B1.2.1 - Generalized Structure of an Amino Acid:

• Amino acids are the fundamental units of proteins, and each possesses a common structure.
• A generalized amino acid structure consists of:
  • Amine group (NH2): This group provides the amino part of the amino acid.
  • Carboxyl group (COOH): The carboxyl group contributes the acidic component of the amino acid.
  • Alpha carbon (Cα): Serving as the central carbon atom, it connects the amine and carboxyl groups.
  • R group (side chain): The variable R group differentiates amino acids from one another and imparts unique chemical properties to each.

B1.2.2 - Condensation Reactions Forming Peptides:

• Dipeptide: A dipeptide is a molecule resulting from a condensation reaction between two amino acids. The reaction forms a peptide bond, linking the amine group of one amino acid with the carboxyl group of another. (Amine Group of one is linked with Carboxyl group of another)
• Oligopeptide: An oligopeptide is a short chain of amino acids, typically consisting of a few amino acid residues.
• Polypeptide: A polypeptide is a longer chain of amino acids, which acts as a precursor to proteins. These chains can be relatively short or extensive, depending on the protein's function.
• Peptide bond formation occurs in ribosomes, the cellular organelles responsible for protein synthesis. During translation, amino acids are joined together to create polypeptide chains.

B1.2.3 - Dietary Requirements for Amino Acids:

• Comparison of Amino Acid Sources:
  • Plant cells primarily obtain amino acids by synthesizing them from simple precursors.
  • Animal cells acquire amino acids from their diet by consuming other organisms or plant-based foods.
• Essential Amino Acids: These are amino acids that the body cannot synthesize independently in sufficient quantities and must be obtained from the diet. The list of essential amino acids includes histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
• Non-Essential Amino Acids: Non-essential amino acids are those that the body can synthesize internally, and dietary sources are not necessarily required.
• Vegan diets require attention to food combinations to ensure essential amino acids are consumed adequately. Combining plant-based protein sources (e.g., legumes and grains) can help meet amino acid requirements.

B1.2.4 - Infinite Variety of Peptide Chains:

• The endless diversity of DNA base sequences results in a wide array of possible peptide chains.
• DNA base sequences serve as the genetic code, determining the specific order of amino acids in proteins.
• Different combinations of amino acids give rise to unique proteins, each with distinct structural and functional properties. This diversity enables the body to perform a broad range of biological processes.

B1.2.5 - Effect of pH and Temperature on Protein Structure:

• Denaturation: Denaturation refers to the process by which a protein loses its functional, three-dimensional structure. Denatured proteins often become biologically inactive.
• Effect of pH: Extreme pH levels, either highly acidic or highly alkaline, can disrupt protein structure. This disruption occurs by interfering with ionic interactions and hydrogen bonds that maintain the protein's conformation. As a result, the protein may lose its functionality.