Cell biology and structure

¶ … Cell

Plasma (Cell) Membrane: The cell membrane regulates what enters and leaves the cell. It has a double wall that separates the inside and the outside of the cell, and it provides structure and shape for the cell.

Rough Endoplasmic Reticulum: The rough endoplasmic reticulum is an organelle within the cell that is responsible for protein production from amino acids, and also the "coding" process of protein folding to specify the destination of the proteins. It is called "rough" because its surface is covered with ribosomes.

Smooth Endoplasmic Reticulum: The smooth endoplasmic reticulum is tubular in shape and can be found throughout the cytoplasm. It is called "smooth" because, unlike the rough ER, it is not covered in ribosomes. The smooth ER is responsible for creating and sometimes metabolizing lipids within the cell. It also detoxifies and converts organic material to useful and safe water-soluble products.

Ribosomes: Ribosomes are organelles composed of proteins and nucleic acids. They can be found floating in the cytoplasm and also attached to rough ER. They are responsible for translating the information transported from the nucleus by the mRNA and using it to create polypeptides from the amino acids gathered by the tRNA.

Golgi apparatus: The Golgi apparatus is a group of flat discs found near the endoplasmic reticulum. They are responsible for sorting the proteins created by the ribosomes on the rough ER, packaging them in vesicles, and delivering them to their proper destination. This structure was named after its discoverer, Camillo Golgi.

Mitochondria: The mitochondria are found through the cell, and are responsible for using oxygen to convert the food within the cell to usable energy through a process called oxidative phosphorylation. Mitochondria are structured similarly to a cell, with a double-walled membrane providing shape and strength.

Lysosomes: Lysosomes are spherical organelles bound by a membrane and containing powerful hydrolytic enzymes. These enzymes carry out a waste management function within the cell, digesting degrading and expired material within the cell and breaking it down into simple compounds, which can then be reused by the cell.

Centrioles: Centrioles are organelles that are only found in animal cells. They are composed of microtubules positioned in a star-like pattern, and they always come in pairs arranged at right angles. Centrioles function as organizing forces during the division of a cell. They are responsible for arranging the microtubules into the spindle pattern necessary for alignment of chromosomes during division.

Vesicles: Vesicles are the transport and storage mechanism of the cell. They are composed of a double membrane, one side of which separates it from the cytosol, and the other side of which contains the material that it is transporting. Their membranes can be joined with the plasma membrane to deliver material into and out of the cell, and can be fused with other organelles to gather material for digestion, storage, or transport.

Cilia: Along with the flagella, the cilia are used to move the cell or to move material around the cell. They are tin, fingerlike protusions from the surface of the cell. Their name comes from the Latin for "eyelash."

Flagella: The flagella are tail-like structures that protrude from the surface of cells. With the cilia, they help to move the cell and to move debris and fluids around the cell. The name comes from the Latin word for "whip."

Cytoskeleton: The cytoskeleton refers to the interwoven protein filaments that provide rigidity to the cell wall and a stable base for the cilia and flagella.

Vacuole: Only found in plants, vacuoles are a type of vesicle used to store water, store nutrients, and break down complex molecules. They can be very large, and when full they help to provide structure to the cell.

Nucleolus: The nucleolus is a structure found within the nucleus. It is one of the few cellular structures not bound by a membrane. Its purpose is to create building blocks that pair to become ribosomes.