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Basic Biology Information

Cell Organelles

Cells, the basic building block of life, are composed of many different parts, or organelles, the most important being the nucleus. The nucleus is the “brain” of the cell that controls cellular activity and holds important genetic information (DNA).

For Animal cells, the cell is enclosed by the Cell Membrane. The Cell Membrane helps protect the cell and give it shape, as well as controlling what molecules can go in and out of the cell. Depending on the size of the cell and what can be brought in by diffusion or osmosis, the pores of the cell membrane decide what can be brought in or exit out of the cell.

As well as a Cell Membrane, Plant cells have a Cell Wall. The cell wall is composed mainly of carbohydrates and helps give protection and shape to the plant cell.

Inside a cell is the Cytoplasm. The Cytoplasm is a fluid like colloid that exists between the nucleus and the cell membrane. As well as holding the cell organelles, cytoplasm gives the ingrediants for the bio-chemical reactions that occur here, called Metabolism.

The Cytoskeleton is the supportive material made of microtubules and microfilaments that helps hold the organelles inside the cell along with the cytoplasm. Also, the movement of organelles within the cell normally occur along these tracks.

The Endoplasmic Reticulum (part of the nuclear membrane) is made of tubes that transport materials from the nuclear membrane to the cell and from the cell membrane into the cell nucleus. Some ER has ribosomes attached (Rough ER) which is involved in Protein Synthesis. Without the presence of ribosomes, ER (Smooth ER) is involved primarily in Lipid Synthesis.

The Golgi Complex, also called the Golgi Apparatus, works with the ER to secrete proteins and lipids into the cell. After the proteins are produced in the ribosomes attached to the ER, they are secreted into the Golgi Complex and then distributed to their proper places. For this reason the Golgi Complex is known as the “packaging center” for the cell. The Golgi Complex also is involved with Carbohydrate Synthesis.

The Lysosome is a digestive sac that contains enzymes for the breaking down of waste materials in the cell such as water, salt, and other small molecules.

The Mitochondria are known as the “power house” of the cell, being the site where ATP, or energy production occurs. Without this important organelle, the cell would soon die.

The Vacoule is the “storage chamber” of the cell. These are sacs where waste that has not yet been broken down in the lysosome is stored. In Animal cells, there are usually several small vacuoles, while in the plant cell there is one large central vacuole whose function is not only to store waste but to help give structure to the cell.

Ribosomes are small organelles that are composed of rRNA, or Ribosomal RNA. Ribosomes are the site of protein synthesis, and are either attached to ER, or floating free in the cytoplasm of the cell.

A Chloroplast is an oblong structure with a folded inner membrane that is found only in plant cells. This important organelle houses Chlorophyll, the green pigment that gives plants its color, and also where photosynthesis (a process that converts the energy of the sun into chemical energy) occurs.

The Nucleolus is located within the nucleus, and is the site for ribosome synthesis. This and the nucleus it is housed by is protected by the nuclear membrane, which controls what enters and exits the nucleus much like the cell membrane protects and guides the cell.

As you might have noticed, some cell organelles have certain labels such as "Power House" of the cell (Mitochondria). Memorizing this is a good way to help you remember what each cell part does... so here's a list!:

Nucleus: Brain of the cell Golgi Complex: Packaging Center Rough ER: Protein Synthesis Helper Smoothe ER: Lipid Producer Ribosome: Protein Synthesiser Nucleosome: Ribosome Producer Mitochondria: Power House Lysosome: Trash Compactor Vacoule: Storage Chamber

Note: This is not an extensive list of the organelles found within plant and animal cells!

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