In this essay, I will be discussing the structure of the typical human cell and talking about the functions of structures. Moreover, I will also be touching on some detail of typical human cells, including processes. Typical human cell structures contain linear DNA, which is in the nucleus. Thus, the nucleus contains genetic information and controls what happens in the cell. Also, a cell contains a cytoplasm, cell membrane, rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), larger-80S ribosomes, lysosomes and Golgi bodies.
All high resolution typical human cells structure is only seen under an electron microscope because of the valuable magnification limit the electron microscope has. The useful magnification of the electron microscope is up to 500,000 times. All typical human cells contain membrane surrounded organelles. This is because they are eukaryotic cells, all but primitive cells. Eukaryotic cells are 10-100 micron meters in diameter.
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The nucleus has structures, nucleolus, genetic material (chromosomes and DNA) and heterochromatin which is the dark stained area. A nuclear envelope surrounds the nucleus; this has two membranes, an inner membrane and an outer membrane and about 10 micrometres. The nuclear envelope has nuclear pores in it, which let genetic information go in and out. In addition, the nucleolus of the nucleus produces the RNA that is used to make ribosomes.
Linked to the nucleus is the rough endoplasmic reticulum, which consists of compartments, and these compartments are called cisternae. There are also organelles on the ‘cytoplasm face’ of the rough endoplasmic reticulum called ribosomes. These have a small and dense structure, like a giant enzyme, plus it has two units, a large and small unit joined together. Moreover, the ribosomes and rough endoplasmic reticulum produce proteins and proteins enzymes. Ribosomes are the sites of translation.
The function of the ribosomes is essential as they give proteins their characteristics by controlling the order of the amino acids in the polypeptide chain in the primary structure, by bonding the amino acids in a particular order by peptide bonds when condensation reactions occur. Furthermore, the nucleus sends out instructions. The ribosomes and rough endoplasmic reticulum send out protein or protein enzymes. The rough endoplasmic reticulum packages and transports them in a transfer vesicle.
The Golgi body modifies the chemical products (proteins and protein enzymes etc.). The Golgi body receives the chemical products on the forming face and modifies the chemicals, e.g. protein enzymes modified from inactive to active protein enzymes. The Golgi has flattened cavities like saucers; as they go from the forming face to the releasing face, each flattened cavity gets circular around the edges, plus this is where the modified chemicals are.
Finally, at the releasing face, the Golgi body packages the modified chemicals in lysosomes; the lysosomes come from the round edges of the flattened cavities, giving the lysosomes a surrounding membrane. The lysosomes contain powerful digestive enzymes; therefore are, involved in metabolic reactions; lysosomes secrete out of the cell via the cell membrane. Some of the lysosomes remain in the cell and hydrolyses old and dead organelles, or surplus organelles of the cell take place. Furthermore, the lysosomes can even be used to break down material that has entered the cell by the process of endocytosis. The tertiary structure of the protein lysosome is an anti-bacterial compound.
The nucleus/DNA information also controls what the cell membrane lets in and out. What is more, the cell membrane has a phospholipids bilayer. The phospholipids are made from two fatty acids, a glycerol and a phosphate group. The glycerol and two amino acids join by condensation reactions, and the oxygen atom is shared in the ester bonds, between the two fatty acids and the glycerol molecule. The phospholipids have a phosphate group that ionizes and gets a positive and negative charge, because of the positive and negative charge it is polar and hydrophilic and attracts water and will, therefore, dissolve in water.
The phospholipids bilayer has hydrophilic heads (phosphate group and glycerol) and hydrophobic (two fatty acids) tails. The hydrophobic tails attract each other and are in the middle of the cell membrane. The plasma membrane is so small that if you have an electron microscope at 500,000x magnification, because of the sort wavelength you can see two lines, which represent the plasma (cell) membrane. Now I will introduce an organelle that is playing a vital role in our cells and helping us keep alive.
The cell has a very important organelle that has evolved to work for the cell; this has been captured by the typical human cell, what more is that these are primitive cells. This organelle used to be a prokaryotic cell which is clearly identifiable when you compare the typical bacterial cell with this organelle called mitochondria. This is because the mitochondria contain circular DNA, which is a similarity to prokaryotic cells. The mitochondrion is a rod-shaped organelle.
Furthermore, the structure of a mitochondrion contains matrix (fluid in the mitochondrion), cristae (folded inner membrane) and circular DNA, ribosomes, inner membrane and an outer membrane. The matrix (fluid) contains enzymes that catalyze reactions in the stages of respiration. The ribosomes inside of a mitochondrion produce the mitochondrion’s own protein enzymes. What’s more is that the folded inner membrane of the mitochondrion, cristae contains enzymes that are concerned with the later stages of respiration.
The great importance of the mitochondria is that it respires to give out energy to the cell, and the cell has several of these organelles respire aerobically to give out ATP energy to power active transport by using enzymes, ATP is used to make big molecules and help muscle contract this is about 1-10 micrometres in size up to 1000 in the cytoplasm of each cell. Another organelle that a typical human cell has is the smooth endoplasmic reticulum. This is not connected to the rough endoplasmic reticulum.
The SER also has compartments in which there are cisternae. Furthermore, the SER is involved in lipid and phospholipids production. Also, the synthesis of steroids takes place here as well. Sometimes this is linked to the rough endoplasmic reticulum is further away in the cell. Hence in you can see that the typical human cells have a complex structure, when each structure does its particular function then it all adds up to carry out a particular job in a typical human cell.