Biomolecules and Nutrition Notes

Biomolecules

  • Large macromolecules.

  • Naturally occurring and organic.

    • Carbon-based, often including hydrogen, nitrogen, and oxygen.

  • Essential to all cells for life's functions and forming physical components.

Macromolecules

  • Composed of smaller units called monomers.

  • Monomers are connected to form the macromolecules.

Building Macromolecules

  • Monomers bond through dehydration synthesis.

    • Removal of water molecule (H_2O).

    • "Dehydrate to put together."

Breaking Down Macromolecules

  • Macromolecules break down via hydrolysis.

    • Addition of water molecule (H_2O).

    • "Lyse (or blast apart) with water."

Biomolecules and Cellular Structure

  • Foundation of cellular structure illustrated through levels:

    • Level 1: Monomeric units (nucleotides, amino acids, sugars).

    • Level 2: Macromolecules (DNA, protein, cellulose).

    • Level 3: Supramolecular complexes.

    • Level 4: The cell and its organelles.

Major Classes of Biomolecules

  • Saccharides (Carbohydrates).

  • Lipids (Fats).

  • Peptides (Proteins).

  • Nucleic acids (DNA and RNA) - not covered in this lab topic.

  • Key information for top 3 classes:

    • Monomers or building blocks.

    • Major biological functions.

Organic Compounds

  • Carbohydrates:

    • Polysaccharides.

      • Composed of many Monosaccharides.

    • Disaccharides.

      • Composed of two Monosaccharides.

  • Lipids:

    • Triglycerides.

      • Composed of Fatty acids and Glycerol.

  • Proteins:

    • Peptides.

      • Composed of Amino acids.

  • Nucleic Acids:

    • RNA & DNA.

      • Composed of Nucleotides.

Saccharides - Carbohydrates

  • Key Functions:

    • Carbon supply for building other biomolecules.

    • Structural components of cells.

    • Fuel for cells.

    • Glucose storage for metabolism.

  • Two Classes:

    • Simple sugars - monosaccharides.

    • Complex carbohydrates - polysaccharides.

Simple Sugars - Monosaccharides

  • Mono = one; saccharide = sugar.

  • Examples: Glucose, fructose, galactose, glucosamine.

  • Exist in linear and ring forms.

  • Found in foods like fruit, soda, and candy; labeled as "sugar" on nutrition labels.

  • Quickly digestible for temporary energy bursts.

Complex Carbohydrates

  • Formed when multiple monosaccharides bond via dehydration synthesis.

Disaccharides

  • 2 bonded monosaccharides.

Polysaccharides

  • 3+ monosaccharides bonded, forming a chain; dietary starches.

  • Many bonds; slow to digest.

  • Provide sustained energy.

Polysaccharide Examples

  • Glycogen: Energy storage in animals.

  • Starch: Energy storage in plants.

  • Cellulose: Primary plant cell wall component; dietary fiber.

    • Indigestible by humans; reduces cholesterol and heart disease risk.

Lipids (Fats)

  • Hydrophobic - "water fearing"; insoluble in water.

  • Major energy source: 2X+ calories than carbs/proteins.

  • Insulation source.

  • Major cell membrane component.

  • Required for hormone production.

Lipids - Monomers and Types

  • Monomers: Glycerols and fatty acids.

  • Three major types:

    • Triglycerides.

    • Phospholipids.

    • Sterols.

Triglycerides

  • Main animal & vegetable fat component.

  • Glycerol head and three fatty acid tails.

    • "Tri" = 3 and "glycer" = glycerol.

Phospholipids

  • Glycerol "neck" and hydrophilic phosphate "head".

  • Two hydrophobic fatty acid tails.

  • Compose the cell membrane.

Cell Membrane

  • Phospholipid bilayer.

  • Hydrophobic tails sandwiched inside the bilayer.

  • Hydrophilic heads face outside/inside the cell.

Sterols

  • Cholesterol derivatives.

  • Steroid hormones (testosterone, estrogen).

  • Chemical messengers.

  • Other examples:

    • Cholesterol.

    • Plant sterol (healthy diet component).

Plant Sterols

  • Actively lower cholesterol absorption.

  • Block cholesterol from being absorbed into the bloodstream.

  • Increases removal of cholesterol from the body.

Proteins

  • Dietary requirement for animals.

  • Serve as physical structures:

    • Building bone, hair, muscle, cellular cytoskeletons.

  • Transport molecules (hemoglobin).

  • Cell signaling, cell adhesion (clotting), and cell cycle (mitosis).

  • Stored nutrients:

    • Albumen (eggs, blood).

