Parts of a Eukaryotic Cell

Cell Theory

• All living things are made up of cells.

• Cells are the smallest working units of all living things.

• There are two types of cell:– Prokaryotic– Eukaryotic

Prokaryotic

• One-celled• No nucleus• DNA looks like a

twisted rubber band• No membrane-

covered organelles• All have a cell wall

outside the cell membrane

• Ex: Bacteria

• Larger• Have a nucleus• Have membrane-covered organelles• Some (ex: plants) have a cell wall

PlantAnimal

Eukaryotic

Two Types of Eukaryotic Cells

• Animal cells

• Plant cells

“Typical” Animal Cell

“Typical” Plant Cell

Cell PartsOrganelles

Organelles• “little organs”• Have specific jobs that

help keep the cell alive• Like the organs in your

body have specific jobs to help keep you alive

Surrounding the Cell

Cell Wall• Stiff outer layer that supports & protects the cell • All plant cells have a cell

wall that is made of a sugar called “cellulose”

• (All prokaryotic cells, like bacteria, also have cell walls)

• Animal cells do not have cell walls

←←

Cell Membrane• Surrounds & protects the cell (inside of the cell

wall on plants, fungi, and prokaryotes)• Every cell has a cell membrane• Made of proteins

and lipids that control the move- ment of materials in & out of the cell

• Allows nutrients and water in

• Lets waste go out

Inside the Cell

Proteins• Control the chemical reactions in the cell• Provide cells with structure• The messages of how to make proteins are given

by the DNA

Not THIS kind of protein!

Cytoskeleton• A web of proteins inside the cell that anchors the

organelles• Acts as a skeleton &

a muscle• Helps the cell keep

its shape• Also helps other cells,

like bacteria, move

Nucleus

• Only in eukaryotic cells

• Large & in the center

• Contains genetic material - DNA

• Directs cell activities

• Covered by two membranes which allow materials to go in and out

Ribosomes• Smallest organelles in cell• Each cell contains

thousands • Makes protein• Found floating around

inside cell • Or attached to

membranes or organelles• Unlike most organelles,

ribosomes are not covered by a membrane

→→

Endoplasmic Reticulum (ER)

• Membranes with many folds• Makes lipids & proteins• Part of the cell’s delivery

system: folds have passageways = move materials around cell

• Two types: – Smooth ER: no ribosomes, makes lipids, breaks

down materials that can harm the cell– Rough ER: ribosomes attached, makes proteins

to be delivered to other parts of the cell

Mitochondria

• Main power source of the cell

• Make energy by breaking down sugar

• Energy is stored in molecule called ATP

• The cell uses the ATP to do work

• Has its own DNA that is different from the cell’s DNA

Chloroplasts

• Usually found in plant and algae cells• Contain green chlorophyll (traps the energy of

sunlight to make sugar make food)• Where photosynthesis takes place (Sun + CO2 +

H2O O2 + sugar)

Vesicles

• A small envelope that surrounds material to be moved from one part of a cell to another

• Made from the cell membrane• Or from the Golgi complex . . .

Golgi Complex• Packages & delivers materials

within and out of the cell • The “Post Office” of the cell

The “Post Office”1. The ER delivers materials to the Golgi complex

2. The Golgi complex can change these so that they can do different jobs

3. They’re enclosed in pieces of the Golgi’s membrane

4. The membrane pinches off to make vesicles

5. The vesicles move the materials to other parts of the cell or out of the cell

Lysosomes• Responsible for digestion

– Destroy worn-out or damaged organelles

– Get rid of wastes– Protect cell from

harmful products

1. Material is enclosed in a vesicle

2. Lysosome bumps into vesicle and pours enzymes into it (breaks down what’s inside of it)

Vacuoles• A type of vesicle• Also help with

digestion (like Lysosomes)

• In plants: large vacuole in center store water, which helps plants keep their shape (plants wilt when vacoules lose water)