Introduction to Biology

Domains of Life

The domain system classifies all living organisms into three major groups based on cellular structure and genetics.

• Bacteria: Prokaryotic, unicellular organisms lacking a nucleus.

• Archaea: Prokaryotic, often found in extreme environments, genetically distinct from bacteria.

• Eukarya: Eukaryotic organisms with cells containing a nucleus and organelles; includes animals, plants, fungi, and protists.

Hierarchy of Living Organisms

Biological organization ranges from simple to complex structures.

• Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism

Shared Characteristics of Living and Nonliving Things

• Living things: Exhibit metabolism, growth, reproduction, response to stimuli, and homeostasis.

• Nonliving things: May have structure and mass but lack biological processes.

Scientific Method

The scientific method is a systematic approach to investigation.

1. Observation

2. Hypothesis

3. Experiment

4. Data Collection

5. Analysis

6. Conclusion

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite external changes.

• Examples: Regulation of body temperature, blood pH, and glucose levels.

Chemistry of Life

Most Abundant Elements in Humanity

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

• Phosphorus (P)

• Sulfur (S)

Elements vs. Molecules

• Element: Pure substance consisting of one type of atom (e.g., O2).

• Molecule: Two or more atoms bonded together (e.g., H2O).

Types of Bonds

• Ionic Bonds: Transfer of electrons between atoms, forming charged ions.

• Covalent Bonds: Sharing of electrons between atoms.

• Hydrogen Bonds: Weak attraction between a hydrogen atom and another electronegative atom.

Polarity

• Polar Molecules: Unequal sharing of electrons, resulting in partial charges (e.g., water).

• Nonpolar Molecules: Equal sharing of electrons, no charge separation (e.g., methane).

Acids, Bases, and pH

• Acidic: pH < 7

• Basic (Alkaline): pH > 7

• Neutral: pH = 7

Radioisotope Technology

• Used in medical imaging, cancer treatment, and biological research.

• Radioisotopes emit radiation, allowing tracking of biological processes.

Reductionism

• Analyzing complex systems by studying their simpler components.

• Helps understand biological functions at molecular and cellular levels.

Atoms and Charge

• Atoms change charge by gaining or losing electrons, forming ions.

• Negatively charged elements (anions) attract positively charged elements (cations).

Structure & Function of Cells

Cell Organelles: Names, Functions, and Shapes

Cell organelles perform specialized functions essential for cell survival.

Cell Size and Surface Area

• Smaller cells have a higher surface area-to-volume ratio, facilitating efficient exchange of materials.

• As cell size increases, surface area grows slower than volume.

Microscopy Types

• Light Microscopy: Used for viewing live cells and tissues.

• Electron Microscopy: Provides high-resolution images of cell structures.

• Fluorescence Microscopy: Visualizes specific molecules using fluorescent tags.

Plasma Membrane Structure

• Composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

• Selective permeability regulates movement of substances.

What Can and Can't Pass Through the Plasma Membrane

• Can pass: Small, nonpolar molecules (e.g., O2, CO2), water (via aquaporins).

• Cannot pass: Large, polar molecules and ions without transport proteins.

Types of Junctions

• Tight Junctions: Seal cells together, preventing leakage.

• Gap Junctions: Allow communication between cells.

• Desmosomes: Provide mechanical strength.

Tissues & Organ Systems

Types of Tissues and Their Functions

Types of Connective Tissues

• Loose Connective Tissue: Supports and binds other tissues.

• Dense Connective Tissue: Provides strength (e.g., tendons, ligaments).

• Cartilage: Flexible support.

• Bone: Rigid support and protection.

• Blood: Transport of nutrients and waste.

Location of Each Tissue Type

• Epithelial: Skin, lining of digestive tract.

• Connective: Bones, tendons, blood.

• Muscle: Skeletal muscles, heart (cardiac muscle), stomach (smooth muscle).

• Nervous: Brain, spinal cord, peripheral nerves.

Type of Muscle in the Stomach

• Smooth Muscle: Involuntary, non-striated muscle found in the stomach and other internal organs.

Cellular Processes

Diffusion

• Movement of molecules from high to low concentration.

• Passive process, does not require energy.

Active Transport

• Movement of substances against concentration gradient.

• Requires energy (ATP).

Isotonic Solution

• Has equal solute concentration as the cell.

• Cells retain their normal shape; no net movement of water.

Cellular Respiration

Glycolysis

• First step in cellular respiration.

• Breaks down glucose into pyruvate, producing ATP and NADH.

Electron Transport Chain and ATP Production

• Most ATP is produced in the ATP synthase protein complex during the electron transport chain.

Electron Carriers in the Citric Acid Cycle

• NAD+ and FAD are electron carriers.

• They gain electrons from metabolic reactions and transfer them to the electron transport chain.

DNA and Its Importance

• DNA: Deoxyribonucleic acid; stores genetic information, directs cell activities, and enables inheritance.

Additional info:

• Some details about microscopy, cell junctions, and reductionism were inferred for completeness.

• Tables were recreated for organelles and tissue types for clarity.