Exam 1 Review: Foundations of Biology, Chemistry of Life, and Macromolecules

Scientific Inquiry and Data Types

Quantitative vs. Qualitative Data

In biological research, data can be classified as either quantitative or qualitative. Understanding the distinction is crucial for designing experiments and interpreting results.

• Quantitative Data: Numerical measurements (e.g., height, weight, temperature).

• Qualitative Data: Descriptive, non-numerical information (e.g., color, texture, presence/absence of a trait).

• Example: Measuring the growth of plants in centimeters (quantitative) versus describing leaf color (qualitative).

Controls in Experiments

A control is a standard for comparison in scientific experiments. It helps ensure that the results are due to the variable being tested.

• Positive Control: Expected to produce a known result.

• Negative Control: Expected to produce no effect.

• Example: Testing a new drug, the control group receives a placebo.

Hypothesis, Theory, and Law

• Hypothesis: A testable, falsifiable statement explaining an observation.

• Theory: A well-substantiated explanation based on a body of evidence (e.g., theory of evolution).

• Law: A statement describing consistent natural phenomena (e.g., Mendel's laws of inheritance).

Biological Classification and Nomenclature

Binomial Nomenclature

The binomial nomenclature system assigns each species a two-part scientific name: Genus species (e.g., Homo sapiens).

• Genus: Capitalized, groups closely related species.

• Species: Lowercase, identifies the specific organism.

Cell Theory and Types of Cells

Basic Units of Life

• Cell: The fundamental unit of structure and function in living organisms.

• All living things are composed of cells.

Prokaryotic vs. Eukaryotic Cells

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	No	Yes
Membrane-bound organelles	No	Yes
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Chemical Foundations of Life

Atoms and Subatomic Particles

• Atom: Smallest unit of matter retaining element properties.

• Subatomic Particles: Protons (+, mass 1), Neutrons (0, mass 1), Electrons (-, negligible mass).

• Atomic Number: Number of protons.

• Mass Number: Protons + Neutrons.

Calculating Subatomic Particles

• Given atomic number (Z) and mass number (A):

• Number of protons = Z

• Number of neutrons = A - Z

• Number of electrons = Z (in a neutral atom)

Chemical Bonds

• Covalent Bonds: Sharing of electron pairs between atoms. Each bond involves 2 electrons.

• Ionic Bonds: Transfer of electrons from one atom to another, forming ions.

• Hydrogen Bonds: Weak attractions between a hydrogen atom (covalently bonded to O or N) and another electronegative atom.

• Valence Electrons: Electrons in the outermost shell; determine bonding behavior.

• Importance of Weak Bonds: Allow for dynamic interactions (e.g., DNA base pairing, protein folding).

Electronegativity

• Electronegativity: Atom's ability to attract electrons in a bond.

• Increases across a period, decreases down a group in the periodic table.

• Difference in electronegativity determines bond type (nonpolar covalent, polar covalent, ionic).

Organic Molecules and Isomerism

Organic Molecules and Hydrocarbons

• Organic Molecules: Contain carbon and hydrogen, often with O, N, S, P.

• Hydrocarbons: Molecules of only carbon and hydrogen; nonpolar, hydrophobic, high energy content.

Isomers

• Isomers: Compounds with the same molecular formula but different structures.

• Types:

  • Structural Isomers: Differ in covalent arrangement.

  • Cis-Trans (Geometric) Isomers: Differ in spatial arrangement around double bonds.

  • Enantiomers: Mirror images, differ in arrangement around an asymmetric carbon.

Key Vocabulary

• Element: Pure substance of one type of atom.

• Compound: Substance of two or more elements in fixed ratio.

• Matter: Anything that has mass and occupies space.

• Solvent: Substance that dissolves another (e.g., water).

• Solute: Substance dissolved in a solvent.

• Polar: Molecule with uneven charge distribution.

• Non-polar: Molecule with even charge distribution.

• Hydrophobic: Repels water.

• Hydrophilic: Attracts water.

Functional Groups

• Hydroxyl (-OH): Alcohols, polar.

• Carbonyl (C=O): Aldehydes/ketones.

• Carboxyl (-COOH): Acids.

• Amino (-NH2): Amines, basic.

• Sulfhydryl (-SH): Thiols.

• Phosphate (-PO42-): Organic phosphates.

• Methyl (-CH3): Methylated compounds.

Acids, Bases, and pH

pH and [H+] Relationship

• pH: Measure of hydrogen ion concentration.

• Relationship: $pH = -\log_{10}[H^+]$

• As [H+] increases, pH decreases (more acidic).

• Acid: Donates H+ (lowers pH).

• Base: Accepts H+ (raises pH).

Calculating pH and [H+]

• Given [H+], calculate pH: $pH = -\log_{10}[H^+]$

• Given pH, calculate [H+]: $[H^+] = 10^{-pH}$

Buffers

• Buffer: Substance that minimizes changes in pH by accepting or donating H+.

• Good Buffer: Has a pKa close to the desired pH and can neutralize added acids or bases.

• Example: Bicarbonate buffer system in blood.

Properties of Water

• Cohesion: Water molecules stick together via hydrogen bonds.

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water resists temperature change.

• High Heat of Vaporization: Requires much energy to evaporate.

• Expansion upon Freezing: Ice is less dense than liquid water.

• Versatile Solvent: Dissolves many substances due to polarity.

Macromolecules

Major Macromolecules and Their Monomers

Macromolecule	Monomer	Major Functions
Carbohydrates	Monosaccharides	Energy storage, structure
Lipids	Glycerol, fatty acids	Energy storage, membranes, signaling
Proteins	Amino acids	Catalysis, structure, transport, signaling
Nucleic Acids	Nucleotides	Genetic information storage and transfer

Polymerization and Depolymerization

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Examples and Functions

• Carbohydrates: Starch (plants), glycogen (animals), cellulose (plant cell walls).

• Lipids: Fats, phospholipids (membranes), steroids (hormones).

• Proteins: Enzymes, structural proteins, antibodies.

• Nucleic Acids: DNA (genetic code), RNA (protein synthesis).

DNA Base Pairing

• Adenine (A) pairs with Thymine (T); Guanine (G) pairs with Cytosine (C).

• Base pairing is stabilized by hydrogen bonds.

Protein Structure Levels

• Primary: Amino acid sequence (peptide bonds).

• Secondary: Alpha helices and beta sheets (hydrogen bonds).

• Tertiary: 3D folding (interactions among R groups).

• Quaternary: Multiple polypeptide chains.

• Stabilizing Forces: Hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions.