Biochem Lecture 1 Review

Amino Acid Structure and Function

• Amino acids are organic compounds composed of an amino group, a carboxyl group, and a unique side chain (R group) that determines their properties.
• Peptides and proteins are formed through peptide bonds, linking amino acids via condensation reactions.

Essential Amino Acids

• Essential amino acids cannot be synthesized by the body and must be obtained from diet.
• Mnemonic ''PVT TIM HiLL'' helps recall the nine essential amino acids:
  • P: phenylalanine
  • V: valine
  • T: tryptophan
  • T: threonine
  • I: isoleucine
  • M: methionine
  • H: histidine
  • L: leucine
  • L: lysine

Amino Acid Degradation

• Degradation involves the removal of amino groups to convert amino acids into intermediates like pyruvate, acetyl-CoA, or Krebs cycle intermediates.

Conversion of Amino Acids

• Amino acids can serve as substrates for the Krebs cycle, contributing to energy production and biosynthesis of key molecules.

Protein Structure and Classification

• Proteins are classified by structure: primary (sequence of amino acids), secondary (alpha helices and beta sheets), tertiary (3D shape), and quaternary (multiple polypeptides).

Carbohydrates

• Monosaccharides such as glucose, fructose, galactose, and ribose are fundamental for energy storage and metabolism.

Lipids: Classification, Structure, and Function

• Lipids include triglycerides, phospholipids, and steroids; they are essential for cell membranes, energy storage, and signaling.
• Saponifiable lipids can be hydrolyzed to yield fatty acid salts, while nonsaponifiable lipids cannot undergo this reaction.

Water-Soluble Vitamins

• Important water-soluble vitamins include B vitamins and vitamin C; deficiency leads to conditions such as scurvy and beriberi.

Fat-Soluble Vitamins

• Fat-soluble vitamins A, D, E, and K are absorbed with dietary fat; deficiencies can lead to various disorders affecting vision, bone health, and blood clotting.

Function of Minerals

• Key minerals include calcium (bone health), magnesium (energy production), sodium (fluid balance), phosphate (energy transfer), copper (iron metabolism), and potassium (muscle function).

Enzyme Function

• Enzymes are biological catalysts that accelerate biochemical reactions, lowering activation energy and increasing reaction rates.

Nucleic Acid Formation and Degradation

• DNA and RNA are formed through nucleotides; degradation involves hydrolysis, resulting in the release of nucleotides for recycling.

Glycolysis

• Glycolysis occurs in the cytoplasm, converting glucose into pyruvate with a net gain of ATP, and is regulated by key enzymes such as phosphofructokinase.

Gluconeogenesis

• The process of gluconeogenesis generates glucose from non-carbohydrate substrates, occurring primarily in the liver and regulated by hormones like glucagon.

Lactate and the Cori Cycle

• The Cori cycle converts lactate produced in anaerobic conditions back into glucose in the liver, facilitating continuous energy supply during intense exercise.

Glycogen Metabolism

• Glycogen is synthesized by adding glucose to glycogenin and broken down by glycogen phosphorylase; it is primarily stored in the liver and muscle, and helps regulate blood glucose levels.

Pentose Phosphate Pathway (PPP)

• The PPP generates NADPH for biosynthetic reactions and ribose-5-phosphate for nucleotide synthesis; it is active in tissues requiring high levels of reducing power, such as liver and immune cells.

Beta Oxidation

• Beta oxidation is the process of breaking down fatty acids in the mitochondria, producing acetyl-CoA for energy production through the Krebs cycle; it leads to the formation of ketone bodies during fasting or uncontrolled diabetes.

4 macromolecules