Nicola Eld 18 May at 19:05
Proteins:
Amino acids are the monomer units that are linked to from polymer units called polypeptides. Polypeptides can be combined to form proteins. Amino acids are linked by peptide bonds.
Two monomers can be joined together to form dipeptides. The process is pretty much the same as a monosaccharide making a disaccharide; a condensation reaction, where a water molecule is taken out between them, only it is joined by the carbon and nitrogen joining together, and this is called a dipeptide bond.
After a series of condensation reactions, a polypeptide chain is formed. (100’s of amino acids joined up together.)
The amino acid sequence defines the shape, so a change in this could stop it carrying out it’s function.
The secondary structure is formed by hydrogen bonds forming between the N-H, and C-O as they have opposite charges. This twists the chain into a 3D shape; such as the alpha helix.
The tertiary structure is formed by the bending and twisting of the polypeptide helix into a more compact shape, all three types of bonding, disulfide, hydrogen and ionic, take part in holding the shape together.
The quaternary structure is formed by several polypeptide chains and prosthetic groups joining together into one complex molecule.
The test for proteins is the Biuret test. You place a sample of the solution with equal volumes of Sodium Hydroxide into a test tube. You then add a few drops of copper sulphate, and mix. A purple colouration indicates the presence of peptide bonds, and therefore, a protein. Without, it stays blue.
1) Dipeptide bonds link amino acids together.
2) A condensation reaction is involved in linking amino acids together.
3) The four different components of an amino acid are: An amino group, a carboxyl group, a hydrogen atom, and a functional ‘R’ group.
Enzyme Action:
Enzymes speed up chemical reactions by lowering the activation energy of the reaction. In this way, the reactions can take place at a lower temperature then what they usually would. So, in other words, the reaction can that would take far longer at a lower temperature, would be made quicker with a catalyst, as what they spend the time overcoming has been lowered.
The structure of enzyme molecules related to their function in that they are globular proteins, and therefore, have a specific 3D shape (which is a result of their sequence of amino acids.) Although enzymes are large, only the active site really takes part in anything. It forms a hollow depression within the much larger enzyme molecule. When the substrate & active site form an enzyme substrate complex, the substrate is held there by bonds that temporarily form between the amino acids of the active site and groups on the substrate molecule.
The lock and key model of enzyme action proposes that enzyme s work in the same way as a lock and key; only shape of key will fit one specific lock, which applies, as a substrate would be the key, which only fits one specific enzyme, the lock.
The induced fit model shows how the enzyme is not rigid, but flexible. It compares the enzyme to more of a glove then a lock. A glove has a complimentary shape to a hand, and when a hand (like the substrate) fits into it, it sort of ‘moulds’ around it.
As the enzyme changes shape it puts a strain on a particular bond, which makes the activation energy needed to break that bond lower, which is how enzymes work.
1) A Catalyst is a globular protein that speeds up a reaction, by lowering the activation energy, but doesn’t directly take part and can be re-used.
2) Enzymes are effective in tiny quantities as they can be reused repeatedly.
3) By changing one of the amino acids that make up the active site, it would change the primary structure, (sequence) which would affect the tertiary structure, and the shape that it makes, and therefore change the shape of the active site, meaning the substrate that was meant to fit there would no longer fit, and the enzyme would not me able to produce products from the substrate as it would not fit, and it would therefore, not be active.
4) Because changing amino acids not near the active site would change the primary structure, and in turn, change the tertiary, which would change the shape, and this 3D shape that is made is important as it makes each protein distinctive so it can be recognised and recognise (by) other molecules, and if this is changed, it won’t be recognised, so the substrate will not locate the enzyme, and that way, no products will be made.
Amino acids are the monomer units that are linked to from polymer units called polypeptides. Polypeptides can be combined to form proteins. Amino acids are linked by peptide bonds.
Two monomers can be joined together to form dipeptides. The process is pretty much the same as a monosaccharide making a disaccharide; a condensation reaction, where a water molecule is taken out between them, only it is joined by the carbon and nitrogen joining together, and this is called a dipeptide bond.
After a series of condensation reactions, a polypeptide chain is formed. (100’s of amino acids joined up together.)
The amino acid sequence defines the shape, so a change in this could stop it carrying out it’s function.
The secondary structure is formed by hydrogen bonds forming between the N-H, and C-O as they have opposite charges. This twists the chain into a 3D shape; such as the alpha helix.
The tertiary structure is formed by the bending and twisting of the polypeptide helix into a more compact shape, all three types of bonding, disulfide, hydrogen and ionic, take part in holding the shape together.
The quaternary structure is formed by several polypeptide chains and prosthetic groups joining together into one complex molecule.
The test for proteins is the Biuret test. You place a sample of the solution with equal volumes of Sodium Hydroxide into a test tube. You then add a few drops of copper sulphate, and mix. A purple colouration indicates the presence of peptide bonds, and therefore, a protein. Without, it stays blue.
1) Dipeptide bonds link amino acids together.
2) A condensation reaction is involved in linking amino acids together.
3) The four different components of an amino acid are: An amino group, a carboxyl group, a hydrogen atom, and a functional ‘R’ group.
Enzyme Action:
Enzymes speed up chemical reactions by lowering the activation energy of the reaction. In this way, the reactions can take place at a lower temperature then what they usually would. So, in other words, the reaction can that would take far longer at a lower temperature, would be made quicker with a catalyst, as what they spend the time overcoming has been lowered.
The structure of enzyme molecules related to their function in that they are globular proteins, and therefore, have a specific 3D shape (which is a result of their sequence of amino acids.) Although enzymes are large, only the active site really takes part in anything. It forms a hollow depression within the much larger enzyme molecule. When the substrate & active site form an enzyme substrate complex, the substrate is held there by bonds that temporarily form between the amino acids of the active site and groups on the substrate molecule.
The lock and key model of enzyme action proposes that enzyme s work in the same way as a lock and key; only shape of key will fit one specific lock, which applies, as a substrate would be the key, which only fits one specific enzyme, the lock.
The induced fit model shows how the enzyme is not rigid, but flexible. It compares the enzyme to more of a glove then a lock. A glove has a complimentary shape to a hand, and when a hand (like the substrate) fits into it, it sort of ‘moulds’ around it.
As the enzyme changes shape it puts a strain on a particular bond, which makes the activation energy needed to break that bond lower, which is how enzymes work.
1) A Catalyst is a globular protein that speeds up a reaction, by lowering the activation energy, but doesn’t directly take part and can be re-used.
2) Enzymes are effective in tiny quantities as they can be reused repeatedly.
3) By changing one of the amino acids that make up the active site, it would change the primary structure, (sequence) which would affect the tertiary structure, and the shape that it makes, and therefore change the shape of the active site, meaning the substrate that was meant to fit there would no longer fit, and the enzyme would not me able to produce products from the substrate as it would not fit, and it would therefore, not be active.
4) Because changing amino acids not near the active site would change the primary structure, and in turn, change the tertiary, which would change the shape, and this 3D shape that is made is important as it makes each protein distinctive so it can be recognised and recognise (by) other molecules, and if this is changed, it won’t be recognised, so the substrate will not locate the enzyme, and that way, no products will be made.
No comments:
Post a Comment