CHR3 notes

Overview of Macromolecules

  • Macromolecules are large organic molecules composed of smaller building blocks or subunits.

  • There are four essential types of macromolecules in living organisms:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

Carbohydrates

  • Carbohydrates function primarily as fuel for cells.

  • They are critical components of cell structure in all organisms.

  • Chemical Composition:

    • Composed of carbon (C), hydrogen (H), and oxygen (O)

    • Structure: Cx(H2O)y, indicating a generally equal number of carbon atoms to water units.

Monosaccharides

  • Monosaccharides are the simplest form of carbohydrates, known as simple sugars, and primarily include:

    • Glucose: C6H12O6

    • Fructose: C6H12O6

    • Galactose: C6H12O6

Energy Storage and Usage

  • The carbon-hydrogen bonds in carbohydrates store substantial energy, which can be easily broken down for cellular mechanisms.

  • When glucose is utilized, it can take one of three paths:

    • Fuel for Cellular Activity

    • Stored as Glycogen (temporary storage in muscles and liver)

    • Converted to Fat (for long-term energy storage)

Additional Notes on Energy

  • A pound of glycogen stores approximately four pounds of water, leading to significant weight loss from water weight during dieting.

Complex Carbohydrates

  • Carbohydrates may combine into larger structures, resulting in more complex carbohydrates.

    • Disaccharides: Formed by the union of two simple sugars; examples include sucrose (table sugar), lactose.

    • Polysaccharides: Formed by union of many simple sugars, leading to complex structures like starch (consisting of hundreds of glucose molecules).

Non-Digestible Carbohydrates

  • Not all carbohydrates are digestible.

    • Examples include:

    • Cellulose: Found in plants, offers dietary fiber and aids in digestion.

    • Chitin: Found in invertebrates and gives structure.

Lipids

  • Lipids are macromolecules that serve several functions including energy storage.

  • They are characterized by a high number of C-H bonds, leading to more energy storage compared to carbohydrates.

  • Insoluble in Water: Nonpolar and greasy, lipids vary widely in function.

Types of Lipids

  1. Fats - Long-term energy storage and insulation.

  2. Sterols - Regulate growth and development.

  3. Phospholipids - Form cellular membranes.

Saturation of Fats

  • Saturated Fats:

    • Each carbon is bound to two hydrogen atoms (C-H bonds).

    • Solid at room temperature due to tight packing of molecules.

  • Unsaturated Fats:

    • Contain at least one double bond between carbons, preventing tight packing and remaining liquid at room temperature.

Trans Fats

  • Generated through hydrogenation, which adds hydrogen to unsaturated fats, making them behave more like saturated fats.

  • Trans fats can adversely impact health while improving food quality.

Cholesterol

  • A key component of cell membranes and can contribute to heart disease through plaque buildup in arteries.

  • Cells in the liver produce near 90% of circulating cholesterol levels.

Proteins

  • Proteins are essential macromolecules that perform a variety of functions throughout organisms.

  • They are built from 20 different amino acids, which contain Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

Amino Acids

  • Each amino acid has a carboxyl group and amino group; differences arise from varying side chains.

  • Examples of amino acids: Alanine, Glycine, Tryptophan.

Protein Functions

  1. Structure: Aid in the formation of living tissues (e.g., hair, nails).

  2. Protection: Help fight infection and coagulate blood.

  3. Regulation: Control cellular activities and some act as hormones.

  4. Contraction: Contribute to muscle function.

  5. Transportation: Carry molecules (e.g., oxygen).

Protein Sources

  • Proteins are obtained through diet, with some being essential and needing to be consumed (essential amino acids):

    • Complete Proteins: Contain all essential amino acids, typically from animal sources.

    • Incomplete Proteins: Mostly plant-based sources lack some essential amino acids.

    • Complementary Proteins: When eaten together, provide all essential amino acids.

Protein Structure and Function

  • Proteins have four structural levels:

    1. Primary Structure: Sequence of amino acids.

    2. Secondary Structure: Local folding into alpha-helices or beta-sheets.

    3. Tertiary Structure: Overall 3D shape formed by interactions between side chains.

    4. Quaternary Structure: Assembly of multiple polypeptide chains.

Denaturation

  • External factors causing proteins to unfold, losing their functional shape, leading to loss of function.

Enzymes

  • Proteins that catalyze biochemical reactions by lowering the activation energy required.

  • Each enzyme has an active site specific to its substrate, facilitating transformation into products.

Factors Influencing Enzyme Activity

  1. Concentration of Enzymes and Substrates: Higher concentrations generally lead to increased reaction rates due to more frequent collisions.

  2. Temperature: Higher temperatures can increase reaction rates up to an optimum but can also cause denaturation.

  3. pH Levels: Enzymatic activity is influenced by pH; optimal range enhances activity while extremes may inhibit functionality.

  4. Presence of Inhibitors/Activators: Chemicals that can increase (activators) or decrease (inhibitors) reaction rates depending on binding to the enzyme or altering its shape.

Nucleic Acids

  • Nucleic acids are macromolecules that serve as information carriers in organisms.

  • Comprised of nucleotides, which consist of three components: a sugar, a phosphate group, and a nitrogenous base.

Types of Nucleic Acids

  1. DNA (Deoxyribonucleic Acid): Stores genetic information structured as a double helix.

  2. RNA (Ribonucleic Acid): Translates DNA information into proteins and is single-stranded.

Base Pairing in DNA

  • Specific base pairing rules: Adenine pairs with Thymine and Cytosine pairs with Guanine.

RNA Functions

  • Acts as an intermediary by carrying instructions for protein synthesis from DNA to ribosomes where protein assembly occurs.