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24 Cards in this Set
- Front
- Back
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What are the 2 main groups of 3D shapes of proteins? |
Globular and fibrous |
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What is the structure of fibrous proteins? |
They form long fibres and have regular repetitive sequences of amino acids. They're also flexible due to hydrogen bonds. |
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Are fibrous proteins soluble or insoluble? |
Insoluble in water |
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What is the function of fibrous proteins? |
They usually have structural roles. For example, myosin in muscles and keratin in hair. |
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What is an example of a fibrous protein? |
Collagen |
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Where is collagen found? |
In skin, bones and ligaments |
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What is the structure of collagen? |
It has three identical polypeptide chains which form a triple helix. In each chain, every third amino acid is glycine. |
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What effect does glycine have on the structure? |
It's small, so it allows 3 polypeptides to pack close together. |
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What holds the chains together? |
Hydrogen bonds |
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How are the collagen molecules linked? |
They're cross linked through covalent bonds (histadine bonds). This forms fibres which make collagen strong. |
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What is the function of collagen? |
It has a structural role in hair, skin, bone and tendons. |
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What are globular proteins? |
Proteins that fold up into a compact ball shape. |
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What is the structure of globular proteins? |
The hydrophobic R groups point towards the centre of the protein, whilst the hydrophilic R groups are on the outside. |
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Are globular proteins soluble or insoluble? |
Soluble in water |
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What is the function of globular proteins? |
They have metabolic roles such as antibodies, enzymes and plasma proteins. |
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What is the structure of globular proteins? |
They have a wide range of amino acid sequences. |
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What is an example of a globular protein? |
Haemoglobin |
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What is the structure of haemoglobin? |
It has 4 polypeptide chains. 2 alpha chains and 2 beta chains. |
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What is a feature of haemoglobin? |
It has a prosthetic group ( non-protein group ). This is the iron ion Fe2+. |
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What is the function of haemoglobin? |
It carries oxygen around the body. |
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What is the test for proteins? |
1) Put 1cm3 of protein solution in a test tube. 2) Add 1cm3 of sodium hydroxide and 5 drops of copper sulphate ( biuret solution ). |
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What will happen if proteins are present? |
It will turn purple. |
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What does hydroxylating mean? |
Adding a hydroxyl group (OH) |
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How do you work out the number of peptide bonds in a protein? |
Number of amino acids - 1 |
