D1.1 - The Molecules of Living Systems (Updated 2024) PDF

D1.1 - The Molecules of Living Systems I can… Describe the chemical nature of carbohydrates, lipids, proteins and their enzymes Explain enzyme action and factors influencing their action Macromolecules Macromolecules: Large, complex organic (based on living things) molecules The ma...

D1.1 - The Molecules of Living Systems I can… Describe the chemical nature of carbohydrates, lipids, proteins and their enzymes Explain enzyme action and factors influencing their action Macromolecules Macromolecules: Large, complex organic (based on living things) molecules The majority of compounds we obtain from food fall into three categories of macromolecules: ○ Carbohydrates ○ Lipids ○ Proteins Created from smaller subunits Macromolecules Assembled through dehydration synthesis Broken down through hydrolysis (water breaking up) reactions Carbohydrates The main role of carbohydrates is to provide energy for the body We are unable to synthesize them ourselves (unlike plants), so we must obtain them from our food Carbohydrates are found in all plant-based foods (e.g. fruits, vegetables, and grains) Carbohydrates Contain carbon, oxygen, and hydrogen Two atoms of hydrogen and one atom of oxygen for every carbon Can be classified as: 1. Monosaccharides 2. Disaccharides 3. Polysaccharides Carbohydrates Monosaccharide: Carbohydrate molecule with 3-7 carbon atoms Ex. Fructose, glucose, galactose Carbohydrates Disaccharide: Double sugar (made up of two simple sugars) Saccharide means “simple sugars” Disaccharides are produced from dehydration synthesis, which involves the loss of a hydroxide (OH-) ion from one monomer and hydrogen ion from another in order to form a bond Ex. Sucrose, maltose, lactose Carbohydrates Polysaccharides: Long chains of simple sugars (more than two sugar units) Ex. Starch and cellulose Cellulose is more difficult for our bodies to break down than simple sugars; offer little energy as a result, but are a good source of fibre Carbohydrates Animals store carbohydrates in the form of a polysaccharide (glycogen) Cellulose: Plant walls are comprised of this polysaccharide Over 50% of the organic carbon in the biosphere is tied up as cellulose (in the form of starch) Practice Questions 1. What is the primary function of carbohydrates? 2. Name 3 simple sugars and indicate where you would expect to find these sugars. 3. What happens to carbohydrates that are not immediately used by your body? Why might you want to limit your carbohydrate intake? 4. How are starch and cellulose alike? How do they differ? Lipids Lipids: Consist of glycerol (3-carbon chain) and fatty acids, whose composition may vary Fat: A lipid composed of glycerol and saturated fatty acids ○ Solid at room temperature Oil: a lipid composed of glycerol and unsaturated fatty acids ○ Liquid at room temperature Insoluble in water Lipids are found in foods which contain animal-based fats and plant-based oils. Lipids Function as long term energy storage molecules Other lipids (phospholipids) form membranes that separate cells from its internal environment Some lipids help carry vitamins, are steroids, and play a role in hormone synthesis Lipids Differences in bonding between carbon atoms: Saturated fatty acids: Don’t have double bonds between any of the carbon atoms, only single bonds ○ Have maximum number of hydrogen atoms bonded to them *molecule can stack* ○ Solid at room temperature and remains solid (Ex. butter) Unsaturated fatty acids: Have double bonds between some of the carbon atoms ○ Have less than the maximum number of hydrogen atoms bonded to them *molecule can’t stack* ○ Liquid at room temperature (Ex. oil) Hydrogenation Hydrogenation is used to convert unsaturated fats into saturated fats This involves the breaking of double bonds and addition of hydrogen Practice Questions 1. What are fats? What are the 2 structural components of fats? 2. How do saturated fats differ from unsaturated fats? 3. Are fats essential to your diet? Explain your answer. Proteins Proteins: Formed by tiny amino acid molecules that are bonded together in long chains ○ Individual amino acids are bonded together by a peptide bond Proteins do NOT provide energy for our cells They play many other important roles in our bodies, including forming the structural components of cells, repairing damage to cells, speeding up chemical reactions (enzymes), and helping defend against disease (antibodies) Protein Synthesis There are