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bio - [1] biological molecules > [1.6] proteins > Flashcards

[1.6] proteins Flashcards

1
Q

what are 10 functions of proteins?

and examples of each :D

A
  1. structure - collagen, keratin
  2. enzymes - amylase, catalase
  3. transport - haemoglobin
  4. hormones - insulin, glucagon
  5. receptors - rhodopsin
  6. antibodies - immunoglobulin
  7. blood clotting - thrombin, fibrin
  8. lubrication - glycoproteins in synovial fluid
  9. toxins - diptheria toxin
  10. antifreeze - glycoproteins in arctic flea
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2
Q

what elements are proteins made from?

A
  • carbon, hydrogen, nitrogen, and oxygen
  • they can also contain sulphur or phosphorus
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3
Q

what is the basic structure of amino acids? (5)

A
  1. central carbon
  2. hydrogen atom
  3. side chain
  4. amine group
  5. carboxyl group
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4
Q

how many naturally occurring amino acids are there and how do they differ?

A
  • there are 20 naturally occurring amino acids
  • they have the same basic structure but with different R groups
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5
Q

how can R groups vary?

A
  • size
  • polarity
  • charge
    > acid (+) or base (-) depending on H+ ion concentration

~ this gives every amino acid different properties

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6
Q

how is a dipeptide formed?

A
  • two amino acids are joined together during a condensation reaction to form a dipeptide
  • the condensation reaction occurs between the carboxyl group (-COOH) and the amino group (-NH₂) on adjacent amino acids
  • a molecule of water is released as one oxygen and two hydrogen atoms are removed from the amino acids
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7
Q

what is a peptide bond?

A

it is a covalent bond formed when two amino acids are joined together to form a dipeptide in a condensation reaction

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8
Q

how is a polypeptide formed?

A

when many amino acids are joined together in a series of condensation reactions

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9
Q

how is a protein formed?

A

when one or many polypeptide chains fold into a specific shape that allows it to perform a specific function

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10
Q

how can a dipeptide be broken down into two amino acids?

A
  • through a hydrolysis reaction
  • this required a molecule of water as one oxygen and two hydrogen atoms are added to the dipeptide
  • this breaks the peptide bond, forming two amino acids
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11
Q

in what ways can polypeptides be broken down?

A

polypeptides can be broken down into amino acids by a series of hydrolysis reactions. this can happen in two ways:

O=O=O=O ➞ O=O=O + O ➞ O=O + O + O ➞ O + O + O + O

or

O=O=O=O ➞ O=O + O=O ➞ O + O + O + O

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12
Q

what is the primary structure of proteins?

A

a simple, linear chain of amino acids

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13
Q

what is the secondary structure of proteins?

A

bonds within the structure cause it to form either:

  • an alpha helix or
  • a beta pleated sheet
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14
Q

what causes the shape to change in the secondary structure?

A

hydrogen bonds form between the NH of one amino acid’s peptide bond and the C=O of another peptide bond

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15
Q

what is the tertiary structure of proteins?

A
  • folded into a 3D shape
  • the different R groups allow different bonds to form within it
    > hydrogen bonds (weak)
    > ionic bonds (medium)
    > disulphide bonds in cysteine (strong)
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16
Q

what is the quaternary structure of proteins?

A

they are made of multiple polypeptide chains held together by bonds

17
Q

what happens if you change the order of amino acids?

A
  • proteins are made from amino acids
  • a different protein is formed if the order of amino acids is changed
  • the bonds form in different positions so the protein may become useless
18
Q

what are primary bonds?

A

they are permanent forces of attraction which join together atoms/molecules to form larger molecules

19
Q

what are the 3 types of primary bonds?

A
  1. glycosidic bond - links sugars
  2. peptide bond - links amino acids
  3. ester bond - attaches the alcohol with an acid (lipids)
20
Q

what are secondary bonds?

A
  • they are essential for maintaining complex structures of biological molecules
  • eg. hydrogen bonds
21
Q

what are the properties of globular proteins?

A
  • compact, roughly spherical and soluble in water
  • non-polar hydrophobic R groups towards the centre
  • polar hydrophilic R groups on the outside
    > this makes them soluble in water
22
Q

examples of globular proteins and why are they important?

A
  • eg. haemoglobin, immunoglobin, enzymes
  • they have an important physiological role as they can be easily transported around organisms and are involved in metabolic reactions
23
Q

what are the properties of fibrous proteins?

and examples

A
  • little/no tertiary structure
  • large number of hydrophobic R groups makes them insoluble
  • limited number of amino acids with the sequence being highly repetitive
  • very organised, strong structures
  • eg. keratin, collagen

bio - [1] biological molecules (11 decks)

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