Metabolism and Energy

Metabolism & Energy

• Metabolism refers to the sum of all chemical reactions within cells.
• Cellular respiration is the process of converting sugars into energy, carbon dioxide, and water.
• Simple sugars are the basic carbohydrates that provide energy.
• Energy-rich molecules obtained from food fuel metabolic processes.
• Calories are units measuring the energy content in food.
• Calorimetry is a method for determining the energy value of food through combustion.
• A bomb calorimeter measures the heat of combustion of food.
• Combustion analysis involves burning food to measure the energy released.
• Temperature rise refers to the increase in water temperature during combustion measurement.
• The heat of combustion is the total energy released when food is completely burned.
• The formula q = mcΔT is used to calculate heat energy transfer.
• Energy value calculation determines the energy content per gram of food.
• Water mass is the mass of water used in calorimetry experiments.
• Temperature change is the difference in temperature before and after combustion.
• Energy content is the amount of energy provided by food per serving.
• Digestion converts food into simple sugars.
• A healthy lifestyle involves maintaining well-being through balanced energy intake.
• Food packaging provides energy information for food items.
• Joules are units of energy, equivalent to calories.
• kJ g-1 represents kilojoules per gram, a measure of energy density.
• All organisms need energy for survival
• Autotrophs produce their own food.
• Heterotrophs consume others for energy.
• Photoautotrophs convert light energy into glucose via photosynthesis.
• Chemoautotrophs extract energy from inorganic compounds.
• The overall equation for cellular respiration is C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP.
• Active transport is the movement of molecules against a concentration gradient, requiring energy.
• ATP breakdown releases energy for cellular activities.

Water Properties & Importance

• A polar molecule has partial positive and negative charges.
• A covalent bond is formed by sharing electron pairs.
• Electronegativity is the tendency of an atom to attract electrons.
• Hydrogen bonding occurs between polar molecules due to hydrogen.
• Water has a high specific heat, absorbing heat without significant temperature change.
• Thermal stability is the ability to maintain a stable temperature in organisms.
• Evaporation cooling results from water changing to vapor.
• Water is considered a universal solvent due to its ability to dissolve many substances.
• Hydrophilic substances dissolve easily in water, while hydrophobic substances do not.
• Water acts as a transport medium for substances in organisms.
• Biochemical reactions essential for life occur in water.
• Adhesive forces are the attraction between liquid molecules and their container.
• Capillary action is the rising of a liquid in a tube due to adhesion and cohesion.
• Cohesive forces are the attraction between molecules within a liquid.
• Surface tension is the resistance of a liquid to increase its surface area.
• The skin effect refers to the surface of water supporting small organisms.
• Water is densest at 4°C.
• Ice floats because it has a lower density than liquid water.
• Water provides habitat stability for organisms.
• The transparency of water allows light to penetrate for photosynthesis.
• Photosynthesis can occur underwater due to water's transparency.
• Different wavelengths of light penetrate water differently.
• Biological reactions necessary for life occur in aqueous environments.
• Thermal properties refer to water's ability to moderate temperature changes.
• Polarity of water is due to the unequal distribution of charge in water molecules.

Metabolic Pathways & Enzymes

• Metabolism is the network of all biochemical reactions in life.
• Metabolic pathways are enzyme-catalyzed reactions maintaining cellular functions.
• Enzymes are proteins that speed up chemical reactions.
• Activation energy is the energy required to initiate a chemical reaction.
• Exothermic reactions release more energy than required.
• The active site is the region on an enzyme where substrates bind.
• An enzyme-substrate complex forms when a substrate binds to an enzyme's active site.
• The induced-fit model describes how substrate binding induces a change in an enzyme's active site.
• Optimal temperature is the temperature at which enzyme activity is maximized.
• Denaturation is the loss of enzyme function due to structural changes.
• pH affects enzyme activity through charge interactions.
• Higher substrate concentration increases reaction rate until saturation.
• Enzyme inhibitors reduce or prevent enzyme activity.
• Competitive inhibitors have a similar structure to the substrate and compete for the active site.
• Non-competitive inhibitors bind elsewhere, altering the enzyme's shape and function.
• End-product inhibition regulates using the pathway's end product to inhibit enzymes.
• Allosteric enzymes are affected by non-competitive end-product inhibitors.
• An allosteric inhibitor binds to the allosteric site, affecting enzyme activity.
• Negative feedback occurs when the accumulation of the end product reduces further production.
• The conversion of threonine to isoleucine is an example of end-product inhibition in metabolic pathways.
• Collision theory states that reactions depend on collisions between molecules.
• High temperatures cause enzyme structural breakdown, leading to denaturation.
• Low temperatures slow molecular movement, reducing enzymatic reactions.
• Different enzymes have unique optimal pH levels.
• Substrate saturation is the point where increasing substrate concentration no longer affects reaction rate.
• Enzymes are specific to their substrates.
• Metabolic control regulates pathways to prevent overproduction.
• Biological reactions release energy through exothermic processes.
• Enzymes have a specific shape for substrate binding.
• The frequency of molecular collisions affects reaction rates.
• Temperature, pH, and substrate concentration influence enzyme activity.
• Enzymes control glucose breakdown in respiration.

