3.6, 3.7, Proteins, Types of Protein Flashcards

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1
Q

What are the properties of each amino acid determined by?

A

Their Variable group

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2
Q

Describe the basic structure of an amino acid.

A

-There are 3 groups in an amino acid.
-One Amine group (NH2)
-One Carboxyl group (COOH)
-One Variable Group (R)

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3
Q

Are amino acids soluble or insoluble?

A

-Amino acids are soluble in water, and form polar ions when added to water, some some R groups are non-polar.

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4
Q

What are peptides?

A

-Polymers made up of amino acid molecules

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5
Q

What are proteins made up of?

A

Proteins consist of one or more polypeptides arranged as complex macromolecules, and all have specific biological functions

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6
Q

What do all proteins contain?

A

Carbon, Hydrogen, Oxygen and Nitrogen

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7
Q

What group determines which amino acid it will be?

A

The R group.

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8
Q

How many different amino acids are there?

A

20

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9
Q

How is a dipeptide produced?

A

When the amine group of one amino acid and the carboxyl group of another react with eachother in a condensation reaction

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10
Q

What type of bond connects two amino acids together?

A

A peptide bond

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11
Q

What catalyses the reaction between two amino acids?

A

Peptidyl transferase

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12
Q

What type of reaction is it when polypeptide is broken down?

A

Hydrolysis reaction.

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13
Q

How do polypeptides form proteins?

A

Different R groups of the amino acids making up a protein interact with eachother, forming different types of bond.

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14
Q

What determines the shape of a protein?

A

The sequence of the amino acids

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15
Q

What does the shape of a protein determine?

A

Its function

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16
Q

How many levels of protein structure are there? And what are their names?

A

4, Primary, Secondary, Tertiary, Quarternary

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17
Q

What is the Primary Structure of a protein?

A

-The sequence in which the amino acids are joined.

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18
Q

What are amino acids joined by in a polypeptide chain?

A

Peptide bonds

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19
Q

What directs the sequence of amino acids?

A

Information carried within DNA

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20
Q

What does the particular amino acids in a sequence influence?

A

How the polypeptide folds to give the protein’s final shape.

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21
Q

What is the Secondary Structure of proteins the result of?

A

Hydrogen bonds pulling polypeptide chains into different shapes.

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22
Q

How is the Secondary Structure formed?

A

-The oxygen, nitrogen and hydrogen atoms of the repeating structure of the amino acids interact.
-Hydrogen bonds form within the amino acid chain, or between polypeptide chains, and pull the structures into one of two shapes.

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23
Q

What are the two shapes found in secondary structure?

A

Alpha Helix or Beta Pleated Sheet

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24
Q

Do all proteins have a secondary structure?

A

Yes

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25
Q

True or false: Proteins can only have one shape in their structure

A

False, proteins can have both alpha helixes AND beta pleated sheets in their structure, but the helix is the most common of the two

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26
Q

How do proteins form the secondary structure of an alpha helix?

A

Hydrogen bonds form WITHIN an amino acid chain, pulling it into a coiled shape, which is the alpha helix.

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27
Q

How do proteins form the secondary structure of a beta pleated sheet?

A

-Hydrogen bonds join SEPARATE polypeptide chains that lie parallel to eachother.
-The pattern formed by the individual amino acids causes the structure to appear pleated (forming the shape of a beta-pleated sheet)

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28
Q

Where do the Secondary Structures form?

A

Regions along long protein molecules

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29
Q

What is Tertiary Structure?

A

The folding of a protein into its final shape, that often involves sections of secondary structure.

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30
Q

How does Tertiary Structure form?

A

The folding of sections of proteins into their secondary structures brings R groups of different amino acids closer together, so they are close enough to interact and further foldings of these sections occurrs.

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31
Q

What are the different types of interactions between R-Groups in Tertiary Structure?

A

-Hydrophobic and Hydrophilic interactions
-Hydrogen bonds
-Ionic bonds
-Disulfide bonds/bridges

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32
Q

What are hydrophilic and hydrophobic interactions in Tertiary Structure?

A

Weak interactions between polar and non-polar R groups

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33
Q

What are hydrogen bonds in Tertiary Structure?

A

The weakest of the bonds formed

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34
Q

What are ionic bonds in Tertiary Structure?

A

Stronger than hydrogen bonds, and formed between oppositely charged R groups. Vulnerable to changes in pH

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35
Q

What are disulfide bonds in Tertiary Structure?

A

Covalent, and the strongest of the bonds.
Only formed between R-groups that contain sulfur atoms, between adjacent cysteine molecules.

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36
Q

What does Tertiary Structure produce?

A

A variety of complex-shaped proteins, with specialised characteristics and functions.

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37
Q

What is Quarternary Structure?

A

A result of the association of two or more individual polypeptide chains.

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38
Q

What makes Quarternary Structure similar to Tertiary Structure?

A

The interactions between the subunits are the same.

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39
Q

What makes Quarternary Structure different to Tertiary Structure?

A

In Tertiary Structure, the subunits in the interactions are amino acids in the same protein molecule. In Quarternary Structure, the subunits are different protein molecules.

40
Q

What are the subunits in Quarternary Structure?

A

Individual proteins

41
Q

True or false: Protein subunits have to be different in Quarternary Structure

A

False, they can be identical OR different

42
Q

What types of subunits do Enzymes contain?

A

Two identical proteins

43
Q

What types of subunits does Insulin contain?

A

Two different proteins

44
Q

What types of subunits does Haemoglobin contain?

A

4 subunits, made up of 2 sets of 2 identical proteins

45
Q

Is a protein the same thing as a polypeptide chain?

