Metabolic Processes

Metabolic Processes

A cell continuously carries on metabolic processes.

Metabolic Processes

Anabolic metabolism

Anabolic metabolism consists of constructive processes (such as dehydration synthesis) in which smaller molecules are used to build larger ones.

In dehydration synthesis, hydrogen atoms and hydroxyl grottps are removed, water is formed, arid smaller molecules become bonded by shared atoms.

Complex carbohydrates are synthesized from mono-saccharides, fats are synthesized from glycerol and fatty acids, and proteins are synthesized from amino acids. 

Catabolic metabolism

Catabolic metabolism consists of decomposition proces.ses in which larger molecules arc broken down into smaller ones.

In hydrolysis a water molecule Is used to supply a hydrogen atom to one portion of a molecule and a hydroxyl group to a second portion; the bond between these two portions is broken.

Complex carbohydrates are decomposed into monosaccharides fats are decomposed into glycerol and fatty acids, and proteins are decomposed into amino acids.

Control of Metabolic Reactions

Metabolic reactions are controlled by enzymes.

1. Enzymes and their actions
2. Metabolic reactions require energy to get them started.
3. Enzymes are proteins that promote metabolic reactions.
4. An enzyme acts upon a molecule by temporarily combining with it and straining its chemical bonds.
5. The shape of an enzyme molecule .seems to fit the shape of its substrate molecule.
6. When an enzyme combines with its substrate, the substrate is changed, resulting in a product, while the enzyme is unaltered.
7. The rate of enzyme-controlled reactions depends upon the number of enzyme and substrate molecules present and the efficiency of the enzyme.

Cofactors and coenzymes

1. Co-factors are necessary parts of some enzyme molecules.
2. A cofactor may be an ion or a small organic molecule called a coenzyme.
3. Vitamins, which provide coenzymes, usiialh cannot be synthesized by human cells in adequate amounts.

Factors that alter enzymes

1. Enzymes are proteins and can be denatured.
2. Factors that may denature enzymes include excessive heat, radiation, electricity, and certain chemicals.

Energy for Metabolic Reactions

1. Energy is a capacity to produce change or to do work. Common forms of energy include heat, light, sound, electrical energy, mechanical energy, and chemical energy.
2. Whenever changes take place, energy is being transferred from one part to another.

Release of chemical energy

1. Most metabolic processes utilize chemical energy that is released when molecular bonds are broken.
2. The energy released from glucose during cellular respiration is used to promote metabolism.
3. Cellular respiration is controlled by enzymes in the cytoplasm and mitochondria.

Anaerobic respiration

1. The first phase of glucose decomposition occurs in the cytoplasm and is anaerobic.
2. Some of the energy released is transferred to molecules of ATP.

Aerobic respiration

1. The second phase of glucose decomposition occurs within the mitochondria and is aerobic.
2. Considerably more energy is transferred to ATP molecules during this phase than during the anaerobic phase.
3. The final products of glucose decomposition are carbon dioxide, water, and energy.

ATP molecules

1. Thirty-eight molecules of ATP can be produced for each glucose molecule that is decomposed.
2. Energy is captured in the bond of the terminal phosphate of each ATP molecule.
3. Captured energy is released when the terminal phosphate bond of an ATP molecule is broken.
4. An ATP molecule that loses its terminal phosphate becomes an ADP molecule
5. An ADP can be converted to an ATP by capturing some energy and a phosphate.