Chapter 1-5 BIO189

What is Science?

  • Study of the natural world through observation and systematic experimentation.

The Scientific Method:

  • A standardized approach for testing ideas and answering questions.

General Process:

  1. Make observations.

  2. Ask questions about observations.

  3. Develop hypotheses and make predictions.

  4. Experimentation with data collection to test hypotheses.

  5. Analyze data.

  6. Draw conclusions about hypothesis support or rejection.

Key Characteristics of Hypotheses:

  • Must be testable (experiments can generate data).

  • Must be falsifiable (possible outcomes can disprove the hypothesis).

  • Hypotheses can be supported by data but are never proven true due to potential future discoveries.

A Theory:

  • A comprehensive explanation for natural phenomena based on extensive research.

Biological Science:

  • Biology = life = chemistry + physics.

  • Hierarchical organization: Atoms → Molecules → Macromolecules/Biomolecules → Organelles → Cells → Organisms.

Matter:

  • Anything with mass occupying physical space.

  • Atoms: smallest units of matter; 118 elements total, with N, C, H, O, P, S making up ~98% of organisms.

Atomic Structure:

  • Element boxes contain:

    • Element symbol and name.

    • Atomic number (top left).

    • Atomic weight (decimal number).

Nuclear Processes:

  • Nuclear fusion: two nuclei combine to form a larger element.

  • Radioactive decay: unstable isotopes decay spontaneously.

Chemical Bonds:

  • Molecules: two or more bonded atoms.

  • Compounds: molecules made of atoms from different elements.

  • Ionic bonds: form between atoms with very different electronegativities.

  • Covalent bonds: occur when atoms share electrons.

    • Polar covalent bonds: unequal sharing of electrons.

    • Non-polar covalent bonds: equal sharing.

Biological Molecules:

  • Built on a carbon framework, known as organic molecules.

  • Polymers: macromolecules composed of monomers linked by dehydration synthesis.

Carbohydrates:

  • Sugars; amylose (starch) and cellulose (plant cell walls).

Proteins:

  • Chains of amino acids linked by peptide bonds. Central dogma: DNA → RNA → Protein via transcription and translation.

Protein Structure:

  1. Primary: amino acid sequence.

  2. Secondary: alpha helixes and beta sheets from hydrogen bonding.

  3. Tertiary: 3-D shape from interactions among secondary structures.

  4. Quaternary: complexes formed by multiple folded proteins.

Cell Components:

  • Nucleus: houses DNA; surrounded by a membrane.

  • Organelles: Rough and smooth ER, Golgi apparatus, lysosome, peroxisome.

  • Cytosol: jelly-like fluid with dissolved solutes.

  • Cell membrane: lipid-rich bilayer with proteins.

Plant Cell Features:

  • Cell wall, central vacuole, chloroplasts, and plasmodesmata.

Enzyme Action:

  • Catalysts that enhance reaction rates without permanent change.

  • Active site: where substrates are processed (induced fit model).

Osmosis:

  • Movement of water between solutions of different solute concentrations:

    • Isotonic: equal concentration.

    • Hypertonic: higher outside concentration.

    • Hypotonic: lower outside concentration.