Cell Structure and Function: Subcellular Components and Compartmentalization

Cell Structure and Function

Introduction to Cells

Cells are the basic structural and functional units of every organism. All living things are composed of cells, which perform essential life processes.

• Plasma membrane: All cells are bound by a plasma membrane that regulates the movement of substances in and out of the cell.

• Cytosol: The semi-fluid substance inside the cell where organelles are suspended.

• Chromosomes: Structures that carry genetic information (DNA).

• Ribosomes: Complexes that synthesize proteins.

Types of Cells

Prokaryotes vs. Eukaryotes

Cells are classified into two main types: prokaryotic and eukaryotic cells. These types differ in structure, complexity, and the presence of membrane-bound organelles.

Prokaryotes	Eukaryotes
Includes Bacteria and Archaea DNA is located in the nucleoid region (no true nucleus) Generally smaller in size No membrane-bound organelles Have ribosomes	Includes Protists, Fungi, Animals, and Plants DNA is enclosed in a nucleus Approximately 10 times larger than prokaryotes Contain membrane-bound organelles

Example: Escherichia coli is a prokaryote; human skin cells are eukaryotes.

Organelles

Definition and Overview

Organelles are specialized, membrane-bound structures within eukaryotic cells that perform distinct functions necessary for cellular life. Prokaryotic cells lack most organelles but do contain ribosomes.

• Membrane-bound organelles: Found only in eukaryotes; include the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, and (in plants) chloroplasts.

• Non-membrane-bound organelles: Ribosomes are found in both prokaryotes and eukaryotes.

Compartmentalization: The presence of organelles allows eukaryotic cells to compartmentalize different metabolic reactions, increasing efficiency and preventing interference between incompatible processes.

• Increases surface area for reactions

• Prevents conflicting reactions from occurring in the same location

Summary Table: Key Differences Between Prokaryotic and Eukaryotic Cells

Feature	Prokaryotes	Eukaryotes
Organisms	Bacteria, Archaea	Protists, Fungi, Animals, Plants
DNA Location	Nucleoid (no membrane)	Nucleus (membrane-bound)
Size	Smaller	Larger (approx. 10x)
Membrane-bound Organelles	Absent	Present
Ribosomes	Present (smaller)	Present (larger)

Additional info: The images in the slides show typical prokaryotic and eukaryotic cell structures, highlighting the differences in internal organization.