Mitosis is how most of the cells in the body divide. There are two types of cell division: mitosis and meiosis. Cells need to divide for a number of reasons, including the growth of an organism and to fill gaps that dead and destroyed cells leave after an injury, for instance. The human body constantly replaces cells. Some ribosomes float freely in the cytoplasm while others attach to the ER. Ribosomes read the RNA and translate it into proteins by sticking together amino acids in the order the RNA defines. The nucleus transcribes segments of DNA into ribonucleic acid (RNA), a molecule similar to DNA, which directs the translation of RNA into proteins. However, mitochondria have a number of other jobs, including calcium storage and a role in cell death. They help turn energy from food into energy that the cell can use - adenosine triphosphate. People may often refer to mitochondria as the powerhouses of cells. Once materials leave, they may be useful inside or outside the cell. People tend to consider the Golgi apparatus the post office of the cell, where items go through packaging and labeling. Once the ER processes the molecules, they travel to the Golgi apparatus. There are two ER types: rough ER and smooth ER. In particular, it synthesizes, folds, modifies, and transports proteins.Ĭisternae are long sacs that make the ER. The endoplasmic reticulum (ER) processes molecules within the cell and helps transport them to their final destinations. The cytoskeleton also helps with cell signaling through the uptake of material from the endocytosis, or the area outside the cell, and moving materials within the cell. It plays a role in cell division and cell motility - the ability of some cells to move, such as sperm cells, for instance. However, unlike regular scaffolding, the cytoskeleton is flexible. It helps the cell maintain the correct shape. The cytoskeleton forms the scaffolding within the cytoplasm of the human cell. Many of the important reactions that take place in the cell occur in the cytoplasm. It includes the organelles and a jelly-like fluid called the cytosol. The cytoplasm is the interior of the cell that surrounds the nucleus. Fasteners: Some receptors help bind the cell to its neighbors.Communicators: Some receptors help the cell communicate with other cells and the environment.Markers: These receptors act as name badges, informing the immune system that they are part of the organism and not foreign invaders.Gatekeepers: Some receptors allow certain molecules through and stop others.The plasma membrane contains a range of receptors, which carry out a number of tasks, including being: Phospholipids make most of this membrane and prevent water-based substances from entering the cell. To ensure each cell remains separate from its neighbor, a special membrane, known as the plasma membrane, envelops the cell.
Nuclear pores within the membrane allow small molecules and ions to cross back and forth, while larger molecules need to transport proteins to help them through. The nucleus sends out messages to tell the cell to grow, divide, or die.Ī membrane called the nuclear envelope separates the nucleus from the rest of the cell. The nucleus contains the majority of the cell’s DNA, and the mitochondria house a small amount. Skeletal muscle cells, for instance, have two. The nucleus represents the cell’s headquarters. Below are some of the most important: Nucleus These are known as organelles or mini-organs. Share on Pinterest Alexander Spatari/Getty ImagesĮxperts estimate that there are around 200 cell types in the human body.Ĭell types can look different, and carry out distinct roles within the body.įor instance, a sperm cell resembles a tadpole, a female egg cell is spherical, and nerve cells are essentially thin tubes.ĭespite their differences, cells often share certain structures.
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