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Basic biochemistry: A Biotechnology Perspective.
The unit of all life is the cell.
Single-cllled organisms: Bacteria and protozoa
Multicelled organisms: All plants and animals
Hierarchy of cellular life:
Cells -->Tissues -->Organs -->Organisms -->Populations
Tissues are composed of specialized cells types”
Examples: Blood, muscle, nerve, adipose
Organs are systems composed of several tissues, and
have specific functions:
Examples: Heart, kidney, liver, brain
MEMBRANE
RIBOSOMES
CELL WALL
DNA
ATP
ADP + P
PROTONS
NUTRIENTS
Small molecules of life
What are the elements of living molecules?
CHONPS – biogenic elements: carbon, hydrogen, oxygen, nitrogen,
phosphorus, sulfur
Compose ~ 99 percent of the organic matter in living cells.
How do biogenic elements produce the small molecules of life?
Biogenic elements by themselves cannot be part of life, but instead
are present as five kinds of molecular compounds.
1. Hydrocarbon derivatives (fatty compounds such as fat, plant oils,
phospholipids, sterols
2. Carbohydrates (sugars, starches, cellulose)
3. Amino acids
4. Nucleotides
5. Metabolic intermediates
The Four Molecules of Life
Hydrocarbons HC
Octane = C8H18
(Lipids)
Carbohydrates CHO
Glucose = C6H12O6
(Sugars)
Amino acids CHON(S) Glycine = C2H5O2N
(Proteins)
Nucleotides
CHONP AMP =
C10H14N5O7P
(DNA,RNA)
Why are hydrocarbons important in life
processes and biotechnology?
Life is based on carbon, yet carbon by itself only forms graphite, diamonds and
soot. But if carbon bonds to
hydrogen, molecules called hydrocarbons are formed:
Example: Octane = C8H18 = H3C-CH2-CH2-CH2-CH2-CH2-CH2-CH3
Hydrocarbon derivatives include fatty acids and sterols.
Example of a fatty acid:
+
+
Fatty acids are a major energy source for the heart and other muscle
tissues.
Fatty acids (as triglyceride, or “fat”) provide energy storage capacity
for animals and plants.
Example of a sterol: cholesterol.
Cholesterol is also a component of most cell membranes.
Cholesterol is used to synthesize steroid hormones such
as estrogen, testosterone, and cortisone.
Why is cholesterol important in biotechnology?
In heart disease cholesterol accumulates in coronary
arteries to form atherosclerotic plaques. This process
can be inhibited by drugs that lower the levels of
cholesterol circulating in the blood.
All cells are bounded by a cell membrane.
The cell membrane maintains larger molecules of life in
an enclosed volume so that they can interact.
Cell membranes also provide a selective permeability
barrier that allows certain molecules such as nutrients
into the cell, but excludes others.
Membrane surface receptors permit the cell to
communicate with other cells.
Membrane receptors are important sites of drug action.
Membranes are composed of amphiphilic
molecules called lipids. Amphiphiles are organic
molecules having both a hydrophobic non-polar
portion (hydrocarbon chains) and a hydrophilic
polar head group.
Phospholipid and cholesterol are biological amphiphiles that
assemble into the lipid bilayers of all biomembranes.
LIPID VESICLES
HYDROCARBON
CHAINS
WATER
Why are membranes important in
biotechnology?
Cell boundary – certain kinds of pharmaceutical
agents must cross the membrane to enter the
cell and produce an effect.
Drug receptors are present on the membrane
surface. Many drugs bind to membrane
receptors to produce a desired effect.
What is a carbohydrate?
A carbohydrate typically contains carbon, hydrogen and
oxygen in the ratio C:H2O, from which the name is derived.
Example: glucose – C6H12O6
Carbohydrates are sources of energy for most tissues,
particularly the brain.
Carbohydrates are also used in cellular structures.
For instance, cellulose is a polymer of glucose.
Why are carbohydrates important
in biotechnology?
A major health problem is diabetes, one form of which
occurs when the hormone insulin cannot be produced by
specialized cells in the pancreas. Insulin activates the
transport of glucose across cell membranes. In its
absence, glucose cannot cross cell membranes and
accumulates in the blood, often leading to serious
circulatory problems. The synthesis of insulin to treat
diabetes is a multibillion dollar industry.
