Questions On Biology

Submitted By ohlay1946
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Survey of Biological Sciences
Chapter 3 and 4

1. The cell theory is all organisms composed of one or more cells, the basic living unit of structure and function in organisms.
2. The plasma membrane is a phospholipid bilayer in which protein molecules are either partially or wholly embedded. The phospholipid bilayer has a fluid consistency, comparable to that of light oil. The proteins are scattered throughtout the membrane; therefore they form a mosaic pattern.
3. Integral proteins are embedded within the lipid bilayer. They cannot easily be removed from the cell membrane without the use of harsh detergents that destroy the lipid bilayer.
Peripheral proteins are attached to the exterior of the lipid bilayer. They are easily separable from the lipid bilayer, able to be removed without harming the bilayer in any way. Peripheral proteins are less mobile within the lipid bilayer.
Lipid-bound proteins proteins are located entirely within the boundaries of the lipid bilayer.
4. The nucleus is a cell structure that contains hereditary information, or DNA, and controls cellular growth and reproduction.
5. Ribosomes are the structures responsible for protein synthesis or site of protein synthesis, composed of two subunits rRNA and protein molecules.
6. The role of rough endoplasmic reticulum is processing, folding, and modification of proteins.
Smooth ER synthesizes phospholipids and steroids, stores calcum ions, and various other function, depending on cell types.
Golgi bodies apparatus collects, sorts, packages, and distributes materials such as proteins and lipids.
7. Mitochondria are the cell's power producers. They convert energy into forms that are usable by the cell. Located in the cytoplasm, they are the sites of cellular respiration which ultimately generates fuel for the cell's activities.
8. Describe the functions of the following microbodies
a. Lysosomes acts as garbage disposals of the cell, it breaks down unwanted, foreign substances or worn-out parts of cells, and brings macromolecules into the cell.
b. Peroxisome functions vary amongst cells. In liver cells, they metabolize fats or produce bile. In germinating plant cells, they oxidize fatty acids.
9. The Cytoskeleton is a network of fibers which extend throughout the cytoplasm. Its function is to support the cell, provide motility, and regulation.
10. In addition to having a nucleus, plant cells also contain other membrane-bound organelles, or tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Organelles have a wide range of responsibilities that include everything from producing hormones and enzymes to providing energy for a plant cell.
11. The differences between a prokaryotic and eukaryotic cell are:
a. Eukaryotes have a nucleus, while prokaryotes do not.
b. Eukaryotes have membrane-bound organelles, while prokaryotes do not. The organelles of eukaryotes allow them to exhibit much higher levels of intracellular division of labor than is possible in prokaryotic cells.
c. Eukaryotic cells are, on average, ten times the size of prokaryotic cells.
The DNA of eukaryotes is much more complex and therefore much more extnsive than the DNA of prokaryotes.
d. Prokaryotes have a cell wall composed of peptidoglycan, a single large polymer of amino acids and sugar . Many types of eukaryotic cells also have cell walls, but none made of peptidoglycan.
e. The DNA of prokaryotes floats freely around the cell; the DNA of eukaryotes is held within its nucleus and associated with histones.
f. Eukaryotes undergo mitosis; prokaryotes divide by binary fission.

Survey of Biological Sciences
Chapter 5

1. The cell cycle is divided into two main parts: interphase and mitosis. During interphase, the cell grows and replicates its chromosomes. Interphase accounts for all but an hour or two of a 24-h cell cycle, and is subdivided into three phases: gap phase 1 (G1), synthesis