Proteins Flashcards

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1
Q

What is the structure of an amino acid?

A
  • A central carbon atom
  • A amine group to the left
  • A carboxyl group to the right
  • A variable group at the top
  • A hydrogen group at the bottom
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2
Q

How many amino acids do all living organisms contain?

A

20

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3
Q

How does a peptide bond form?

A
  • A condensation reaction between the OH from the carboxyl group of one amino acid and the H from the amine group of another amino acid
    -This forms a dipeptide
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4
Q

What is polymerisation?

A

The process in which many amino acids are joined together through a series of condensation reactions

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5
Q

What is the primary structure of a protein?

A
  • The sequence of amino acids in a polypeptide chain
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6
Q

What is the secondary structure of a protein?

A
  • Due to the overall of positive charge in the amine group and
    the negative charge of the carboxyl group, hydrogen bonding occurs
  • This results in the automatic coil into either an alpha helix or beta pleated sheet
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7
Q

What is the tertiary structure of a protein?

A
  • When amino acids coil and fold further, this causes a specific 3D shape maintained by bonds such as ionic bonds, disulfide bridges and hydrogen bonds
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8
Q

How do disulfide bridges form?

A
  • between two molecules of cysteine as their R groups contain sulphur
  • These are fairly strong and not easily broken
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9
Q

How do ionic and hydrogen bonds form?

A

between oppositely charged parts of molecules

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10
Q

What is the quaternary of proteins?

A
  • Proteins that contain many polypeptide chains held together by bonds
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11
Q

What is the difference between fibrous and globular proteins?

A

Globular = circular and compact
FIbrous = long and therefore used to make fibres

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12
Q

What is the test for proteins?

A
  • Add drops of sodium hydroxide to your food sample to make it alkaline
  • Add drops of copper sulfate solution
  • A positive test is a colour change from blue to purple
    (biuret)
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