The electron microscope shows the cell membrane to be a phosphor-lipid-protein-bi-layer. Small, fatty molecules in bi-layers are the lipids. Larger protein molecules are inserted at intervals or completely throughout the bi-layer. Phospholipids are lipid molecules. Phosphate head is water soluble and two lipid chains are soluble in water. The lipid chains face one another as the two layers are aligned. Tissue fluid, the fluid that surrounds the cells and the cytoplasm are both situated in watery environments which are placed next to the phosphate heads.
Cytoplasm This is a semi-fluid material that properties are almost similar to a gel and it has a slow movement. Chemical reactions are all carried out in the cytoplasm. The collective term for the reactions is metabolism. The dark pigment that is responsible for our skin/hair colour is found in cytoplasm. Nucleus The nucleus is simply the largest structure within the cell. Mainly all cells have a single, central, spherical nucleus but these can vary a lot.
There are some muscle cells that have a lot of nuclei and are therefore called ‘multinucleate’. There are red bloods cells that lose their nucleus during their development and therefore are said to be ‘anucleate’. There are also white blood cells that nuclei are lobed and very distinct. Red blood cells don’t have the ability to reproduce and therefore when they are separated from their nuclei then they will die. Cell organelles This is a tiny body inside a cell, which carries out its own functions. Organelles include:
1. Mitochondria – Spherical or rod shaped bodies scattered in the cytoplasm and concerned with energy release. There are at least 1000 of these in the body. Each mitochondrion has a double layered membrane, like the cell membrane, but the inner layer is folded at intervals. 2. The endoplasmic reticulum- Can be shortened to ER. Two variations called smooth and rough ER. It fills the cell interior. Membranes of the channels are similar in structure to the cell membrane and continue with the nuclear membrane.
Passageways are made for the transportation of materials throughout different parts of cell. Rough ER is called this because it has tiny black bodies which are known as ribosomes, they have the function of making cell proteins and acting as a temporary storage. Sugar is added to proteins to make glycoproteins. 3. The Golgi apparatus- Appears like flattened sacs filled with fluids. These are stacked. Tiny fluid-filled globules or bags that is close to the main stack which are known ad vesicles.
The Golgi apparatus packages proteins for delivery to other organelles. It is also responsible for producing lysosomes. 4. Lysosomes- Lysosomes hold enzymes that were created by the cell. The lysosome digests things and this is its main purpose. Lysosomes contain powerful enzymes capable of digesting all major chemical components of living cells. They travel freely throughout the cell and destroy all the olf or damaged organelle and even entire cells.