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INTRODUCTION TO BIOCHEMISTRY
ANDCARBOHYDRATES
BYDR. MARYJANE
Biochemistry is the study of the chemical processes and
transformations in living organisms
Biochemistry is the study of the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules
AMINO ACIDS
BYDR. MARYJANE
INTRODUCTION
• There are about 300 amino acids that occur in nature but only 20 of them are found in proteins.
• Each amino acids has the following four groups or atoms attached to the alpha (α) carbon:
• 1. amino group (NH₂)• 2. carboxyl group (COOH)• 3. hydrogen atom (H)• 4. distinctive side chain or radical group (R)
STUCTURE OF AMINO ACIDS
Showing you how the R group varies
• All amino acids can either be:• 1. D- amino acids, i.e., the amino group is
attached to the right of the α-carbon. This is found in some antibiotics and bacteria cell walls• 2. L-amino acid, i.e., the amino group is
attached to the left of the α-carbon. This is found in proteins.• These two forms are called stereoisomers
or enantiomers
Classification according to charge and polarity Amino acids with Nonpolar side chains or
R-groups Amino acids with Polar side chains: a. uncharged polar side chains b. acidic side chains c. basic side chains
Nonpolar side chains
CLASSIFICATION OF AMINO ACIDS• A. Amino acids with nonpolar side R- Groups.• Glycine (Gly)• Alanine (Ala)• Valine (Val)• Leucine(Leu)• Isoleucine (Ile)• Phenylalanine (Phe)• Tryptophan (Trp)• Methionine (Met)• Proline (Pro)
• Proline differs from the other amino acids in that it the α-amino N form a rigid, five membered ring structure and also contains a secondary amino group rather than a primary amino group. Therefore it is frequently referred to as an imino acid
Imino acid proline
AMINO ACIDS WITH POLAR R-GROUPS
• Amino acids with uncharged polar R-Groups:• Serine• Threonine• Tyrosine• Asparagine• Glutamine• cysteine
Disulfide bond• The side chain of cysteine
contains a sulfhydryl group (-SH). The –SH group of two cysteines can become oxidized to form cystine which contains a covalent cross link called disulfide bond (-S-S-).
• C. Amino acids with acidic R- Groups: are proton donors & negatively charged at physiologic pH
• Aspartic acid (Asp) • Glutamic acid (Glu)
• D. amino acids with basic R- Groups: are proton acceptors & positively charged at physiologic pH
• Histidine (His)• Lysine (Lys)• Arginine (Arg)• Histidine and arginine are needed in growing
children
CLASSIFICATION ACCORDING TO THE AMINO ACID STRUCTURE.
• Can either be aromatic or aliphatic• A. aromatic amino acids• B. aliphatic amino acids
Aromatic amino acids
Phenylalanine: contains a benzene ring Tyrosine: contains a phenol group Tryptophan: contains a heterocyclic
structure, indole
Amino Acids Abbreviations
Nutritional classification of amino acids Essential amino acids Non essential amino acids
Essential amino acids
Arginine Histidine Isoleucine Leucine Threonine Lysine Methionine Phenyalanine Tryptophan Valine Histidine and arginine are essential only for
periods when cell growth exceeds production such as during childhood
Non essential amino acids
Tyrosine Glycine Alanine Cysteine Serine Aspartate Asparagine Glutamate Gutamine proline
METABOLIC CLASSIFICATION• Are classified according to their metabolic fate in the body
into
• Glucogenic amino acid• Ketogenic amino acid• Both glucogenic and ketogenic amino
acid
• ketogenic amino acids: these gives ketone bodies. Leucine and Lysine are the only ketogenic amino acid.
• glucogenic and ketogenic amino acids: these gives both ketone bodies and glucose. They are: phenylalanine, tyrosine, tryptophan and isoleucine.
• glucogenic amino acids: it gives glucose. They include the rest of amino acids not included in the 1st and 2nd groups, they are: alanine, valine, proline, methionine, glycine, serine, threonine, cysteine, asparagine, glutamine, aspartate, glutamic acid, arginine and histidine.
FUNCTIONS OF AMINO ACIDS.• A. structural functions: these are amino acids found in the
structure of:• 1. body peptides and proteins: e.g., plasma proteins, tissue
proteins, enzymes etc.• 2. hormones; some hormones are amino acid derivatives
e.g., thyroxine and catecholamines.• 3. amines; some amino acids give corresponding amines by
decarboxylation e.g. histidine gives histamine.• B. Neurotransmitters: some amino acids, glutamate acts as
neurotransmitters.• C. Detoxification: some amino acids are used in
detoxification reactions e.g., glycine• D. Health and growth: essential amino acids support growth
in infants and maintain health in adults.
TyrosineTyrosine is involved in the synthesis of:
DopamineCatecholamines-Epinephrine,nor epinephrine,dopamineChemical messengers-Transmit impulses across the neurons in the brain and onward to the musclesControl muscle movement
TyrosineNor Epinephrine
TyrosineMelaninTyrosinase-Deficiency-Albinism
Phenylalanine
Epinephrine
Phenylalanine
TryptophanTryptophan is involved in the synthesis of:
Melatonin
Serotonin
Niacin
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