General Biology Exam 1 Study Guide: Foundations, Chemistry of Life, and Macromolecules

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Biology is unified by several core themes that help explain the diversity and complexity of life.

Organization
- Biological levels of organization: from molecules to the biosphere.
- Reductionism and emergent properties: understanding complex systems by studying their parts and the new properties that arise at each level.
- Relationship of structure and function: biological structures are adapted to their functions.
- The cell: the basic unit of life; distinction between prokaryotic and eukaryotic cells.
Information
- Genetic information is stored in DNA and transmitted across generations.
- Chromosomes: organization of DNA within cells.
- Transmission and expression of genetic information: central dogma of molecular biology (DNA → RNA → Protein).
Interactions
- Organisms interact with each other and their environment, affecting both their survival and the ecosystem.
- Forms of organismal interactions include competition, predation, symbiosis, etc.
Evolution
- Explains the unity and diversity of life.
- Three domains of life: Bacteria, Archaea, Eukarya.
- Darwin’s theory of natural selection: mechanism for evolution based on heritable variation and differential survival.
- Scientific evidence for evolution includes fossil records, comparative anatomy, and molecular biology.
Scientific Method
- Observation, hypothesis, experimentation, and conclusion.
- Experimental design: includes control and experimental groups, independent and dependent variables.

Elements: Substances that cannot be broken down by chemical means (e.g., C, H, O, N).
Atoms: Smallest unit of an element, composed of protons, neutrons, and electrons.
Protons: Positively charged particles in the nucleus.
Neutrons: Neutral particles in the nucleus.
Electrons: Negatively charged particles orbiting the nucleus.

Mass number: Sum of protons and neutrons.
Atomic number: Number of protons, defines the element.
Isotopes: Atoms of the same element with different numbers of neutrons; can be stable or radioactive.

Valence electrons: Electrons in the outermost shell, determine chemical reactivity.
Valence shells: Energy levels where electrons reside.

Ionic bonds: Transfer of electrons between atoms, forming cations and anions.
Covalent bonds: Sharing of electrons; can be single or double bonds.
Polarity: Difference in electronegativity leads to polar (unequal sharing) or nonpolar (equal sharing) covalent bonds.
Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., O or N).

Cohesion: Water molecules stick together via hydrogen bonds.
Adhesion: Water molecules stick to other substances.
Temperature change: High specific heat and heat of vaporization; water resists temperature changes.
Density: Ice is less dense than liquid water due to hydrogen bonding.
Solvent properties: Water is a versatile solvent due to its polarity.
Hydrophilic vs. hydrophobic: Hydrophilic substances dissolve in water; hydrophobic substances do not.

Versatility: Carbon forms four covalent bonds, allowing for diverse molecules.
Hydrocarbons: Molecules consisting only of carbon and hydrogen; nonpolar and hydrophobic.

Groups of atoms attached to carbon skeletons that confer specific properties (e.g., hydroxyl, carbonyl, amino, phosphate, sulfhydryl, methyl).

Monomers and Polymers: Polymers are long chains of monomers joined by dehydration reactions and broken by hydrolysis.

Monosaccharides: Simple sugars (e.g., glucose).
Disaccharides: Two monosaccharides joined by glycosidic linkage.
Polysaccharides: Storage (starch in plants, glycogen in animals) and structural (cellulose in plants, chitin in fungi and arthropods).
Glycosidic linkage: Covalent bond joining monosaccharides.

Fats: Glycerol + fatty acids; energy storage.
Saturated vs. unsaturated fatty acids: Saturated have no double bonds; unsaturated have one or more double bonds.
Phospholipids: Major component of cell membranes; form bilayers in water.

Enzymes: Catalysts that speed up chemical reactions.
Amino acids: Building blocks of proteins; 20 different types.
Levels of protein structure:
- Primary: sequence of amino acids.
- Secondary: alpha helices and beta sheets.
- Tertiary: overall 3D shape.
- Quaternary: association of multiple polypeptides.
Denaturation: Loss of protein structure and function due to environmental changes.

DNA (deoxyribonucleic acid) and RNA (ribonucleic acid): Store and transmit genetic information.
Nucleotides: Monomers consisting of a sugar, phosphate group, and nitrogenous base.
Bases: Purines (A, G) and pyrimidines (C, T, U; U in RNA instead of T).
Base pairing: A-T (or A-U in RNA), G-C.