Section 2 Introduction to CellsChapter 4

Objectives

• Describe the three basic parts of a cell.

• Compare prokaryotic cells and eukaryotic cells.

Section 2 Introduction to CellsChapter 4

Basic Parts of a Cell

• The three basic parts of a cell are the plasma membrane, the cytoplasm, and the nucleus.

» Pg 74 – Figure 4-6 shows surface of cell membrane and the diagram below is also shown

Section 2 Introduction to CellsChapter 4

Basic Parts of a Cell, continued

• Plasma Membrane– The cell’s outer boundary, called the plasma

membrane (or the cell membrane), covers a cell’s surface and acts as a barrier between the inside and the outside of a cell.

» All materials enter or exit through the plasma membrane

Section 2 Introduction to CellsChapter 4

Basic Parts of a Cell, continued

• Cytoplasm– The region of the cell that is within the plasma

membrane and that includes the fluid, the cytoskeleton, and all of the organelles except the nucleus is called the cytoplasm.

Section 2 Introduction to CellsChapter 4

Basic Parts of a Cell, continued

• Nucleus– The nucleus is a membrane-bound organelle that

contains a cell’s DNA. » This is often called the control center of cells

Section 2 Introduction to CellsChapter 4

Two Basic Types of Cells• Prokaryotes

– Prokaryote cells lack a nucleus and membrane-bound organelles.

– Prokaryotes are divided into domains Bacteria and Archaea

• These existed on Earth before Eukaryotes

Section 2 Introduction to CellsChapter 4

Two Basic Types of Cells, continued

• Eukaryotes– Eukaryote cells have a nucleus and membrane-

bound organelles.» Eukaryotes cells are generally much larger than

prokaryotic cells

» Amoeba is an example of a Eukaryotic cell

» Ex. Pg 75, Figure 4-8 shows white blood cell (eukaryotic) attacking a much smaller bacteria cell (prokaryotic)

– Organelles are intracellular bodies that perform specific functions for the cell

Prokaryote Two Cell Types EukaryoteNo nucleus Nucleus

No membrane- Many organellesbound organelles

Existed first Existed second

small large

Circular chromosome linear chromosome

Binary fission mitosis