Biology - Glucose Breakdown and Amino Acids

Glucose Breakdown

• Slow breakdown releases energy slowly, provides more control, is not destructive, and can be used effectively.
• Slow breakdown allows for energy to be stored when not needed, making it more efficient.
• Fast breakdown releases energy quickly, provides less control, is destructive, and cannot be utilized effectively.
• Fast breakdown results in energy loss as heat and light.

Pyruvate Acid Pathways

• Pyruvate acid can be broken down into lactic acid in human connective tissues through anaerobic respiration in the cytosol.
• Pyruvate acid can be broken down into ethanol through anaerobic respiration in the cytosol.

Amino Acids

• Amino acids are monomers that make up proteins.
• Amino acids consist of an amino group, a carboxylic acid group, and an R-side chain.
• The R-side chain determines the properties and appearance of the amino acid.
• Nonpolar amino acids are hydrophobic because there is little to no polarity in their R-side chain.
• Polar amino acids are hydrophilic because they are more soluble in water and can form hydrogen bonds.
• Acidic amino acids have a pH of 7.0.
• Hydrophobic interactions contribute to the stability of protein structures.

Protein Structure

• Disulphide bonds stabilize the tertiary and quaternary structures of proteins.
• The primary structure of a protein refers to the sequence of amino acids, as determined only by peptide bonds.
• Secondary structure refers to the local folded structures within a protein chain due to interactions between backbone atoms.
• Secondary structure is shaped by interactions between NH2 and -COOH groups, such as alpha-helices and beta-pleated sheets.
• Tertiary structure is formed from interactions between secondary structures to form a 3D structure.
• Tertiary structure involves the interactions of amino acids within a single polypeptide chain; amino acids share the same atomic composition but have different chemical group arrangements.

Enzyme Activity

• Ligases are a type of enzyme that catalyzes the formation of bonds using ATP cleavage (ATP hydrolysis).
• The active site of an enzyme is where the substrate binds.
• The active site is formed as a result of protein folding involving secondary, tertiary, and quaternary structures.
• The lock and key hypothesis states that a substrate fits precisely into the active site of an enzyme.
• The induced fit hypothesis states that the substrate and active site change shape slightly during binding.

Glycogen

• Glycogen is a highly branched carbohydrate polymer.
• Glycogen is less soluble in water than glucose, as it is a larger molecule, and therefore cannot diffuse easily.
• Alpha- 1,4-glycosidic bonds connect linear alpha-glucose molecules.
• Alpha-1,6-glycosidic bonds connect branched alpha-glucose molecules.
• Branching in glycogen increases the rate of glucose release.
• Branching creates more non-reducing ends, which serve as active sites for enzyme activity, resulting in faster glucose release.

Reducing vs Non-Reducing Ends

• Reducing ends have a free carbon number 1 with no branching; they cannot be used for rapid release of glucose.
• Non-reducing ends do not have a free carbon-1; they have branching and can be used for rapid release of glucose.

ATP

• ATP is an unstable molecule that dissolves quickly in water.
• ATP breakdown releases energy into the environment, forming ADP + Pi.
• ATP must be constantly regenerated through cellular respiration.
• ATP is not ideal for long-term storage of energy.

High Carbohydrate Diets

• High carbohydrate diets result in high amounts of glucose during digestion.
• Starch is broken down to glucose during digestion.

Glucose Breakdown

• Glucose breakdown involves many steps because slow breakdown provides more control and prevents destructive energy release.
• Fast breakdown leads to less control and results in energy loss as heat/light.

Pathways of Metabolism of Pyruvate Acid

• Lactic Acid: Produced in humans under anaerobic conditions.
• Ethanol: Produced under anaerobic conditions in the cytosol/cytoplasm of certain organisms.

Metabolism

• Anabolism: Reactions that build up substances.
• Catabolism: Reactions that break down substances.
• Aerobic: Reactions that require oxygen.
• Anaerobic: Reactions that do not require oxygen.
• Substrate: A molecule that an enzyme reacts with.
• Enzyme: Proteins that speed up metabolic or chemical reactions in the body.
• Product: Anything produced after a reaction takes place.
• NADH: Reduced Nicotinamide Adenine Dinucleotide; NAD+ is oxidized to NADH.
• Glyceraldehyde: A triose monosaccharide formed as an intermediate in carbohydrate metabolism, yielding glycerol on reduction.
• Dehydration Synthesis: The creation of larger molecules from smaller monomers with the release of a water molecule.

Collagen Formation

• Collagen is a tightly folded protein composed of three chains that coil together to form tropocollagen.
• Tropocollagen forms interchain bonds to assemble into collagen fibers.
• Collagen fibers are tough and insoluble in water.
• Collagen makes up approximately 30% of bone tissue.

Gelatin Formation

• Gelatin is formed from collagen through the breaking of intermolecular and inter-polypeptide chain bonds.
• Gelatin is soft, jelly-like and soluble in water.

Collagen vs. Gelatin

• Collagen: Highly folded protein with stable quaternary structures, insoluble in water, structural component of skin, bones, and tendons.
• Gelatin: Unfolded protein with no secondary or quaternary structures, soluble in water, provides textural effects.

Factors Affecting Enzyme Activity

High Temperature

• Enzymes denature above their optimum temperature (37°C).
• The active site is destroyed as protein folding is disrupted, preventing substrate binding.

Low Temperature

• Lower temperatures decrease kinetic energy, resulting in fewer collisions between substrate and enzyme.

pH Level

• Deviation from neutral pH (7) affects electrostatic interactions between acidic and basic amino acids, causing protein denaturation and active site destruction.

Enzyme Concentration

• Increasing enzyme concentration increases the rate of reaction until substrate becomes the limiting factor.

Substrate Concentration

• Increasing substrate concentration increases the rate of reaction until saturation point is reached.

Catalyst

• Reduces the activation energy of a reaction, speeding up the rate of reaction without altering free energy.