BIOL 106 Final Exam Review: Core Concepts in Biology

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Hypothesis: A proposed explanation for an observation, based on limited evidence and subject to testing. It is distinct from a theory (a well-supported explanation) and a law (a statement based on repeated experimental observations).
Variables in Experiments:
- Dependent Variable: The factor measured or observed in response to changes in the experiment.
- Independent Variable: The factor intentionally changed to test its effect.
- Controlled Variables: Factors kept constant to ensure a fair test.
Data Types:
- Quantitative Data: Numerical measurements (e.g., height, mass).
- Qualitative Data: Descriptive observations (e.g., color, texture).

Atomic Structure: Atoms consist of protons (positive) and neutrons (neutral) in the nucleus, with electrons (negative) orbiting outside. Valence electrons (outermost shell) are involved in chemical bonding.
Types of Chemical Bonds:
- Covalent Bonds: Atoms share electrons.
- Ionic Bonds: Electrons are transferred, forming charged ions.
- Hydrogen Bonds: Weak attractions between polar molecules (e.g., between water molecules, DNA strands).
- Hydrophobic Interactions: Nonpolar molecules aggregate to avoid water, influencing protein folding and membrane structure.
Acidity & pH:
- pH Scale: Measures hydrogen ion concentration; acids have pH < 7, bases have pH > 7, and pH 7 is neutral.
- Examples: Lemon juice (pH ~2) is more acidic than tap water (pH ~7).

Osmosis: Movement of water across a semi-permeable membrane from low to high solute concentration. Differs from diffusion (movement of solute), facilitated diffusion (protein-assisted), and active transport (requires energy).
Organic Molecules: Contain carbon; include carbohydrates, lipids, proteins, and nucleic acids. Inorganic molecules (e.g., water, salts) do not contain carbon.
Macromolecules:
- Dehydration Synthesis: Joins monomers, releasing water.
- Hydrolysis: Breaks polymers into monomers using water.
- Building Blocks:
  - Proteins: Made of amino acids.
  - Nucleic Acids: Made of nucleotides.
  - Carbohydrates: Made of sugars (monosaccharides).
  - Lipids: Made of fatty acids and glycerol.
- Enzymes: Proteins that catalyze (speed up) chemical reactions.

Mitochondria: Site of cellular respiration (Krebs cycle, electron transport chain). Not involved in photosynthesis (chloroplasts) or protein synthesis (ribosomes).
Plant Cells: Have a cell wall and central vacuole. Both plant and animal cells contain mitochondria, a nucleus, and Golgi apparatus.
Prokaryotes vs. Eukaryotes:
- Prokaryotes: (Bacteria, Archaea) Lack a nucleus and membrane-bound organelles; smaller and simpler.
- Eukaryotes: Have a nucleus and membrane-bound organelles.
Transport Across Membranes:
- Passive Transport: (Diffusion, osmosis) Does not require energy.
- Active Transport: Uses ATP to move substances against a concentration gradient.

Photosynthesis:
- Occurs in chloroplasts.
- Light reactions split water, releasing oxygen.
- Calvin cycle (dark reactions) uses CO2 to synthesize glucose.
Cellular Respiration:
- Aerobic Respiration: Uses oxygen, produces most ATP via the electron transport chain (ETC).
- Anaerobic Respiration (Fermentation): Occurs without oxygen, yields less ATP.
- Glycolysis: Occurs in the cytoplasm, does not require oxygen.
- Krebs Cycle and ETC: Occur in mitochondria.

Cell Cycle Phases:
- G1: Cell growth.
- S: DNA replication.
- G2: Preparation for division.
- M: Mitosis (nuclear division).
- Cytokinesis: Division of cytoplasm.
Mitosis: For growth, repair, and asexual reproduction; produces genetically identical diploid cells.
Meiosis: Produces haploid gametes (sperm, egg); involves crossing over and increases genetic variation.
Telophase: Final phase of mitosis where the nuclear envelope reforms.

DNA Processes:
- Replication: DNA is copied in the nucleus.
- Transcription: DNA is transcribed to RNA in the nucleus.
- Translation: RNA is translated into protein at ribosomes in the cytoplasm.
Types of RNA:
- mRNA (Messenger RNA): Carries genetic code from DNA to ribosomes.
- tRNA (Transfer RNA): Brings amino acids to the ribosome during translation.
- rRNA (Ribosomal RNA): Structural and functional component of ribosomes.
Mutations:
- Point Mutation: Single base change.
- Frameshift Mutation: Insertion or deletion shifts the reading frame.
- Nonsense Mutation: Mutation creates a premature stop codon.

Blood Type Inheritance:
- Type O: Two O alleles.
- Type AB: One A and one B allele; cannot be a parent of a type O child.
Sex-Linked Traits:
- X-linked Recessive: More common in males (one X chromosome); females need two copies to express the trait.

Natural Selection: Individuals with advantageous traits are more likely to survive and reproduce.
Artificial Selection: Humans breed organisms for desired traits (e.g., dog breeds).
Transgenic Organisms: Contain DNA from another species.
Species Concept: A species is a group of organisms that can interbreed and produce fertile offspring.

Classification Hierarchy:
- Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
Domains:
- Bacteria: Prokaryotic cells.
- Archaea: Prokaryotic, often extremophiles.
- Eukarya: Eukaryotic cells.
Kingdom Plantae: Multicellular, photosynthetic autotrophs.

Levels of Organization:
- Population: Individuals of one species in the same place/time.
- Community: All living species in the same place/time.
- Ecosystem: Community plus abiotic factors (e.g., climate, soil).
Carbon Cycle:
- CO2 is removed from the atmosphere by photosynthesis.
- CO2 is returned by respiration, decomposition, and combustion.
Trophic Levels:
- Producers: Autotrophs (plants).
- Primary Consumers: Herbivores.
- Secondary Consumers: Carnivores that eat herbivores.
- Tertiary/Quaternary Consumers: Top predators.
Predation: One organism kills and consumes another. Differs from parasitism (harm without immediate death) and mutualism (both benefit).

Bond Type	Description	Example
Covalent	Electrons shared between atoms	H2O, O2
Ionic	Electrons transferred, forming ions	NaCl
Hydrogen	Weak attraction between polar molecules	Between water molecules, DNA strands

Macromolecule	Monomer	Function
Carbohydrate	Monosaccharide	Energy storage, structure
Lipid	Fatty acid & glycerol	Energy storage, membranes
Protein	Amino acid	Enzymes, structure, transport
Nucleic Acid	Nucleotide	Genetic information