Biological molecules -proteins Flashcards
What are the primary dietary sources of protein?
-Animal products (e.g., meat, eggs, milk)
-Protein-rich plant products (e.g., nuts, seeds, legumes, wheat, soya beans)
-Fungi (e.g., mushrooms, mycoprotein)
What percentage of the average person’s Calorie intake should come from protein?
Around 15-20%.
Define “protein” as a material and as a structure.
Material: Refers to polypeptides and amino acids in a cell or diet.
Structure: Refers to a functional unit made of one or more polypeptides.
What are the four levels of protein structure?
Primary: Amino acid sequence.
Secondary: Local folding (e.g., alpha helices, beta-pleated sheets).
Tertiary: 3D folding of the entire polypeptide.
Quaternary: Arrangement of multiple polypeptides or prosthetic groups.
What are fibrous and globular proteins?
Fibrous Proteins: Structural (e.g., collagen); resistant to heat and damage.
Globular Proteins: Functional (e.g., enzymes, receptors); require complex tertiary structures.
How are polypeptides formed and broken down?
Formation: Condensation reactions (releasing water).
Breakdown: Hydrolysis reactions (consuming water).
How many amino acids are used in human protein synthesis?
20 amino acids, with 9 being essential and obtained from the diet.
Describe peptide bonds.
A chemical bond formed between the amine group of one amino acid and the carboxyl group of another via a condensation reaction.
What happens to proteins during denaturation?
Heat or pH changes break intermolecular forces, causing the protein to lose its shape and function.
What are the main uses of proteins in the body besides protein synthesis?
Energy release (respiration).
Biosynthesis of nitrogen-containing molecules (e.g., DNA, hormones).
Excretion of nitrogen waste as urea.
What are enzymes and their primary function?
Enzymes are biological catalysts (proteins) that increase reaction rates by lowering activation energy.
What role do hydrogen bonds play in protein structure?
They help stabilize secondary and tertiary structures by forming between polar groups.