All life uses polymers for structure and function.
What are monomers and polymers?
o o o o o o o  o-o-o-o-o-o-o-o-o-o-o
Monomers
Polymer
Like loose beads
Beads on a string
Ethylene, propylene and styrene are common monomers
Polyethylene, polypropylene and polystyrene, are
polymers – common plastics in industry.
Two biological polymers are fundamental to
all life: proteins and nucleic acids
Monomers
Amino acids
Polymers
Peptides and proteins
Nucleotides
Nucleic acids (DNA, RNA)
What is an amino acid?
Twenty different kinds of amino acids are used by
living organisms to produce proteins
An amino acid is a molecule containing an amine
(-NH2) an acid (-COOH) and a third chemical group
(-R) that defines the amino acid. In glycine, the
simplest amino acid, R is –H, or a hydrogen atom.
In alanine, R = -CH3. The R groups give specific
properties to each amino acid, and to the proteins
composed of amino acids.
R
|
Structure of an amino acid: H2N – C – COOH
H
Why are amino acids important in biotechnology?
Amino acids are used by the body to produce
hormones and neurotransmitters that are essential
in regulating physiological functions.
Thyroxin regulates metabolic rate, and insulin regulates blood sugar
levels. Thyroxin is synthesized from the amino acid tyrosine, and
insulin is a small protein composed of 52 amino acids. Both hormones
are produced commercially by pharmaceutical companies.
Examples of neurotransmitters include the amino acids glycine,
aspartic acid, glutamic acid, and gamma amino butyric acid (GABA).
Norepinephrine and epinephrine are synthesized from the amino acid
tyrosine, and serotonin is synthesized from the amino acid
tryptophan.
Many toxins and psychoactive drugs affect the way that
neurotransmitters modulate the nervous system.
What is a nucleotide?
Structure:
Base-sugar-phosphate
In DNA, the sugar is deoxyribose, and in RNA it is ribose.
Bases of DNA are adenine, thymine, guanine and cytosine (ATGC)
Bases of RNA are adenine, uracil, guanine and cytosine (AUGC)
Nucleotides are linked in polymers called nucleic acids (DNA, RNA)
Base – sugar – phosphate
Base – sugar – phosphate
Base – sugar – phosphate
Base – sugar – phosphate
Why are nucleotides important in biotechnology?
Besides their role as monomers in nucleic acids, some
nucleotides are also important regulatory agents.
For instance, the nucleotide ATP is used by cells to produce
cyclic AMP (cAMP) which controls many cell functions
such as the response of heart cells to adrenaline.
Understanding the regulatory function of nucleotides
leads to the development of pharmaceutical agents
that can modify physiological functions.
Example: beta blockers are used to treat hypertension
(high blood pressure). This drug inhibits the effect of
adrenaline on heart tissue by blocking the beta receptors
for adrenaline on heart cells.
Cells grow by linking monomers into polymers.
Enzymes
Monomers  Polymers
Energy
Ribosomes
Amino acids  Proteins
Energy
Polymerases
Nucleotides  DNA, RNA
Energy
Why is it important to understand cell growth processes?
Certain infective agents can grow in the body and produce disease:
Bacterial diseases:
“Strep throat” and scarlet fever produced by streptococcus.
Staphylococcus (“staph”) infections
Food poisoning (E. coli, Salmonella)
Bacterial meningitis
Leprosy
Tuberculosis
Plague
Anthrax
Typhoid fever
Diphtheria
Syphilis
Most bacterial species are not pathogens. In fact, bacteria are
essential to the biosphere, and in their absence advanced life would
not be possible on the Earth.
However, a few bacteria have become pathogens. Bacterial infections
occur when pathogenic bacteria invade the body and begin to
grow in the extracellular space.
Pharmaceutical agents called antibiotics can interrupt
bacterial growth processes. Examples of antibiotics:
penicillin, streptomycin, tetracycline, vancomycin –
all inhibit polymer synthesis pathway in bacteria,
but not in eukaryotic cells. This fundamentally important
advance in biotechnology has led to a vast improvement
in human health over the past 80 years.
Viruses cannot be treated by antibiotics, since they infect
cells directly and grow within the cell, using cellular
biosynthetic machinery to reproduce.