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CHARACTERISTICS OF LIVING THINGS & BIOCHEMISTRY Workbook Topic 1 Textbook Chapters 5 & 6 Characteristics of Life Organism: a living thing All organisms have similar life functions Life function: the activities carried out by living things Metabolism: all the chemical reactions that occur within a living thing Homeostasis: the maintenance of a stable internal environment Life Functions 1. Nutrition: obtaining materials from the environment and processing them for use 2. Transport: absorption and movement of materials in an organism 3. Respiration: processes that provide the energy needed for life 4. Excretion: removal of waste products Life Functions, cont’d 5. Synthesis: formation of large molecules from smaller ones 6. Regulation: the control and coordination of an organism’s activities 7. Growth: an increase in size and/or cell number Life Functions, cont’d 8. Reproduction: the production of new individuals to allow the species to survive Tip: If organisms don’t carry out these life functions, they die. If organisms don’t reproduce, their species goes extinct. Matter and Atoms Matter: anything that has mass and takes up space All matter is made up of units called atoms Atoms are the smallest parts of matter Tip: Everything on Earth is made of matter and atoms. Elements and Compounds Elements: different types of atoms ◦ 118 elements ◦ Cannot be broken down into smaller parts The 6 most important elements for organisms: ◦ ◦ ◦ ◦ ◦ ◦ Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N) Phosphorus (P) Sulfur (S) You are 96% carbon, oxygen, hydrogen, and nitrogen Elements and Compounds, cont’d Elements combine with each other to form new substances called compounds Compounds are held together by chemical bonds Examples of compounds: ◦ Water (H2O) is two hydrogen atoms bonded to one oxygen atom ◦ Carbon dioxide (CO2) is one carbon atom bonded to two oxygen atoms Chemical bond H O H Organic Compounds Organic compounds contain carbon Our bodies use organic compounds to: ◦ ◦ ◦ ◦ ◦ 1. make energy 2. build new structures 3. store materials 4. repair existing structures 5. keep all chemical activities working properly These reactions are all part of metabolism Organic Molecules, cont’d Polymers: large organic molecules made by linking smaller parts together Monomers: smaller parts (subunits) of molecules ◦ Monomer + Monomer = Polymer Condensation synthesis: the process of linking monomers together to make polymers Hydrolysis: the process of breaking down polymers into monomers Building blocks Large molecule Carbohydrates Carbohydrates are sugars Made of the elements carbon, hydrogen, and oxygen The functions of carbohydrates are: ◦ 1. to store energy ◦ 2. to provide building materials for the body The monomers of carbohydrates are simple sugars or monosaccharides Examples: glucose and fructose Carbohydrates, cont’d When two simple sugars are linked together, they form a disaccharide Example: glucose + fructose = sucrose ◦ Sucrose is table sugar Lactose, the sugar found in milk, is also a disaccharide Tip: Notice that the sugars’ names all end in –ose. Glucose C6H12O6 CH2OH C O H H H C OH C OH H C C H OH OH Carbohydrates, cont’d When many simple sugars are linked together, they form a polysaccharide Polysaccharides store large amounts of energy Humans use the polysaccharide glycogen Plants use the polysaccharide starch Lipids Fats and oils are lipids Lipids are made of long chains of carbon and hydrogen atoms Lipids store energy more efficiently than carbohydrates do The energy stored in lipids is for longterm use and is not used up quickly ◦ It takes a lot of exercise to burn fat Lipids, cont’d Lipids are made of two different parts: one glycerol molecule and three fatty acid molecules The fatty acids can be very long Tip: Make sure you know the monomers for each type of large polymer. Glycerol 3 Fatty Acids H H H H C C C H O O O O H H H H C C C C C H H H H O H H H H C C C C C H H H H O H H H H C C C C C H H H H H H H Lipids, cont’d There are two types of fats: saturated and unsaturated Saturated fats contain as many hydrogen atoms as they can ◦ Solid at room temperature Unsaturated fats are missing some hydrogen atoms ◦ Liquid at room temperature When a fat is missing many hydrogen atoms, it is polyunsaturated Saturated fat Glycerol O H H H H C C C C C H H H H H Unsaturated fat Glycerol O H C C H C H C C H H Lipids, cont’d Polyunsaturated fats are less likely to cause heart disease than