Biology Chapter 2: Chemical Basis of Life

Properties of Life

• Life exhibits several key characteristics: regulation (homeostasis), growth and development, reproduction, response to environment, and energy processing.

Levels of Organization (Largest to Smallest)

• Biosphere
• Ecosystem
• Communities
• Populations
• Organisms
• Organ systems
• Organs
• Tissues
• Cells
• Organelles

Groups within Domain Eukarya

• Protists
• Fungi
• Plants
• Animals

Hypothesis

• A testable explanation for observations, narrower than a theory. It is based on available data and inductive reasoning.

Theory

• A broader explanation supported by extensive evidence, generating further hypotheses.

Chapter 2: Chemical Basis of Life

Matter and Compounds

• Matter: Anything with mass and occupies space.
• Compound: Two or more elements combined in a fixed ratio.

Subatomic Particles

• Atoms are composed of neutrons (neutral charge), protons (positive charge), and electrons (negative charge).
• Neutrons and protons located in the nucleus.
• Electrons orbit the nucleus.

Atomic Number and Mass Number

• Atomic number: Number of protons in an atom (also equals number of electrons).
• Mass number: Sum of protons and neutrons in an atom.

Isotopes

• Isotopes: Atoms of the same element with different mass numbers (due to varying neutron numbers).

Water Properties

• Water's formula: H₂O (hydrogen and oxygen).
• Water molecules are held together by hydrogen bonds.
• Individual water molecules are bonded by covalent bonds.
• Ice is less dense than liquid water.
• pH scale: Each step represents a 10-fold difference.

Chemical Bonds

• Ionic bond: One atom loses an electron permanently to another (e.g., NaCl).
• Covalent bond: Atoms share electrons to complete their outer shells (e.g., water).

Chapter 3: The Molecules of Cells

Carbon

• Carbon's characteristic: Four valence electrons allowing for many covalent bonds.

Isomers

• Isomers: Compounds with the same chemical formula but different arrangements of atoms.

Macromolecules (Polymers and Monomers)

• Carbohydrates (polysaccharides): Monosaccharides (glucose, galactose, fructose)
• Proteins: Amino acids
• Nucleic acids: Nucleotides

Carbohydrates

• Monosaccharide: The simplest carbohydrate, including glucose, galactose, and fructose.
• Polysaccharides: Chains of monosaccharides.
  • Starch: Found in plants like potatoes (energy storage).
  • Glycogen: Found in animal muscle tissues (energy storage).
  • Cellulose: Found in plant cell walls (structural).

Dehydration Reaction

• Dehydration reaction: Monomers link to form polymers, losing a water molecule in the process.

Fats (Lipids)

• Saturated fats: Solid at room temperature.
• Unsaturated fats: Liquid at room temperature.

Proteins

• Proteins contain carbon, hydrogen, oxygen, and nitrogen.

Chapter 4: A Tour of the Cell

Cell Theory

• All living things are composed of cells.
• Cells are the basic units of structure and function in living things.
• New cells are produced from existing cells.

Microscopes

• Transmission electron microscope (TEM): Produces 2D images of thin slices of specimens.
• Scanning electron microscope (SEM): Creates 3D images of a specimen's surface without sectioning.

Organelles: Plant vs. Animal Cells

• Plant cells only: Cell wall, chloroplasts, central vacuole
• Animal cells only: Lysosomes, centrioles, centrosomes, intermediate filaments.

Organelles and Functions (Note: Review specific details from your course material for full understanding.)

Explore the properties of life and the levels of biological organization in this quiz. Delve into the chemical basis of life, including matter, compounds, and the structure of atoms. Test your knowledge on eukaryotic domains and the scientific concepts of hypothesis and theory.