Tour of the Cell Biology Paper

Topics: Cell, Organelle, Eukaryote Pages: 9 (3257 words) Published: March 1, 2012
Learning about Cells.
First thing I want to show you is two beautiful pictures of a Cell. Imagine all of this is in something so small we cannot see it with our naked eyes. About 10,000 average-sized human cells can fit on the head of a pin. There are a few exceptions, but the average cell is very tiny.

Here are a few beautiful examples of a cell structure to kind of give you an idea of its beauty, and how they fit together.

Plasma Membrane (cell membrane)
First we are going to learn about the Plasma membrane it is also called the cell membrane. No, it is not the same thing as the Plasma Tv. Most of you are probably familiar with. As you can see with the above picture the Plasma membrane is on the outer side of the cell. Plasma membrane is what separates the interior of the cell from the outside environment. It is like the peel on an orange. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It is basically the fence that protects the cell from outside forces. It does allow a few things through though. Carbon Dioxide, oxygen and water are mostly what it allows through. The cell membrane also plays a role in anchoring the cytoskeleton to provide shape to the cell, and in attaching to the extracellular matrix and other cells to help group cells together to form tissues. Biological membranes can be considered as a two-dimensional liquid in which all lipid and protein molecules diffuse more or less easily. Although the lipid bilayers that form the basis of the membranes do form two-dimensional liquids by themselves, the plasma membrane also contains a large quantity of proteins, which provide more structure. Here is an illustration of the Cell Membrane or Plasma membrane.

The Nucleus
Next I want to tell you about the core or center of the cell. The nucleus is the center of the cell. Yes, we skipped from the outermost to the innermost part of a cell. The Nucleus is extremely important, because it holds most of the cell’s DNA. As we know our DNA is what makes us what we are. Not only our DNA, but how we use it. The Nucleus is the control center of the cell. In cell biology, the nucleus (is a membrane-enclosed organelle found in eukaryotic cells. It is complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression — the nucleus is the control center of the cell. The nucleus is the largest cellular organelle in animals. It occupies about 10% of the total cell volume. The viscous liquid within it is called nucleoplasm, and is similar in composition to the cytosol found outside the nucleus. It appears as a dense, roughly spherical organelle. The outer envelope, otherwise known as nuclear membrane, consists of two cellular membranes, an inner and an outer membrane, arranged parallel to one another. The nuclear envelope completely encloses the nucleus and separates the cell's genetic material from the surrounding cytoplasm, serving as a barrier to prevent macromolecules from diffusing freely between the nucleoplasm and the cytoplasm. The outer nuclear membrane is continuous with the membrane of the rough endoplasmic reticulum (RER), and is similarly studded with ribosomes. The space between the membranes is called the pronuclear space. In this picture HeLa cells stained for the cell nucleus DNA with the Blue Hoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed ready for division.

Now we have something that a lot of people have heard about chromosomes. Our chromosomes tell us how we will look, our innate personality, and how our bodies will grow. Chromosomes are an organized...
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