Organic Molecules

Definition and Classification

Organic molecules are compounds primarily composed of carbon atoms bonded with hydrogen, oxygen, nitrogen, and other elements. They form the basis of all living organisms.

• Polymers: Large molecules made by joining smaller units called monomers.

• Monomers: The basic building blocks of polymers (e.g., amino acids, monosaccharides).

• Dehydration Synthesis: The reaction that joins monomers by removing a water molecule, forming covalent bonds.

• Hydrolysis: The reaction that breaks covalent bonds between monomers by adding a water molecule.

Biological Macromolecules

There are four major classes of biological macromolecules:

• Carbohydrates: Provide energy and structural support (e.g., glucose, starch).

• Lipids: Store energy, form membranes, and act as signaling molecules (e.g., fats, oils, phospholipids).

• Proteins: Perform a wide range of functions including catalysis, structure, and transport (e.g., enzymes, antibodies).

• Nucleic Acids: Store and transmit genetic information (e.g., DNA, RNA).

Macromolecule Testing Reagents

Specific reagents are used to test for the presence of biological macromolecules:

Example: Benedict’s reagent turns from blue to orange/red in the presence of reducing sugars.

Cells: Plasma Membrane, Diffusion, & Osmosis

Plasma Membrane Structure

The plasma membrane is a selectively permeable barrier composed of:

• Phospholipids: Arranged in a bilayer with hydrophilic heads facing outward and hydrophobic tails inward.

• Proteins: Embedded or attached to the membrane, serving as channels, carriers, or receptors.

• Cholesterol: Stabilizes membrane fluidity.

• Carbohydrates: Attached to proteins or lipids, involved in cell recognition.

Transport Mechanisms

• Diffusion: Passive movement of molecules from high to low concentration; does not require ATP.

• Osmosis: Diffusion of water across a selectively permeable membrane; does not require ATP.

• Active Transport: Movement of molecules against their concentration gradient; requires ATP.

Solution Types and Water Movement

Example: Placing a cell in a hypotonic solution causes water to enter the cell, potentially leading to lysis.

Dialysis Tubing Experiment

• Dialysis tubing acts as a selectively permeable membrane.

• Small solutes (e.g., glucose) can diffuse through, while larger molecules (e.g., starch) cannot.

Surface Area to Volume Ratio

The surface area to volume ratio is critical for cell function:

• As cells grow, volume increases faster than surface area.

• High ratio allows efficient exchange of materials.

• Limits cell size; larger cells may struggle with transport.

Enzymes

Enzyme Structure and Function

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

• Activation Energy: The energy required to start a reaction; enzymes lower this barrier.

• Active Site: The region on the enzyme where substrates bind and reactions occur.

• Substrate: The molecule upon which an enzyme acts.

Factors Affecting Enzyme Activity

• Temperature: Optimal range increases activity; extreme heat can denature enzymes.

• pH: Each enzyme has an optimal pH; deviations can reduce activity.

• Substrate Concentration: Increased concentration increases activity up to a saturation point.

• Inhibitors: Molecules that decrease enzyme activity.

Enzyme Inhibition and Denaturation

• Inhibitors: Can be competitive (bind to active site) or noncompetitive (bind elsewhere).

• Denatured: Loss of enzyme structure and function due to extreme conditions; usually irreversible.

Catalase Reaction

Catalase catalyzes the breakdown of hydrogen peroxide:

• Reactants: Hydrogen peroxide (H2O2)

• Products: Water (H2O) and oxygen (O2)

Equation:

Measurement: Catalase activity is often measured by the rate of oxygen production.

Enzyme Research Project & Experimental Design

Experimental Controls and Hypotheses

• Null Hypothesis: States there is no effect or difference; used as a baseline for statistical testing.

• Negative Control: A group where no response is expected; ensures the experiment is not affected by outside variables.

• Positive Control: A group where a known response is expected; confirms the experiment is working as intended.

Statistical Analysis

• p value: Probability that observed results occurred by chance; a low p value (<0.05) suggests statistical significance.

• t-test: Compares means between two groups.

• ANOVA: Compares means among three or more groups.

Example: Use a t-test to compare enzyme activity between treated and untreated samples; use ANOVA for multiple treatments.

Additional info: Statistical tests help determine if experimental results are meaningful or due to random variation.