The Cell

Cell Theory All living things are composed of cells. Cells are the basic units of structure and function in living things. New cells are produced from existing cells.

Prokaryotes No nuclei Have genetic material, but not contained in a nucleus Generally smaller and simpler than eukaryotes Do carry out every activity associated with living things – they grow, reproduce, respond to the environment and move Bacteria are good examples of prokaryotes

Eukaryotes Has a nucleus, where its genetic material is separated from the rest of the cells Generally larger and more complex than prokaryotic cells Contain many structures and internal membranes that are highly specialized Display variety – some are unicellular organisms, some make up multicellular organisms Plants, animals, fungi and protists are examples of eukaryotes

Eukaryotic Cells (can be compared to a factory) Have specialized organs called “organelles” Can be divided into 2 major parts – nucleus & cytoplasm The organelles are found in the cytoplasm

Prokaryotes vs. Eukaryotes http://www.phschool.com/science/biology_place/biocoach/cells/common.html

Cytoplasm Cytoplasm is the liquid material that fills the cell which all of the organelles “float” in. Everything that is inside the cell membrane and is not nucleus is considered a part of the cytoplasm

Organelles - Nucleus Contains nearly all the cell’s DNA (which contains the coded instructions for making proteins & other important molecules) Surrounded by a nuclear envelope which is composed of 2 membranes and is dotted with thousands of nuclear pores that allow material to move into & out of the nucleus. The materials that move through the pores are proteins, RNA and other molecules.

Organelles - Nucleus There is a granular material inside the nucleus called chromatin. It is made of DNA bound to protein. Most of the time, chromatin is spread throughout the nucleus, but when the cell divides, the chromatin comes together to form chromosomes, which contain the genetic information that is passed on from one cell to the next Most nuclei also contain a small, dense region known as the nucleolus. This is where ribosomes are made.

Organelle - Nucleus The nucleus can be compared to the main office of a factory – sends out all of the orders to the rest of the factory. The nuclear pores can be compared to the communication system of the factory – transfers all of the messages and orders from the office to the other parts of the factory.

Organelles - Ribosomes Small particles of proteins and RNA found throughout the cytoplasm They produce proteins by following coded instructions that come from the nucleus Ribosomes can be compared to small machines in the factory that make products (proteins) as instructed by the main office (nucleus)

DNA and RNA DNA stands for deoxyribonucleic acid RNA stands for ribonucleic acid Nucleic acids are macromolecules containing hydrogen, oxygen, nitrogen, carbon and phosphorus. They are made of chains of small pieces called nucleotides. Nucleotides are made of 3 parts – a 5-carbon sugar, a phospate group, and a nitrogenous base.