Lecture 1 - Introduction to Macromolecules

Macromolecules

• macromolecule: large molecule

• four major macromolecules essential for living organisms:

  • Carbohydrates

  • Proteins

  • Nucleic Acids

  • Lipids

• Monomer: subunit that makes up a polymer

• Polymer: chain of monomers

Carbohydrates

• Functions of carbohydrates:

  • Major energy source for living organisms, including humans.

  • Energy storage in cells.

  • Structural components in cells, such as cell walls and capsules around bacteria.

• Key carbohydrate involved in cellular respiration: Glucose

  • Glucose: Glucose is a monosaccharide and serves as a monomer for carbohydrates.

• Carbohydrate Structure:

  • Composed of six carbon atoms attached to hydroxyl groups and hydrogens.

  • Can exist in a linear form or a ring structure; the ring form is more common in storage.

  • Common representation: a hexagon shape with an oxygen on one corner.

    

    
    

• Monomer of Carbohydrates: Monosaccharide

  • Simplest form

  • example: glucose.

• Polymer of Carbohydrates: Disaccharide and Polysaccharides

• Polysaccharides examples:

  • Starch: Energy storage in plants and algae.

  • Glycogen: Energy storage in animals and bacteria.

  • Cellulose: found in plant cell walls

Dehydration and Hydration Reactions:

• dehydration synthesis: making a polymer by removing water

  • also called condensation

    • water is being removed, molecule is dehydrated

      

• hydration synthesis: breaking a polymer by adding water

  • also called hydrolysis, decomposition, and degradation reaction

    • adding water to break a bond

      

Proteins

• Functions of proteins:

  • Serve as structural components of cells.

  • Play a vital role in cellular mobility, help movement

  • Help transport substances in and out of cells

  • Regulate chemical reactions and processes

  • enzymes are proteins that speed up reactions.

• Example Disease – Tetanus is a Protein

  • toxic protein affecting neurotransmission.

    • blocks human neurons that inhibits muscle contraction

    • leads to rigid paralysis and death

• Monomer of proteins: amino acids

• polymers of proteins: polypeptide

  • polypeptides are bonded by peptide bonds, created via dehydration synthesis.

• Structure of Proteins:

  • Amino group (NH2)

  • Carboxylic acid group (COOH)

  • Hydrogen atom (H)

  • R group (side chain): Varies among amino acids, determining their properties

    

• Protein Folding Levels:

  • Primary Structure: Sequence of amino acids.

  • Secondary Structure: Localized folding patterns held together by hydrogen bonds.

    • forms alpha helices OR beta sheets

  • Tertiary Structure: Overall 3D shape determined by interactions between R groups.

    • sometimes, done folding and completely functional at tertiary structure

      • other times need quaternary structure to be functional

  • Quaternary Structure: Combination of multiple polypeptide chains into one functional proteins

    

• Denaturation: Unfolding of proteins, caused by extremes in temperature, pH, or chemicals; results in loss of function.

  • occurs due to heat, chemicals, pH levels

  • example: killing microbes via cleaning

Nucleic Acids

• Functions of nucleic acids:

  • DNA store hereditary information in cells and some viruses

    • information is needed to build and control cells

  • RNA store genetic information for viruses.

    • information is needed to build and control cells

  • functions in building proteins

• Monomer: Nucleotide

• Polymer: DNA and RNA

• Structure of a nucleotide includes:

  • Sugar: (deoxyribose in DNA; ribose in RNA)

  • Phosphate group

  • Nitrogenous base: (Adenine, Thymine, Cytosine, Guanine for DNA; Adenine, Uracil, Cytosine, Guanine for RNA)

    • Base Pairing Rules: A pairs with T (or U) and C pairs with G

      

• DNA Structure:

  • Double helix model where the strands run antiparallel

  • Each strand has a 5' and 3' end

    • 3’ end contains OH

    • 5’ end contains phosphate

  • held together by hydrogen bonds

Transcription and Translation

• Transcription: copying DNA sequence to mRNA

  • mRNA: copy of gene that encodes proteins

• Translation: decoding mRNA dequence into chain of amino acids (protein)

  • rRNA: part of ribosome

  • tRNA: delivers amino acids to ribosomes

Lipids

• Lipids are hydrophobic molecules and are insoluble in water.

• Types of lipids:

  • Phospholipids:

    • function: Major component of cell membranes

    • structure: phosphate group, glycerol, and 2 fatty acids

      • phosphate group, glycerol: hydrophilic (polar) head

      • 2 fatty acids: hydrophobic (nonpolar) tails.

        

    • Membrane Structure:

      • Phospholipids form bilayers in aqueous environments

  • Triglycerides:

    • function: Long-term energy storage

    • Structure: made of glycerol and three fatty acids

      • also formed through dehydration synthesis.

        

  • Steroids:

    • function: strengthens cell membrane

    • Structure: Composed of four fused carbon rings

      • three 6 carbon rings and one 5 carbon ring

    • Types of steroids:

      • cholesterol in eukaryotes which regulates fluidity in membranes and can act as hormones.

      • hopene in prokaryotes cell membranes

        

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