ObjectivesObjectives

-Define each of the following:-Define each of the following:

Prokaryotes , eukaryotes ,cell

-Draw and label -Draw and label Prokaryotes and and eukaryotes

-Mention the function of the main organelles -Mention the function of the main organelles

in the cellin the cell

-Compare between -Compare between Prokaryotes and eukaryotes cell

1. Leeuwenhoek : - used a single powerful lens.

- was the first person to see tiny living organisms in a drop of water.

- Made detailed drawings of each kind of organisms.

2. Robert Hooke : - examined thin slices of cork.

- found that it contains thousands of chambers called them cells.

3. Schleiden : - All plants are made of cells.

4. Schwann : - All animals are made of cells.

5. Virchow : - cells are produced from existing cells.

Discovery of the cell

Cell theory states :

1. All living things are composed of cells.

2. Cells are the basic units of structure and function in living things.

3. New cells are formed by the division of pre-existing cells.

4. Cell contain genetic material which is passed on from parent to

daughter cells Cells differ in their shape and size, but all cells share common structures.

• All cells have Cell membrane , Cytoplasm and Nucleus

•.

• Cell membrane : thin flexible barrier around the cell.

• Nucleus : Contains genetic materials and controls cell activity in most cells.

• Cytoplasm : material inside the cell membrane but not including the nucleus.

Cell theory

Basic cell structures

Cell structures

Cell Wall Cell membrane Nucleus Organelles in the cytoplasm

Ribosomes Lysosomes Vacuoles Chloroplasts

Endoplasmic reticulum Golgi apparatus Mitochondria

Eukaryotic CellsEukaryotic Cells(yew KAYR ee yah tihk) (yew KAYR ee yah tihk)

cells cells withwith membrane- membrane-bound structuresbound structures

EX: EX: animalsanimals, , plantsplants, , fungifungi and and protistsprotists

Cells divided into two categories :

1. Porkaryotic cells : do not have nucleus.

2. Eukaryotic cells : have nucleus.

Prokaryotic cellProkaryotic cell Eukaryotic cellEukaryotic cell

Smaller and simplerSmaller and simpler Larger and more complexLarger and more complex

Has cell membrane cytoplasm Has cell membrane cytoplasm but no nucleusbut no nucleus

Has cell membrane cytoplasm Has cell membrane cytoplasm and nucleusand nucleus

Does not have organellesDoes not have organelles Has organellesHas organelles

In bacteriaIn bacteria All plants, animals, fungi, and All plants, animals, fungi, and many microorganismsmany microorganisms

Prokaryotes and eukaryotes

Nucleus

- Nucleus was discovered by Robert Brown.

- Nearly all eukaryotic cells contain nucleus.

Function of the nucleus :

1. Control most of cell processes.

2. Contains The hereditary information ( DNA )

Components of the nucleus :

- Chromatine : granular material spread out through the nucleus

contain DNA and protein.

When the cell divide chromatine condenses to form chromosomes

1. Nucleolus : small dense region where the assembly of ribosomes begin.

2. Nuclear envelope : double-membrane layer surround the nucleus.

Contains many pores that allow materials to move in and out of the cell.

protectsprotects the cell the cell

gives gives shapeshape

is made of is made of cellulosecellulose

A cell wall is found in A cell wall is found in plantsplants, , algaealgae, , fungifungi, , & most & most bacteriabacteria..

CELL WALLCELL WALL

CYtoskeleton

Cell Wall