A

Yes

46
Q

What polypeptide chains does haemoglobin contain?

A

Two alpha subunits, two beta subunits. ALSO a non-protein group known as a PROSTHETIC GROUP

47
Q

What is haemoglobin required for?

A

Oxygen transport in the blood

48
Q

Describe the group in Haemoglobin

A

It is a non-protein group known as a PROSTHETIC GROUP, called HEME, that contains Iron 2+. In one molecule of Haemoglobin, there are 4 FE2+ ions present.

49
Q

What 3 groups can proteins be classified into?

A

Globular, conjugated and fibrous

50
Q

What determines what role the protein will play in the body?

A

The tertiary and quarternary structure of the protein.

51
Q

What is the general shape of globular proteins?

A

Compact, spherical shape

52
Q

What is the name for a protein without a prosthetic group?

A

Simple protein

53
Q

Are globular proteins water soluble?

A

Yes

54
Q

Why are globular proteins water soluble?

A

Because the Amino acids with hydrophobic R groups are on the inside of the sphere, and amino acids with hydrophilic R groups are on the outside. This is a feature of tertiary structure.

55
Q

Are globular proteins affected by temp change and pH?

A

Yes, they denature at high temperatures and extreme pH.

56
Q

Are globular proteins generally reactive or unreactive?

A

Reactive

57
Q

Are globular proteins repetitive or not?

A

Not, there are few repetitive amino acid sequences

58
Q

Give an example of a globular protein.

A

Insulin

59
Q

What is insulin?

A

A globular protein involved in the regulation of blood glucose concentration. It is soluble and precisely shaped

60
Q

Why are globular proteins precisely shaped?

A

So that they can bond to complementary receptors on the plasma membrane of cells

61
Q

State the features and properties of globular proteins.

A

-Precise 3D shape
-Spherical
-Soluble
-Simple protein
-Compact
-Reactive
-Affected by changes in pH and temp.

62
Q

What is produced when a protein and a carbohydrate react?

A

A glycoprotein

63
Q

What is produced when a protein and a lipid react?

A

A lipoprotein

64
Q

What are conjugated proteins?

A

Globular proteins that contain a non-protein component (or prosthetic group)

65
Q

What is a prosthetic group?

A

A non-protein component

66
Q

List some of the different types of prosthetic groups.

A

Lipids, carbohydrates, metal ions, molecules derived from vitamins

67
Q

What is the name of the prosthetic group that both Catalase and Haemoglobin contain?

A

Haem group

68
Q

What is haemoglobin?

A

A red, oxygen-carrying pigment found in red blood cells. Contains a haem group, containing Fe2+ ions that can combine reversibly with an oxygen molecule, which enables it to transport oxygen around the bloodstream.

69
Q

What enables haemoglobin to carry oxygen around the bloodstream?

A

The haem group which contains Fe2+ ions that can combine reversibly with an oxygen molecule

70
Q

What is Catalase?

A

An enzyme that catalyses the breakdown of hydrogen peroxide.

71
Q

What is hydrogen peroxide?

A

A common byproduct of the metabolism, damaging to cells and cell components if allowed to accumulate.

72
Q

What are fibrous proteins?

A

Proteins formed from long, insoluble molecules that are strong.

73
Q

Are fibrous proteins soluble?

A

No.

74
Q

What makes fibrous proteins insoluble?

A

Contains a high proportion of amino acids with hydrophobic R groups, making them non-polar and therefore insoluble in water.

75
Q

Do fibrous proteins have a repetitive structure? Why?

A

Yes, because there is a limited range of amino acids, usually with small R groups.

76
Q

Why do fibrous proteins have very organised structures?

A

Because there are a limited range of amino acids, usually with small R groups

77
Q

What are the general properties of Fibrous proteins?

A

Insoluble in water, flexible, unreactive, high tensile strength, not affected by changes in pH or temp.

78
Q

Are there crosslinkages in fibrous proteins? Between what?

A

Yes, between amino acids of adjacent polypeptide chains.

79
Q

List the structures that fibrous proteins have.

A

Repetitive primary structure, limited secondary structure (because they are not folded into 3D shapes), very limited tertiary structure.

80
Q

Give some examples of fibrous proteins.

A

Keratin, Elastin, Collagen

81
Q

Where is Keratin present?

A

In hair, skin and nails

82
Q

What is a large proportion of keratin made of?

A

The amino acid Cysteine

83
Q

What determines the flexibility of keratin?

A

The amount of disulfide bonds in the protein strand

84
Q

What type of protein is Keratin?

A

Fibrous protein

85
Q

What type of protein is Elastin?

A

Fibrous protein

86
Q

What type of protein is Collagen?

A

Fibrous protein

87
Q

What is collagen?

A

A fibrous protein and connective tissue

88
Q

Where is collagen found?

A

Skin, tendons, ligaments and the nervous system.

89
Q

What is a key property of collagen?

A

Flexible

90
Q

What are all the forms of collagen made up of?

A

3 polypeptides wound together in a long and strong rope-like structure

91
Q

Where is elastin found?

A

Walls of blood vessels, skin, and the alveoli in the lungs

92
Q

What is the role of elastin?

A

To give the structures it is found in the flexibility to expand when needed

93
Q

What is the quarternary structure of elastin made from?

A

Many stretchy molecules called tropoelastin

94
Q

Describe a typical fibrous protein structure

A

-3 long parallel polypeptide chains
-Hydrogen bonds forming cross-linkages between the chains, forming a tight triple helix.

95
Q

What does lysozyme break down?

A

Peptidoglycan, the molecule found in the cell walls of bacterial cell walls.