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Module 2 - Biology > Lesson 9.2 - Types of proteins > Flashcards

Lesson 9.2 - Types of proteins Flashcards

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1
Q

What are the two types of proteins?

A

Globular and fibrous

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2
Q

Features of globular proteins?

A
  • Soluble in water
  • Compact
  • Spherical shape roughly
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3
Q

When are globular proteins formed?

A

When the protein folds into its tertiary structure.
- Hydrophobic R-groups in amino acids are kept away from the aqueous environment.
- Hydrophilic R-groups in amino acids are on the surface of proteins.

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4
Q

Why are globular proteins soluble in water?

A

Hydrophilic amino acids on the surface of the protein.

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5
Q

Why is it important for globular proteins to be soluble in water for their function?

A
  • Chemical reactions
  • Immunity
  • Contraction
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6
Q

Examples of globular proteins?

A
  • Insulin
  • Haemoglobin
  • Catalase
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7
Q

What is insulin?

A

A globular protein. It is the hormone involved in the regulation of blood glucose concentration.

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8
Q

Why is it important that insulin is soluble?

A

Transported in the bloodstream

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9
Q

Structure of insulin?

A

Have to fit to specific receptors on cell-surface membranes to have effect. Precise shapes.

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10
Q

Conjugated proteins?

A

Type of globular protein. Contains non-protein component called a prosthetic group.

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11
Q

Name of proteins without prosthetic groups?

A

Simple proteins

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12
Q

Types of prosthetic groups:

A
  • Lipids can combine with proteins to form lipoproteins
  • Carbohydrates can combine with proteins to form glycoproteins
  • Metal ions
  • Molecules derived from vitamins
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13
Q

Examples of globular conjugated proteins that contain haem prosthetic group?

A
  • Haemoglobin
  • Catalase
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14
Q

What is haemoglobin?

A

Red, oxygen carrying pigment found in red blood cells.

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15
Q

Structure of haemoglobin?

A

Quaternary protein made from 4 polypeptides (2 alpha and 2 beta subunits).

Each subunit contains a prosthetic haem group.

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16
Q

Purpose of prosthetic haem group in haemoglobin?

A

Iron II (Fe2+) ion found in each haem group. Each can combine reversibly with an O2 molecule.

This enables haemoglobin to transport oxygen around the body.

17
Q

What is catalase?

A

Enzyme that catalyses (increases the rate of reaction) for the break down of hydrogen peroxide.

18
Q

Structure of catalase?

A

Quaternary structure containing 4 haem prosthetic groups.

19
Q

Purpose of haem prosthetic groups in catalase?

A

Iron II ions allows catalase to interact with hydrogen peroxide and speed breakdown.

20
Q

Why should hydrogen peroxide be removed from the body?

A

Common by-product of metabolism. Damaging to cells and cell components when accumulates.

21
Q

What are fibrous proteins?

A

Long, insoluble molecules. Strong and do not tend to be folded into complex three-dimensional shapes.

22
Q

Why are fibrous proteins insoluble?

A

High proportion of amino acids with hydrophilic R-groups in their primary structures.

23
Q

Primary structure of fibrous proteins?

A

Contain limited range of amino acids, usually with small R-groups. Primary sequence of amino acids is quite repetitive. Very organised structures reflected in the roles fibrous proteins have.

24
Q

Examples of fibrous proteins?

A
  • Keratin
  • Collagen
  • Elastin
25
Q

Where is Keratin present?

A
  • Nails
  • Hair
  • Skin
26
Q

Amino acids in Keratin?

A

Large proportion of cysteine (amino acid containing sulfur).

27
Q

Result of cysteine in Keratin?

A

Forms disulfide bridges:
- Strong
- Inflexible
- Insoluble materials

28
Q

What determines the flexibility of hair in comparison to nails?

A

Less disulfide bonds between cysteine amino acids in Keratin.

29
Q

Why does hair / skin smell bad when burnt?

A

Large quantities of sulfur present.

30
Q

Where is elastin found?

A
  • Elastic fibres
  • Small protein fibres
31
Q

Where are elastic fibres present?

A
  • Walls of blood vessels
  • Walls of alveoli in lungs
32
Q

What is the purpose of elastic fibres in bodily structures?

A

Give structures the flexibility to expand when needed. Also return to normal size.

33
Q

Structure of elastin?

A
  • Quaternary structure
  • Made from many stretchy molecules called tropoelastin.
34
Q

What is collagen?

A

Connective tissue found in skin, tendons, ligaments and nervous system.

35
Q

Structure of collagen?

A

All made up of three polypeptides wound up together in a long, strong, rope-like structure.

36
Q

Features of collagen?

A

Flexible

Module 2 - Biology (15 decks)

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