Genetic Influences andTechnology
Genetic Technology outline
How environmentaffects genes
Genetic modification
Transgenicorganisms
Gene therapy
Cloning
Selective breeding
Hybridization
Inbreeding
Test cross
Section 12.2 Summary – pages 315 - 322
As an organism develops, many factors caninfluence how the gene is expressed, or evenwhether the gene is expressed at all.
For example, flowers called hydrangea bloom blueif grown in acidic soil and bloom pink if grown in nonacidic soil.
Section 12.2 Summary – pages 315 - 322
temperature
nutrition
light
chemicals
bacteria/viruses
Environmental Influences on genes
Environmental Influences on genes
Section 12.2 Summary – pages 315 - 322
Influence of external environment
Influence of external environment
arctic foxes
In the summer, enzymesproduce brown pigment.These enzymes don’twork in the cold,therefore, no pigment isproduced in the winter.
The fur color of a Siamesecat is influenced by temp.The ears, nose, paw, and tailare darker than the rest of thebody because those bodyparts are cooler than thenormal body temp.
The genetic code is universal, so genes can be transferredfrom one organism to another, even if they are members ofdifferent species.
Genetically modified organism (GMO): organism that hashad genes transferred to it from another organism
*also called transgenic organisms
Genetic modification: process of transferring genes fromone organism to another
ex. 1 transfer a gene for making growth hormone
from cattle to chickens
ex. 2 transfer a gene for making human insulin from
human to bacteria
Transgenic organisms – plants or animalsthat contain genes from an organism of adifferent genus.
Example – inserting a gene from a firefly intoa tobacco plant.
The Result – a glowing
tobacco plant.
In this example the tobacco
plant is the transgenic organism.
Maize (corn) crops are often damaged byborer insects. A gene from a bacterium(Bacillus thuringiensis) has been transferredto maize. The gene codes for a bacterialprotein called Bt toxin that kills corn borersfeeding on the maize
Other recent examples:
Bacteria that can absorb arsenic
*useful to remove poison fromgroundwater in places like Bangladesh
Algae that can make jet fuel
Ruppy, the glow-in-the-dark puppy (2009)
Gene Therapy
Treatment of a genetic disease byaltering the genotype.
Involves the replacement of defectivegenes.
Cloning
Producing identical copies of genes, cells,or organisms.
Clone: a group of genetically identicalorganisms or a group of cells artificiallyderived from a single parent cell.
Gene Cloning
Clones are genetically identical copies.
In 1997, a sheep named Dolly was cloned,and since then various other mammalsincluding mice, goats,
cattle and pigs
have been cloned.
Applied Genetics
Selective Breeding – Choosing the organismswith the most desirable traits and breedingthem.
This has been done for centuries with plants aswell as animals. Ex. Horses, corn
Through selective breeding, farmers can increasethe frequency of a certain allele within apopulation. This is the essence of genetictechnology.
Types of Selective Breeding:
Hybridization: crossing dissimilar individuals tobring together the best of both
*produces hybrids that are hardier than parents
*ex. Corn, mules
Inbreeding – mating between closely relatedindividuals.
Risks: because genetically similar, recessivealleles causing genetic defects appear moreoften ex. Blindness, deafness, joint problems
Horses and dogs areexamples of animalswhere breeders havecreated pure breedsusing inbreeding.
In many plants, crossingpure breeds results inbigger and moreproductive hybrids.
Test Cross
Testcross: crossing individual ofunknown genotype with one of knowngenotype (usually homozygous recessive)
example: There is a black sheep but wedon’t know if it is BB or Bb but if we mateit with a white sheep (since we know it isbb) then if any white offspring = dad is Bb
but if all black offspring = dad is BB