Science as a Way of Knowing

Science as a Way of Knowing, Doing, and Looking

• Science relies on evidence, explains phenomena and predicts, avoids bias.
• Scientific knowledge includes facts, concepts, theories, and laws.
• Science is organized into subjects like biology, chemistry, and physics.
• Science uses flexible and iterative methods (observation, experimentation, inference).
• Scientific knowledge is changeable, the universe is understandable, and science has limitations.
• Science examines individual and social dimensions of scientific work.
• Scientific skills include intellectual honesty, objectivity, open-mindedness, critical thinking, and curiosity.

Measurements

• The International System (SI) is used for measurements (meters, kilograms, seconds, etc.).
• Accuracy is closeness to the true value, precision is consistent repeated measurements.
• Significant figures indicate measurement reliability.
• Tools like rulers, balances, and thermometers ensure accuracy and precision.

Biomolecules

Carbohydrates

• Monosaccharides (simple sugars): glucose, fructose, galactose.
• Disaccharides: formed from two monosaccharides (e.g., sucrose, lactose).
• Polysaccharides (complex sugars): starch, glycogen, cellulose.

Proteins

• Made of amino acids. Diverse functions (enzymes, structural components, antibodies).

Lipids

• Includes fats, oils, phospholipids, steroids.
• Functions: energy storage, cell membranes, signaling.

Atwater System

• Estimates food caloric value:
  • Carbohydrates and proteins: 4 kcal/g
  • Lipids: 9 kcal/g
  • Alcohol: 7 kcal/g
• Formula: Multiply nutrient gram quantity by respective kcal value.

Data Tables and Graphs

• Pie graphs: represent parts of a whole.
• Bar graphs: compare quantities across categories.
• Line graphs: show trends over time.
• Graphs need titles, axis labels, legends, and clear scales.

Fundamental vs Derived Quantities

• Fundamental quantities: basic units (length, mass, time; meters, kilograms, seconds).
• Derived quantities: calculated from fundamental quantities (e.g., area, volume, speed, force).

Cell Theory

Overview

• The Cell Theory is a key biological concept explaining cells as life's building blocks.

Key Contributors

• Robert Hooke (1665): coined "cell" after observing cork under a microscope.
• Anton van Leeuwenhoek: Father of Microscopy, observed living cells and "animalcules".
• Robert Brown (1831): discovered the nucleus while studying plant cells.
• Mathias Schleiden (1838): proposed cells are the basic unit of life in plants.
• Theodor Schwann (1839): extended Schleiden's idea to animals: Animal tissues are composed of cells.
• Rudolf Virchow (1839): established that all cells come from pre-existing cells ("Omnis cellula e cellula").

Six Tenets of Cell Theory

• Cells are the basic unit of life.
• All living things are made of cells.
• All cells come from pre-existing cells.
• Cells reproduce through division (e.g. mitosis).
• DNA is passed during cell division, explaining heredity.
• Cells of similar species share similar structure and function.
• Energy flow occurs within cells, including metabolism like photosynthesis.

Domains of Life

• Three domains: Bacteria, Archaea, and Eukarya.
• Bacteria and Archaea are prokaryotes (single-celled, no nucleus).
• Eukarya includes eukaryotes, which are multicellular and have a nucleus.

Prokaryotes

• Lack a nucleus and membrane-bound organelles.
• Important structures: pili, plasmid, ribosomes, cytoplasm, cell membrane, cell wall, capsule.

Eukaryotes

• Have a nucleus and membrane-bound organelles.
• Key organelles: nucleus, endoplasmic reticulum (rough and smooth), Golgi apparatus, mitochondria, vacuoles, lysosomes, centrioles.

Specialized Structures

Animal Cells

• Cytoskeleton: maintains cell shape, facilitates movement (cilia, flagella).
• Centrioles: organize microtubules for cell division.

Plant Cells

• Cell wall: provides structure and protection.
• Chloroplasts: contain chlorophyll for photosynthesis.
• Central vacuole: stores substances.