PHAROS UNIVERSITY FACULTY OF ALLIED MEDICAL SCIENCE
BIOCHEMISTRY 1 (MGBC-101)
Dr. Tarek El Sewedy
Department of Medical Laboratory Technology
Faculty of Allied Medical Sciences
Lecture 5
Amino acids and proteins Part 2
By the end of this lecture, students will learn:
1. Amino Acids classification.
INTENDED LEARNING OUTCOMES
LECTURE CONTENT
• Classification of amino acids
• Amino Acids and proteins nutritional facts
Structure of amino acids
• The basic structure of an amino-acid molecule consists of a carbon atom
bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen
atom, and a fourth group that differs from one amino acid to another and
often is referred to as the-R group or the side chain.
• The-R group, which can vary widely, is responsible for the differences in
chemical properties.
Amino acids may be characterized
as α, β , or γ
depending on the location of the
amino group on the carbon chain.
α are on the carbon adjacent to the
carboxyl group.
β are on the 2nd carbon
γ on the 3rd carbon from the
carboxyl group.
α, β, or γ Amino Acids
α− amino acidsAmino acids found in proteins are α− amino
acids.
The amino group is always found on the carbon
adjacent to the carboxyl group
Metabolic Classification of the Amino Acids
Essential and Non-essential
Glucogenic and Ketogenic
Essential Amino AcidsOnly 11 Of the 20 amino acids that make up proteins can
be synthesized by the human bodyThe other 9 amino acids must be acquired from food
sources. These amino acids are known as essential amino acids
Non essential Amino Acids
Glucogenic or ketogenic Amino acids
Glucogenic amino acids are
degraded to compounds that
can be used as carbon
skeletons for glucose
synthesis via gluconeogenesis.
Ketogenic amino acids are
degraded to compounds that
can only be used to generate
the ketone bodies.
Glucogenic Amino Acids
Ketogenic Amino AcidsMetabolized to acetyl CoA or acetoacetyl
CoA then to ketone bodies
Leucine
Lysine
Amino Acid Functions1. Amino acids are the
building blocks of proteins.
2. Some amino acids and
their derivatives function
as neurotransmitters
hormones.
3. It may supply the
carbohydrates pool with
glucose ?????????.
Protein functions1. - Catalytic functions [enzymes]
2. - Receptor [insulin receptor]
3. - Structural function [collagen]
4. - Transport [hemoglobin]
5. - Protective functions [Antibodies]
Protein function (cont…)
6. - Hemostasis [clotting factors]
7. - Hormonal functions [insulin, glucagon, GH]
8. - Control of gene expression [transcription factors]
9. - DNA packing [histones]
10.- Act as buffers.
Protein nutritional facts
Spirulina
quinoa
soybeans
Almond
Good sources of protein
Amino Acid nutrition
Our body doesn’t use proteins in a direct way; first proteins are decomposed
into amino acids and then amino acids are used for the resynthesize of
muscular proteins
Protein and diet
Protein and diet
• An individual's daily protein requirement depends on several factors, including:
1. Age - a growing child's needs will not be the same as an individual aged 80 years
2. Sex - males generally require more protein than (non-pregnant or non-breastfeeding) females
3. Weight - an individual who weighs 100 Kg will require more protein compared to somebody who
weighs 50 Kg.
4. Muscular exertion - an individual who earns his living delivering pianos will require more protein
than a computer programmer of the same age and height.
5. Muscle mass - a muscle-bound weight trainer will need more dietary protein than a marathon
runner
6. Health - a person who is recovering after an illness or medical procedure may need more dietary
protein than other people.
• Percentage of energy that should come from protein:
• Children aged 1 to 3 years - 5% to 20%
• Children aged 4 to 18 years - 10% to 30%
• Adults - 10% to 35%
• According to the US Department of Agriculture, our protein intake should be:
• Infants - 10 grams per day
• Teenage boys - up to 52 grams per day
• Teenage girls - up to 46 grams per day
• Adult men- approximately 56 grams per day
• Adult women - approximately 46 grams per day
• Pregnant or lactating (breastfeeding) women - about 71 grams per day
Protein deficiency Mental retardation and reduced IQ.
Growth problems
Wasting and shrinkage of muscle tissue
Apathy
Swollen belly
Anemia
Weaker immune system
Protein Excess
Weight gain.
Intestinal irritation.
Risk of heart disease
Kidney problems
Gout disease
Students selected for assignment
الخضري صالح أالء
ASSIGNMENTS• Selected students are requested to prepare slides about one of the
following topics (To be delivered before next lecture):
• Digestion of proteins
• Essential amino acids.
• Non essential amino acids
• Physical properties of amino acids.
• Chemical properties of amino acids.
• Disease resulting from disturbance in amino acid metabolism.
• Ketone bodies and amino acids
• Translation of RNA
Study QuestionWrite three points about :
Classification of amino acids1-
2-
3-
Principles of Biochemistry, Donald J. Voet,
Judith G. Voet, Charlotte W. pratt; Willey, 3rd
ed.
Suggested readings: