Biotechnology

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Biotechnology

• 4.4 Syllabus points

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4.4.1 PCR

• Outline use of PCR to copy and amplify minute
  quantities of DNA
• PCR polymerase chain reaction
• Helps to get enough DNA to analyze when a sample
  is very small
• Thermocycler - machine automates the copying of
  the DNA
• Millions of copies in a few hours

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PCR

• Uses DNA polymerase from bacteria that lives in
  hot springs Thermus aquaticus
• 3 steps
• Denature heat up breaks double into single
  strand (about 98 degrees C)
• Anneal cool and primers can attach to either a
  top or bottom strand
• Extension Taq polymerase makes complementary
  strand

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PCR

• Repeated cycles of heating and cooling stimulates
  the primers to attach to copies and copies of
  copies
• Result is exponential increase in number of
  copies of DNA

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4.4.2

• Gel electrophoresis separates DNA by size as move
  in electric field
• DNA negative charge move towards positive pole
• Agarose gel forms mesh of cross linked polymers
• DNA stained to visualize the separated bands

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4.4.3

• Gel electrophoresis of DNA used in DNA profiling
• Matching an unknown sample with a known to see if
  they match up is DNA profiling
• Identical band patterns means that is the
  individual in question similar patterns usually
  mean the individuals are relatives

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4.4.4 Applications of DNA profiling

• Paternity legal identification of biological
  father
• Forensic investigations compare samples from
  crime scene with suspect
• Cold cases reopen with new DNA technology such as
  PCR
• Release of wrongly imprisoned individuals

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4.4.5 Analyze gels

• Use gel banding patterns to determine matches
  between individuals to solve crimes or determine
  paternity

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4.4.6 Human Genome Project

• Outline three outcomes of sequencing the complete
  human genome
• 1990-2003 international effort
• Government and private labs
• Aimed to identify the entire sequence of bases in
  human DNA
• Created in essence a map of all genes on all 23
  chromosomes

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4.4.6 Human genome

• Allows identification of location of genes
  causing diseases
• Production of new medications by identifying
  products made by healthy individuals determine
  the gene responsible copy the gene and use it to
  produce the desired molecule
• Evolutionary relationships and migration patterns
  of humans

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4.4.7 Gene transfer

• Genes can be transferred between species because
  DNA is universal language and code for the same
  amino acids
• So gene will produce the same protein no matter
  what organism it is placed into

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Examples gene transfer

• Cold resistant tomatoes
• Bt-corn (Bacillus thuringiensis)
• Spider silk goats

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4.4.8 Technique Gene Transfer

• Cut and paste genes using restriction enzymes AKA
  endonucleases find and cut at target sequences
• Paste genes using DNA ligase enzyme which
  recognizes the sticky ends of the fragments and
  attaches them

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Copy paste using plasmid DNA

• Use host cell often Escherichia coli or yeast
• Prokaryotes most DNA in single chromosome but
  also have extra DNA is small loops called
  plasmids
• To copy DNA it needs to be pasted into a plasmid

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4.4.8 Pasting into plasmid

• Remove plasmid from cytoplasm of bacteria
• Cut open plasmid using restriction enzyme
• Paste new gene using DNA ligase into the open
  plasmid
• Modified plasmid called a recombinant plasmid
• Recombinant plasmid used to deliver new gene into
  genome of target organism

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4.4.9 Genetically Modified organisms

• Golden rice beta carotene into rice prevent
  blindness
• Salt resistant tomatoes
• Proponents will help solve world hunger
• Critics world hunger is distribution not
  production issue

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4.4.10 Benefits/Risks GMO

• Benefits
• Improve food production
• Reduce chemicals if plants have own pest control
  substances
• Reduce cost and pollution of making medicines
• Farmers have added control of crops and livestock
• Globally GM crops need less water and pesticides

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4.4.10 Risks

• Risks- long term risks unknown
• Pollen escapes into wild integrated possibly into
  wild genome
• Genes could cross species seen in labs could it
  happen in wild?
• Bt crops harmful to humans pesticide throughout
  plant not just on surface
• Allergies
• Large corporations will own large part of food
  supply
• High tech not always better than simple solutions
• Decrease in biodiversity

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4.4.11 Cloning

• Define clone
• Group of identically identical organisms or group
  of cells artificially derived from a single
  parent
• Farmers have cloned plants for years by
  regenerating plant material

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4.4.12 Technique cloning

• Enucleate unfertilized egg and transfer nuclear
  material from donor cell
• Electrical current fuses egg and nucleus
• Zygote divides and forms embryo which is
  implanted in surrogate mother
• Donor cell may be adult differentiated cell (non
  gamete) rather than from an egg cell
• Offspring is clone of donor organism

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4.4.13 Ethics therapeutic cloning

• Cloning using undifferentiated cells
• AKA embryonic stem cells
• Requires production of human embryos
• Is it ethical to generate new humans for medical
  research?
• However, stem cells allow repair of burns, new
  heart muscle, new kidney tissue

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Types of Cloning

• Therapeutic cloning makes new tissues
• Reproductive cloning makes new organisms