Cell Structure Review

Eukaryotic Cells• Have a nucleus• Found in multi-cellular

organisms & some unicellular organisms

Prokaryotic Cells

• Do not have a nucleus• Found in bacteria

Cell Membrane• Thin, flexible layer• Separates the cell from its surrounding

environment• Controls movement of materials into and out

of the cell• Helps maintain the cell’s internal

environment

Chromatin

• Coils of DNA and protein that form chromosomes.

• Can be thought of as chromosomes without shape.

• Granular-like material found in the nucleus containing genetic information

Chromosome

Worm-like / rod-like structures formed from chromatin during cell reproduction.

• They become distinct during the reproductive part of the cell cycle as the cell divides.

• Composed of DNA

Cytoplasm• Thick, jelly-like

substance contained within the cell membrane

• Most of the work of the cell is carried out here.

• The majority of the organelles are suspended in the cytoplasm.

DNA

• The genetic material found in all living cells.

• Contains the information needed for an organism to grow, maintain itself, and reproduce

• Stands for deoxyribonucleic acid

Endoplasmic Reticulum• Network of channels/tubes leading from

the nuclear membrane into the cytoplasm• Helps transport materials between the

nucleus and the cytoplasm• Also involved in transporting proteins• Two types:

- Smooth E.R. = no ribosomes-Rough E.R. = contains ribosomes

Golgi Bodies Serve as storage and packaging centers.• Look like stacks of flattened sacs• Proteins made by the ribosomes are

packaged into vesicles (small pockets)• These packages are used by the cell and

sometimes are released from it.

Lysosomes Sac-like structures that

contain enzymes• Where digestion of cell

nutrients & food molecules take place

• Breaks down cellular waste or things that are harmful to the cell• Similar to the job of

white blood cells

Mitochondria Organelles that cause the release of energy

by using oxygen to break down sugars.• Usually round or tube shaped• Releases food molecules that supply energy

to the cell; it is known as the powerhouse of the cell.

• Usually more than one in a cell

Nuclear Envelope

• Has a double-layered membrane that separates the nucleus from the cytoplasm.

• Contains pores to help facilitate the exchange of materials between the nucleus and the cytoplasm

Nucleus• Control center of the cell• Manages all of the cell’s

activities• Largest organelle• Contains the genetic

material (chromatin) the cell needs to reproduce and function.

• Is surrounded by the nuclear envelope and also contains the nucleolus and chromatin.

Ribosomes

• Sites of protein manufacturing in the cell

• Assemble proteins that:• Create chemical

messages to run a cell.• Build cell organelles

• Line the membrane of the rough endoplasmic reticulum & are found in the cytoplasm