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Animal Cells Essay

The NUCLEUS is the largest organelle in the majority of cells. It contains genetic information in DNA, which is responsible for the cells unique characteristics. The nucleus is separated from the rest of the cell by…. …The NUCLEAR ENVELOPE is used as a barrier which separates the contents of the nucleus from the cytoplasm, all in all keeping the DNA safe and intact. The nuclear envelope regulates the flow of substances into and out of the nucleus. The NUCLEOLUS is an important structure found within the nucleus. The RNA, which will be made into ribosomes is synthesised in the nucleolus. The ribosomes move out of the nucleus to help with protein synthesis. The ROUGH EDOPLASMIC RETICULUM looks rather “pebbeled” through a microscope because of the ribosome’s that are present on the surface. The ribosomes have under gone protein synthesis and so they collect here to be transported to the Golgi apparatus.

The SMOOTH EDNOPLASMIC RETICULUM appears “smooth” through a microscope (hence the name), these carry out different functions depending on the type of cells for example they allow lipid and steroid hormone synthesis to occur, the breakdown of lipid-soluble toxins within liver cells and they control the calcium released in cell contraction. The GOLGI APPARATUS is a membrane bound structure with a single membrane, these are important in packaging macromolecules (large molecules e.g. protein, which is made up of smaller components connected together) for transporting elsewhere within the cell. Proteins that are made by the rough endoplasmic reticulum for export are shut of so that a layer of membrane surrounds them, this structure is called a vesicle and will move through the cyosol and fuse with the membrane of the Golgi apparatus.

The RIBOSOMES are too small to be seen through a light microscope. They are the site of protein synthesis, where messenger RNA from the nucleus of the cell is transferred along the ribosome where amino acid molecules are added to lengthen the protein chain. The MITOCHONDRIA provides energy which the cell needs to carry out simple but vital things e.g. move, divide… They are roughly the size of bacteria but defer in shapes depending on the cell type. Mitochondria have a double membrane: the outer membrane is fairly smooth, called the matrix.

The inner on the other hand is complex; it is folded inwards forming projections called cristae. Most of the reactions for aerobic respiration take place in the mitochondria. Cristae increase the inner membranes surface area and it is on these that food combines with oxygen to produce ATP- an energy source for the cell. LYSOSOMES are common in animal cells containing specific enzymes used in intracellular (within the cell) digestion. Lysosome contents are released into the vacuole to kill/digest the bacteria. If too much is released in some circumstances it can cause cell death also known as necrosis. How is the ———– adapted to carry out its function?-

Nucleus and Nucleolus
Largest organelle to allow the storage of DNA
Has a nuclear envelope around it to ensure that only certain substances are able to enter The Nucleolus is able to change its size basing on ribosomal production
Endoplasmic Reticulum
It works alongside the Golgi apparatus and Lysosome
Rough endoplasmic
Reticulum is studded with ribosome’s
It can change overtime depending upon the cells needs
Golgi apparatus
It has a distinctive structure making it easier to act as a delivery system It also has sub sections which are responsible for the transmission of protein Ribosomes
Small so lots of them fit within one area, as well as ensuring they fit between the folds in the rough endoplasmic reticulum as well as be able to travel through the nuclear envelope
Mitochondria:

Matrix, is fluid filled and contains enzymes for the link reaction as well as the Krebs cycle Cristae, folded inner membrane, where electron transport takes place and creates a large surface area for ATP synthesis ATP synthase, it contains the enzyme for phosphorylation (ADP + Pi ATP) Outer membrane, this controls the entry and exit of substances in and out of the mitochondria (O2 moves in and CO2 moves out)


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