygen on red blood cells.
• Feedback inhibition is the inhibition of an enzyme by the final product in the metabolic pathway.
• Metabolism has three main purposes
  • The conversion of food/fuel to energy to run cellular processes
  • The conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates
  • The elimination of nitrogenous wastes
• Co-factors are inorganic ions that help enzymes combine with substrate molecules and come from mineral supplements.
  • Ex. iron helps oxygen bind to hemoglobin
• Coenzymes are organic molecules that help enzymes combine with substrate molecules and come from vitamins.

Nutrients

• Good nutrition is required for a healthy and disease-resistant human body.
• All living things are made of chemicals.
• Specific chemicals must be acquired from the food we eat to grow, develop, and maintain bodily structures and functions.
• Nutrients are divided into the following categories:
  • Carbohydrates
  • Lipids
  • Proteins
  • Vitamins
  • Minerals
  • Nucleic Acids

Carbohydrates

• Carbohydrates are sugar-based molecules that are metabolized for energy.
• Carbohydrates make up the structural components of plant cell walls.

Lipids

• Lipids are fat-based molecules that store large quantities of energy.
• Lipids make up the structure of cell membranes.

Proteins

• Proteins are polypeptide molecules that can store energy.
• Proteins provide the structural building blocks for cells and make enzymes.

Vitamins

• Vitamins are organic molecules that help mediate enzyme action by promoting the binding of an enzyme to a substrate.
• Vitamins are also called coenzymes.

Minerals

• Minerals are inorganic molecules that mediate enzyme activities by promoting the binding of an enzyme to a substrate.
• Minerals are also called cofactors.

Nucleic Acids

• Nucleic acids are what make up DNA, RNA and ATP.
• Polymers are compounds made up of two or more subunits, often joined by dehydration synthesis.
• Monomers are compounds made up of single subunits, which can be produced by the hydrolysis of polymers.
• Carbohydrates are either single unit sugar molecules called monosaccharides, two unit sugar molecules called disaccharides, or multiple unit sugar molecules called polysaccharides.
• All sugar molecules are made up of subunits with either a 6-ring (hexose) or a 5-ring (pentose) base structure.
• Monosaccharides are simple single sugars compounds composed of 5 unit monomers (pentoses) or 6 unit polymers (hexoses).
• Disaccharides and polysaccharides are created from monomers by a process called dehydration synthesis or dehydrolysis.
• During this process, water molecules are removed, and a saccharide bond is formed.
• Polysaccharides are complex carbohydrates such as glycogen, starch or cellulose.
• Benedicts test detects reducing sugars (all monosaccharides and some disaccharides).
• Benedicts reagent turns from blue to orange/red when reducing sugars are present.
• Starch test detects the presence of complex carbohydrates or starch.
• Iodine is added and creates a blue-black iodine starch complex.
• Lipids are non-polar, water insoluble, high-energy molecules composed of glycerol and fatty acids.
• Lipids combine by dehydration synthesis.
• Saturated fatty acid molecules have no double bonds in the carbon chain.
• Saturated molecules have as many hydrogen atoms as they can hold.
• Saturated fats are solid at room temperature and relatively unreactive.
• Unsaturated fatty acid molecules have one or more double bonds in the carbon chain.
• Additional hydrogen atoms can be added to unsaturated molecules through hydrogenation.
• Unsaturated fats are liquid at room temperature and are more reactive.
• Translucence test: lipids cause unglazed brown paper to become translucent and Non-lipids do not.
• Sudan IV test: lipids dissolve in the sudan IV indicator turning it from a black granular form to a pink or red paste.
• Proteins are polymers made up of combinations of 20 different amino acid subunits joined together by dehydration synthesis.
• Amino acids are held together by peptide bonds.
• Proteins form structural components of cells and enzymes, and they store useful energy.
• All amino acids have a basic amino group and a carboxylic acid.
• Different amino acids have different R groups or side chains. There are 20 different amino acids in total.
• Proteins are formed from long chains of amino acids that are joined together by peptide bonds.
• These bonds form from a dehydration synthesis reaction.
• Hydrogen bonds cause proteins to fold into pleated sheets, or coil into helixes.
• Further folding of a polypeptide creates a larger globular structure, like hemoglobin.
• Quaternary structure proteins are large globular ones formed from two or more interacting polypeptides.
• When the blue biuret reagent is added to proteins, the peptide bonds turn the biuret reagent a purple color which is the Biuret Test.
• When exposed to excessive heat, radiation or changes in pH, the hydrogen bonds that hold proteins together break down, disrupting the configuration of the protein.
• This process is called protein denaturation.
• When the change is irreversible, the process is called coagulation.
• Boiling an egg or cooking meat is an example of protein coagulation.
• Anemia results from a diet too low in iron, can result in low blood oxygen levels which can cause low energy and tiredness.
• Anemia is often more common in females because of menstruation.
• Anemia also can be caused by diets low in iron like potentially vegetarian or vegan diets
• Foods that are iron rich include dark leafy greens such as spinach, and red meats.
• Vitamin C deficiency can lead to scurvy
• Symptoms of scurvy include rashes, loose teeth, low energy, painful joints/muscles, and loss of appetite
• Foods with high vitamin C content include citrus fruits.
• High fat diets can lead to high cholesterol, plaques forming in the blood vessels.
• High fat diets increase the risk of atherosclerosis which is the hardening of blood vessels (like arteries and veins).
• Hardening of blood vessels leads to high blood pressure, heart disease and heart attack.
• Diets high in processed food and meat are therefore risky.
• Diets high in refined sugars can potentially lead to excessive weight gain as the body converts excess sugar to glycogen and fats.
• High sugar diets puts people at risk of developing type II diabetes;
  • Type II diabetes is when insulin (a hormone produced and released by the pancreas to help lower blood sugar) is not function properly
  • Not enough insulin is being produce to accommodate the high sugar diet.