General Biology: Foundations, Biochemistry, and Macromolecules Study Guide

Unit 1: Foundations of Biology

Key Biological Organization Levels

Biology studies life at multiple levels of organization, from the smallest chemical units to the complexity of ecosystems.

• Atom: The smallest unit of matter that retains the properties of an element.

• Molecule: Two or more atoms bonded together.

• Macromolecule: Large, complex molecules such as proteins, nucleic acids, carbohydrates, and lipids.

• Cell: The basic unit of life.

• Tissue: Groups of similar cells performing a specific function.

• Organ: Structures composed of different tissues working together.

• Organ System: Groups of organs that perform related functions.

• Organism: An individual living entity.

• Population: A group of organisms of the same species living in a specific area.

• Community: All populations of different species in a given area.

• Ecosystem: The community plus the nonliving environment.

• Biosphere: All ecosystems on Earth.

Energy Flow and Producers

Energy flows through ecosystems, primarily entering via photosynthesis.

• Producers (autotrophs) convert solar energy to usable energy through photosynthesis.

• Consumers (heterotrophs) obtain energy by eating producers or other consumers.

• Photosynthesis equation: $6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2$

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite external changes.

• Examples: Regulation of body temperature, pH, and glucose levels.

Scientific Method and Experimental Design

The scientific method is a systematic approach to understanding the natural world.

• Hypothesis: A testable explanation for an observation.

• Variable: Any factor that can change in an experiment.

• Independent Variable: The variable that is changed or controlled by the experimenter.

• Dependent Variable: The variable being tested and measured.

• Control Group: The group not receiving the experimental treatment, used for comparison.

• Statistical Significance: Results are statistically significant if it is unlikely they occurred by chance.

Unit 2: Basic Chemistry for Biology

Atoms and Elements

All matter is composed of atoms, which are the building blocks of elements.

• Atom: Consists of protons, neutrons, and electrons.

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

• Valence Electrons: Electrons in the outermost shell, important for chemical bonding.

Chemical Bonds

Atoms form chemical bonds to achieve stability.

• Ionic Bond: Transfer of electrons from one atom to another, resulting in oppositely charged ions.

• Covalent Bond: Sharing of electron pairs between atoms.

• Polar Covalent Bond: Unequal sharing of electrons, leading to partial charges.

• Nonpolar Covalent Bond: Equal sharing of electrons.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

Properties of Water

Water's unique properties are essential for life.

• Cohesion: Water molecules stick to each other due to hydrogen bonding.

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water can absorb a lot of heat before changing temperature.

• Solvent Properties: Water dissolves many substances due to its polarity.

• pH: Measure of hydrogen ion concentration; water is neutral at pH 7.

Unit 3: Biological Macromolecules

Carbohydrates

Carbohydrates are organic molecules made of carbon, hydrogen, and oxygen, serving as energy sources and structural components.

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• General formula: $(CH_2O)_n$

Lipids

Lipids are hydrophobic molecules, including fats, oils, and steroids, important for energy storage and membrane structure.

• Triglyceride: Composed of glycerol and three fatty acids.

• Saturated Fatty Acids: No double bonds; solid at room temperature.

• Unsaturated Fatty Acids: One or more double bonds; liquid at room temperature.

• Phospholipids: Glycerol, two fatty acids, and a phosphate group; major component of cell membranes.

• Steroids: Four fused carbon rings (e.g., cholesterol).

Proteins

Proteins are polymers of amino acids, performing a wide range of functions in cells.

• Amino Acid: Building block of proteins; contains an amino group, carboxyl group, hydrogen atom, and R group.

• Peptide Bond: Covalent bond between amino acids.

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Local folding (alpha-helix, beta-sheet).

• Tertiary Structure: 3D folding due to side chain interactions.

• Quaternary Structure: Association of multiple polypeptides.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• DNA (Deoxyribonucleic Acid): Double helix, stores genetic information.

• RNA (Ribonucleic Acid): Single-stranded, involved in protein synthesis.

• Nucleotide: Monomer of nucleic acids; consists of a sugar, phosphate group, and nitrogenous base.

Tables and Data Interpretation

Example: Distribution of Slugs Table

This table shows the average distance between sea slugs at different times of day, illustrating how environmental or biological factors can affect animal behavior.

Time of Day	Average Distance Between Individuals (cm)
Midnight	8.0
4 A.M.	8.9
8 A.M.	44.8
NOON	174.0
4 P.M.	530.5
8 P.M.	36.0
Midnight	8.0

Main Purpose: To illustrate changes in animal spacing over time, possibly due to environmental or behavioral factors.

Sample Practice Questions and Applications

Triglyceride Structure and Properties

Triglycerides are a type of lipid formed by condensation reactions between glycerol and three fatty acids.

• Chemical Property: All lipids are hydrophobic (insoluble in water).

• Formation: A triglyceride is formed from one glycerol and three fatty acids, releasing three water molecules.

• Phospholipids vs. Triglycerides: Phospholipids have two fatty acids and a phosphate group, making them amphipathic (hydrophilic head, hydrophobic tails), while triglycerides have three fatty acids and are entirely hydrophobic.

Water's Role in Life

• Water is a polar molecule, with partial negative charge near the oxygen and partial positive charge near the hydrogens.

• This polarity allows water to form hydrogen bonds, contributing to its solvent properties and high specific heat.

Enzyme Activity and pH

Enzymes are proteins that catalyze biochemical reactions, and their activity is affected by pH.

• Bromelain: A protein-digesting enzyme found in pineapples.

• Enzyme activity is optimal at a specific pH; deviations can denature the enzyme and reduce activity.

• For bromelain, activity decreases at pH values far from its optimal range (3.5 to 5.1).

Glossary of Key Terms

• Atom, Element, Isotope, Ionic Bond, Covalent Bond, Hydrogen Bond, pH, Buffer, Monomer, Polymer, Monosaccharide, Disaccharide, Polysaccharide, Fatty Acid, Triglyceride, Phospholipid, Amino Acid, Peptide Bond, Primary Structure, Secondary Structure, Enzyme, Nucleotide, ATP, DNA, RNA

Additional info: Some explanations and context have been expanded for clarity and completeness, including the scientific method, properties of water, and macromolecule structure and function.