PROTEINS Flashcards

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1
Q

what are proteins

A

diverse group of large and complex polymer molecules, made of long chains of amino acids

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2
Q

what are amino acids

A

basic monomer units which combine to form a polymer called polypeptide, which can be combined to form proteins

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3
Q

role of proteins

A

structural-proteins are the main component of body tissues, such as muscle, skin, ligaments and hair
catalytic- all enzyme are proteins catalyzing many biochemical reactions
signaling-many hormones ad receptors are proteins
immunological-all antibodies are proteins

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4
Q

how many naturally occuring amino acids are there

A

20

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5
Q

formation of a peptide bond

A

Amino acid monomers combine to form a dipeptide, containing a peptide bond, by a condensation reaction

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6
Q

how is a polypeptide formed

A

The –OH group from one of the amino acids combine with the –H from amino group of the other amino acid

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7
Q

describe the primary structure of a protein

A

sequence of amino acids within proteins
the sequence is determined through an organisms DNA
determines the ultimate shape and therefore function of a protein
a change in a single amino acid can change the shape of the protein and stop it from functioning

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8
Q

describe the secondary structure of proteins

A

hydrogen on the -NH has a positive charge, while the Oxygen in -C=O has a negative charge
these two groups form weak bonds called hydrogen bonds
this causes the chain to be twisted into an alpha helix, creating a 3D shape

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9
Q

describe the tertiary structure of proteins

A

alpha helix can be twisted and folded even further to give the complex 3D structure of each protein
maintained by a different number of bonds:
disulfide bonds-fairly strong and only occur if the protein has amino acids containing sulphur
ionic bonds- formed between carboxyl and amino group which are easily broken
hydrogen bonds- numerous but easily broken

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10
Q

describe the quaternary structure of proteins

A

large and complex molecule
contains a number of individual polypeptide chains that are linked in various ways
may also be a non-protein group associated with the molecule, which helps with its function
e.g. hemoglobin contains an iron-containing haem group

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