Lecture 1

The cell

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.

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The Cell

. All organisms are composed of cells.

.All cells represent a continuous line of

descent from the first living cells.

Cell Size

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Characteristics of All Cells

• A surrounding membrane• Protoplasm – cell contents in thick fluid• Organelles – structures for cell function• Control center with DNA

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Cell Types

• Prokaryotic • Eukaryotic

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Prokaryotic Cells

-lack a membrane-bound

nucleus.

-genetic material is present in

the nucleoid

Examples of prokaryote:

-virus

-bacteria

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Flagella

-present in some prokaryotic cells

-used for locomotion

-rotary motion propels the cell secretion

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Eukaryotic Cells

-possess a membrane-bound

nucleus

- many cellular functions within

organelles

-possess a cytoskeleton

for support and maintain cellular

structure

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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

Questions1.What are the two big groups into which cells are classified? Cells can be

classified as eukaryotic or prokaryotic2.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:cytoplasmB: ectoplasmC: cytokinesis

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