Biological Macromolecules Notes

Biological Macromolecules

• Overview: Biological macromolecules include proteins, nucleic acids, carbohydrates, and fats. They play essential roles in cellular structure and function.

Proteins

• Learning Objectives:

  • Define different levels of protein structure.
  • Explain components of amino acids.
  • Describe how amino acids form proteins.

• Functions of Proteins:

  • Enzymes: Catalyze chemical reactions.
  • Receptors: Detect chemical signals.
  • Transport: Move molecules in/out of cells and within the body.
  • Storage: Store nutrients both in cells and body fluids.
  • Structural: Provide frameworks for cells (e.g., hair, nails).
  • Energy source: Can be utilized as fuel.

• Protein Basics:

  • Proteins are polymers made of amino acids, linked in a linear chain with no branches.

• Amino Acids:

  • There are 20 types of amino acids, each with a common structure consisting of:
  • Alpha carbon
  • Amine group
  • Carboxylic acid
  • Hydrogen
  • Variable side chain (R-group)

• Protein Synthesis:

  • Amino acids link via dehydration/condensation reactions, losing water to form peptides.
  • A protein is a chain of more than 50 amino acids.

• Levels of Protein Structure:

  • Primary: Sequence of amino acids.
  • Secondary: Organized patterns (e.g., alpha helices, beta sheets).
  • Tertiary: 3D shape of the complete protein.
  • Quaternary: Structure formed by multiple peptide chains (sub-units).

Nucleic Acids

• Learning Objectives:

  • Describe the structure of DNA and mRNA.
  • Explain components of nucleotides.
  • Define key terms: chromosome, gene, replication, transcription, translation.
  • Explain genetic code characteristics and variability.

• Uses of Nucleic Acids:

  • Serve as genetic material for organisms, playing a key role in protein synthesis.

• Types:

  • DNA: Deoxyribonucleic acid; double-stranded and carries genetic information.
  • RNA: Ribonucleic acid; single-stranded with several roles in protein synthesis.

• Structure:

  • DNA and RNA are linear polymers of nucleotides, consisting of:
  • A nitrogenous base (4 types: A, T, G, C for DNA; A, U, G, C for RNA)
  • A sugar (deoxyribose for DNA, ribose for RNA)
  • A phosphate group.

• DNA Double Helix:

  • Composed of base pairs (A-T and G-C), joined by hydrogen bonds in an anti-parallel arrangement.

• Chromosomes:

  • DNA wrapped around proteins called histones.
  • Humans typically have 23 pairs of chromosomes.

• Genes:

  • Specific segments of DNA coding for peptides; include coding and non-coding sequences.

• Genetic Code:

  • Composed of triplet nucleotide sequences that encode amino acids.
  • Universal and degenerate (multiple codes for same amino acid).

• Genetic Variability:

  • Polymorphisms can result in variations that may be benign or disease-causing (e.g., sickle cell anemia).

• Gene Processes:

  • Replication: Copying DNA for cell division; enzyme involved is DNA polymerase.
  • Transcription: RNA synthesis from DNA, done by RNA polymerase.
  • Translation: mRNA is translated into proteins with help from tRNA and rRNA.

Carbohydrates

• Learning Objectives:

  • Compare carbohydrates to proteins and nucleic acids.
  • Discuss complexities of carbohydrate biochemistry.
  • Describe carbohydrate examples unrelated to energy/nutrition.

• Uses of Carbohydrates:

  • Most abundant biomolecules; serve as energy stores, structural components, and binding sites.

• Structure of Carbohydrates:

  • Composed of carbon, hydrogen, and oxygen (CHO).
  • Monomers (simple sugars) can form ring structures and complex polymers.

• Monosaccharides:

  • Examples include glucose and fructose; can be modified.

Fats/Lipids

• Learning Objectives:

  • Describe types of membrane lipids and fatty acids.
  • Identify roles of fatty acids/lipids beyond nutrition.

• Uses of Lipids:

  • Energy storage, structural roles in membranes, signaling, and hormonal functions.

• Lipid Structure:

  • Membrane lipids such as phospholipids and cholesterol form the structural foundation of cell membranes.

• Fatty Acids:

  • Long carbon chains; categorized as saturated (no double bonds) or unsaturated (one or more double bonds).

• Membrane Properties:

  • Saturated fats create more rigid membranes; unsaturated fats introduce kinks, affecting fluidity.