Biology 200

Eukaryotic Cells and Organelles

1.1 Eukaryotic Cells and Organelles

What is a cell?● membrane bound autonomous living unit capable of carrying out essential life processes ~ basic unit of life● maintains stable internal environment with concentration of ions and molecules different from outside ~ homeostasis● Can assimilate and transform material, reproduce, and has several special functionsAll living cells have1.Similar Basic Chemistry2.Similar Genetic Instructions→ Stored in DNA molecules.→ Constructed out of same chemical building blocks.→ Interpreted/Read by essentially the same chemical machinery.→ Replicated in the same ways (depending on the type of cell) NOTE:-Viruses are NOT cells ~ not living, rely on hosts to carry out biological processes-mitochondria are NOT cells ~ not fully autonomous (used to be cells, but evolved away)

Prokaryotic Cells Vs. Multicellular Organisms

Prokaryotic Cells● No organelles● No membrane bound nucleus
Multicellular Organisms● Cells can be units of an organism● Organisms are a living thing that have/can develop the ability to act/function independently● Capable of: → metabolism/maintenance to homeostasis→ growth and reproduction→ response to the environmentIn multicellular organisms, cells often will specialize to carry out specific functions! These differentiated cells have the same genome with a different subset of genes expressed in each cell.
Unit of Cells - all cells have similar genetic instruction!● stored in DNA molecules as genes● constructed out of the same chemical building blocks● interpreted by the same (ish) chemical machinery and duplicated in similar ways.

Organelles

What is an Organelle?● a specialized sub-cellular structure having a special function
Why are Organelles important?● Control passage of materials between compartments by forming compartments● Provide optimal local environment for metabolic reactions and other functions● high local concentration within a compartment can be achieved

Eukaryotic Cells

Nucleus● Double membrane bound organelle containing DNA● Usually, the most prominent organelle in a eukaryotic cell
Endoplasmic Reticulum (ER)● Network of flattened interconnected sacs/vesicles occupying much of the cytoplasm● Ribosomes bound to the cytosolic surface of ER are sites of protein synthesis
Golgi Apparatus● Series of flatted membranous sacs, which receive and chemically modify the molecules (proteins) made in the ER and direct them to various locations.
Membrane-Enclosed Organelles● Distributed throughout the cytoplasm● Cytosol is the place between the nucleus and the cell membrane● not all organelles are membrane bound.