Just leaving this here.
The structure and functions of these biological compounds relate to the roles of energy storage, enzyme function and cell membrane within these cells. These roles are vital within animal cells energy storage.
The main energy storage compounds are starch in plants and glycogen in animals. Energy storage is essential for animals as they need energy as a reserve. There are two hormones within the body that are responsible for the maintenance of glucose concentration levels. These are insulin and glucagon. Insulin is released when the blood sugar levels are too high, in response to this the transport of glucose across the cell membrane is increased in order for it to enter the cells. It then becomes metabolised. Glucagon happens when blood sugar levels drops too low. Within glucose are atoms, the structure of these atoms are in a covalent bond (therefore has a strong structure). When these covalent bonds are broken, this results in a huge amount of energy being released. This explains why it is a good source of energy as these bonds are strong. The structure of glycogen is known for being broken down easily and converted to glucose. This is a good source of energy.
Starch is useful as an energy storage compound within plants because of many factors such as they do not affect the water concentration inside cells and they do not move away from the storage areas in the plant. starch can be converted into other substances in plants. For example, cellulose for cell walls and proteins for growth and repair. Starch also enables a large amount of energy to be stored in a small space. Being not very soluble in water is useful for a storage compound.
Each protein has a unique tertiary structure, this allows for its own functions and properties. Below is a diagram showing this tertiary protein structure. (insert image of tertiary protein structure).
These are held together by bonds which are known as hydrogen and ionic between the ‘R’ groups on adjacent chains. Enzymes are only able to function a narrow range of temperatures and pH levels due to the hydrogen bonds. This is because the hydrogen bonds are holding the structure together. The amino acids consist of proteins; this would mean they have a basic structure. These have amino groups, carboxyl acid group and a hydrogen atom. The 4th bond to the ‘alpha’ carbon links the amino acid side of the chain. This is marked as ‘R’. The 3D shape these bonds maintain is high in numbers, however it is weak. The 3D structure of enzymes form pockets and protrusion that can hold and fit into their substrate molecules. The shape of these structures is important being a factor in the specificity of the enzyme. The binding of the substrate to the enzyme also changes the shape of the enzyme is many cases. This change in shape is essential for catalysing the product formation. This means these bonds are easily broken down resulting in the enzyme to lose its shape. This process is known as ‘enzyme denaturation’. This explains why enzymes are only active over certain range in temperature and pH.
Below shows the enzyme substrate complex process: (insert image).
Lock and Key theory:
⦁ Enzymes Are Locks
Enzymes work like a lock in the chemical reaction process that's necessary to maintain life. Each enzyme can attract its specific substrate and accelerate the chemical reaction that must occur in the appropriate time span.
⦁ Enzymes Sites Are Keyholes
The enzyme sites work like the keyhole in a lock. Like the lock on a door, only certain keys will fit in the keyholes, and perhaps only one key will open the lock. Put the wrong key into the keyhole, and you can prevent the correct key from unlocking the door.
⦁ Substrates Are Keys
Each enzyme will only respond to one or two substrates, which work like keys for the enzyme lock. The molecular structure of the substrate must correspond in size and shape to the receptor site on the enzyme to produce the desired chemical response. When the enzyme locates its appropriate substrate, the substrate enters the receptor site and both the enzyme and substrate transform to create a complete union so the chemical reaction can occur.
Below shows the structure of enzymes in relation to the enzyme denaturation process. (insert image).
The cell membranes structure is influenced by phospholipids and proteins. Phospholipids are produced from triglycerides, however within the structure one of the fatty acid chains is replaced with a phosphate group. There are other atoms which are attached to the phosphate. As the phosphate group is negativity charged, it attracts water. The phospholipids create a layer within the cell in order to control the entrance and exits of molecules. This phospholipid layer gives a fluid like structure. the partially permeable membrane of the bilayer determines by the distribution of proteins and phospholipids.
The interior of the cell is primarily made of water. Likewise, the exterior of the cell is usually surrounded by watery fluid. This means that the plasma membrane could not possibly consist of just one layer of phospholipids. This is because the hydrophobic (or water fearing) tail region would have to interact with one of the watery regions inside or outside of the cell. So instead, the cells have evolved to have two layers of phospholipids.
Reference list
. 2016. . [ONLINE] Available at: http://www.3dmoleculardesigns.com/Teacher-Resources/Enzymes-in-Action-Kit.htm.
BBC - GCSE Bitesize: Denaturing of enzymes. 2016. BBC - GCSE Bitesize: Denaturing of enzymes. [ONLINE] Available at: http://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/cells/enzymesrev3.shtml.
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