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The nucleus is the largest organelle in the cell; all cells have a nucleus except for red blood cells. It’s surrounded by a double membrane and within that membrane are nuclear pores, which allow for the exchange of substances between the nucleus and the cytoplasm. The nucleus contains chromatin and a structure called the nucleolus. Chromatin is made from proteins and DNA, DNA controls the cells activities and the nucleolus makes ribosomes.
The mitochondria are oval-shaped and are about 1μm wide and up to 7μm long. It has a double membrane which creates compartments within the organelle, each membrane having a different function. The outer membrane is a phospholipid bilayer, which is permeable to small molecules such as nutrient molecules and adenosine triphosphate which is ATP. The inner membrane is folded over many times and is called cristae, they are the sites of ATP synthesis, the folds increase the surface area so more ATP can be produced. The inner membrane is permeableonly to oxygen, www.abcbodybuilding.com
carbon dioxide and water. The fluid inside the mitochondria is called the matrix and contains enzymes, dissolved oxygen, carbon dioxide and water. The main function of the mitochondria is to synthesis energy for cellular activity, in the form of ATP by the process of aerobic respiration.
There are two types of endoplasmic reticulum, rough and smooth. The endoplasmic reticulum is a series of flattened membrane bound sacs called cisternae. It is continuous with the outer membrane of the nuclear envelope. Rough endoplasmic reticulum has ribosomes attached to the membrane and ribosomes are the site of protein synthesis. However smooth endoplasmic reticulum has no ribosomes attached
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to its membrane, this the visual difference between the smooth and the rough. They both have different functions, the rough endoplasmic reticulum is involved in protein synthesis and the
packaging of some proteins in vesicles, as some may be used in the cell and some will be transported out of the cell by exocytosis e.g.: insulin. The smooth endoplasmic reticulum is
involved in metabolic processes such as the synthesis of steroids, lipids and the detoxification of some toxic chemicals.
The golgi apparatus is also called the golgi body or golgi complex and is made up of a series of membrane fluid-filled flattened sacs. Proteins secreted by the endoplasmic reticulum are transported to the golgi apparatus in vesicles. The golgi apparatus’ main function is to collect, process and sort molecules such as proteins, and the products of this process are stored for later use, or transported to the plasma membrane, and then excreted. www.britannica.com
Lysosomes have a simple structure; they are a round organelle, surrounded by a single membrane but with no clear internal structure. They contain digestive enzymes, which are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down worn out components of the cell. Lysosomes can do this by fusing with vacuoles and dispensing their enzymes into the vacuoles, digesting their contents. The lysosomes are used for the digestion of
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molecules from phagocytosis, and autophagy. Phagocytosis is when a phagocyte moves towards the area of invasion and attaches itself to the microorganism’s receptors e.g.: bacteria. The microorganism is then engulfed by the phagocyte in to a phagosome (vacuole). Inside the
phagocyte are Lysosomes, which fuse with the phagosome and releases digestive enzymes. The digested contents are removed from the phagocyte by exocytosis. Autophagy is when a cell has an inadequate amount of nutrients in their extracellular fluids and begins to digest internal organelles, then recycling the organelles components to use elsewhere.
Bibliography
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encyclopedia2.thefreedictionary.com/Lysosome
www.ofeducationcommission.com/help_for_middle_school_students.htm
http://micro.magnet.fsu.edu/cells/animals/nucleus.html
www.abcbodybuilding.com/magazine03/8weekstobiggertibialis.htm
academic.brooklyn.cuny.edu/biology/bio4fv/page/rougher.htm
www.britannica.com/EBchecked/topic-art/238040/114953/The-Golgi-apparatus-or-complex-plays-an-important-role-in
www.uni-bielefeld.de/chemie/bc1/BCI_Forschung.htm
