BMS 204
Lecture 1
Introduction to Biochemistry
Dr. Reem Arafa
Prof. of Biomedical Sciences
Spring 2020
Introduction
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What is the Biochemistry?
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History and development
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How to study Biochemistry?
1. Biochemistry
Definition: The chemistry of life
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The science concerned with the chemical basis of life.
The science concerned with the various molecules that occur in living
cells and organisms and with their chemical reaction.
Anything more than a superficial comprehension of life – in all its
diverse manifestation - demands a knowledge of biochemistry.
Biochemistry
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Aim: to describe and explain, in molecular terms, all chemical processes
of living cells
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Structure-function
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Metabolism and Regulation
Biochemistry
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Significance: be essential to all life sciences as the common
knowledge
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Genetics; Cell biology; Molecular biology
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Physiology and Immunology
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Pharmacology and Pharmacy
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Toxicology; Pathology; Microbiology
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Zoology and Botany
Biochemistry
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Students who acquire a sound knowledge of biochemistry will be in a
strong position to deal with two central concerns of the health sciences:
(1) the understanding and maintenance of health
(2) the understanding and effective treatment of disease
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Causes of cancers
Molecular lesions causing various genetic diseases
Rational design of new drugs
2. History and development of Biochemistry
1903, Neuberg (German):
“Biochemistry”
“Chemistry of Life”
Two notable breakthroughs
(1) Discovery of the role of enzymes as catalysts
(2) Identification of nucleic acids as information molecules
Flow of information: from nucleic acids to proteins
DNA
RNA
Protein
Some historic events
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In 1937, Krebs for the discovery of the Citric Acid Cycle - won the Nobel
Prize in Physiology or Medicine in 1953
In 1953，Watson & Crick for the discovery of the “DNA Double Helix” won the Nobel Prize in Physiology or Medicine in 1962
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In 1955, Sanger for the determination of insulin sequence - won the Nobel
Prize in Physiology or Medicine in 1956
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In 1980, Sanger & Gilbert for Sequencing of DNA - won the Nobel Prize
in Chemistry in 1980
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In 1993, Kary B. Mullis for invention of PCR method - won the Nobel
Prize in Chemistry in 1993
HGP from 1990, completed in 2003
3. What dose the Biochemistry discuss?
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structure and function of cellular components
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proteins, carbohydrates, lipids, nucleic acids and other biomolecules
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Metabolism and Regulation
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Gene expression and modulation
DNA
RNA
Protein
Polymers and Monomers
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Each of these types of molecules are polymers that are
assembled from single units called monomers.
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Each type of macromolecule is an assemblage of a different
type of monomer.
Macromolecule
Monomer
Carbohydrates
Monosaccharide
Lipids
Not always polymers;
Hydrocarbon chains
Proteins
Amino acids
Nucleic acids
Nucleotides
How do monomers form polymers?
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In condensation reactions
(also called dehydration
synthesis), a molecule of
water is removed from
two monomers as they are
connected together.
Anabolic
 Building block
 Macromolecule
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Simple sugar
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Polysaccharide
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Amino acid
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Protein (peptide)
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Nucleotide
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RNA or DNA
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Fatty acid
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Lipid
Catabolic
4. Cells
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Basic building blocks of life.
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Smallest living unit of an organism.
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A cell may be an entire organism (unicellular) or it may be one of billions
of cells that make up the organism (multicellular).
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Grow, reproduce, use energy, adapt, respond to their environment.
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Many cannot be seen with the naked eye
 a typical cell size is 10 µm; a typical cell mass is 1 nanogram
Cells May be Prokaryotic or Eukaryotic
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Prokaryotes (Greek: pro-before; karyon-nucleus)
include various bacteria
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lack a nucleus or membrane-bound structures called
organelles
Eukaryotes (Greek: eu-true; karyon-nucleus)
include most other cells (plants, fungi, & animals)
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have a nucleus and membrane-bound organelles
• Cell membrane & cell wall
• Nucleoid region contains the DNA
• Contain ribosomes (no membrane)
• Cell Membrane
• Nucleus
• Cytoplasm with organelles
Characteristic Bio-membranes and Organelles
• Plasma Membrane-Cell’s defining boundary
Providing a barrier and containing transport
and signaling systems.
