1. Stephanie Okpara
October 8, 2009
AP Biology- Pd. 1
Free Response
The function of the lysosome is to digest cellular materials that have exceeded
their lifetime or are no longer useful to the cell. Lysosomes break down cellular waste
products, fat, carbohydrates, proteins, and other macromolecules into simple compound,
which later get transferred back into the cytoplasm as new cell-building materials.
Basically, lysosomes digest and recycle. Lysosomes are spherical organelles contained by
a single layer membrane, which protects the rest of the cell from the harsh digestive
enzymes contained in the lysosomes. The Golgi apparatus is composed of membrane-
bound stacks know as cisternae, which have five functional regions. The function of the
Golgi apparatus is to modify, sort, and package proteins and other materials from the ER
for storage in the cell or secretion outside the cell.
In a prokaryote, DNA floats around the cell freely, while the eukaryote’s DNA is
held inside its nucleus. This DNA is much more complex and thus more extensive that
the prokaryote’s DNA. The cell wall of a prokaryote is composed of peptidoglycan, a
single large polymer of amino acid and sugar. This cell wall provides shape and form for
a bacterium and acts like a physical barrier between the bacterium and its environment.
Many eukaryotes have cell walls, which are not made of peptidoglycan, but of a thick
polysaccharide. This cell wall provides protection and support.
According to the Endosymbiotic Theory, the origins of mitochondria and plastids
began as separate prokaryotic organisms that were taken inside the cell as
endosymbionts, any organism that lives in the body or cells of another organism. Both
chloroplasts and mitochondria have circular DNA, which means genetic similarities to
bacteria. They both have their own ribosomes, which synthesis protein.