Cells

What is a cell?

• Cell – the basic unit of structure and function in living things

• An organism has many different types of cells, but they all contain the same DNA.

The Cell Theory-Review

1. All organisms are made of one or more cells; all living organisms are made up of one or more cells.

2. All cells carry on life activities; cells are the basic unit or structure and function

3. New cells come from other preexisting living cells; by the process of cell division. Remember: Life comes from life.

Two types of cells

• Prokaryotic Cells - are found in prokaryotes, they have no nucleus– Ex. bacteria

• Eukaryotic Cells - are found in eukaryotes, they have a nucleus– Ex. animals, plants, fungi, protists

Cell Membrane• Actively allow some materials in and out of

the cell: cell membrane is a regulator• Serves as a boundary• Cell Membrane is part of the living cell.

Cell Wall

• Rigid structure for shape and support• Found in plant cells, fungi, some protist and

some bacteria, NOT in animal cells

Not considered to be part of the living cell. Remember Hooke and the cork cell.

Cytoplasm• Cytoplasm is all the material inside the cell

membrane excluding the nucleus.• Organelles + cytosol-nucleus=cytoplasm• Cytosol is the watery material used for

transport.• Many important chemical reactions occur in

the cytoplasm, where water acts as an important solvent.

Nucleus• Control center-----AKA as the brain• Contains most of the DNA-known as chromatin or

chromosomes

• Nucleus is actually a structure made up of many parts.Nucleus: nuclear envelope, nuclear pores, chromatin and nucleolus

Two major demands on the nucleus:1.DNA MUST be protected2.DNA MUST be available for use at the proper times.

Nucleolus

• Dense area located inside the nucleus where ribosomes are produced.

• There can be multiple nucleoli (plural) in the nucleus.

ER (endoplasmic reticulum)

• Pathways/channels are series of membranes for transport in a cell

• ER aids in the production of proteins and lipids.

Interconnected network of thin folded membranes. The membrane composition is very similar to the cell membrane and nuclear membrane.

ER (endoplasmic reticulum)-cont.

• The ER membranes form a maze of enclosed spaces. The maze is called lumen. Numerous processes, including the production of proteins and lipids occur both on the surface of the ER and inside the lumen.

• Note: All the folding allows for greater surface area but it takes up less space within the cell.

ER-Continued

• There are two types of ER. Smooth and Rough Endoplasmic reticulum.

• Rough ER: Ribosomes are attached to the ER giving it a bumpy of rough appearance. Proteins are produced on the ribosomes and then enter the lumen where the protein may be modified.