General Biology: Foundations, Chemistry, and Cell Structure Study Notes

Biology: The Scientific Study of Life

Definition and Scope of Biology (1.1–1.3)

Biology is the scientific study of life, encompassing the structure, function, growth, and evolution of living organisms. It investigates the processes that sustain life and the diversity of living forms.

• Biology is the study of life, including reproduction, growth, development, energy processing, regulation, response to the environment, and evolutionary adaptation.

• Domains of Life: Life is classified into three domains: Bacteria, Archaea, and Eukarya. Domains Bacteria and Archaea contain prokaryotic cells, while Domain Eukarya includes protists and the kingdoms Fungi, Plantae, and Animalia.

• Biological Organization: Life is organized in a hierarchy: organism > organ system > organ > tissue > cell > organelle > molecule. Properties emerge at each level due to interactions among components.

• Emergent Properties: New properties arise at each level of organization that are not present at lower levels, due to the arrangement and interactions of parts.

The Process of Science

Scientific Inquiry and Method (1.4–1.8)

Science uses evidence-based processes to investigate the natural world. The scientific method involves observation, hypothesis formation, experimentation, and analysis.

• What is Science? Science is based on evidence and involves observation, hypothesis, prediction, and testing.

• Hypothesis: A testable explanation for a set of observations. Hypotheses can be supported or refuted by data.

• Controlled Experiments: Experiments that use control and experimental groups to test the effect of a single variable.

• Experimental Groups: Groups that receive the variable being tested, while control groups do not.

Elements, Atoms, and Compounds

Basic Chemical Principles (2.1–2.4)

All living organisms are composed of elements, which combine to form compounds. Atoms are the basic units of matter, consisting of protons, neutrons, and electrons.

• Elements: Substances that cannot be broken down into simpler substances. Common biological elements include carbon, hydrogen, oxygen, nitrogen, calcium, and phosphorus.

• Compounds: Substances formed by the chemical combination of two or more elements.

• Atoms: The smallest units of matter, composed of protons, neutrons, and electrons.

• Trace Elements: Elements required in small amounts, such as iron and iodine, essential for life.

• Isotopes: Atoms of the same element with different numbers of neutrons. Some isotopes are radioactive and can be used in medical imaging.

Subatomic Particle	Charge	Location
Proton	+1	Nucleus
Neutron	0	Nucleus
Electron	-1	Electron cloud

Chemical Bonds

Types and Properties of Bonds (2.5–2.9)

Chemical bonds hold atoms together in molecules and compounds. The type of bond affects the properties of the substance.

• Electron Distribution: Determines an atom's chemical properties and ability to form bonds.

• Covalent Bonds: Atoms share electrons to form molecules. Can be polar (unequal sharing) or nonpolar (equal sharing).

• Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions that attract each other.

• Hydrogen Bonds: Weak bonds important in the structure of water and biological molecules.

• Chemical Reactions: Involve making and breaking chemical bonds, resulting in new substances.

Bond Type	Description	Example
Covalent	Atoms share electrons	H2O (water)
Ionic	Atoms transfer electrons	NaCl (salt)
Hydrogen	Weak attraction between polar molecules	Between water molecules

Introduction to Organic Compounds

Properties and Diversity (3.1–3.3)

Organic compounds are based on carbon and form the molecular foundation of life. The diversity of organic molecules arises from variations in carbon skeletons and functional groups.

• Properties of Carbon: Carbon can form four covalent bonds, allowing for a variety of molecular shapes and sizes.

• Hydrocarbons: Compounds composed only of carbon and hydrogen.

• Functional Groups: Groups of atoms that confer specific chemical properties to organic molecules.

• Macromolecules: Large molecules made from smaller subunits (monomers).

Carbohydrates

Structure and Function (3.4–3.7)

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as energy sources and structural components in cells.

• Monosaccharides: The simplest carbohydrates, such as glucose and fructose. They are single sugar units.

• Disaccharides: Formed by joining two monosaccharides, e.g., sucrose (table sugar).

• Polysaccharides: Long chains of sugar units, such as starch, glycogen, and cellulose. They serve as energy storage and structural materials.

• Dietary Importance: Carbohydrates are a major source of energy in the diet.

Type	Example	Function
Monosaccharide	Glucose	Energy source
Disaccharide	Sucrose	Transported sugar in plants
Polysaccharide	Starch	Energy storage in plants
Polysaccharide	Cellulose	Structural support in plant cell walls

Introduction to the Cell

Cell Structure and Function (4.1–4.4)

Cells are the basic units of life. Microscopes reveal their structure and allow scientists to study their organization and function.

• Microscopy: Light and electron microscopes are used to study cells. Electron microscopes provide higher magnification and resolution.

• Cell Membrane: The plasma membrane encloses the cell and regulates the movement of substances in and out.

• Prokaryotic vs. Eukaryotic Cells: Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells have both.

• Compartmentalization: Eukaryotic cells are divided into functional compartments (organelles).

Cell Type	Nucleus	Organelles
Prokaryotic	No	No
Eukaryotic	Yes	Yes

The Nucleus and Ribosomes

Genetic Information and Protein Synthesis (4.5–4.6)

The nucleus stores genetic information, while ribosomes are the sites of protein synthesis.

• Nucleus: Contains the cell's DNA and directs protein synthesis via messenger RNA (mRNA).

• Ribosomes: Assemble amino acids into proteins according to instructions from mRNA.

• Location: Ribosomes can be free in the cytoplasm or attached to the endoplasmic reticulum.

The Endomembrane System

Cellular Organization and Function (4.7–4.12)

The endomembrane system is a network of membranes within eukaryotic cells that compartmentalizes cellular activities.

• Components: Includes the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and vesicles.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids and processes toxins.

• Function: The endomembrane system is involved in the synthesis, modification, and transport of cellular products.