EUCARYOTES
Look at figures on pg. 100, Tortora et.al., 7th ed - this is the generic eucaryotic cell. Note the size difference between this cell and the prokaryotic cell described on pg. 80, Tortora et.al., 7th ed.
A.
Membrane - structure and function is very similar to what we covered with bacteria.Eucaryotic cells have many
Some of these organelles traffic around within the cell.
Some are involved in endocytosis (phagocytosis and pinocytosis) as well as exocytosis events at the cytoplasmic membrane.
Eucaryotic cell membranes also contain sterols. (bacterial membranes don't except for some mycoplasma).
B. Cell movement - see figures on pg. 101, Tortora et.al., 7th ed
1.) Cilia and flagella (both can be called undulipodia).
Both of these structures are built on microtubules composed of tubulin and dynein.
At the base of an undulipodium is a structure called a microtubule organizing region or a basal body.
Another microtubule organizing region is the centriole.
Centrioles make the microtubules which help to move the cell's chromosomes during cell division.
(Margulis discusses Mixotricha paradoxica with regard to the evolution of undulipodia).
2.) Cell contraction and amoeboid movement.
Microfilaments
(actin filaments) in association with myosin allow the cell to contract and expand and allow endocytosis and exocytosis to occur.a..)
C. The
endoplasmic reticulum (the ER)See pictures on pgs. 100, 103, 104, 105, Tortora et.al., 7th ed. Also note the
golgi in these pictures.The ER is a meshwork of membrane tubes or channels throughout the cell. It is an industrial complex.
The
The
rough ER is the site of synthesis of proteins which are bound for export or for packaging within membrane vessicles.D. The
golgi complex is found in close association with the ER.It can be thought of as a shipping and receiving plant for the molecules made in the ER industrial complex. Some of the molecules are "modified" here -- for instance proteins get sugars attached to them (they get glycosylated).
Among the most important type of vessicles which pinch off of the golgi are the
These vessicles are filled with digestive enzymes. Lysosomes can fuse with endocytic vacuoles to form digestive vacuoles.
E. The ribosomes. ribosomes are found free in the cytoplasm as well as attached to the rough ER. Cytoplasmic ribosomes make cytoplasmic proteins.
F. The nucleus. See page 103, Tortora et.al., 7th ed.
This organelle contains DNA and RNA as well as many proteins.
The nucleus is surrounded by a double membrane with numerous pores.
The DNA is arranged as chromosomes.
The proteins include numerous enzymes needed for replication and expression of the genetic information contained within the DNA.
Histones
are another group of proteins which play an important role in organizing and packaging the long strands of DNA.G. The mitochondria. See page 106, Tortora et.al., 7th ed.
This is the site of aerobic respiration and most of the ATP in the cell is made here.
This organelle has a double membrane essential to its ATP synthesizing function.
Mitochondria contain their own DNA and they have bacteria-like small ribosomes.
These characteristics suggest that mitochondria may have arisen through endosymbiosis.
The ameoba Pelomyxa paradoxica has been shown to contain bacteria instead of mitochondria.
H. The chloroplasts. See page 107, Tortora et.al., 7th ed.
This is the site of photosynthesis in photosynthetic eucaryotes.
These organelles contain chlorophyll, the pigmented substance which is capable of capturing light energy.
Chloroplasts have their own DNA and they have small ribosomes like bacteria and mitochondria.