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Yr 1 - Proteins & Enzymes > Protein Intro > Flashcards

Protein Intro Flashcards

1
Q

What is a proteome?

A

Full set of proteins encoded by the human genome (NOT same as number of genes as 1 gene doesn’t equal 1 protein)

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2
Q

What are single nucleotide polymorphisms (SNPs)? What do they give rise to?

A

Changes in a single base. Give rise to proteins that differ by one amino acid (function slightly differently)

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3
Q

What is the function of enzymes?

A

Required to catalyse metabolic reactions, digestive enzymes break down nutrients into small pieces that can be readily absorbed

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4
Q

What is phenylketonuria?

A

Enzymes can’t break down phenylalanine (important amino acid found it many proteins in diet)

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5
Q

What is haemophilia?

A

The ability of the blood to clot is severely reduced, causing the sufferer to bleed severely from even a slight injury.

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6
Q

What is haemophilia typically caused by?

A

The condition is typically caused by a hereditary lack of a coagulation factor, most often factor VIII.

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7
Q

What is ferritin?

A

A blood protein that contains iron

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8
Q

What is an example of a disease caused by faulty transport proteins?

A

Sickle cell anaemia; Hb isn’t synthesised correctly so problems with transport of oxygen around body

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9
Q

What is myosin an example of?

A

Muscle/motor protein

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10
Q

What is Duchenne muscular dystrophy?

A

Protein dystrophin is absent/ineffective so lose ability to use muscles

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11
Q

What is type 2 diabetes?

A

Non-insulin dependent diabetes –> insulin receptor is faulty so can’t bind insulin properly

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12
Q

What is type 1 diabetes?

A

Insulin lacking as cells in pancreas which synthesise it have been destroyed

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13
Q

What is myasthenia gravis?

A

Body creates antibodies that bind to neurotransmitter receptor which leads to difficulty in getting muscles to respond to neurological signals

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14
Q

How are amino acids joined?

A

By peptide bonds to make a polypeptide chain during a condensation reaction (water is eliminated)

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15
Q

Peptide bonds have partial double bond characteristics. What does this mean?

A
  • limited rotation around bond

- bond resonates between 2 forms; makes bonds quite rigid

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16
Q

What is the 1ary structure?

A

The order of amino acids (sequence)

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17
Q

What is the 1ary structure determined by?

A

The gene that codes for the protein

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18
Q

What does the 1ary structure determine?

A

Structure and function of final folded protein (order of amino acids and R groups they contain)

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19
Q

What is the backbone?

A

Amino acid chain (consist of alpha carbons of each amino acids connected by peptide bonds)

20
Q

What is a residue?

A

An amino acid in the polypeptide chain

21
Q

Why does a polypeptide chain have direction?

A

As amino acids have different ends (C and N terminus)

22
Q

What is 2ary structure of protein?

A

Describes local spatial arrangements of amino acids in peptide chain

23
Q

What is 2ary structure affected by?

A

Hydrogen bonds between amino acids in chain

24
Q

What do hydrogen bonds form between?

A

Between N-H and C=O groups (intrachain H bonds; occur between different parts of same chain)

25
Q

What do these hydrogen bonds do to the chain?

A

Make chain coil into alpha helix or fold into beta pleated sheet

26
Q

Describe an alpha helix

A

Formed by backbone of chain and side chains extend outside helix
- H bonds lie parallel to helix

27
Q

Describe beta pleated sheet

A

Polypeptide chains run alongside one another

  • stabilised by H-bonding between strands
  • may be several strands making up sheet which are part of same chain (intrachain) or between different amino acid chains (interchain)
  • R grounds lie outside plane of sheet
  • strands can run parallel or anti-parallel
28
Q

Describe rigidity of beta pleated sheet

A

Fully extended polypeptide chain; no elasticity (rigid)

29
Q

Describe rigidity of alpha helix

A

H bonds lie parallel to helix; gives helix some elasticity

30
Q

What is the 3ary structure?

A

Overall 3D protein shape of 1ary and 2ary structures (how protein folds)

31
Q

How do soluble proteins fold?

A

Fold so interior is hydrophobic and exterior is hydrophilic

32
Q

What is 4ary structure?

A

Only some proteins consist of more than one polypeptide chain; sub-units

4ary describes spatial arrangement of sub-units

33
Q

What are the strongest forces holding structures together? Why?

A

Disulphide bonds –> strongest as covalent between pairs of Cys (sulphur containing amino acid)

N.B. the 2 Cys may be in different polypeptides so attach 2 chains covalently together

34
Q

What is Cys?

A

Cysteine - sulphur containing amino acid

Contains a thiol (-SH) group and can form covalent bonds with other cysteines

35
Q

What happens when 2 Cys residues are brought close together in a folded protein?

A

The 2 SH groups may react to form sulphide bond

36
Q

What is the 2nd strongest force holding structures together?

A

Electrostatic interactions (ionic bonds)

37
Q

What are ionic bonds?

A

Attraction between oppositely charged side chains

This is called an ion pair and interaction is called a salt bridge

38
Q

What do ionic bonds do?

A

Stabilises structure (chains with same charge would repel and destabilise)

39
Q

What are dipoles?

A

A range of weak process that occur in electrically neutral molecules (permanent dipoles, dipole-induced interactions, London dispersion forces)

40
Q

Where do dipoles occur?

A

Occur across covalent bonds between atoms of different electronegativity so attract shared electrons in bond to different degrees

41
Q

What do dipoles lead to?

A

Polar molecules

42
Q

Why does a C=O have a dipole?

A

O has high EN so slightly -ve charge

C has slightly +ve charge

43
Q

What are hydrogen bonds?

A
  • Example of bond created by dipole formation
  • Attraction between H atom of donor group (e.g -OH and =NH) and non-bonding electrons on acceptor group (e.g O=C-)
  • Stabilise 3ary and 4ary interaction
44
Q

What are Van der Waal’s?

A

Temporary induced dipoles. May occur by chance of be induced by proximity of another charged atom

45
Q

What interactions are most important in stabilising proteins?

A

Hydrophobic interactions

46
Q

How do hydrophobic interactions force folding of the chain?

A
  • Drives hydrophobic molecules together

- Drives polar amino acids (hydrophilic) to surface of protein

Yr 1 - Proteins & Enzymes (8 decks)

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