BIO 101 Exam 1 Study Guide: Chapters 1-6 (Themes of Biology, Chemistry of Life, Water, Carbon, Macromolecules, Cells)

Chapter 1: Themes of Biology and Evolution

Five Themes of Biology

• Organization: Biological systems are structured in a hierarchy from molecules to the biosphere. Emergent properties arise at each level due to interactions among components.

• Information: Life processes are directed by genetic information encoded in DNA, which is transmitted from one generation to the next.

• Energy and Matter: Living organisms require energy to carry out life processes. Energy flows through ecosystems (mainly from sunlight), while chemicals cycle within them.

• Interactions: Organisms interact with each other and their environment, affecting both their own survival and the ecosystem.

• Evolution: The process by which populations change over generations, explaining both the unity and diversity of life.

Cell Types and Genetic Information

• Eukaryotic cells: Have a nucleus and membrane-bound organelles.

• Prokaryotic cells: Lack a nucleus and most organelles.

• DNA: The molecule that stores genetic information; its sequence determines inherited traits.

Producers vs. Consumers

• Producers: Organisms (like plants) that make their own food via photosynthesis.

• Consumers: Organisms that obtain energy by eating other organisms.

Feedback Regulation

• Negative feedback: A process in which a system responds to a change by returning to its original state.

Climate Change

• Refers to long-term shifts in temperatures and weather patterns, mainly due to human activities such as burning fossil fuels.

Evolution and Diversity of Life

• Three domains of life: Bacteria, Archaea, and Eukarya.

• Charles Darwin: Proposed natural selection as the mechanism of evolution.

Scientific Inquiry

• Inductive reasoning: Drawing general conclusions from specific observations.

• Deductive reasoning: Making specific predictions based on general principles.

• Hypothesis: A testable explanation for an observation.

• Theory: A broad explanation supported by a large body of evidence.

• Variables: Independent variable is manipulated; dependent variable is measured.

Chapter 2: The Chemical Context of Life

Atoms, Elements, and Compounds

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

• Compound: A substance consisting of two or more elements in a fixed ratio.

• Essential elements: Elements required for life (e.g., C, H, O, N).

Atomic Structure

• Atom: Smallest unit of an element, composed of protons, neutrons, and electrons.

• Atomic number: Number of protons in the nucleus.

• Atomic mass: Sum of protons and neutrons.

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

• Electron shells: Electrons occupy energy levels around the nucleus; valence electrons determine chemical behavior.

Chemical Bonds

• Covalent bonds: Atoms share electrons.

• Ionic bonds: Atoms transfer electrons, resulting in oppositely charged ions.

• Hydrogen bonds: Weak bonds between a hydrogen atom and an electronegative atom (e.g., O or N).

• Van der Waals interactions: Weak attractions due to transient local charges.

• Nonpolar covalent bonds: Electrons shared equally.

• Polar covalent bonds: Electrons shared unequally, creating partial charges.

Chemical Reactions

• Processes that make and break chemical bonds, rearranging matter.

Chapter 3: Water and Life

Structure and Properties of Water

• Polar covalent bonds: Oxygen is more electronegative than hydrogen, creating a polar molecule.

• Hydrogen bonds: Hold water molecules together, giving water unique properties.

Four Key Properties of Water

• Cohesion: Water molecules stick together due to hydrogen bonding.

• Moderation of temperature: Water has a high specific heat, stabilizing temperatures.

• Floating of ice: Solid water is less dense than liquid water due to hydrogen bond arrangement.

• Universal solvent: Water dissolves many substances due to its polarity.

Other Properties

• Surface tension: Measure of how difficult it is to stretch or break the surface of a liquid.

• Adhesion: Water molecules stick to other substances.

• Evaporative cooling: As water evaporates, it removes heat from surfaces.

Solutions and pH

• Solution: Homogeneous mixture of two or more substances.

• Solvent: Dissolving agent (e.g., water).

• Solute: Substance dissolved in the solvent.

• Hydrophilic: Substances that have an affinity for water.

• Hydrophobic: Substances that repel water.

• pH: Measure of hydrogen ion concentration; acidic (pH < 7), basic (pH > 7).

• Acids and bases: Acids increase H+ concentration; bases decrease it.

• Buffers: Substances that minimize changes in pH.

Chapter 4: Carbon and Life

Organic Chemistry and Carbon

• Organic chemistry: Study of carbon compounds.

• Stanley Miller's experiment: Demonstrated abiotic synthesis of organic molecules.

