biotechnology
DESCRIPTION
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BIOTECHNOLOGYPrinciples, Applications,and Social Implications
General DefinitionThe application of technology to improve a biological organism
Detailed DefinitionThe application of the technology to modify the biological function of an organism to produce useful usually commercial products
But we know nature does not have all of the traits we need
• Here we see bean has many seedcoat colors and patterns in nature
•Nature has a rich source of variation
These definitions imply biotechnologyis needed because:
But nature does not contain all thegenetic variation man desires
•Fruits with vaccines
•Grains with improved nutrition
GENOMICSDNA and Genetic Engineering
Genomics
• the study of genomes• a broad field that encompasses
whole-genome comparisons, structural analysis of gene products, and surveys of small-scale variations in sequence
DNA Profiling• identifying an individual by analyzing
the unique parts of his or her DNA
Short tandem repeats• in chromosomal DNA, sequence of 4
to 5 bases repeated multiple times in a row
DNA Cloning
• uses living cells to mass-produce particular DNA fragments
Recombinant DNA
• a DNA molecule that contains genetic material from more than one organism
Restriction enzyme
• type of enzyme that cuts specific nucleotide sequences in DNA
Cloning vector
• a DNA molecule that can accept foreign DNA and get replicated inside a host cell
Genetic Engineering• process by which deliberate changes
are introduced into an individual’s genome.
Genetically modified organism (GMO)
• organism whose genome has been modified by genetic engineering
Transgenic• refers to a genetically modified
organism that carries a gene from a different species
Gene therapy
• the transfer of recombinant DNA into an individual’s body cells, with the intent to correct a genetic defect or treat a disease.
Gene therapy is the use of DNA as a drug to treat disease by
delivering therapeutic DNA into a patient's cells. The most
common form of gene therapy involves using DNA that
encodes a functional, therapeutic gene to replace a
mutated gene.
In gene therapy, DNA must be administered to the patient, get to the cells that need repair, enter the
cell, and express a protein. Generally the DNA is incorporated into an
engineered virus that serves as a vector, to get the DNA through the
bloodstream, into cells, and incorporated into a chromosome.
Severe Combined Immunodeficiency Disorder (SCID)• a severe x-linked genetic disorder
due to mutated allele; infected individuals can survive only in germ-free environment due to impairment of the immune system
ANTIBIOTICS
SOME GENERAL PRINCIPLES
• Antibiotics can be naturally produced, semi-synthetic, or synthetic substances
• Designed to have as much selective toxicity on the bacteria as possible
EXAMPLES OF SELECTIVE ACTION
• Penicillin on bacterial cell wall (organisms without cell wall won’t be inhibited eg Mycoplasma pneumoniae)
• Sulphonamides prevent bacteria synthesising folic acid whereas humans can use preformed folate
• Generally drugs acting on cell membranes or protein synthesis are more toxic to humans
ANTIBIOTICS ACTING ON CELL WALL OF BACTERIA
• Beta lactams:• Penicillins, cephalosporins, carbapenems,
monobactam
• Glycopeptides:• Vancomycin, teicoplanin
PENICILLIN
• They act by inhibition of bacterial cell wall synthesis, thus exposing the osmotically less stable membrane
• These agents are bactericidal• Active against multiplying and not resting
bacteria; inactive against mycobacteria, protozoa, fungi and viruses
Penicillin G (Benzyl penicillin)Highest activity against Gram-positive organisms but susceptible to Beta-
lactamase. Effective against :Gram-positive aerobic cocci - Staph. aureus- not producing penicillinase,
S.pneumoniae ( group A ) ,S.pyogenes Gram-negative aerobic cocci -N.meningitidis
Gram- positive bacilli : Bacillus anthracis Anaerobes Clostridium spp but inactive against B.fragilis Actinomycetes israelii ( actinomycosis )
Penicillin G benzathin
Duration 3- 4 weeks Painful at the injection site ( limits its use ) Uses 1. Syphilis 2. Rheumatic fever prophylaxis( inhibits group A beta- hemolytic streptococci) 3. Streptococcal pharyngitis
Disadvantages of penicillin G
A. Destroyed by gastric HCLB. Inactivated by penicillinaseC. Narrow spectrum of activity
Phenoxy- methyl penicillin ( penicillin V)
Acid resistant penicillins ( spectrum of activity is similar to penicillin G )UsesGroup A Streptococcal pharyngitisProphylaxis against group A streptococci in points with
history of rheumatic heart disease.DisadvantagesReadily hydroyzed by beta-lactamase
Penicillinase-resistant penicillins
Are the choice for infections caused by
penicillinase producing S. aureus.
• Methicillin • Dicloxacillin• Floxacillin• NafcIlli• Oxacillin• Cloxacillin
Broad- spectrum penicillins
Less active than penicillin G against
G+ cocci. Active against G- organisms.
• Ampicillin • Ampicillin-
sulbactam• Bacampicillin• Amoxicillin• Amoxicillin-
clavulanic acid ( augmentin )
USES
• H. Influenza infections (otitis media, sinusitis, chronic bronchitis, pneumonia, bacterial meningitis ).
• E. Coli infections (Urinary & biliary infections)• Samonella infections (typhoid fever)• Shigella infections (ampicillin)• Gonococcal infections (alternative for
penicillin in the treatment of gonorrhea)
DISADVANTAGES
• Amoxicillin & ampicillin alone are readily destroyed by Staph. Penicillinase
Adverse effects of penicillins
1.Hypersensitivity reactions Urticarial rash Fever Bronchspasm Serum sickness Exfoliative dermatitis Stevens- Johnson syndrome Anaphylaxis2. Super infections3. Diarrhoea4. May cause convulsions after high doses by i.v or in
renal failure
Some clinically important antibiotics
Antibiotic Producer organism ActivitySite or mode of
action
Penicillin Penicillium chrysogenumGram-positive bacteria
Wall synthesis
CephalosporinCephalosporium acremonium
Broad spectrum Wall synthesis
Erythromycin Streptomyces erythreusGram-positive bacteria
Protein synthesis
Streptomycin Streptomyces griseusGram-negative bacteria
Protein synthesis
Tetracycline Streptomyces rimosus Broad spectrum Protein synthesis
Vancomycin Streptomyces orientalisGram-positive bacteria
Protein synthesis
THE IDEAL ANTIBIOTIC?:PENICILLIN
• Bactericidal• Widely distributed in body esp. CNS• Excreted by the kidneys