saturated fats Vegetable oils contain polyunsaturated fats; meats and dairy contain saturated fats Lipids, cont’d Steroids are also lipids Made of carbon atoms arranged in a ring Cholesterol is a steroid that is found in food and is also made in the body High levels of cholesterol can lead to hardening of the arteries (atherosclerosis) which can cause heart disease The male hormone testosterone and the female hormone estrogen are also steroids cholesterol testosterone estrogen Proteins Proteins are much more diverse than the other macromolecules No two people except for identical twins have exactly the same proteins Proteins have many functions: ◦ 1. building materials (collagen and elastin) ◦ 2. transport other materials (hemoglobin in the blood) ◦ 3. send signals (insulin and other hormones) ◦ 4. defense against disease (antibodies) ◦ 5. control metabolism (enzymes) Proteins, cont’d Proteins are large polymers made of amino acid monomers There are 20 different amino acids The order of the amino acids determines the protein’s properties Some amino acids are attracted to each other and others are repelled This makes the protein fold up in unique ways Each protein has its own specific shape called its conformation Basic Amino Acid Structure Amine group H O C C Carboxyl group H H N OH R Side chain (different in every amino acid) Nucleic Acids Nucleic acids consist of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) DNA and RNA store genetic information DNA and RNA are made up of many nucleotide monomers linked together Tip: Your DNA is unique, and it is what makes all your proteins unique as well. Nucleic Acids, cont’d Nucleotides consist of a sugar, a phosphate, and a nitrogenous base Phosphate P 5-Carbon sugar Nitrogenous base Nucleic Acids, cont’d The sequence of nucleotides in DNA determines the sequence of nucleotides in RNA The sequence of nucleotides in RNA determines the sequence of amino acids in a protein DNA RNA Protein Enzymes Enzymes: proteins that speed up reactions in organisms Organic catalysts Enzymes work on substances called substrates Substrates are turned into products Enzymes have an area called the active site that matches the shape of the substrate Enzymes are specific for their substrates Enzymes, cont’d The names of enzymes usually end in ―ase and refer to their substrate ◦ Ex: maltase breaks down the disaccharide maltose Lipases break down lipids Proteases break down proteins How Enzymes Work Old model: lock and key model ◦ The active site and substrate are said to fit together just as a key fits in a lock New model: induced-fit model ◦ The active site changes shape slightly to better fit the substrate Tip: The induced fit model is the result of many scientists completing experiments with enzymes. How Enzymes Work, cont’d The substrate fits into the active site of the enzyme to make an enzymesubstrate complex Enzymes change the substrate, but the enzyme itself is not changed The same enzyme can be reused many times 1 2 Enzyme-substrate complex Products 4 3 Enzyme breaks the bond holding the substrate together How Enzymes Work, cont’d An enzyme works by lowering the energy a reaction needs to change a substrate All reactions require a “push” to get started This push is called the activation energy The more activation energy a reaction needs, the slower the reaction Enzymes lower the amount of activation energy needed Activation energy without an enzyme ENERGY Activation energy with an enzyme REACTION Enzymes and Temperature All enzymes have a temperature at which they work best ◦ This is called its optimum temperature Enzymes that function in humans will have optimum temperatures close to normal body temperature (37°C) If the temperature gets too high, the enzyme can denature When an enzyme denatures, its active site loses its shape it cannot do its job Optimum temperature = highest activity ENZYME ACTIVITY Enzyme is denatured TEMPERATURE Enzymes and pH pH is a measure of how acidic or basic a substance is The pH scale ranges from 0 to 14 ◦ 0-6 = acidic ◦ 7 = neutral ◦ 8-14 = basic For most enzymes in humans, the optimum pH is around neutral because most of the body is neutral Enzymes and pH, cont’d Salivary amylase, which breaks down sugars as we chew, works best around pH 7 Pepsin, an enzyme that works in the stomach, has an optimum pH around 2 ◦ The stomach is an acidic environment If the pH becomes too low or too high, the enzyme will denature Salivary amylase Pepsin ENZYME ACTIVITY 0 1 2 3 4 pH 5 6 7 8 9