• Major elements: C, H, O, N, S, P.

• Carbon: Can form four covalent bonds due to four unpaired electrons.

Hydrocarbons and Isomers

• Hydrocarbons: Molecules consisting only of carbon and hydrogen.

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

• Structural isomers: Differ in covalent arrangements.

• Cis-trans isomers: Differ in spatial arrangement around double bonds.

• Enantiomers: Mirror-image isomers; important in pharmaceuticals.

Chemical Groups and ATP

• Chemical groups: Functional groups attached to carbon skeletons affect molecular function.

• ATP (Adenosine triphosphate): Main energy currency of the cell.

Chapter 5: Large Biological Macromolecules

Polymers and Monomers

• Polymers: Long molecules made of repeating units (monomers).

• Monomers: Building blocks of polymers.

• Enzymes: Catalysts that speed up chemical reactions.

• Dehydration reaction: Joins monomers by removing water.

• Hydrolysis: Breaks polymers by adding water.

Carbohydrates

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

• Disaccharides: Two monosaccharides joined by a glycosidic linkage.

• Polysaccharides: Many monosaccharides linked together (e.g., starch, glycogen, cellulose, chitin).

• Glycosidic linkage: Covalent bond joining sugars.

Lipids

• Fats and oils: Composed of glycerol and 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: Major component of cell membranes.

• Steroids: Lipids with four fused rings (e.g., cholesterol).

Proteins

• Amino acids: Monomers of proteins; 20 types.

• Peptide bonds: Link amino acids.

• R groups (side chains): Determine properties of amino acids.

• Four levels of protein structure: Primary, secondary, tertiary, quaternary.

• Denaturation: Loss of protein structure and function.

• Sickle cell disease: Caused by a single amino acid change in hemoglobin.

Nucleic Acids

• DNA vs. RNA: DNA stores genetic information; RNA helps express genes.

• Double helix: Structure of DNA; strands are antiparallel.

• Nucleotides: Monomers of nucleic acids; consist of a sugar, phosphate, and nitrogenous base (adenine, guanine, cytosine, thymine in DNA; uracil replaces thymine in RNA).

• Pyrimidines: Cytosine, thymine, uracil.

• Purines: Adenine, guanine.

Chapter 6: A Tour of the Cell

Microscopy

• Light microscopes: Use light to view cells; limited resolution.

• Electron microscopes: Use electrons for higher resolution images.

Cell Structure

• All cells: Surrounded by a plasma membrane, contain cytosol, chromosomes, and ribosomes.

• Prokaryotic cells: No nucleus; DNA in nucleoid region.

• Eukaryotic cells: DNA in nucleus; contain membrane-bound organelles.

Organelles and Structures

• Nucleus: Contains DNA; surrounded by nuclear envelope.

• Ribosomes: Sites of protein synthesis.

• Chromosomes: DNA molecules with associated proteins.

• Chromatin: DNA and protein complex in the nucleus.

• Nucleolus: Site of ribosome assembly.

Endomembrane System

• Nuclear envelope: Double membrane around nucleus.

• Endoplasmic reticulum (ER): Rough ER (with ribosomes) synthesizes proteins; smooth ER synthesizes lipids.

• Golgi apparatus: Modifies, sorts, and packages proteins and lipids.

• Lysosomes: Digestive organelles.

• Vacuoles: Storage and support (large in plant cells).

• Plasma membrane: Selectively permeable barrier.

Energy-Related Organelles

• Mitochondria: Sites of cellular respiration; produce ATP.

• Chloroplasts: Sites of photosynthesis in plants and algae.

• Peroxisomes: Break down fatty acids and detoxify harmful substances.

Cytoskeleton and Cell Surfaces

• Cytoskeleton: Network of protein fibers (microtubules, microfilaments, intermediate filaments) for support and movement.

• Cell wall: Rigid structure outside plasma membrane in plants, fungi, and some protists.

• Extracellular matrix (ECM): Network outside animal cells for support and signaling.

• Cell junctions: Connections between cells (plasmodesmata in plants; tight junctions, desmosomes, gap junctions in animals).

Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	Absent	Present
Membrane-bound organelles	Absent	Present
Size	Small (1-10 μm)	Larger (10-100 μm)
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Example:

Plant cells contain chloroplasts for photosynthesis, a large central vacuole for storage, and a cell wall for support, distinguishing them from animal cells.

Additional info: This guide expands on the study guide points with definitions, examples, and a comparison table for clarity.