just 20 amino acids which comprise all proteins 8 of these must be obtained through eating (our body is able to synthesize the rest) Proteins are found in meat, eggs, dairy products, and even some plants (ex. legumes) Examples of Proteins Protein Shapes Structure is due to attraction and repulsion between amino acids and electrically charged R-groups Charged R-groups attract water ○ End up on the outside of the final protein (Ex. enzymes, hemoglobins) ○ Soluble in water Uncharged R-groups are repelled by water ○ End up on inside of final protein (Ex. keratin in fingernail) ○ Insoluble in water Protein Shapes Macromolecules of Life Macromolecules Examples of Main function Examples of subunits macromolecules Carbohydrates Sugars (glucose) & Energy storage Starches, sugars, polymers of glucose glycogen Lipids Glycerol & 3 fatty Energy storage and Fats, oils, and acids OR glycerol & cell membranes phospholipids 2 fatty acids Proteins Polymers of amino Transport, blood Hemoglobin, fibrin, acids clotting, support, collagen, antibodies, immunity, catalyst, enzymes, actin, and muscle action myosin Nucleic acids Polymers of Transfer and DNA and RNA nucleotides expression of genetic info Vitamins Vitamins: Are organic compounds that often help enzymes function ○ Organic compounds are made up of mostly C, H, O Small amounts of needed by body for tissue development, growth, and resistance to disease ○ Ex. Sun (Vitamin D), milk (Vitamin B12) Minerals Minerals are inorganic compounds Small amounts needed by the body Absorbed into bloodstream Help build bones and cartilage (Ex. potassium in bananas) Also help some chemical reactions to occur Ex. Essential molecules such as hemoglobin, hormones, enzymes, and vitamins Enzyme Terminology Enzyme: A protein catalyst that permits chemical reactions to process at low temperatures Catalyst: A chemical that increases the rate of chemical reactions without altering the products or being altered itself Substrate: A molecule on which an enzyme works Active site: the area of an enzyme that combines with the substrate Cofactor: An inorganic ion that helps an enzyme combine with a substrate molecule Coenzyme: An organic molecule synthesized from a vitamin that helps an enzyme to combine with a substrate molecule Enzymes Enzymes are a biological catalyst made of proteins They increase rates of reaction by reducing the amount of energy required to start a reaction ○ The enzyme is not used up in the reaction Name of enzyme tells you which molecule the enzyme targets ○ Ex. “Lactase” targets lactose; “sucrase” targets sucrose Enzymes Two types of models: 1. Lock and key: Enzyme and substrate fit perfectly together 2. Induced fit: Enzyme changes/molds to fit substrate, then goes back to its original shape Enzymes Factors that affect enzymes 1. Temperature: Functions best within optimal temperature range (range is narrow for most human enzymes) 2. pH: Functions best within optimal pH range (human enzymes - pH: 6-8); stomach enzymes are in an acidic environment 3. Substrate concentration: An enzyme can only catalyze a reaction if the appropriate substrate (the substance on which an enzyme acts) binds to its active site (receptor). So, if substrate concentration increases, enzyme activity also increases. Inhibitors Inhibitors: Molecules that attach to the enzyme and reduce its ability to bond to a substrate Two classes: ○ Competitive: Competes with the substrate for active site, therefore blocking substrate from binding Is often the end product of enzymatic reaction As more product is created and binds to the active site, enzyme activity is inhibited ○ Non-competitive: Changes shape of enzyme by bonding to it, but not at the active site However, it changes the shape of the active site, therefore inhibiting enzyme activity Practice Questions 1. Explain the importance of enzymes in metabolic reactions. 2. How do cofactors and coenzymes work? 3. How do enzymes increase the rate of reactions? Summary 1. Carbohydrates are molecules that contain hydrogen, carbon, and oxygen. Carbohydrates are the preferred source of energy for cells. 2. Lipids are compounds formed from glycerol and fatty acids. Lipids are energy-storage compounds. 3. Proteins are molecules constructed of amino acids. Proteins are the structural components of cells. 4. Chemical reactions within cells are regulated by enzymes. Enzymes are protein catalysts that lower activation energy and permit chemical reactions to process at body temperature.