Cells and Their Functions

The Fundamental Units of Life

• Cells are the foundation of living systems, similar to atoms in chemistry.
• Cells are involved in various bodily functions, such as muscle contraction and nerve cell communication.
• All organisms, single-celled or multicellular, are composed of cells.
• Multicellular organisms rely on specialized cells working together to function.
• Cells are the basic unit of structure and function in all organisms.
• Cells descended from previous cells, leading to diverse adaptations.
• Despite their variations, cells share fundamental characteristics.

Tools to Study Cells

• Microscopes and biochemical techniques are used to study cells.
• Microscopes, invented in the 1590s, enabled the discovery and initial study of cells.
• Robert Hooke observed cell walls in dead cells in 1665 using a microscope.

Microscopy

• Stains used for light microscopy differ from those used for electron microscopy.
• Researchers use microscopy to identify organelles and their functions.

Prokaryotic Cells

• Prokaryotes lack a nucleus.
• Prokaryotes include bacteria and archaea.
• The term prokaryotic means “before nucleus”.
• Prokaryotes evolved before eukaryotic cells.

Eukaryotic Cells

• Eukaryotic cells have internal membranes that compartmentalize their functions.
• The region between the nucleus and the plasma membrane in a eukaryotic cell is called the cytoplasm
• Cytosol is the fluid within the cytoplasm.

The Endomembrane System

• The endomembrane system regulates protein traffic and performs metabolic functions.
• The endomembrane system includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and the plasma membrane.
• The endomembrane system synthesizes proteins, transports proteins, metabolizes lipids, and detoxifies poisons
• The membranes of the endomembrane system can be connected by direct physical continuity or transfer of membrane segments in vesicles.

Endoplasmic Reticulum (ER)

• The endoplasmic reticulum (ER) is an extensive network of interconnected tubules and flattened sacs.
• The ER is a biosynthetic factory.
• Smooth ER is involved in lipid synthesis, detoxification, and calcium storage.
• Rough ER is studded with ribosomes and involved in protein synthesis.
• The ER lumen is the space enclosed by the ER membrane.

Golgi Apparatus

• The Golgi apparatus is a stack of flattened sacs known as cisternae.
• The Golgi apparatus modifies, sorts, and packages proteins and lipids from the ER.

Lysosomes

• Lysosomes are membrane-bound organelles that contain enzymes for digestion.

Vacuoles

• Vacuoles are large membrane-bound sacs.
• Vacuoles store water and other substances.

Plasma Membrane

• The plasma membrane is a selectively permeable barrier that surrounds the cell
• The plasma membrane controls the movement of substances into and out of the cell.
• The plasma membrane is composed of a phospholipid bilayer with embedded proteins.
• The cell membrane is also known as the plasma membrane.

The Importance of Surface Area to Volume Ratio

• As a cell grows, its volume increases faster than its surface area.
• A smaller object has a greater surface area to volume ratio.
• A high surface-to-volume ratio allows for efficient exchange of materials between a cell and its environment.

Compartmentalization

• The internal membranes of eukaryotic cells divide the cells into different compartments.
• Compartmentalization provides specific environments for different metabolic functions.

Explore the fundamental units of life through this quiz on cells. Learn about the structure, function, and specialized roles of cells in both single-celled and multicellular organisms. Test your knowledge on historical tools like microscopes that revolutionized cell study.