    • Casein (cow’s milk).

  • Enzymes (vital to metabolic processes).

Proteins - Monomers

  • Monomers: Amino acids.

  • Amino acids bound by peptide bonds forming a polypeptide.

Peptide Bonds

  • Amino Acids Peptide Bonded form a Polypeptide a Protein.

Protein Structure Types

  • 4 types:

    • Primary.

    • Secondary.

    • Tertiary.

    • Quaternary.

  • Structures build with increasing complexity.

Primary Protein Structure

  • Basic polypeptide chain; linear sequence of amino acids.

Secondary Protein Structure

  • Single strand of amino acids (primary structure) coiled or pleated.

  • Held by hydrogen bonds.

  • Not a "functional protein"; part of a larger structure.

Tertiary Protein Structure

  • Complex of folded alpha helices and beta-pleated sheets (secondary structures).

  • 3-dimensional.

  • Maximum stability and can have a function.

  • A protein subunit.

  • Chemical/biological function depends on 3D shape.

Quaternary Protein Structure

  • 3D complex of two or more tertiary polypeptide chains weakly bonded.

  • Bonds are weak, so proteins are often unstable and can denature easily.

  • Structure and function depends on stability of interactions between subunits.

  • Examples: hemoglobin, certain enzymes, protein channels in cell membranes.

Biomolecules and Nutrition

  • Food's energy content measured in Calories.

  • Calorie needs depend on metabolic rate.

  • Food labels base values on a 2000 Calorie/day diet (% Daily Value).

  • Calorie Calculation:

    • Carbohydrates: 4 Calories/gram.

    • Lipids: 9 Calories/gram.

    • Proteins: 4 Calories/gram.

  • Fun fact: Calorie (capital "C") = kilocalorie = 1000 calories (lowercase "c").

Lab Assignment Part One: Biomolecules and Nutrition

  • Evaluate nutrition value using labels.

  • Calculate percent daily values (% D.V.) and Calories from fat/protein.

  • Include units!

Practice Problem

  • 120 total Calories in one serving (from fat, protein, carbs).
    *How many Calories from protein?(given; calculate)
    *Example:
    9 \text{ grams of protein} \times 4 \frac{\text{Calories}}{\text{gram of protein}} = ?

Units

  • Show math and include units for full credit!
    *Example:
    9 \text{ grams of protein} \times 4 \frac{\text{Calories}}{\text{gram of protein}} = 36 \text{ Calories from protein}

More Practice

*What is the percent daily value (%DV) of total Calories in this food item?
*There are 120 Calories in the item.
*There are 2000 Calories in the daily diet.
*120 is what percent of 2000?
*Set up a fraction or ratio:
\frac{\text{part}}{\text{whole}} = \frac{120}{2000} = 0.06 \text{ or } 6\%
*OR
*120 \div 2000 = 0.06 \text{ or } 6\%

Lab Assignment Part Two: Testing for Biomolecules

*Conduct four tests to determine biomolecule content in food items.
*Tests are colorimetric. Reagents may change color to indicate the presence of a
molecule.
*Complete the Data Sheet in your Lab Assignment.

Sudan IV Test for Lipids

*Sudan IV stain reacts with lipids to produce a range of pink/red colors
*Pink is negative – the color of the Sudan dye
*Dark pink is positive; there are lipids in the item
*Dark red means there is a high concentration of lipids

Benedict’s Test for Simple Sugars

*Testing three beverages for SIMPLE sugars (monosaccharides, a.k.a. reducing sugars)
*Results in a range of colors (see below)
*(Blue is the color
of Benedict’s
solution)

Lugol’s Test for Starch

*Recall, starch is a complex carbohydrate, a polysaccharide
*Iodine is the testing reagent; turns blue or black in the presence of a starch (but not simple sugars)

Biuret Test for Proteins

*Biuret reacts to the presence of peptide bonds between the amino acids of a protein.
*Positive result: Light purple to TTU purple color change
*Negative: Blue (the color of Biuret reagent)
*Intensity of color indicates protein concentration

Helpful Hints

*For the nutrition label calculations, SHOW YOUR WORK and include the units!
*For the food tests, watch the video and record each item that was tested, observed color
changes, and concentrations of biomolecules in each item.
*For the quiz, you do NOT need to memorize the names of the food tests. You just need to know that a
color change is a positive result, and no color change is negative.
*For the quiz, you do NOT need to know molecular structures or formulas, but be able to recognize the
hydrophobic and hydrophilic parts of a phospholipid, and the four protein structures (primary, secondary,
tertiary, and quaternary).