Manipulating Genomes Flashcards
What is DNA sequencing ?
Identifying the base sequence of a DNA fragment
How have sequencing methods Changed over time ?
- Used to be a manual process, however now it has become automated
- Entire genomes can now be read
Give some benefits of genome-wide comparisons
- Comparing between species allows us to determine evolutionary relationships
- Comparing between individuals of the same species allows us to tailor medical treatment to individuals
How can DNA sequencing be used in synthetic biology ?
Knowing the sequence of a gene allows us to predict the sequence of amino acids that will make up the polypeptide it produces. This in turn allows us for development of synthetic biology
What is DNA profiling ?
Identifying the unique areas of a persons DNA, in order to create a profile that is individual to them
Give uses of DNA profiling
- Forensics = DNA obtained during crime investigations can be compared to that of victims or suspects
- Medicine = To screen for a particular base sequence in rider to identify heritable diseases
How can we amplify DNA fragments in order to sequence them ?
Using the polymerase chain reaction (PCR). Makes millions of a copies of a fragment, which are then cut at different lengths in order to b sequenced
Describe the reaction mixture in the first stage of PCR
Contains the DNA fragment to be amplified, primers that are complementary to the start of the fragment, free nucleotides to match up to exposed bases, and DNA polymerase to create the new DNA
Summarise the process of amplifying DNA fragments using PCR
- Heated to break apart DNA strands
- Cooled to allow the primers to bind
- Heated again to activate DNA polymerase and allow free nucleotides to join
- New DNA acts as template for next cycle
How is gel electrophoresis used in DNA profiling ?
- DNA fragments of varying lengths are placed at one end of a slab of gel
- Electric current is applied; DNA fragments move towards the other end of the gel
- Shorter fragments travel further. The pattern of bands created is unique to every individual
What is meant by genetic engineering ?
Where a DNA fragment from one organism is inserted into the DNA of another organism, sometimes across different species. This is done through use of a vector and a host cell
Summarise the process of isolating a DNA fragment
Restriction enzymes (RE) cut DNA at specific sequences. Different Restriction Enzymes at different points, but one RE will always cut the same sequence. Therefore using particular REs allows you to cut out a certain gene of interest
Summarise the process of inserting a DNA fragment into a vector
A plasmid (Circular DNA from bacteria) is used as the vector, and is cut using the same restriction enzymes s the DNA, so that the ends are complementary. DNA ligaments joins the fragment and plasmid together
Summarise the process of inserting a vector into a host cell
The host cell (bacteria) are mixed with the vectors in an ice-cold solution, then shocked to increase the permeability of the cell membrane (electroporation) which encourages the cells to take up the vectors
Give some ethical issues around genetic engineering
+ Insect resistance can be introduced to crops
+ GE animals used to produce pharmaceuticals
+ GE pathogens can be produced for research
- GE seeds would be hard to acquire for poorer farmers
