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Relating the structure and function of cell organelles

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Introduction

Relate the structure and function of cell organelles Cells are like cities with intricate organelles 'living and working' in it. There are basically two kinds of cells, namely Prokaryotic and Eukaryotic. Both plant cells and animal cells are eukaryotic while prokaryotic cells are simplier organisms that possess non-membrane bounded organelles. In most cells they contains the following organelles which carry out unique functions and allow cells to work properly. To start off with, nucleus is a large roundish organelle enclosed by a double membrane with numerous openings, namely nuclear pores, for nuclear traffic. It contains chromosomes and one or more nucleoli. Nucleolus is a spherical site where ribosomes are formed. Chromosomes contain DNA which tends to be packed in form of chromatin. Only during interphrase (a stage before a cell divides in a cell division process), chromosomes will be unravelled for easier replication. Tiny, hollow cylinders of protein called centrioles form a network of spindle fibres in the nucleus during nuclear division to pull chromosomes apart. The inner membrane of nucleus will break down and allow chromosomes lying freely in cytoplasm. ...read more.

Middle

New protein are synthesised in the rER and buds-off at the other end into the cytoplasm. Part of the rER containing cell products moved to the Golgi apparatus (also known as Golgi body). The Golgi apparatus is layers of fluid-filled flattened sacs with smaller vacuoles or vesicles at both ends of the main structure and roughly parallel to each other. It serves as a packaging department to deliver protein products made in the cell. Molecules from rER are processed and packaged in the sacs to form other substances such as carbohydrates and enzymes so that they are well isolated. When the products are excreted from the Golgi apparatus, they appear as vacuoles at both ends of the body. Lysosomes are also made in the Golgi apparatus. It is a small membrane-bounded sac vesicles in the cytoplasm filled with digestive enzymes to break down and remove worn out parts of the cell. They bud off from the Golgi apparatus and fuse with the food vacuoles. The products packaged from golgi apparatus are then released out of the cell by exocytosis through the plasma membrane. ...read more.

Conclusion

In an animal cell, it is just a tiny waste storage space. A plant cell has all the same organelles with similar functions as animal cells but a few extras. Cell wall and chloroplast are organelles found only in plant cells and other eukaryotic organisms. Cell wall is a rigid layer with plasmodesmata. This allows the exchange of substances with adjacent cells. The cell wall is mainly made of carbohydrate cellulose. Cellulose is a disaccharide with more complex bonding which requires more energy to break the bonds. Thus it can provide mechanical support and protection. Chloroplasts have similar functions as the mitochondria. It is a small, flattened discs surrounded by a double membrane. It contains internal membranes called thylakoids which form coin-like stacks called grana and linked by thin, flat pieces of thylakoids membranes called lamellae. Photosynthesis takes place in the thylakoids membranes to provide the cell with glucose. There is also a thick fluid called stroma in the chloroplast where photosynthesis takes place there sometimes. In general, the structures and the functions of organelles have a close linkage. With the above information, it is shown that all organelles have their unique way of operation which none of it is dispensable. ...read more.

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This is a very well researched and concisely written report.
1. Improvements could be made by including images to illustrate concepts
2. The use of key terms and language is excellent
3. The conclusions is very brief
*****

Marked by teacher Luke Smithen 17/09/2013

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