Applications of genetics Flashcards
What is Sanger sequencing?
Using chemically altered bases which cause DNA polymerase to stop when base is incorporated
What are the aims of the human genome project?
-Determine sequences of 3 billion base pairs in human DNA
-Identify all gene loci, and which chromosome it’s on
-Understand coding for amino acids and protein
-Store info in databases
What are the uses of the human genome project?
-Better prediction of the effect of drugs
-Improved design of drugs
-Development of new and improved treatment of disease
What are the limitations of the human genome project?
-Sample size too small
-Doesn’t represent different ethnicities
-Anonymous, so we don’t know the health of individuals
What are the aims of the 100k genome project?
-Study variation
-Locate genes responsible for conditions
-Research treatments
What are the strengths of the 100k genome project?
-Sample of people selected based on cancer/disorder status
-Larger sample to identify variation
-More ages, sex, ethnicities
What are the limitations of the 100k genome project?
-Doesn’t include Africa and S. America
-Not representative of human population
What are the ethical issues of genome sequencing?
1) concern of ownership of data
2) Cherry picking embryos
3) Screening can cause anxiety
4) Concerns over storage
Why was Anopheles gambiae sequenced?
-Rapid evolution of insecticide resistance
-Develop new chemicals to kill mosquito and lower transmission
Why was plasmodium sequenced?
-Developing multidrug resistance
-Develop more effective drugs for humans
What goes into the PCR machine?
-Primers
-Nucleotides
-Gene
-TAQ polymerase
-Buffer
What is the method for PCR?
1) 95c: Separates DNA into 2 strands
2) 55c: Allow primers to anneal to complimentary bases and start replication
3) DNA polmerase synthesizes complimentary strand, forming phosphodiester bonds
What are the limitations of PCR?
-Contamination
-Error rate
-Limited amplification
-Suitable DNA fragment size
-Sensitivity to inhibitors
What is the method for gel electrophoresis?
1) DNA is extracted using restriction endonuclease, and loaded into wells
2) Gel exposed to electric current
3) Negatively charged DNA fragments move towards positive terminal
4) Smaller fragments move longer distance in same time
5) Use DNA ladder to estimate fragment size
What can be used to visualize gel electrophoresis?
-Blue dye
-Radioactive probes
What can DNA profiling be used for?
-Paternity testing
-Identify dead bodies
-Store genetic info
-Composition of food
What is the definition of genetic engineering?
Transfer of a gene from one organism to another gene expressed in a new host cell (transgenic/recombinant)
What are the steps of genetic engineering?
1) Identify and isolate gene
2) PCR
3) Insert gene into vector
4) Insert Vector into host cell
5) Production of protein by host cell (transcribe and translate)
Describe the use of restriction endonuclease
-A bacterial enzyme that will cut DNA at a specific nucleotide sequence
-Cut phosphodiester bonds staggered, creating sticky ends
What are the limitations of restriction endonuclease?
-Need to know gene loci
-Could cut within gene
-Eukaryotic genes contain introns, whilst prokaryotes don’t, so bacteria may not have the enzymes needed to processs pre mRNA
-Any proteins with AA aren’t functional
Describe the use of Reverse transcriptase
-Extract mRNA
-Reverse transcriptase makes complimentary single stranded cDNA
-DNA polymerase makes complimentary double stranded DNA
-Sticky ends added
Describe the use of viral vectors
-Infect host cell with genetic information
-Concerns over pathogen and fast mutation rate
Describe the use of plasmids
1) Bacteria cell wall and membrane destabilised
2) Plasmids isolated from bacteria
3) Plasmid cut open using same RE (same stickey ends)
4) DNA ligase joins gene to plasmid, forming phosphodiester bonds
Describe the purification of recombinant genes
-Bacteria cells put into fermenter
-Transcribe and translate
What are the concerns of genetically engineered bacteria?
-Could exchange plasmids with antibiotic resistance to other bacteria
-Could transfer or activate oncogenes
What are the advantages of genetically engineered bacteria?
-Produce complex proteins
-Produce medical products
-GM crops
-Treat tppth decay
What are the disadvantages of genetically engineered bacteria?
-Expensive to upscale
-Synthesis of quarternary proteins could involve several genes
-Difficult to identify useful genes in large genome
-Restriction enzymes produce milliosn of useless fragments
-Not all eukaryote genes can be transcribed and translated in prokaryotes
What are the uses of GM crops?
-Enhance nutritional value
-Disease resistant plants
-Increases food supply
-Drought tolerance
How can genes be inserted into GM crops?
-Gene gun
-Electroporation
-Microinjection
-Bacterial vector (Agrobacterium tumefaciens)
What are the advantages of GM crops?
-Superior keeping qualities
-Higher crop yield
-Herbicide resistance
-Plants can produce pharmaceutical molecuels and hormones
What are the concerns of GM crops?
-Economic (intellectual property)
-Unknown effect if eaten
-Dispersal of herbicide resistance pollen to wild plants
-Reduction in biodiversity and smaller gene pool
Describe GM soya
-Important food source
-Used worldwide
-Gene with Roundup herbicide resistance
Describe GM tomatoes
-Ripen slow
-Flavour savr overcomes ripening in transit
-insecticidal proteins produced
What is the definition of gene therapy?
Technique where defective allele is replaced with cloned healthy allele
Describe somatic cell therapy
-healthy gene placed in liposomes and incorporated into body
-Has to occur regularly as body replaces cells
Describe Cystic Fibrosis
-Normal genes corde for CFTR protein channels which allow Cl ions into mucus, lowering water potential so water moves in via osmosis, creating fluid mucus.
-Thick mucus clogs alveoli and pancreatic duct
Describe germ-line therapy
Introduction of new gene to egg, sperm, or early stage embryo so that every cell in organism contain engineered gene
Describe DMD
-Recessive, sex linked disease caused by deletions of dystrophin gene
-Gene has 79 exons- deletions alter reading from mRNA
-Ribosome meets stop codon too soon
How can gene engineering help DMD?
1) Gene transcribed
2) Complimentary drug binds to mRNA
3) mRNA is single stranded, so can’t be translated
4) ribosomes skip it, restores reading frame, provides partial dystrophin
What is the goal of tissue engineering?
Repair, improve, or replace biological functions by replacement of tissue/organ cells by cells cultured in lab
What are the advantages of tissue engineering?
-High production speed
-Large scale
What are the disadvantages of tissue engineering?
-Expensive and unreliable
-Pathogens in plants can cause problem
-Inadvertent selection of disadvantageous alleles
-Premature ageing
-Ethical issues
What are stem cells?
-Undifferentiated cell capable of specialising into other cells
-ESC: totipotent
-ASC: pluripotent
-Induced pluripotent stem cells
What are the ethical issues of ESC?
-Destroy potential life
-Moral status of embryo
-Weighing up embryo vs research
-Fears of human cloning
What are the advantages of SC?
-Can become any type of cell
-Grows easiler in culture
-Own SC less likely to cause immune response
What are the disadvantages of SC?
-Rrae and expensive tech
-Recent, no long term studies
-Premature ageing
