Theories and Perspectives in Biology: Biochemistry and Metabolism
Theories and Perspectives in Biology – Biochemistry and Metabolism.
Metabolism is the term used to describe the chemical reactions that take place inside a cell. Metabolic pathways are a series of these reactions catalysed by enzymes, and are carried out in small steps so that the product of one step can be the substrate of the next. The synthesis of larger molecules from this is called anabolism (e.g. constructing tissue) and the breaking down of these larger molecules is called catabolism (Dow et al., 1995, pp185-186).
All of these reactions are fuelled by ATP (adenosine triphosphate), a molecule that serves as the body’s “energy currency” and permits work to be carried out in a cell.
Thes
The liver is the organ mainly responsible for ridding the body of harmful molecules in a process called detoxification. This ensures that these molecules are converted to products that are safer for the body to deal with until they can be excreted. Toxins may be produced by the body as a product of a metabolic pathway (eg ammonia as a result of deamination of amino acids), or they may have entered the body from an external source.
Ethanol (Alcohol) is a toxin that is quite commonly and regularly consumed by individuals, yet it contains a lot of potential energy when converted to Acetyl CoA. This is an essential component of the Kreb’s (citric acid) cycle and the synthesis of ATP. Alcohol is an open-chain (aliphatic) compound, and dissolves easily in water due to hydrogen bonding between the water and its hydroxyl group. It enters the bloodstream by simple diffusion through the small intestine (having passed through the stomach), and is readily transported around the body due to its miscibility. It has a hydrophilic hydroxide group whereas the ethyl group is hydrophobic, but overall it has no charge so can easily cross cell membranes without the use of a channel protein.
Metabolism is the term used to describe the chemical reactions that take place inside a cell. Metabolic pathways are a series of these reactions catalysed by enzymes, and are carried out in small steps so that the product of one step can be the substrate of the next. The synthesis of larger molecules from this is called anabolism (e.g. constructing tissue) and the breaking down of these larger molecules is called catabolism (Dow et al., 1995, pp185-186).
All of these reactions are fuelled by ATP (adenosine triphosphate), a molecule that serves as the body’s “energy currency” and permits work to be carried out in a cell.
Thes
The liver is the organ mainly responsible for ridding the body of harmful molecules in a process called detoxification. This ensures that these molecules are converted to products that are safer for the body to deal with until they can be excreted. Toxins may be produced by the body as a product of a metabolic pathway (eg ammonia as a result of deamination of amino acids), or they may have entered the body from an external source.
Ethanol (Alcohol) is a toxin that is quite commonly and regularly consumed by individuals, yet it contains a lot of potential energy when converted to Acetyl CoA. This is an essential component of the Kreb’s (citric acid) cycle and the synthesis of ATP. Alcohol is an open-chain (aliphatic) compound, and dissolves easily in water due to hydrogen bonding between the water and its hydroxyl group. It enters the bloodstream by simple diffusion through the small intestine (having passed through the stomach), and is readily transported around the body due to its miscibility. It has a hydrophilic hydroxide group whereas the ethyl group is hydrophobic, but overall it has no charge so can easily cross cell membranes without the use of a channel protein.