Carbohydrates

• Carbohydrates are organic molecules commonly referred to as sugars.
• The general formula of carbohydrates is Cx(H2O)y.
• Monosaccharides are the simplest form of carbohydrates.
• Monosaccharides contain a carbonyl group and at least two hydroxyl groups.
• The empirical formula of monosaccharides is CH2O.
• Examples of monosaccharides include glucose, fructose, and galactose.
• Hexose sugars contain six carbon atoms.
• Hexose sugars have low molar mass, are sweet, soluble in water, and have a crystalline structure.
• Monosaccharides with aldehyde groups are called reducing sugars.
• The molecular formula of hexose sugars is C6H12O6.
• Monosaccharides adopt a ring structure in aqueous solution.
• Two ring structure isomers of glucose are α-glucose and β-glucose.
• Monosaccharides undergo condensation reactions to form disaccharides and polysaccharides.
• A glycosidic link is the bond formed between hydroxide groups on adjacent monosaccharides during condensation.
• Disaccharides are composed of two monosaccharides joined together and are soluble molecules.
• Disaccharides can be broken down into their component monosaccharides through acid hydrolysis or enzyme catalyzed reactions.
• Common disaccharides include lactose, maltose, and sucrose.
• Lactose is composed of β-galactose + β-glucose and is found in milk.
• Maltose is composed of α-glucose + α-glucose and is found in cereal, pasta, beer, potatoes and processed foods that have been sweetened.
• Sucrose is composed of α-glucose + β-fructose and is commonly known as cane sugar.
• Polysaccharides are long chains of monosaccharides held together by glycosidic bonds.
• Polysaccharides have large molar mass, are not sweet, are insoluble or slightly soluble in water and are non-reducing.
• Starch, glycogen, and cellulose are glucose-based polysaccharides.
• Starch is a polymer of α-glucose and the main form of carbohydrate storage in plants, existing in amylose (straight chain) and amylopectin (branched) forms.
• Glycogen is a polymer of α-glucose and the main form of carbohydrate storage in animals.
• Cellulose is a polymer of β-glucose and the structural material in the cell walls of plants.
• Dietary fibre consists of substances that pass through the digestive system intact, and are helpful in preventing conditions such as constipation
• A linear polymer with 1-4 β-glycosidic linkages forming an uncoiled structure is cellulose.
• The main form of carbohydrate storage in animals is glycogen.
• The main form of carbohydrate storage in plants is starch.

Proteins

• Proteins contain nitrogen, carbon, hydrogen, and oxygen and are responsible for most of the chemical functions that take place in the cells of the body.
• Keratin is a structural protein forming the protective covering in hair and fingernails.
• Collagen is a structural protein composing connective tissue in skin and tendons.
• Myosin is a structural protein responsible for contractile action in muscles.
• Lactase is an enzyme that hydrolyzes lactose into glucose and galactose.
• Insulin is a hormone that controls and maintains glucose levels in the blood.
• Immunoproteins are protective proteins that act as antibodies.
• Hemoglobin is a transport protein that carries oxygen in red blood cells.
• Casein is a storage protein found in milk
• Proteins are polymers of amino acids.
• An amino acid contains an amine functional group at one end and a carboxylic acid functional group at the other end.
• There are 20 naturally occurring amino acids.
• Amino acids can act as both an acid and a base.
• The central carbon in naturally occurring amino acids is the α-carbon.
• Most amino acids contain one acid group and one alkaline group are 'neutral'.
• Some amino acids contain side chains (R groups) that contain -NH2 groups which makes them basic amino acids.
• Others contain -COOH in their side chains which makes them acidic amino acids.
• Amino acids are colourless, crystalline solids with relatively high melting points for organic compounds, and are generally soluble in water but not in organic solvents.
• With 2-amino acids, when R ≠ H, the 2-carbon atom gives rise to optical isomerism.
• Amino acids exist as zwitterions and are amphoteric in nature in the crystalline state and in aqueous solution.
• Their amphoteric nature makes it possible for amino acids to act as buffers in aqueous solution.
• A dipeptide is a substituted amide made up of two amino acids joined by a peptide bond or peptide linkage.
• A polypeptide contains many peptide bonds.
• A polypeptide undergoes folding, and becomes a protein.
• Amino acids undergo condensation reactions to form substituted amides in the presence of enzymes.
• Protein conformation refers to the three-dimensional shape of a functional protein.
• A polypeptide chain is a sequence of amino acids linked by peptide bonds.
• The four levels of protein structure are primary, secondary, tertiary, and quaternary structures.
• Primary structure is the unique sequence of amino acids in a protein.
• Sickle-cell disease is a disorder caused by a single amino acid substitution.
• Secondary structure involves coiled or folded segments of polypeptide chains.
• Hydrogen bonds stabilize secondary structures.
• An alpha helix is a coiled secondary structure held by hydrogen bonds.
• A pleated sheet is a folding pattern with parallel regions in proteins.
• Tertiary structure is the irregular folding due to side chain interactions.
• Nonpolar side chains cluster away from water, leading to hydrophobic interactions.
• Disulfide bridges are covalent bonds between cysteine monomers in proteins.
• Attractions between positively and negatively charged side chains are ionic bonds.
• Quaternary structure involves the aggregation of multiple polypeptide chains into a protein.
• Collagen is a fibrous protein with a triple helix structure.
• Hemoglobin is a globular protein with four polypeptide subunits.
• Chemical bonds are forces that stabilize protein structures.
• R-groups are side chains of amino acids influencing protein shape.
• Molecular forces such as; Hydrogen bonds, Disulphide Bridges, Van der Waals
• A peptide bond is the covalent bond linking amino acids in a chain.
• A functional protein is an active protein with a specific three-dimensional conformation.
• A macromolecule is a large complex molecule, such as proteins.
• Electronegativity is the tendency of atoms to attract electrons.
• Cysteine is an amino acid with a sulfhydryl group.
• A polypeptide backbone is the main chain of amino acids in a protein.