• Nucleus – Cell’s information center
Double membrane surrounding the chromosomes and the
nucleolus. The place where almost all DNA replication and
RNA synthesis occur. The nucleolus is a site for synthesis of
RNA making up the ribosome
• Mitochondria- the power generators
Mitochondria (Greek: mitos-thread; chondros-granule):
Surrounded by a double membrane with a series of folds called
cristae. Functions in energy production through metabolism.
Contains its own DNA.
Endoplasmic reticulum (ER) – The transport network for molecules
• Rough endoplasmic reticulum (RER)
Covered with ribosomes (causing the "rough" appearance) which
are in the process of synthesizing proteins for secretion or
localization in membranes.
• Ribosomes
Protein and RNA complex responsible for protein
synthesis.
• Smooth endoplasmic reticulum (SER)
A site for synthesis and metabolism of lipids.
•Golgi apparatus -process and package the macromolecules.
A series of stacked membranes. Vesicles carry materials from
the RER to the Golgi apparatus. Vesicles move between the
stacks while the proteins are "processed" to a mature form.
•Lysosomes-contain digestive enzyme
A membrane bound organelle that is responsible for degrading
proteins and membranes in the cell.
•Cytoplasm
enclosed by the plasma membrane, liquid portion called cytosol
and it houses the membranous organelles.
5. Biomolecules
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Just like cells are building blocks of tissues, biomolecules are building
blocks of cells.
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Animal and plant cells contain approximately 10,000 kinds of
biomolecules.
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Water constitutes 50-95% of cells content by weight.
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Ions like Na+, K+ and Ca2+ may account for another 1%.
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Almost all other kinds of biomolecules are organic (C, H, N, O, P, S).
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Organic compounds are compounds composed primarily of a Carbon
skeleton.
Carbon
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Carbon is more abundant in living organisms than it is in the rest of the
universe.
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What makes Carbon Special? Why is Carbon so different from all the
other elements on the periodic table?
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The answer derives from the ability of Carbon atoms to bond together to
form long chains and rings.
Carbon can form immensely diverse
compounds, from simple to complex.
Methane with 1
Carbon atom
DNA with tens of Billions
of Carbon atoms
Biomolecules
are
compounds
of carbon
with a variety
of functional
groups
Types of biomolecules
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Small molecules:
 Lipid, phospholipid, glycolipid, sterol,
 Vitamin
 Hormone, neurotransmitter
 Carbohydrate, sugar
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Monomers:
 Amino acids
 Nucleotides
 Monosaccharides
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Polymers:
 Peptides, oligopeptides, polypeptides, proteins
 Nucleic acids, i.e. DNA, RNA
 Oligosaccharides, polysaccharides (including cellulose)
Chemical composition of a normal man (weight 65 kg)
Constituent
Percent (%)
Weight (kg)
Water
61.6
40
Protein
17.0
11
Lipid
13.8
9
Carbohydrate
1.5
1
Minerals
6.1
4
Structural hierarchy in the molecular
organization of cells
Similarities among all types of cells
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All cells use nucleic acids (DNA) to store information
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Except RNA viruses, but not true cells
(incapable of autonomous replication)
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All cells use nucleic acids (RNA) to access
stored information
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All cells use proteins as catalysts (enzymes) for chemical reactions
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All cells use lipids for membrane components
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A few examples of RNA based enzymes, which may reflect
primordial use of RNA
Different types of lipids in different types of cells
All cells use carbohydrates for cell walls (if present), recognition, and
energy generation
How much biochemistry do you need to know
for this course?
1. You are expected to learn the
structure and functions of these
organic compounds:
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Carbohydrates
Lipids
Proteins
Nucleic Acids
2. You will be expected to learn the basic biochemical processes of major
cell functions, such as respiration, protein synthesis and so on.
6. Textbooks and references
• Murray RK, Harper’s Illustrated Biochemistry, 26th ed.
• Nelson DL and Cox MM. Lehninger Principles of Biochemistry, 5th ed.
2008.
7. Some tips for study of biochemistry
• Inspiring interest, confidence
• Previewing and reviewing freshly
• Taking studying notes
• Discussing in groups
• Practice crosstalk with other subjects
• Making use of internet
Final course grade
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Final course grade =
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Please consult the syllabus
Notice: 25% absent, can not take part in the final exam.