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(updated 9/24/05)

Be able to identify, and know the functions of all organelles and parts of cells. Compare and contrast bacterial, animal, and plant cells in terms of size, function(s), and composition.

A prokaryotic cell (bacteria). A nucleus is absent, and only a circular ring of DNA is present.

Photosynthetic bacteria have internal membranes containing chlorophyll.

Animal cell structure (a Eukaryote "true nucleus"). The following drawings and photos show details of the organelles of cells.

A human white blood cell (leukocyte), showing some cellular organelles.

Details of the cell nuclear membrane (scanning electromicrograph).

Drawing of the cell nucleus and membrane pores.

Drawing of a double stranded chromosome, composed of nucleosomes (DNA, histone proteins, and spacer histones).

Photomicrograph of chromosomes of a plant (probably a root tip).

Three images of human sperm cells, the only human cells containing a flagellum. TEM=transmission electromicrograph; SEM=scanning electromicrograph.

Rough (containing ribosomes) endoplasmic reticulum, and smooth (lacking ribosomes) er.

The role of ER, ribosomes, and protein synthesis, storage and transport is shown here.

The Golgi apparatus is involved in cell secretions; secretory vesicles are also shown, which break off the membranes and transport materials to the cell (plasma) membrane.

A combination of RER and the Golgi complex are involved in secretion; proteins, lipids and carbohadrates may be combined into lipoproteins, glycoproteins, and glycolipids for secretion.

Details of protein transport between RER and Golgi complex.

Production and function of lysosomes.

Structure of ribosomes (made of ribosomal RNA).

Mitochondria, the powerhouses of the cell, allow us to survive in an atmosphere containing oxygen, and also to derive energy from our food.

Centrioles are present in most animal cells, but are absent from plants. They play major roles in cell division (mitosis & meiosis), and in controlling actions of cilia and flagella.

The cytoskeleton is composed of protein fibers that give support to the cell, and allow for movements of cells.

Details of cytoskeletal makeup. Actin is also an important component of muscle.

A flagellum ("whip" in Latin) is a long structure, found in sperm cells and many other organisms. Flagella are composed of a '9+2 arrangement' of microtubules. The basal body (a centriole) is composed of nine triple microtubules.

Cilia are shorter than flagella, and usually more numerous.

Plant cell structure.

Details of plant cell structure.

Details of chloroplast structure.

Plant cell walls are composed of cellulose, a starch (polysaccharide), unlike the wall of bacterial cells.

The theory of endosymbiosis states that both mitochondria and chloroplasts are bacteria (both contain DNA, bacteria-like ribosomes, and can reproduce & grow) within the cells of Eukaryotes, and were phagocytized by ancestral eukaryotes.

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