CHAPTER 3MOLECULES OF CELLS

PROTEINS

Ever had a bad hair day?

FUNCTIONS OF PROTEINS1. Homeostatic: 2. Structural:3. Hormonal- neural: 4. Enzymatic:5. Transport:6. Protection:7. Contractile: 8. Storage:

1. Homeostatic: proteins acts as buffers in body fluids

are they water soluble?

2. Structural:connective tissue proteins like

collagen (forming nails, feathers, hair…)are they water soluble?

FUNCTIONS OF PROTEINS

3. Hormonal-neural (signaling): hormones like insulin neurotransmittersreceptors on cell membrane

what is their function?4. Enzymatic:

catalysts in reactionswhat is their function?

FUNCTIONS OF PROTEINS

5. Transport:cell membrane proteinshemoglobin and myoglobin

what do they transport?6. Protection:

antibodiesfibrinogen, thrombin

what do they protect from?

FUNCTIONS OF PROTEINS

7. Contractile: myosin, actin

where are they found?what is their function?

8. Storage: albumin in eggs, bloodcasein in milkaleurone, gluten in seeds

what is their function?

FUNCTIONS OF PROTEINS

Structure of an amino acid

Examples of amino acids

Dipeptide formation

Dipeptide formation

Primary structure of proteins

What is the importance of the primary structure?

Symptoms• Delayed growth in children• Shortness of breath, dizziness and headache • Eye problems• Gallstones and nausea• Ulcers on the legs• Chest pain, lung damage leading to hypertension• Spleen problems leading to blood transfusions

and infections like pneumonia, meningitis, hepatitis

• Multiple organ failure and DEATH• Stroke leading to brain damage, paralysis and

DEATH

What maintains the primary structure?

What determines the primary structure?

Secondary structure of proteins

What maintains the secondary structure?

Tertiary structure of proteins

What maintains the tertiary structure?

What is the importance of the tertiary structure?

Types of tertiary structure

• Fibrous proteins perform structural functions: tendon, hair,

nail-Long polypeptide chains or sheets.-Insoluble in water, very strong and tough

• Globular proteins function as enzymes, antibodies, hormones

-Folded as globular or spherical molecules-Soluble in water

What happens if a protein folds incorrectly?

Cystic fibrosis

1 amino acid loss in a 1480 amino acid long protein

causes this life-threatening disease

Alzheimer’sMad cow disease

Is there a difference between cooked egg white and raw egg white? Describe.

Is there a difference between permed hair and straightened hair? Describe.

Is there a difference between cooked meat and raw meat? Describe.

Can you taste the difference between cooked milk and raw milk?

Denaturation of proteins• Denaturation is a process in which a

protein loses its specific structure and hence function. Factors that cause denaturation of protein

1- High temperature2- pH changes3- Excess salt