Unit 1 - Topic 2 - Proteins - Section C - Protein structure, ligand binding and conformational change - Part I - Amino acid sequence determines protein structure Flashcards

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1
Q

What are proteins

A

Polymers of amino acid monomers

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2
Q

How are amino acids linked

A

By peptide bonds to form polypeptides

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3
Q

Amino acids have the same basic structure differing only by what

A

The R group present

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4
Q

How do R groups of amino acids vary

A

In size, shape, charge, hydrogen bonding capacity and chemical reactivity.

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5
Q

Amino acids are classified according to their R groups which are

A

Basic (positively charged); acidic (negatively charged); polar; hydrophobic

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6
Q

The wide range of functions carried out by
proteins results from what

A

The diversity of R groups

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7
Q

What is the primary structure of a protein

A

The primary structure is the sequence in which the amino acids are synthesised into the polypeptide

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8
Q

What results in secondary structure and what are examples of secondary structures

A

Hydrogen bonding along the backbone of the protein strand results in regions of secondary structure — alpha helices, parallel or antiparallel beta-pleated sheets, or turns

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9
Q

What is tertiary structure

A

The polypeptide folds into a tertiary structure

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10
Q

Conformation is stabilised by interactions between R groups such as

A

Hydrophobic interactions; ionic bonds; London dispersion forces; hydrogen bonds; disulfide bridges

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11
Q

What are disulfide bridges

A

Covalent bonds between R groups containing sulfur.

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12
Q

Where does quaternary structure exist

A

In proteins with two or more connected polypeptide subunits

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13
Q

What is quaternary structure

A

Quaternary structure describes the spatial arrangement of the subunits.

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14
Q

What is a prosthetic group

A

A non-protein unit tightly bound to a protein and necessary for its function

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15
Q

The ability of haemoglobin to bind oxygen is
dependent upon what

A

The non-protein haem group

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16
Q

Interactions of R groups can be influenced by what

A

Temperature and pH

17
Q

How does temperature effect R group interactions

A

Increasing temperature disrupts the interactions that hold the protein in shape; the protein begins to unfold, eventually becoming denatured.

18
Q

How does pH affect R group interactions

A

The charges on acidic and basic R groups are affected by pH. As pH increases or decreases from the optimum, the normal ionic interactions between charged groups are lost, which gradually changes the conformation of the protein until it becomes denatured