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Biological Molecules > Proteins > Flashcards

Proteins Flashcards

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Organic Chemistry 101 flashcards
1
Q

What are proteins made up of?

A

Amino acids

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2
Q

What elements make up a protein?

A 
C
H
O
N
(S)
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3
Q

How many naturally occurring amino acids are there?

A

20

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4
Q

What is the basic structure of an amino acid?

A 
R 
                      I         
H  —  N  —  C  —  C  =  O 
           I          I         I 
          H        H        OH
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5
Q

How are 2 amino acids joined (functional groups) ?

A

Amino group of one

Carboxyl group of another

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6
Q

What type of reaction joins 2 amino acids?

A

Condensation

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7
Q

What is the bond name formed between 2 amino acids?

A

Peptide bond

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8
Q

What is the name of 2 amino acids joined together?

A

Dipeptide

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9
Q

What are the type of bonds which form the 3D structure of the protein?

A

Hydrogen bonds
Iconic bonds
Disulphide bridges

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10
Q

What do the type of bonds formed between amino acid chain depend on?

A

The R group

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11
Q

Which atoms form hydrogen bonds in amino acid chains?

A

Delta negative charge of O (lone pairs)

Delta positive charge of H

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12
Q

What affects hydrogen bonds?

A

Temperature

pH

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13
Q

Which 2 molecules allow the formation of disulphide bridges?

A

Cysteine molecules

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14
Q

How does a disulphides bridge occur?

A

Oxidation reaction between 2 sulfur groups

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15
Q

What is the primary structure of a protein?

A

The sequence of amino acids that make up the polypeptide chain help together by peptide bonds

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16
Q

What is the secondary structure of a protein?

A

The arrangement of the polypeptide chain into a regular repeating structure held together by hydrogen bonds

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17
Q

Give examples of secondary structure.

A

a helix

B pleated sheet

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18
Q

What type of protein is prone to having B pleated sheets as a secondary structure?

A

Fibrous proteins

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19
Q

What is tertiary structure?

A

A level of 3D organisation imposed on top of the secondary structure of many proteins

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20
Q

What type of protein is prone to having tertiary structures?

A

Globular proteins

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21
Q

What is the quaternary structure of a protein?

A

Only seen in proteins consisting of several polypeptide chains

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22
Q

Give examples of quaternary structure.

A

Important enzymes

Blood pigment haemoglobin

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23
Q

What is the name of changes in protein structure leading the bonds to break?

A

Denaturing

24
Q

What are the properties of fibrous proteins?

A

Little or no tertiary structure
Long parallel chains with occasional cross-linkages into fibres
Insoluble in water
Very tough

25
Q

What is the function of fibrous proteins?

A

Structural proteins
Appear in connective tissues
Keratin in hair

26
Q

Give an example of a fibrous protein.

A

Collagen

27
Q

What is the function of collagen?

A

Gives strength to tendons, ligaments, bones and skin

28
Q

What is the primary structure of collagen?

A

3 polypeptide chains
Each up to 1000 amino acids long
Repeating sequences of glycine and 2 other amino acids

29
Q

Which amino acids make up collagen?

A

Glycine and 2 others

Often proline and hydroxyproline

30
Q

How are the amino acids arranged in collagen?

A

Three a - chains are arranged in a unique triple helix

Held together by very large no of hydrogen bonds

31
Q

What disease may result in the triple helix of collagen not forming?

A

Genetic disease osteogenesis imperfecta

32
Q

What are the properties of globular proteins?

A

Complex tertiary (and sometimes quaternary) structure
Spherical shapes
Large size

33
Q

Why are globular proteins insoluble?

A

They are too big

34
Q

What is unusual about globular proteins solubility?

A

Is expected to dissolve in water (ionic properties of amino and carboxyl group) form a colloid instead

35
Q

What is the name of the molecule formed by globular proteins in water?

A

A colloid

36
Q

What is the function of globular proteins?

A

Hold molecules in position in the cytoplasm

37
Q

Give examples of globular proteins.

A

Antibodies
Enzymes
Some hormones
Haemoglobin

38
Q

How is haemoglobin held together?

A

Disulphides bridge

39
Q

What are conjugated proteins?

A

Protein molecules that join with/ conjugate to another molecule called a prosthetic group

40
Q

Give an example of a conjugated protein (including the prosthetic group)

A

Haemoglobin
(Iron containing prosthetic group)
Chlorophyll
(Magnesium containing prosthetic group)

41
Q

What are glycoproteins?

A

Proteins with a carbohydrate prosthetic group

42
Q

What is the problem with glycoproteins?

A

Carbohydrate part of molecule helps them hold lots of water makes it harder for protein digesting enzymes to break them down

43
Q

Give examples of glycoproteins used in the body.

A

Lubricants - mucus and synovial fluid

44
Q

Why are glycoproteins good lubricants?

A

Water holding properties make them slippery and viscous - reduces friction

45
Q

What are lipoproteins?

A

Proteins conjugated with lipids

46
Q

What is the role of lipoproteins?

A

Important in the transport of cholesterol in blood

47
Q

What is the difference between HDLs and LDLs?

A

HDLs contain more protein - so they are denser

48
Q

What are the types of lipoproteins found in blood?

A

High density lipoproteins

Low density lipoproteins

49
Q

What is the test for proteins?

A

Biuret test

Blue solution —> purple solution

50
Q

What are amino acids?

A

The building blocks of proteins

51
Q

What is a peptide bond?

A

The bond formed by condensation reactions between amino acids

52
Q

What are fibrous proteins?

A

Proteins that have long, parallel polypeptide chains with the occasional cross-linkages that form into fibres, but with little tertiary structure

53
Q

What is a disulphide bridge?

A

A strong covalent bond formed as a result of an oxidation reaction between sulfur groups in cysteine

54
Q

What are globular proteins?

A

Large proteins with complex tertiary and sometimes quaternary structures, folded into spherical (globular) shapes

55
Q

What is a prosthetic group?

A

The molecule that is incorporated in a conjugated protein

Biological Molecules (8 decks)

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