Week 6 - Protein & Amino Acids

FST1911

What is the major component of muscles

Protein

Protein and amino acids are made from

CHON

We have _____ common amino acids and ____ essential amino acids. Why are they essential?

20 and 9 essential

• 9 essential amino acids can only be obtained by our diet, body does not produce

What is the structure of amino acids?

1. Carbon atom

2. Hydrogen atom

3. Amino grp - NH2

4. Acid grp - COOH

Essential and non essential amino acids can also be referred to as___?

non essential - dispensable

essential - indispensable

Do non-essential amino acids have to be part of our everyday diet?

no

What are conditionally essential amino acids?

under a specific condition (illness or stress)

E.g body fails to supply essential aa to make tyrosine (non-essential). Tyrosine becomes essential

What do you call an aa chain made from 4-9 aa

Oligopeptide

Does the protein we consume from food become body proteins immediately? Explain.

No.

E.g Eggs (broken down by enzymes) —> free amino acids (recombine) —> proteins

Where does protein digestion begin in the body? Explain what happens.

Stomach: partial breakdown of protein (hydrolysis)

• HCL acid denatures protein (uncoil)

• Digestive enzyme break peptide bond —> Aa

• Aa —> polypeptide

• move to small intestine

Where is protein digestion completed? How?

Small intestine

• pancreatic and intestinal protease break polypeptide

• hydrolyse into di/tripeptide and Aa

• Peptidase hydrolyse peptide bonds on the membrane surface of intestinal cells

—> split di/tripeptide into single Aa

• Absorbed into bloodstream through small intestinal lining

What enzymes are involved in the digestion of protein in the small intestine?

1. Pancreatic and intestinal protease - break polypeptide

2. Peptidase - break peptide bond

What substances are involved in protein digestion in the stomach

1. HCL acid - uncoil

2. Pepsin - break peptide bonds

Where does protein absorbtion happen

Small intestine

• specific carriers transport Aa into the intestinal cells (used for energy & req. components)

What happens to unused amino acids?

transported across cell membrane into the surrounding fluid which enter capillaries on the way to the liver thru the hepatic portal vein

What does the liver do in the context of protein?

Amino acid distribution

Role of proteins: (8) - SEHRATAS

1. Structural materials

2. Enzymes

3. Hormones

4. Regulation of fluid balance

5. Acid-Base regulator

6. Transporter

7. Antibodies

8. Source of energy and glucose

How do proteins act as structural materials?

Collagen is a structural protein that acts as a structural material in a matrix

Explain matrix

Basic substance that gives form to developed structures (teeth and bones)

Enzymes

• aid in the digestion and breakdown of substances

• build (bone and teeth) and transform substances (aa—> glucose)

• each enzyme facilitates a specific chemical reaction (catabolic and anabolic)

Define catabolic and anabolic

Catabolic —> breakdown reaction to produce ATP

Anabolic —> build up reaction requires ATP

Proteins as hormones

• Chemical messenger produced in one area of the body that communicates and controls another

How do proteins regulate fluid balance

Blood proteins contribute to no. of dissolved particles in the blood

• protein lvl dec. —> H2O leaks out of the cell via osmosis —> accumulates in the tissue —> swelling (edema)

Protein can be lost due to…

• Inflammation and critical illness

• Inadequate protein synthesis caused by liver disease

• Inadequate dietary intake of protein

How does protein act as acid base regulators

in blood, hemoglobin acts as a buffer and absorbs excess H+ or release H+ to maintain pH

How do proteins act as transporters?

Some proteins move around body fluids, carrying nutrients and other molecules

• each allocated to a certain compound/grp of related compounds

How do proteins act as antibodies

• protective protein produced by immune system to a specific antigen

How do proteins act as a source of energy and glucose?

Protein calories used as energy source when insufficient fat and carbs

• undergoes deanimation and gluconeogenesis

Deanimation

• Nitrogen part removed (forms ureas for extraction)

• The remaining carbon makes glucose

Define protein requirement

—> Level of protein breakdown determined by amount of urea and other nitrogen containing compounds in urine, faeces and sweat