2.2

• With more advanced microscopes, scientists

discovered that all cells can be grouped into two types:

• prokaryotic cells

• eukaryotic cells

Cell Types

Prokaryotes: NO NUCLEUS!• 1st cells

to evolve• No Nucleus!• The hereditary information

(circular DNA) is contained within the cytoplasm.

• Examples: Archae and Bacteria

The genetic material in a prokaryotic cell is NOT surrounded by a membrane bound nucleus.

Eukaryotes• Evolved from

prokaryotes• Organisms whose cells have a nucleus.• Hereditary information (Linear DNA) is contained within the

nucleus• Examples:

– Animals– Plants– Protists– Fungi– “You” have Eukaryotic cells.

• A cell without a membrane-bound nucleus is a prokaryotic cell.

• A eukaryotic cell has a membrane-bound nucleus and many other specialized organelles.

Unicellular Organisms (cont.)

Can you identify the two organelles that are only found in the plant cell?

-Surrounds all cells

– In a plant cell, it lies beneath the cell wall

– In animal cells, it is the outer boundary (made of cholesterol)

– Serves as a gateway which helps to control materials going in and out of the cell

• It’s like the border of a city!

• Found in both plant and animal cells

• Centrally located in cell

•The nucleus acts as the “brain” of the cell, controls all the activities of the cell and contains genetic information stored in DNA.

• It’s like the Mayor’s Office in City Hall!

In most cells, the nucleus is the largest organelle.

Nucleus (cont.)

EM

Res

earc

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New

cast

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• DNA in the nucleus is organized into structures called chromosomes.

• The nucleolus is also contained in the nucleus and makes ribosomes, organelles involved in the production of proteins.

• The nuclear envelope is a two-membrane structure that surrounds the nucleus.

Nucleus (cont.)

• Found in both plant andanimal cells

• Network of tubes that transports materials throughout the cell

• Two types– Smooth (no ribosomes)– Rough (covered withribosomes)

It’s like a city’s subway!

• Found in both plant and animal cells

• Can be attached to the ER Membrane or floating free in the cytoplasm

• The smallest organelles

•Function: Synthesis- Produce proteins and pass them to the interior of the ER.

• It’s like the brick yard that supplies a city with bricks!

• Found in both plant and animal cells

• Powerhouse of the cell

• Breaks down sugar molecules to release energy

• Function: Respiration- Releasing energy stored in food food is “burned” (combined with oxygen) to produce energy for the cell in the form of ATP

It’s like a city’s powerplant!

It’s like a city’s warehouses, water towers and landfills!

• Fluid-filled sacs found in both plant and animal cells

– In plant cells: very few and very large– In animal cells: many little ones

• Store food, water and waste

• Only found surrounding plant, fungal and bacterial cells

• A cell wall is a stiff structure outside the cell membrane that protects a cell from attack by viruses and other harmful organisms.

• Made of cellulose- a tough, yet flexible material

• Provides support, structure, and protection for the cell

•It’s like the wall that surrounds a medieval city!

• Found in plant cells only

• Green in color due to a pigment called chlorophyll

•They capture energy from the sun and use it to produce food (sugar) for the cell during photosynthesis

http://www.youtube.com/watch?v=PFtzs_cUddI

It’s like the solarpanels on a city’sbuildings!

• Found in both plant and animal cells

• Coiled structures of DNA & protein; found in the nucleus

•City planning office that works

with the Mayor’s office

• Makes Ribosomes• Found in both plant and animal cells• It’s like a Factory!

Lysosomes• Found in both plant and animal

cells

• Function: contains digestive enzymes that digests old cell parts.

• They are the cell’s clean-up crew. They have their own membrane to protect the cell from their chemicals. It’s like a city’s street

sweeper!

Golgi Apparatus• Found in both plant and

animal cells

• Looks like a flattened stack of membranes (or pancakes!)

• They receive proteins from the ER and package them into vesicles .

• Vesicles are organelles that transport substances from one area of a cell to another area of a cell.

• It’s like a city’sPost Office!

Cytoplasm• Surrounds and protects

cell organelles

• Found in both plant and animal cells

• Clear, thick, jelly-like material

• Located beneath cell membrane

• Also contains the cell’s cytoskeleton- a network of threadlike proteins that give a cell its shape

• It’s like the air in a city!

Plant Cell Animal Cell

ribosomes

Golgi bodies or ER Mitochondri

a

chloroplasts

Lysosomes

nucleus

Cell wall or cell membrane

vacuoles