Cell Structure

Review

Prokaryotic Cells

• Do not have a nucleus

• Found in bacteria

Eukaryotic Cells• Have a nucleus

• Found in multi-cellular organisms & some unicellular organisms

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

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.

Nucleolus

� The nucleolus is

located in the nucleus.

� It manufactures the subunits that combine

to form ribosomes, the cell's protein-producing factories.

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

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

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

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.

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

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

Protein

� Your muscles, your organs, and your immune system are made up mostly of protein

� whether you're running or just hanging out, protein is doing important work like moving your legs, moving your lungs, and protecting you from disease.

� Proteins are sometimes described as long necklaces with differently shaped beads.

� Each bead is a small amino acid. These amino acids can join together to make thousands of different proteins.

� Scientists have found many different amino acids in protein, but 22 of them are very important to human health.

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