FOOD20003 Chapter Notes - Chapter 6: Kiha 40 Series, Multiple Choice, Marasmus
28 Jun 2018
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TUTE 5 – PROTEINS & AMINO ACIDS (CHAPTER 6)
1. How does the chemical structure of proteins differ from the structures of carbohydrates and
fats?
Protein = vital structural & working substance
Chemically, proteins have C H O like lipids & carbs
But proteins also have nitrogen atoms
2. Describe the structure of amino acids and explain how their sequence in proteins affects the
proteins’ shapes. What are essential amino acids? (pp. 159–162)
Amino acids = NH2 and COOH group
R group (side) distinguishes each amino acid from each other
oThis makes it more complex than carbs or lipids
oi.e. starch = same repeating units (glucose)
essential amino acids (has to be consumed)
oHistidine
oIsoleucine
oLeucine
oLysine
oMethionine
oPhenylalanine
oThreonine
oTryptophan
oValine
oPhenylalanine can be used to make tyrosine
HENCE, if phenylalanine is not present tyrosine becomes a conditionally essential
amino acid
specific amino acid sequence determines the shape and function of proteins (diff interactions)
3. Describe protein digestion and absorption. (pp. 163–165)
DIGESTION
oLong chain smaller chain tripeptides dipeptides single amino acid
oMouth:
Chewing, crushing moisten the protein-rich foods
Mix them up w/ saliva to be swallowed
oStomach:
HCl denatures protein structure & activates pepsinogen to pepsin
Pepsin cleaves protein into smaller polypeptides
oSmall intestine:
Pancreatic & small intestinal enzymes split polypeptides tri/dipeptides
Enzymes on surface of the small intestinal cells hydrolyse peptides to amino acids
then absorbed
ABSORPTION
oSpecific carriers transport amino acids intestinal cells
oOnce inside, amino acids used for:
Energy
Synthesis of needed compounds
oIf not used in intestinal cells transported capillaries liver
oEnzymes in food, just like proteins, are all digested to amino acids
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Document Summary
Tute 5 proteins & amino acids (chapter 6) How does the chemical structure of proteins differ from the structures of carbohydrates and. Chemically, proteins have c h o like lipids & carbs. Describe the structure of amino acids and explain how their sequence in proteins affects the. Amino acids = nh2 and cooh group. Hence, if phenylalanine is not present tyrosine becomes a conditionally essential amino acid specific amino acid sequence determines the shape and function of proteins (diff interactions) Digestion: long chain smaller chain tripeptides dipeptides single amino acid, mouth: Chewing, crushing moisten the protein-rich foods. Mix them up w/ saliva to be swallowed: stomach: Hcl denatures protein structure & activates pepsinogen to pepsin. Pepsin cleaves protein into smaller polypeptides: small intestine: Pancreatic & small intestinal enzymes split polypeptides tri/dipeptides. Enzymes on surface of the small intestinal cells hydrolyse peptides to amino acids then absorbed. Absorption: specific carriers transport amino acids intestinal cells, once inside, amino acids used for:
