4.2 Parts Of A Eukaryotic Cell

Parts of a Eukaryotic Cell

Cell Theory1) All living things are made up of cells.

2) Cells are the smallest working units of all living things.

3) Cells come from other cells

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

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

twisted rubber band• Do NOT have

membrane-covered organelles

• All have a cell wall outside the cell membrane

• Ex: Bacteria

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

PlantAnimal

Eukaryotic

Two Types of Eukaryotic Cells

• Animal cells

• Plant cells

“Typical” Animal Cell

“Typical” Plant Cell

Cell PartsOrganelles

The Cell . . . The School

• Think of the cell as a tiny, little school

• Just like a school has different things (buildings, people, items) that make it function (work), so does the cell.

• In the cell, organelles are the things that make the cell work.

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

• Like a brick wall around a school

←←

Cell Membrane• Every cell has a cell membrane• Like a wire fence around a school• Surrounds & protects the cell • Controls what goes in

and out of cell• Allows nutrients

and water in• Lets waste go out

Inside the Cell

Nucleus

• Only in eukaryotic cells

• The “brain” or “control center”; directs all activites

• Like the office at a school

• Large, dark, sometimes in center

• Contains genetic material – DNA (= the principal)

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

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

by the DNA (principal)• Like the educated students at a school

Not THIS kind of protein!

Ribosomes• Smallest organelles in cell• Each cell contains

thousands • Like the teachers at a

school• Makes protein

(= educated students)• Found floating inside cell • Or attached to

membranes or organelles• Found in BOTH

prokaryotic and eukaryotic cells

→→

Endoplasmic Reticulum (ER)• Membranes with many folds

• Part of the cell’s transport & delivery system: folds have passageways = move materials around cell

• Like the hallways at a school• Two types:

– Smooth ER: no ribosomes – Rough ER: ribosomes attached

Mitochondria• Main power source

of the cell• Makes energy by

breaking down sugar (food)

• Like the cafeteria of a school

• Energy is stored in molecule called ATP

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

Chloroplasts• Usually found in plant and algae cells• Like solar-powered energy generators at a school• Contain green chlorophyll = traps the energy of sunlight • Where photosynthesis takes place

(Sun + CO2 + H2O O2 + sugar)

Golgi Complex• Packages & delivers materials

within and out of the cell • The “Post Office” of the cell• Like the staff room (with

teachers’ boxes) at a school

Lysosomes• Responsible for cleaning cell

– Destroy worn-out or damaged organelles

– Get rid of wastes– Protect cell from

harmful products

• Like the janitors at a school

1. Material is enclosed in a vessicle

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

Vacuoles• Storage site for cell

• In plants: large vacuole in center of cell store water, which helps plants keep their shape

• Plants wilt when vacuoles lose water

• Like the underground water tanks at a school