1. Lecture 1 The cell

2. Learning Objectives : 1.Explain the difference between prokaryotic and eukaryotic cells and be able to distinguish eukaryotc cells under the microscope. 2.Examine the diversity in cell size and shape. 2

3. 3 The Cell. All organisms are composed of cells..All cells represent a continuous line of descent from the first living cells.

4. Cell Size 4

5. Characteristics of All Cells A surrounding membrane Protoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA 5

6. Cell Types Prokaryotic Eukaryotic 6

7. 7 Prokaryotic Cells -lack a membrane-bound nucleus. -genetic material is present in the nucleoid Examples of prokaryote: -virus -bacteria

8. 8 Flagella -present in some prokaryotic cells -used for locomotion -rotary motion propels the cell secretion

9. 9 Eukaryotic Cells -possess a membrane- bound nucleus - many cellular functions within organelles -possess a cytoskeleton for support and maintain cellular structure

10. 10 Nucleus -stores the genetic material of the cell in the form of multiple, linear chromosomes -surrounded by a nuclear envelope -DNA is organized with proteins to form chromatin

11. Questions 1.What are the two big groups into which cells are classified? Cells can be classified as eukaryotic or prokaryotic 2.Do bacteria cells have a nucleus? In bacteria the genetic material is dispersed in the cytosol and there is no internal membrane that delimits a nucleus. 3.What is the name of the jelly-like substance that is inside the cell? A: A:cytoplasm B: ectoplasm C: cytokinesis 11