Amino Acid Composition

• Amino acid composition is determined via chromatography and electrophoresis methods.
• Peptide bonds must undergo acid hydrolysis for analysis.
• Acid hydrolysis involves using 6 mol dm-3 HCl at 110°C for 1-3 days.
• High performance liquid chromatography identifies and quantifies amino acids post-hydrolysis.
• Paper chromatography separates amino acids based on solubility differences.
• The stationary phase in paper chromatography is the water in the paper.
• The mobile phase in paper chromatography is the eluting solvent, typically 1-butanol and ethanoic acid.
• Capillary action is the rising of the solvent which carries amino acids through the paper.
• The solvent front marks the solvent's highest point on paper during paper chromatography.
• Ninhydrin spray reacts with amino acids to reveal purple spots post chromatography.
• Electrophoresis separates molecules by electric charge and size.
• Acidic and basic groups in amino acids create charges, which are measured via electrophoresis.
• The isoelectric point (pHi) is the pH where an amino acid has no net charge.
• A buffered solution maintains pH during the electrophoresis process.
• Charged amino acids move towards respective electrodes during electrophoresis.
• Amino acids move towards the cathode in low pH due to a positive charge during electrophoresis.
• Amino acids move towards the anode in high pH due to a negative charge during electrophoresis.
• The zwitterionic form is the neutral state of an amino acid at its pHi.
• Sample spotting involves placing a tiny amino acid mixture at the origin on the paper during testing.
• Differences in solubility and the forces of charge cause separation of components.

Lipids

• Lipids are organic compounds that contain carbon, hydrogen, and oxygen.
• Lipids do not dissolve in water (insoluble).
• Lipids dissolve in polar substances (Soluble in Polar Solvents)
• Triglycerides are the main component of fats and oils.
• Glycerol is a three-carbon molecule with alcohol groups.
• Fatty acids are long chain carboxylic acids.
• Esterification reaction forms an ester link between fatty acids and glycerol.
• Saturated fatty acids contain no double bonds, and are solid at room temperature. Monounsaturated Fatty Acids has One double bond in the carbon chain. Polyunsaturated Fatty Acids has More than one double bond in the carbon chain.
• Saturated fats have higher Melting Points.
• Unsaturated fatty acids are Liquid at room temperature, and derived from plants.
• Essential Fatty Acids Cannot be synthesized, must be obtained from diet.
• Linoleic Acid, is a Omega-6 fatty acid which is essential .
• Linolenic Acid, is a Omega-3 fatty acid which is essential .
• Production of Prostaglandin is aided in by Essential fatty acids.
• Hydrolysis Process is Breaking down fats into fatty acids and glycerol.
• Lipases are enzymes that digest fats and oils.
• Steroids Lipids with a four fused ring structure.
• Cholesterol is a Important steroid for hormone synthesis.
• Lipids are transported through the body via :
• LDL (Low-density lipoprotein, transports cholesterol in bloot) HDL (High-density lipoprotein, helps remove cholesterol)
• Phospholipids are Lipids with two fatty acids and a phosphate group.
• Lecithin is a Common phospholipid found in cell membranes.
• Water-attracting part of phospholipids is called Hydrophilic Head
• Water-repelling part of phospholipids is called Hydrophobic Tail
• Phospholipid Bilayer Structure forming cell membranes.
• Stored Energy which is Energy releases from Lipids stores more energy than carbohydrates. Stored lipids release twice as much energy as carbohydrates.
• Adipose Tissue cells provide insulation and protection whilst also storing fat.
• Hydrogenation ,Process modifying fats to increase melting point.
• Byproduct of Hydrogenation causes Trans Fats which is a health risk.
• Atherosclerosis Atherosclerosis ,Lipid deposits in blood vessels causing health issues.
• Obesity excessive lipid storage linked to various diseases.
• Fat-Soluble Vitamins ( Vitamins A, D, E, and K that are absorbed with lipids)
• Bile Salts , Steroid-based compounds aiding fat digestion.
• hydrogenation alters from Cis to trans structure.