Eukaryotes

 

Eukaryotes are the type of cells found within all organisms, except bacteria and archaea. Some of the organelles found within eukaryotic cells are:

1) The cell surface membrane. This is the membrane which surrounds the cell and regulates the movements of substances into and out of the cell.

2) The nucleus. This is the largest organelle found within eukaryotic cells and contains the cell’s genetic information. The          nucleus is surrounded by a double membrane, called a nuclear envelope, with many pores called nuclear pores to let molecules into and out of the nucleus. 

3) Mitochondria. These oval shaped organelles are responsible in the creation of the molecule ATP during aerobic respiration.  ATP is broken down by the cell to release energy. Like the nucleus, mitochondria have a double membrane. The inner membrane is folded to form structures called cristae, which increase the surface area of the inner membrane so more aerobic respiration can take place. Inside the organelle is the matrix and contains all of the enzymes required for aerobic respiration.

4) Ribosomes. These are very small organelles which either float freely or are attached to the membrane of the RER. They are involved in protein synthesis.

5) RER. This organelle is a system of membranes enclosing a fluid-filled space with a surface covered in ribosomes. The RER folds and process proteins that have been made by the ribosome.

6) SER. Similar to the RER, this organelle is involved in lipid synthesis.

7) Golgi apparatus. This organelle is a group of fluid-filled membrane-bound flattened sacs, which package lipids and proteins into small membranes called Golgi vesicles. These vesicles then transport the lipids and proteins out the the cell by endocytosis.

8) Lysosomes. This organelle is a type of Golgi vesicle produced by the Golgi apparatus. Lysosomes contain digestive enzymes which can be released to break down invading cells or worn out organelles.

These three eukaryotic organelles are only found within plant cells.

1) Chloroplasts. Within this organelle is a fluid called stroma, and contains the enzymes required for photosynthesis. There are also many membranes, which are stacked to form grana. Separate grana are linked together by membranes called lamellae. Photosynthesis takes place within the grana and stoma.

2) Cell wall. This is a rigid structure that surrounds the cell. In plants, the cell wall is made of the substance cellulose. This organelle supports the cell and stops it from changing shape.

3) Cell Vacuole. This organelle contains sap within its membrane and is involved in maintaining pressure within the cell and in the isolation of unwanted chemicals.  

 

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