What is PCR (polymerase
chain reaction) used for?
to copy and amplify tiny quantities of DNA.
Very useful if you only have a small sample of DNA (eg. patient's blood sample or crime scene).
You need lots of DNA to do DNA profiling.
How does gel electrophoresis
Gel electrophoresis is used to separate DNA fragments for DNA Profiling.
The negatively charged DNA moves move in an electric field. towards the positive electrode.
Small pieces with more -ve charge move fastest.
What biotechnology applications is gel electrophoresis useful for?
Which electrode (positive or negative) will DNA travel towards in gel electrophoresis ?
because DNA fragments are negatively charged
What are the outcomes of the complete sequencing of the human genome? (Human Genome Project)
knowledge of the number of human genes
What property of the genetic code makes it possible for a gene to be transferred between species?
DNA code is universal
(the same codons code for the same amino acids in all species.)
Outline the basic technique used for gene transfer.
mRNA for a gene is extracted
reverse transcriptase makes a DNA copy of mRNA
a bacterial plasmid is cut with restriction enzymes
DNA copy of the gene (like insulin) is spliced into the plasmid by DNA ligase.
The recombinant plasmid is inserted into new host cells.
What does reverse transcriptase do?
makes DNA from mRNA
It is used in gene transfer and by retroviruses
What does DNA ligase do?
links pieces of DNA together
Give 2 examples of
genetically modified crops or
salt tolerance gene in tomato plants;
sysnthesis of beta-carotene gene in rice;
herbicide resistance genes in crop plants;
factor IX ( blood clotting factor gene) in sheep milk.
What are the potential benefits of GMO crops.
Less expensive food.
New varieties of crop plant - eg salt tollerant.
What are the potential harmful effects of genetic modification
Possibility of allergies from eating GMO foods;
If genetically engineered organisms are
released into the environment they could compete with naturally occurring varieties.