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48 Cards in this Set
- Front
- Back
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What is Primary structure? |
The sequence of amino acids found in a polypeptide chain. |
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What is the Secondary structure? |
When the protein folds in either an alpha helix or a beta pleated sheet as hydrogen bonds are formed between the amine group and the carboxyl group.
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What is the Tertiary structure and how does the protein fold into a particular shape? |
The overall 3D shape of a protein containing only one polypeptide chain. The protein folds into a particular shape by bonds forming between the R groups in each amino acid structure. These bonds are called disulfide, hydrogen, ionic and hydrophilic and hydrophobic interactions.
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What is the Quaternary structure? |
The overall 3D shape of a protein containing more than one polypeptide chain. |
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What are the monomers for proteins called? |
Amino acids. |
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What is the general formula of an amino acid? |
RCH(NH2) COOH |
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What does the tertiary structure depend on? |
The proteins primary structure. |
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What is a conjugated protein? |
A globular protein with a prosthetic group added to the structure of the protein. |
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What is a prosthetic group? |
A substance that isn't a protein that is permanently attached to the protein. |
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What is an example of a conjugated protein? |
Haemoglobin. |
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What are the two types of tertiary structure? |
Globular and Fibrous. |
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What is a Globular protein? |
A protein with a 3D shape that forms after the twisting and folding of the secondary structure. |
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What is a Fibrous protein? |
A protein with a long, rope-like shape that forms a 3D shape by twisting with several polypeptide chains. |
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What two bonds maintaining the proteins structure are strong? |
Peptide and disulfide. |
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When a protein is heated and gains a little bit of kinetic energy what bonds break? |
Hydrogen and hydrophobic and hydrophilic interactions. |
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When there is a change in pH, which bonds break? |
Ionic and hydrogen. |
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What are the properties of globular proteins? (4) |
- Soluble - Round - Denature easily - Compact |
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What are the properties of fibrous proteins? (3) |
- Insoluble - Tough - Don't denature easily |
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What are 4 examples of globular proteins? |
Haemoglobin, insulin, amylase and channel proteins. |
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What are 3 examples of fibrous proteins? |
Collagen, Keratin and Elastin. |
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What is the name of the bond formed between the Nitrogen and Carbon of an amino acid? |
Peptide bond. |
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What is the reaction called when a dipeptide is synthesised? |
Condensation. |
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What is the biuret test for proteins? |
Add NaOH to the sample to form an alkaline solution then add dilute CuSO4, if the solution turns purple protein is present. |
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What is Thin Layer Chromatography? |
A technique used to separate a mixture of similar molecules. |
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What is a disulfide bond? |
A covalent bond between Sulphur atoms. |
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What are enzymes? |
Biological catalysts. |
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What do biological catalysts do? |
Speed up a reaction in the body without being used up in the reaction itself. |
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What type of proteins are enzymes? |
Globular. |
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What are the two types of enzymes and explain them? |
Intracellular enzymes which speed up reactions inside cells and Extracellular enzymes which speed up enzymes outside of cells. |
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How do enzymes speed up a reaction? |
By forming an Enzymes-substrate complex which lowers the activation energy needed to start a reaction. |
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What is the Lock and Key hypothesis? |
The idea that an enzyme's active site and a substrate molecule is complementary in shape so they fit together like a key fits in a lock. |
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What is the induced fit hypothesis? |
The theory that the active site of an enzyme changes shape when the substrate binds to the active site. |
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What happens when an enzyme catalyses a reaction? |
The enzyme and substrate molecule collide and bind to the active site. This forms an Enzyme-substrate complex as they have complementary shape. A product is then formed producing an Enzyme-product complex. The product is then released from the active site. |
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What factors affect enzyme activity? |
Substrate concentration, Enzymes concentration, temperature and pH. |
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How do you calculate Q10? |
Rate of reaction at (T + 10*C) / Rate of reaction at T*C |
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Why does the graph for substrate concentration against rate of reaction level out? |
Because the enzymes become saturated. |
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Why does the graph for enzyme concentration against rate of reaction level out? |
Because the substrate concentration is limited as there are only so many of them to form enzyme-substrate complexes. |
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What is competitive inhibition? |
This is when the inhibitor is a similar shape to the substrate molecule so, it has a complementary shape to the enzyme's active site. The inhibitor binds to the enzyme's active site, preventing a enzyme-substrate complex from forming which slows down the rate of reaction. |
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What is Non-competitive inhibition? |
When the inhibitor doesn't have a similar shape to the substrate molecule therefore, it binds to the allosteric site. This changes the shape of the active site, preventing enzyme-substrate complexes from forming as the substrate can't fit into the active site. |
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What effect does increasing the substrate concentration in a reaction if a competitive inhibitor is involved? |
Reaches the same end point as the reaction without an inhibitor. |
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What effect does increasing the substrate concentration in a reaction if a Non-competitive inhibitor is involved? |
No effect. |
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What are cofactors? |
Non-protein substances that must be present for an enzyme to work. |
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What are the two types of cofactors? |
Inorganic ions and organic coenzymes. |
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What are inorganic ions and what do they do? |
They stabilise the enzyme structure and they are permanently attached to the tertiary structure. |
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What Cl- the cofactor for? |
Amylase. |
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What does the protein become if it has an inorganic cofactor attached to its tertiary structure permanently? |
A conjugated protein. |
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What does a coenzyme that is temporarily attached do? |
They act as carriers and transfer chemical groups like hydrogen ions. |
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What is precursor activation? |
When inactive enzymes require a cofactor in order to become active. |
