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Biology > 2.1.2 - Proteins > Flashcards

2.1.2 - Proteins Flashcards

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1
Q

Structure of proteins

A
  • Proteins are polymers
  • Monomer : Amino acid
  • Made up of C,H,O,N and could contain S,P
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2
Q

Function of proteins

A
  • Structural roles - Muscles or tendons
  • Metabolic roles - Enzymes or hormones
  • Transport roles - Haemoglobin
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3
Q

Amino acids

A
  • Amine group: NH2
  • Central Carbon
  • H
  • R group
  • Carboxyl group : COOH
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4
Q

Synthesis of dipeptides

A
  • Two amino acids are joined together by a condensation reaction to form a dipeptide
  • A peptide bond is the covalent bond formed when two amino acids are joined together
  • Water is removed
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5
Q

Breakdown of dipeptides

A
  • Hydrolysis reaction
  • Water added
  • Peptide bond broken
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6
Q

Primary structure

A

The specific sequence of amino acids in a polypeptide chain

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7
Q

Secondary structure

A

The folding of the polypeptide chain into alpha helix or beta pleated sheet due to the formation of hydrogen bonds

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8
Q

Alpha helix

A

In an alpha helix, the polypeptide chain coils, H bonds form between amino acids and keep the coil stable

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9
Q

Beta pleated sheet

A

Chains form a zigzag and fold over themselves, H bonds stabilise the structure

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10
Q

Tertiary structure

A
  • The overall specific 3D shape determined by interactions between R groups
  • Bonds form between R groups : Hydrogen bonds, ionic bonds, disulphide bonds and hydrophobic and hydrophilic interactions
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11
Q

Hydrogen bonds

A

These form between polar R-groups

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12
Q

Ionic bonds

A

These form between positively and negatively charged R groups

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13
Q

Disulphide bonds

A

These form between sulphur atoms in R groups

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14
Q

Quaternary structure

A

The specific 3D shape of a protein that is determined by the multiple polypeptide chains bonded together

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15
Q

Haemoglobin structure

A
  • Globular protein
  • Made up of four polypeptide chains
  • Quaternary structure
  • Two alpha chains and two beta chains
  • Each polypeptide chain has an iron ion prosthetic group, so it is a conjugated protein
  • The four prosthetic groups are called haem groups and contain a Fe2+ ion
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16
Q

Haemoglobin function

A
  • Found in red blood cells
  • Transports oxygen around the body
  • The haem group allows haemoglobin to combine reversibly with oxygen
17
Q

Conjugated protein

A

Non- protein component

Haem group

18
Q

Insulin structure

A
  • Globular protein
  • Two polypeptide chains
  • Chain A starts with an alpha helix and chain B ends with a beta pleated sheet
  • Both are folded into tertiary structures which are then joined by disulphide bonds
  • Hydrophilic parts outside and hydrophobic parts on the inside
19
Q

Insulin function

A
  • Secreted by the pancreas
  • Important role in maintaining blood glucose concentration
  • The shape of insulin allows it to specifically bind to receptors in cell membranes to help lower blood glucose concentration.
  • Insulin also has hydrophilic R groups on the outside making it soluble in water. This allows insulin to dissolve in the blood and be easily transported around the body.
20
Q

Catalase structure

A
  • Enzyme
  • 4 polypeptide chains
  • 4 haem prosthetic groups(Fe2+ ions)
  • Has a specific active site
21
Q

Catalase function

A
  • Catalysed a reaction, so it increases the rate of reaction
  • Breaks down hydrogen peroxide
  • Hydrogen peroxide can be damaging to cells.
  • It is a byproduct of metabolism so catalyse prevents hydrogen peroxide accumulating in the body.
22
Q

Globular proteins (Properties)

A
  • Spherical shape
  • Soluble
  • Complementary to another molecule
  • Contain prosthetic group
  • Temp/pH sensitive
23
Q

Fibrous proteins (Properties)

A
  • Elongated strands
  • Insoluble
  • Strong/tough
  • Flexible
24
Q

Keratin

A
  • Fibrous protein
  • Hard and strong
  • High amounts of cysteine results in disulphide bonds
  • This gives it a lot of strength
25
Q

Collagen

A
  • Fibrous protein
  • Forms very strong fibres, so it is used to provide strength to many parts of the body
  • Artery walls : Prevents vessels from bursting
  • Tendons : Connect muscles for bone
  • Connective tissue
26
Q

Elastin

A
  • Fibrous protein
  • Elastic properties
  • Can stretch and recoil
  • Found in walls of blood vessels and the alveoli
  • Expand and contract
27
Q

Fibrous protein functions

A
  • Structure: Collagen is a connective tissue
  • Protection : Keratin provides strength to hair and nails
  • Elasticity : Elastin allows blood vessels to expand and contract
28
Q

Globular protein functions

A
  • Enzymes : Catalyse reaction by reducing activation energy. E.g. Catalase catalyses the breakdown of hydrogen peroxide
  • Hormones :Insulin control blood sugar concentration
  • Transportation : Haemoglobin transports oxygen around the body

Biology (15 decks)

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