Proteins are vital for our survival. The human body consists of over 10, 000 different proteins.

Proteins have many different roles in the body:

•Muscle

•Hair

•Skin

•Enzymes

and many, many more.

Proteins:

• C, H, N, and O

• ~ 20 amino acids

• amino acids joined by peptide bond

Protein Structure

1.Primary structure

2.Secondary structure

3.Tertiary Structure

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Fibrous Proteins

•Peptide chains are arranged in parallel strands.

•Play a variety of roles – e.g. – collagen in the skin. (Table 1, p.1, fig. 1.1 p.2)

Skeletal Muscles

•Made of fibres, containing myofibrils, made of sacromeres. (Fig. 1.2 p.3)

•Made of thin actin filaments and thick myosin filaments

•Actin filaments are attached to membrane partition of sacromere, and fit between thick myosin filaments

Made of 3 bands:

1.Light - actin

2. Dark – actin and myosin

3. Medium - myosin

•When muscle contracts, sacromere becomes shorter.

•Actin filaments slide over myosin filaments increasing overlap

•Filaments do not become shorter

Globular Proteins

•Peptide chains folded together into sphere (Fig. 1.1 p.2)

•Held together by hydrogen bonds

Examples:

•Enzymes

•Hormones

•Antibodies

•Transport protein

•Structural protein (e.g., in cell membrane)

Conjugated Proteins

• Globular protein with non-protein component attached

(Fig. 1.1 p.2)

• Examples: 1. Glycoprotein – protein + carbohydrate (mucus)

2. Lipoprotein – protein + lipid (aids fat digestion)

3. Haemoglobin – protein + Haem(Iron) (oxygen transport)

4. Cytochrome – protein + iron (aids energy release)