Proteins

Protein

Crucial biomolecules in the body, derived from the Greek word proteios.

Proteins

Account for 15% of cell mass and half of its dry weight.

Unbranched Polymers

Proteins are unbranched polymers of amino acids linked by peptide bonds.

Structure

Collagen and keratin provide structural support as fibrous proteins.

Catalysis

Enzymes catalyze reactions in organisms for various functions.

Movement

Proteins like myosin and actin enable muscle mobility.

Transport

Hemoglobin transports molecules in blood and across membranes.

Amino Acids

Building blocks of proteins containing carboxyl and amino groups.

Essential Amino Acids

Body cannot synthesize them adequately; must be obtained from the diet.

Standard Amino Acids

Humans have 20 standard amino acids with distinct side chains.

Stereoisomers

Standard amino acids have stereogenic centers, existing as D or L enantiomers.

Fischer Projection

Representation method for D and L stereoisomers of amino acids.

Side Chains

Distinguish amino acids and group them by the polarity of their side chains.

Essential Amino Acids

10 amino acids crucial for a child's normal growth and development.

Arginine

Essential for infants' normal growth, becomes nonessential as they mature.

Conditionally essential amino acids

Needed in diet for premature infants lacking nonessential amino acids until maturity.

Complete dietary proteins

Contain all essential amino acids in sufficient amounts.

Incomplete proteins

Lack one or more essential amino acids.

Gelatin

Incomplete protein with tryptophan as the limiting amino acid.

Complementary dietary protein

Obtained by combining incomplete proteins like rice and beans.

Amphoteric Properties of SAAs

Amino acids with both acidic and basic groups in one molecule.

pH Effects on Amino Acid Structure

Amino acid structure changes at different pH levels.

Specific Ionization Patterns

Histidine, lysine, and arginine have unique ionization patterns at various pH levels.

Acidic to basic solution pH solutions

Acidic amino acids can be both acidic and basic based on pH levels.

Isomeric Peptides

Peptides with similar amino acid residues but in different orders

Oxytocin and Vasopressin

Small peptides with physiological importance

Primary Structure of Proteins

Defined by the number, kind, and sequence of amino acids

Importance of Primary Structure

Determines the protein's three-dimensional structure and function

Secondary Structure of Proteins

Regular localized arrangement of the polypeptide backbone

Factors disrupting the Alpha-Helix Structure

Presence of proline, similarly charged groups, and bulky groups

Tertiary Structure

Overall three-dimensional structure of proteins

Quaternary Structure

Non-covalent association of protein subunits into a supramolecule

Protein Hydrolysis

Disruption of peptide bonds liberating free amino acids

Protein Denaturation

Leads to the unfolding of a protein's three-dimensional structure