VARIATION AND EVOLUTION

VARIATION AND EVOLUTION

1. VARIATION

   • DIFFERENCE IN THE CHARACTERISTICS OF INDIVIDUALS IN A POPULATION
   • VARIATION MAY BE DUE TO DIFFERENCES IN TEH GENES INHERITED, THE CONDITIONS IN WHICH ORGANISMS DEVELOP, OR A COMBINATION OF BOTH GENES AND THE ENVIROMENT

2. EVOLUTION BY NATURAL SELECTION

   • THE THEORY OF EVOLUTION BY NATURAL SELECTION STATES THAT ALL SPECIES OF LIVING THINGS HAVE EVOLVED FROM SIMPLE LIFE FORMS THAT FIRST DEVELOPED OVER 3 BILLION YEARS AGO
   • MUTATIONS OCCUR CONTINUOUSLY. VERY RARELY A MUTATION LEADS TO A NEW PHENOTYPE. IF THE NEW PHENOTYPE IS SUITED TO AN ENVIRONMENTAL CHANGE IT CAN LEAD TO A RELATIVELY RAPID CHANGE IN THE SPECIES

3. SELECTIVE BREEDING

   • SELECTIVE BREEDING IS A PROCESS WHERE HUMAN BREED PLANTS AND ANIMALS FOR DESIRED CHARACTERISTICS
   • DESIRED CHARACTERISTICS INCLUDE: DISEASE RESISTANCE, INCREASED FOOD PRODUCTION IN ANIMALS AND PLANTS, DOMESTIC DOGS WITH A GENTLE NATURE, AND HEAVILY SCENTED FLOWERS
   • PROBLEMS CAN OCCUR WITH SELECTIVE BREEDING INCLUDING DEFECTS IN SOME ANIMALS DUE TO LACK OF VARIATION

4. GENETIC ENGINEERING

   • CROPS THAT HAVE HAD THEIR GENES MODIFIED ARE KNOWN AS GENETICALLY MODIFIED CROPS. GM CROPS OFTEN HAVE IMPROVED RESISTANCE TO INSECT ATTACK OR HERBICIDES AND GENERALLY PRODUCE A HIGHER YIELD
   • GENES CAN BE TRANSFERRED TO THE CELLS OF ANIMALS AND PLANTS AT AN EARLY STAGE OF THEIR DEVELOPMENT SO THEY DEVELOP DESIRED CHARACTERISTICS. THIS IS GENETIC ENGINEERING.
   • IN GENETIC ENGINEERING, GENES FROM THE CHROMOSOMES OF HUMANS AND OTHER ORGANISMS CAN BE 'CUT OUT' USING ENZYMES AND TRANSFERRED TO THE CELLS FO BACTERIA AND OTHER ORGANISMS USING A VECTOR, WHICH IS USUALLY A BACTERIAL PLASMID OR A VIRUS

5. ETHICS OF GENETIC TECHNOLOGIES

   • MODERN MEDIAL RESEARCH IS EXPLORING THE POSSIBILITY OF GENETIC MODIFICATIoN TO OVERCOME SOME INHERITED DISORDERS
   • THERE ARE BENEFITS ASSOCIATED WITH GENETIC ENGINEERING IN AGRICULTURE AND MEDICINE - E.G,
     • THE PROTEINS HUMAN NEED CAN BE MADE IN LARGE QUANTITIES AND IN A VERY PURE FORM
     • IMPROVE GROWTH RATES OF PLANTS/ANIMALS
   • SOME PEOPLE HAVE ETHICAL OBJECTION TO GENETIC ENGINEERING
     • SOME PEOPLE ARE CONCERNED ABOUT THE EFFECT OF EATING GM FOOD ON HUMAN HEALTH
     • ANOTHER CONCERN IS THAT GENES FROM GM PLANTS AND ANIMALS MIGHT SPREAD INTO THE WILDLIFE OF THE COUNTRYSIDE
     • MAIN ETHICAL OBJECTIONS = THE FEARS ABOUT HUMAN ENGINEERING