6.1.3: 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 the individual.
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 for development of
synthetic biology
What is DNA profiling?
Identifying the unique areas of a
person’s 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 order 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 be 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 the DNA strands.
- Cooled to allow 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 REs cut at different
points, but one RE will always cut at 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 as the DNA, so that the
ends are complementary. DNA ligase joins the
fragment and plasmid together.
Summarise the process of inserting a vector into a
host cell
The host cells (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 (pharming).
+ GE pathogens can be produced for research
- GE seeds would be hard to acquire for
poorer farmers.
