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: Life is organized in a hierarchy from molecules to the biosphere. Emergent properties arise at each level due to arrangement and interactions of parts.

• Information: Genetic information is stored in DNA and transmitted from parent to offspring. DNA encodes instructions for building proteins.

• Energy and Matter: Life requires energy transfer and transformation. Energy flows through ecosystems (usually entering as sunlight and exiting as heat), while chemicals cycle within ecosystems.

• Interactions: Organisms interact with each other and their environment, affecting both. Feedback regulation (especially negative feedback) maintains homeostasis.

• Evolution: Explains the unity and diversity of life. All life shares common ancestry, but adaptations lead to diversity.

Cells: The Basic Unit of Life

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

• Prokaryotic cells: Lack a nucleus and most organelles.

Genetic Information and DNA

• DNA: Deoxyribonucleic acid, the molecule of heredity.

• Transmits genetic information from one generation to the next.

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 the end product slows or stops its own production.

Climate Change

• Caused by increased greenhouse gases (e.g., CO2), leading to global warming and altered weather patterns.

Unity and Diversity of Life

• Three domains: Bacteria, Archaea, Eukarya.

Charles Darwin and Natural Selection

• Natural selection: Process by which organisms with advantageous traits survive and reproduce more successfully.

Scientific Inquiry

• Inductive reasoning: Deriving generalizations from specific observations.

• Deductive reasoning: Making predictions based on general premises.

• Hypothesis: A testable explanation for an observation.

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

• Independent variable: The factor manipulated in an experiment.

• Dependent variable: The factor measured in an experiment.

Chapter 2: The Chemical Context of Life

Elements and Compounds

• Element: A substance that cannot be broken down 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).

Structure of the Atom

• Atomic number: Number of protons in the nucleus.

• Atomic mass: Total mass of protons and neutrons.

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

• Valence electrons: Electrons in the outermost shell, determine chemical behavior.

Chemical Bonds

• Covalent bonds: Sharing of electron pairs between atoms.

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

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

• Van der Waals interactions: Weak, transient interactions due to fluctuating charges.

• Nonpolar covalent bonds: Electrons shared equally.

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

Chemical Reactions

• Making and breaking of chemical bonds, leading to changes in the composition of 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: Form between water molecules, leading to unique properties.

Four Properties of Water Essential for Life

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

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

• Floating of ice: Ice is less dense than liquid water, so it floats.

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

Additional Properties

• Surface tension: Cohesion at the surface of water creates a "skin".

• Adhesion: Water molecules stick to other substances.

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

Solutions and pH

• Solution: Homogeneous mixture of two or more substances.

• Solvent: The dissolving agent (e.g., water).

• Solute: The substance dissolved.

• Hydrophilic: Substances that dissolve in water.

• Hydrophobic: Substances that do not dissolve in water.

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

• Acids: Donate H+ ions.

• Bases: Accept H+ ions.

• Buffers: Substances that minimize changes in pH.

Chapter 4: Carbon and Life

Organic Chemistry and Carbon

• Organic chemistry: Study of carbon-containing compounds.

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

• Carbon: Can form four covalent bonds, allowing for diverse molecules.

• Major elements: C, H, O, N, S, P.

• Unpaired electrons: Determine bonding capacity.

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 arrangement.

• 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 (e.g., hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl) affect molecular function.

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

Chapter 5: The Structure and Function of Large Biological Macromolecules

Polymers and Monomers

• Polymer: Long molecule made of repeating units (monomers).

• Monomer: Small building block 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 (e.g., sucrose).

• Polysaccharides: Polymers of sugars (e.g., starch, glycogen, cellulose, chitin).

• Functions: Energy storage (starch, glycogen), structural support (cellulose, chitin).

Lipids

• Fats and oils: Glycerol + 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 with different R groups (side chains).

• Peptide bonds: Link amino acids.

• Protein structure: Four levels:

  1. Primary: Sequence of amino acids.

  2. Secondary: Alpha helices and beta sheets (hydrogen bonding).

  3. Tertiary: 3D shape due to side chain interactions.

  4. Quaternary: Association of multiple polypeptides.

• 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 in gene expression.

• Structure: DNA is a double helix, antiparallel strands.

• Monomers: Nucleotides (adenine, guanine, cytosine, thymine in DNA; uracil replaces thymine in RNA).

• Pyrimidines: Cytosine, thymine, uracil (single ring).

• Purines: Adenine, guanine (double ring).

Chapter 6: A Tour of the Cell

Microscopy

• Light microscopes: Use visible light to observe cells.

• Electron microscopes: Use electron beams for higher resolution.

Cell Types

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

• Prokaryotic cells: No nucleus, DNA in nucleoid, lack membrane-bound organelles.

• Eukaryotic cells: DNA in nucleus, have membrane-bound organelles.

Cell Structures and Organelles

• Nucleus: Contains DNA, surrounded by nuclear envelope.

• Ribosomes: Sites of protein synthesis.

• Chromosomes: DNA molecules with associated proteins.

• Chromatin: DNA and proteins in a less condensed form.

• Nucleolus: Site of ribosome assembly.

Endomembrane System

• Nuclear envelope: Double membrane around nucleus.

• Endoplasmic reticulum (ER):

  • Rough ER: Studded with ribosomes; protein synthesis.

  • Smooth ER: Lipid synthesis, detoxification.

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

• Lysosomes: Contain digestive enzymes.

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

• Plasma membrane: Selective barrier around the cell.

Energy Organelles

• Mitochondria: Site of cellular respiration (ATP production).

• Chloroplasts: Site of photosynthesis (in plants and algae).

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

Cytoskeleton

• Network of fibers for support, movement, and transport.

  • Microtubules

  • Microfilaments

  • Intermediate filaments

Cell Wall, Extracellular Matrix, and Cell Junctions

• Cell wall: Rigid structure outside the plasma membrane (plants, fungi, some protists).

• Extracellular matrix (ECM): Network of proteins and carbohydrates outside animal cells.

• Cell junctions: Connections between cells; four types:

  • Tight junctions

  • Desmosomes

  • Gap junctions

  • Plasmodesmata (in plants)