A cell is the basic building block of human life. The human body consists of trillions of cells. Human cells are comprised of many parts, each of which have specific functions. The cytoskeleton consists of a network of fibers that helps to retain a cell’s shape and allows the cell to move. The cytoskeleton also helps guide the movement of the organelles, which are structures within the cell that execute certain functions. Cytoplasm, a jelly-like fluid, surrounds the organelles and the cell’s nucleus, which is a structure that contains deoxyribonucleic acid (DNA). Each organelle has a certain job to perform within the cell. Types of organelles include:
- Endoplasmic reticulum – assists with sorting, processing and transportation of protein and lipid molecules. It is the largest organelle.
- Golgi apparatus – bundles molecules (such as proteins and lipids) processed by the endoplasmic reticulum and transports them out of the cell.
- Mitochondrion – converts food into energy that the cell can use and synthesizes adenosine triphosphate by a process called oxidative phosphorylation. Mitochondria are the powerhouse of the cell.
- Ribosome – creates proteins for use inside and outside the cell.
- Lysosome and peroxisome – digest foreign bacteria in the cell, rid the cell of toxic materials and recycle worn out cell components. These organelles act as the recycling center of the cell.
The nucleus is often referred to as the control center, or brain, of the cell and contains the DNA, or genetic material. The nucleus is surrounded by the nuclear envelope. For more information on DNA, see section “DNA Definition.”
Cells that contain these features (ie, cytoskeleton, organelles surrounded by cytoplasm and nucleus surrounded by nuclear envelope) are called eukaryotic cells. Human cells are eukaryotic cells.
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