CellsCells

The Discovery of CellsThe Discovery of Cells

Robert Hooke, and English scientist, discovered and named cells in 1665. He looked at thin slices of cork through a light microscope.

Cell TheoryCell Theory

Cells are the smallest unit of living organismsCells are the smallest unit of living organisms All living organisms are composed of one or All living organisms are composed of one or

more cellsmore cells Cells arise from existing cellsCells arise from existing cells

Prokaryotic CellsProkaryotic Cells

Very simpleVery simple Always unicellularAlways unicellular No membrane-bound nucleus (That means No membrane-bound nucleus (That means

there is not a membrane around the DNA)there is not a membrane around the DNA) No membrane-bound organellesNo membrane-bound organelles

Bacteria, cyanobacteria (blue-green algae)Bacteria, cyanobacteria (blue-green algae)

Eukaryotic CellsEukaryotic Cells

Complex Cell StructureComplex Cell Structure Membrane-bound nucleusMembrane-bound nucleus Membrane-bound OrganellesMembrane-bound Organelles

Plants & animalsPlants & animals

Animal Cell

Plant Cell

Inside the cells are organelles

Organelles Found In BOTH plant and animal cells:

Nucleus• Surrounded by a double membrane called

the nuclear membrane

• Contains DNA

• Controls cell

functions

Nucleus

Nucleus

Nucleolus

• Located in the nucleus

• Synthesizes

ribosomes

Nucleolus

Nucleolus

Ribosomes

• Protein Synthesis

• Made of protein and RNA

Ribosomes

Ribosomes

Endoplasmic Reticulum

• Membrane where chemical reactions take place.

• Rough ER – covered with ribosomes. Site of protein synthesis. Located next to the nucleus.

• Smooth ER – not covered with ribosomes. Site of lipid synthesis and carbohydrate metabolism.

Rough Endoplasmic Reticulum

Rough ER

Smooth Endoplasmic Reticulum

Mitochondria• Converts

stored energy (ATP) into cellular energy

• Has it’s own DNA

Mitochondria

Mitochondria

Golgi Apparatus

• Stores macromolecules

until they are needed

by the cell.

Golgi Apparatus (AKA Golgi Complex, Golgi Bodies)

Golgi Apparatus

Cytoskeleton

• Network of protein fibers

• Helps give the cell structure.

• Involved in transport of organelles around the cell

Cytoskeleton

Cytoskeleton

Cell membrane

Double layer of phospholipids

Controls what enters and leaves

the cell

Cell Membrane

• Also called plasma membrane

• Controls what enters and leaves the cell

• Made of a phospholipid bilayer– Hydrophilic heads face out– Hydrophobic tails face in

Cell membrane

Organelles Found ONLY In plant cells:

Chloroplast

• Site of photosynthesis

Chloroplasts

Cell WallGives the cell structure and support

Central Vacuole• Often the largest

structure in a

plant cell

• Contains water

and organics

• Helps keep the

cell rigid (maintains turgor pressure)

Central Vacuole

Organelles Found ONLY In animal cells:

Centrioles

• Involved in

cell division

Centrioles

Lysosomes

Contains digestive enzymes.

Structures used by unicellular organisms for

movement:

Cilia

Lung Tissue

Flagella

NUCLEUSNUCLEOLUSROUGH ENDOPLASMIC RETICULUM

GOLGI APPARATUS

SMOOTH ENDOPLASMIC RETICULUM

MITOCHONDRIARIBOSOME