unit 8 the amino acids. learning objectives state the composition and describe the structure of...
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UNIT 8THE AMINO ACIDS
LEARNING OBJECTIVES
State the composition and describe the structure of amino acids.
Classify amino acids.List essential, semi-essential and non-
essential amino acids.2
AMINO ACID
Principal source: hydrolysis of protein
Proteins: high molecular weight substances (found in all living tissues)
attached to the same α-carbon
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R
AMINO ACID STRUCTURE
R
OH
C+H3N O
BUILDING AN R GROUP
CH3 CH2H CH2
OH
Glycine Alanine Phenylalanine Tyrosine
• With an H, glycine is the simplest amino acid• Alanine with a methyl group is the next simplest.• Phenylalanine arises when a phenyl group replaces an H on alanine’s
methyl group• Tyrosine evolves by adding an –OH group to the para position on the
phenyl ring of phenylalanine
Substances (found in all living tissues)
Upon Acid, base or enzymes catalyzed hydrolysis: Broken into thousands of amino acids molecules Most proteins produce approximately 20 different α-
amino acids Amino Acids - have both an amino & a carboxylic acid
group attached to the same α-carbon
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FUNCTIONS OF AMINO ACIDS
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FUNCTIONS OF AMINO ACIDS
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LEARNING OBJECTIVES
State the composition and describe the structure of amino acids.
Classify amino acids.List essential, semi-essential and non-
essential amino acids.
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Classification and Structure of Amino Acids
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•Aromatic
•Heterocyclic
•Sulphur containing amino acids
•Alipathic
LEARNING OBJECTIVES
State the composition and describe the structure of amino acids.
Classify amino acids.List essential, semi-essential
and non-essential amino acids.
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ESSENTIAL AMINO ACIDS
8 Amino Acids not Synthesized by the body & Therefore Must Be Taken in the Diet
1. Leucine
2. Isoleucine
3. Threonine
4. Tryptophan
5. Phenylalanine
6. Valine
7. Metheonine
8. Lysine
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MnemonicPvt. Tim Hall563 427 18
H – HistidineA – Arginine
ESSENTIAL AMINO ACIDS
Leucine
Isoleucine
Threonine
Tryptophan
Phenylalanine
Valine
Metheonine
Lysine
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To Maintain The Proper Nitrogen
Balance In The Body
CHILD: Growth failure
ADULT: decrease plasma protein and hemoglobin
levels
DEFICIENCY(1 or more)
SEMI-ESSENTIAL AMINO ACIDS
Histidine
Arginine
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Synthesized partially by the bodyBut not at the rate to meet the requirement in growing children, pregnant and lactating women
NON-ESSENTIAL AMINO ACIDS
Alanine
Aspartic acid
Serine
Proline
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•Can be synthesized by the body
•May not be required in the diet
•Derived from carbon skeletons of lipids and carbohydrates during metabolism or from the transamination of essential amino acids
•Complete or Adequate ProteinsComplete or Adequate Proteins:
Animal Proteins- Supply all of the essential amino acids.•Incomplete Proteins:
Vegetable Proteins- Low in one or more of the essential amino acids
ANIMAL PROTEINSANIMAL PROTEINS
SOURCE TYPE OF CHON
MISSING AA
Egg Complete None
Milk (Dairy) Complete None
Meat, Fish Complete None
SOURCE TYPE OF CHON MISSING AA
Wheat Incomplete Lysine
Corn Incomplete Lysine &Tryptophan
Rice Incomplete Lysine
Beans Incomplete Methionine &Tryptophan
Peas Incomplete Methionine
VEGETABLE PROTEINSVEGETABLE PROTEINS
•The two vegetable proteins are called complementary proteins.
–Ex. Rice and Beans
Leu L
-C-C-CONH2-C-CONH2
-C-COOH -C-C-COOH
-H -CH3
-C-OH -C-SH
-C-C-S-C PPro
-C-C C N N+
-C-C-C-C-NH3+ -C-
-C- -OH
-C-N
Central line
Aliphatic
Amide
Acidic
Imino,Circular
Basic
SulfurHydroxy
Aromatic-C-C-C-N-C-N
N+
=
C-C-C-C
C-C-C-C
C C-C
C C C HN C-COOH
-C-C OH
Gln QAsn N
Asp D Glu EPhe F
Arg R
Lys K
His H
Gly G AAAla VVal I Ile
YTyr
Ser S
Thr T Met M
Cys C
Amino Acid Subway MapTrp W
Non-polar
Polar
This is NOT a metabolic pathway
PO
LAR
NO
N-
PO
LAR
Tyr His
Gly
Acidic Neutral Basic
Asp
Glu GlnCys
Asn Ser
Thr Lys
Arg
Ala
ValIle
Leu MetPhe Trp
Pro
Classification of Amino Acids by Polarity
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