Biology unit 11

• Clone

  A cell, a group of cells, or an organism that has been produced asexually, moreover, is genetically identical to a single ancestor
• Cloning is the exact copying of DNA from one organism into another
• Example of a clone

  • Dolly the sheep (the first cloned mammal)
• Cloning is not only artificial. In nature, various organisms produce cloned offspring through asexual reproduction
• Different forms of cloning

  • Somatic Cell Nuclear Transfer
  • Embryo Cloning
  • Cuttings
  • Tissue culture
  • Therapeutic cloning
• Somatic Cell Nuclear Transfer


  1. An egg is extracted from the ovary of sheep A

  2. A cell is taken from the udder of Sheep B

  3. The nucleus is sucked out the egg

  4. The cell from the udder and the enucleated cell are fused together by using electricity

  5. Cell division takes place several times until an embryo is formed

  6. The embryo is implanted into the uterus of sheep A

  7. An offspring is born from sheep A, however, contains the DNA of sheep B
• Embryo Cloning


  Occurs when scientists take an embryo and split it apart so that there are several identical embryos
• Cuttings


  Takes place when parts of a plant (this can be part of the stem or leaves) is cut off and grown to produce a genetically identical plant to the one the cutting was taken from
• Tissue culture


  This process is also referred to as 'micropagation'. Tissue culture occurs when cells are extracted from a parent plant and are grown in agar in which the cells then will grow into a larger mass of undifferentiated cells and - if given the correct conditions - will form into a new plant
• Therapeutic cloning


  The production of embryonic stem cells in an attempt to replace or repair damaged tissues or organs. This type of cloning is achieved by transferring a diploid nucleus from a body cell into an enucleated egg cell
• Creating a clone using specialized cells


  Therapeutic cloning utilizes specialized cells as well as somatic cell nuclear transfer to form embryos which are destroyed later on to get embryonic stem cells to repair or replace damaged tissue or organs
• Arguments against cloning

  • Religious and ethical beliefs state that it is wrong to interfere with nature
  • Endless amounts of embryos do not develop correctly, thus, ultimately have to be destroyed
  • Cloned organisms normally die at a very young age
  • Cloning can be seen as 'playing God'
• Arguments for cloning

  • Cloning can produce organisms that benefit the medical industry and can lead to new medical advancements or a better understanding in particular medical fields
  • Cloning can produce genetically viable organs for transplants that would not be rejected by the patient
  • Cloning can help in increasing the number of endangered species and can ultimately prevent extinction
  • Cloning can produce high-quality plants and animals for food
• Advantages of cloning

  • The offspring are genetically identical with is ideal for farming and can ensure to have higher-quality produce
  • Cloning can result in higher yields as many clones can be produced simultaneously
  • Clones can be produced at any time throughout the year rather than at specific times of the year
  • Cloning can be a very simple, cheap method
• Disadvantages of cloning

  • There is no variation amongst the gene pool of the cloned species
  • If any of the organisms from the cloned population comes in contact with a disease, all organisms would be affected
  • There is a danger of overcrowding of plants, resulting in competition amongst the organisms
  • Cloning raises various ethical concerns
• Selective Breeding

  The intentional breeding of organisms with desirable traits in an attempt to produce offspring with similar, desirable characteristics or with improved traits
• Examples of selective breeding

  - Dogs: There are circa 400 dog breeds that have all been selectively bred from one single ancestor species (being the Gray Wolf).

  - Cows: Cows were selectively bred for better beef in which the cows were also able to survive in harsher conditions.
• Impact of selective breeding on farming

  • Higher yield of produce
  • Results in a higher income as they have more products to sell
  • Can result in organisms (more specifically, crops) that are resistant to disease, therefore are of better quality
  • Can result in organisms that are able to survive harsher conditions
  • Can improve nutrients within crops meat, and other produce
  • Can increase the fertility of animals
• Genetic Engineering/modification

  The formulation of new genetic information or the recombination of the encoded DNA
• Bacterium

  A microscopic, single-celled organism that is found everywhere (found in the soil, the ocean, as well as our bodies). Bacteria are prokaryotes (meaning that they lack a true nucleus)
• Restriction Enzyme

  Enzymes responsible for the 'cutting of DNA' at specific sites that the enzyme recognizes (these are fragments known as 'restriction fragments') which then enables the sequencing of DNA to occur
• Vector

  Something which can carry DNA from one organism to another, such as plasmids or viruses
• DNA Ligase

  An enzyme which can connect pieces of DNA together, furthermore, can be used to insert a gene into a vector such as a plasmid
• Plasmids

  A small, circular, double-stranded DNA molecule that is distinct (or separated) from the cell's chromosomal DNA and can replicate independently. Plasmids naturally occur in bacterial cells, likewise, are found in some eukaryotes
• Genetic modification in bacteria to treat diabetes

  1. Restriction enzymes extract the insulin from a DNA molecule within a genome

  2. The plasmid is then isolated

  3. Restriction enzymes cut and extract a sector of the plasmid

  4. Ligase enzymes insert the extracted insulin gene into the plasmid

  5. This is then inserted back into the bacteria cell

  6. The transgenic bacteria (genetically altered bacteria) reproduces through binary fission, resulting in millions of identical bacterial cells that possess the capability to produce insulin for humans
• Pros of GMOs

  • Developing disease, pest, and drought-resistant crops
  • Increased availability of nutrients
  • Can combat issues and disparities that are associated with hunger or lack of food
  • Have an increased shelf life
  • Enhanced quality of food
• Cons of GMOs

  • Chance of cross-breeding with wild populations
  • Toxicity or allergic reactions associated with the modification of the crops
  • There is a higher demand for organic products
  • There are increased regulations on commercially sold GMOs
  • There is an increase in herbicide use
  • Many health issues are associated with the extensive employment of herbicides as they are toxic substances
  • More antibiotic resistance
• Examples of GMOs

  • Corn - Corn is no 'insect resistant'
  • Canola - Canola has an altered fatty acid composition
• Stem cells


  Pluripotent (can grow into any specialized cell in the body), undifferentiated cells that can differentiate into many cell types
• 3D-Bioprinting

  The process of using cells along with sticky polymers to '3D-print' organs by helping force the cells to grow and differentiate specifically for their goal
• Ethical issues surrounding the use of stem cells

  • It involves the destruction of embryos that had the potential to develop into a fetus
  • It is 'playing God'
• Advantages of bioprinting

  • Can 3D-print working organs that would not get rejected
  • There is a very high demand for organs, however, there are not enough organ donors
• Disadvantages of bioprinting

  • It is very expensive and not everyone can afford it
  • This will lead in disparities amongst the society and will result in a separation amongst the people that can afford such treatments and those that cannot
• Genome

  The complete set of genetic material of an organism
• Genome-mapping

  The process of locating and identifying genes to create a map of the genome
• Genome mapping provides information regarding the location of genes on a particular chromosome
• Advantages of Genome Mapping

  • Can be used to identify risk factors and health hazards
  • Helps identify which genes are responsible for specific traits
  • Can help in crime investigation
• Disadvantages of Genome Mapping

  • May result in a loss in human diversity
  • Could develop a trend in 'designer babies'
  • Information could be used for new weapons
  • There could be a foundation for genetic racism
  • This would create divisions in society as it is only accessible to the wealthy
• Selective breeding

  Does not involve the introduction of foreign DNA into an organism, instead, it is the conscious selection of the desirable traits
• Selective breeding

  Results in organisms that have desirable traits from both parental organisms