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Life is based on carbon compounds, that seem complex, but are all just made from smaller divisions (monomers), that then link together to form polymers.
| Macromolecule (Polymer) | Smallest Unit (Monomer) | Elements |
|---|---|---|
| Carbohydrate | Monosaccharides | Carbon, hydrogen and oxygen. |
| Lipids | Fatty Acids and Glycerol | Carbon, hydrogen and oxygen. |
| Proteins | Amino acids | Carbon, hydrogen, oxygen and nitrogen. Other elements are also often present, for example sulphur and phosphorus |
| Nucleic acids(DNA & RNA) | Nucleotides | Carbon, hydrogen, oxygen, nitrogen and phosphorus. |
Condensation and Hydrolysis...
Parts of Metabolism. thus enzyme-catalyzed. Condensation is an anabolic reaction. During condensation an H2O molecule is released and two monomers are joined with a strong covalent bond. Reversely, during Hydrolysis, a catabolic reaction, H2O molecule is split and replaced into two monomers, broken down from a polymer. Hydrolysis takes place during digestion.
| Macromolecule | Bonds between monomers |
|---|---|
| Carbohydrates | Glycosidic |
| Lipids | Esther |
| Proteins | Peptide |
Amino Acids...
The smallest units(monomers) of a protein, feature an amino and carboxyl group, connected by R-C-H. "R" is a variable that can be different atoms.
Polypeptides...
A polypeptide is the primary structure of a protein. The sequence of the amino acids within a polypeptide is determined by genetic code.
Polypeptides are polymers built of amino acid monomers during a condensation reaction. The amino group, (NH2) of one amino acids, and the carboxyl group (COOH) of another form a peptide bond, forming a dipeptide. This can continue to from a string of amino acids, called a polypeptide.
Building a protein...
A polypeptide becomes a protein when it folds and connects to itself, or to other polypeptides.
Primary structure
Amino acids form a sequence, known as a polypeptide.
Secondary structure (Now a protein)
The polypeptide beings to coil up and bond with itself through hydrogen bonds.
Tertiary (3rd Level) Structure
Secondary structures fold over once more and Ionic bonds and disulfide bridges form.
Quaternary (4th Level) Structure
Quaternary structures are composed of two or more linked polypeptides.
Functions of proteins...
The function of a protein is determined by the shape of its molecule. Proteins are divided into two main types: globular and fibrous proteins.
| Protein | Function |
|---|---|
| Rubisco | An enzyme involved in carbon fixation in photosynthesis. |
| Insulin | A hormone produced by the pancreas which stimulates the liver to take up glucose from the blood and store it as glycogen. |
| Immunoglobulin | A large protein (antibody) produced by the immune system to fight infection. |
| Rhodopsin | A protein linked to a pigment found in the photoreceptor cells in the retina of the eye. |
| Collagen | A structural protein which builds muscle, tendons, ligaments and the skin of vertebrates. |
| Spider silk | A strong and elastic fibrous protein created by spiders to form their webs. |
Denaturation...
Denaturation is an irreversible process when a protein loses it's form due to a PH or Temperature outside it's operating range. The primary structure of the protein will usually remain but secondary, tertiary and quaternary structures are usually lost.
For example enzymes, which are tertiary proteins, are easily denatured by extremes of pH or temperature and lose the ability to function as catalysts.
Enzymes are a type of protein that are natural catalysts. Catalysts are molecules that increase the rate of reaction between two other molecules without being altered themselves.
Enzyme function...
An enzyme functions by allowing for one of the substrates involved in a reaction to bond with the active site of an enzyme, thus reducing weakening the rest of the substrate's bonds and lowering the activation energy required for the second substrate to react with the first.
Enzyme - Substrate specificity...
Different enzymes can only bond with to different, specific sets of substrates, this is known as enzyme-substrate specificity. The form of an enzyme is such that it can only bond with the substrate. The enzyme can, however, mold around a substrate somewhat. Much like a glove stretches and molds around a hand, so can an enzyme.
Factors Effecting the Efficiency of Enzymes...
pH...
As enzymes are proteins, if the pH of it's environment is too low or too high, they will begin to denature, thus losing effectiveness
Temperature...
Similarly to pH, if the temperature in the environment of an enzyme is too high, it will begin to denature. However, low temperatures do not denature the enzyme, only reduce the number and strength of collisions in the substance, and thus the likelihood of a collision with enough kinetic energy to match the activation energy of the reaction.
Substrate concentration...
Simply put, a higher substrate concentration means a greater chance there is a substrate in each enzyme, however, given a high enough concentration, all enzymes in the solution will be occupied, thus further increase in concentration would have no effect.
Enzyme Inhibition...
Enzyme inhibition refers to when an molecule (inhibitor) interacts with an enzyme in order to stall it's function.
Competitive inhibition...
Competitive inhibitors are molecules that have the right form and charge to bond with the active site of an enzyme, however, do not react with the substrate, thus blocking the correct substrate from bonding with the active site. If the substrate concentration increases in the environment of the enzyme however, the inhibitor will be expelled from the active site, and enzyme function will resume as normal.
Non-competitive inhibition...
Non-competitive inhibitors work by bonding to another part of the enzyme, not the active site, and altering the enzyme's form by breaking it's bonds, thus stopping it from working. Unlike competitive inhibitors, this process is not reversable.
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Fatty acids consist of a long chain of carbon atoms that are joined to hydrogen atoms. If the carbon chain is linked to the maximum number of H atoms with no double bonds it is saturated, because no more H atoms can be added. The length of a fatty acid can vary
If the chain contains a double bond between two of the carbon atoms it is unsaturated.
A chain with just one double bond is monounsaturated, while one with two or more double bonds is polyunsaturated.
Polyunsaturated fatty acids tend to be liquids at room temperature and are mainly from plant sources, e.g. sunflower oil and olive oil.
Unsaturated fatty acids may be either cis or trans configuration. If the spaces where additional hydrogen atoms could bond are both on the same side of the fatty acid it is known as a cis fatty acid and the carbon chain is slightly bent. If the spaces are on opposite sides, it is a trans fatty acid, which has a straight chain.
Health Issue...
Trans fatty acids and saturated fatty acids when overconsumed can cause CHD due to it depositing in arteries.
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Covalent bonds...
Bonds that share the electrons between two atoms.
Ionic bonds...
Bonds where electrons are transferred and charge keeps the atoms together.
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Metabolism is the sum of all the enzyme-catalyzed chemical reactions that occur in a living organism. In anabolic reactions complex organic molecules are build from simpler ones using energy, for example photosynthesis. In catabolic reactions complex organic molecules are broken down with the release of energy, for example cellular respiration.
Metabolism = anabolism + catabolism.
Metabolic Pathways...
Metabolism consists of chains and/or cycles of enzyme-catalyzed reactions. These reactions occur in specific sequences and are called metabolic pathways. The specificity of enzymes means that a reaction only occurs in the presence of a specific enzyme.
End-Product Competitive Inhibition...
Sometimes, the final product in a metabolic pathway will act as an inhibitor for the first enzyme, meaning that if the concentration of the end product in the pathway's environment increases, the pathway will shut down, until the concentration decreases once more, allowing for homeostasis, and avoiding over-production of the final product.
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