GENETIC ENGINEERING
STUDENT EXERCISE
CLOZE TEST
Please choose appropriate word/term to complete the passage below:
replicate, extracted, DNA, sticky ends, vectors, asexual, separated, isolated, plasmids, host, restriction
The Making of Recombinant DNA
……….. the cytoplasm of bacteria contains numerous ______, that is small rings of doubles stranded DNA. These pieces are additional to the main circular chromosome of the bacterium and they ______independently of the chromosome. Bacterial plasmids are widely used as ______by which additional DNA is introduced into ______cells.
The importance to humans of plasmids as vectors is that they can be ______from bacterial cells, modified by recombinant ______techniques and returned to the bacterium.
Back in the host, the introduced gene maybe multiplied by replication or expressed and the gene product harvested. The rapidity of ______reproduction in bacterial makes them ideal for the quick production of large quantities of genes or their producers.
The plasmids are extracted from bacteria by breaking up the cells and ______by centrifugation. Once ______the plasmid rings are ‘cut open’ enzymically using a particular ______enzyme. The same enzyme is used to cut the short length of DNA to be inserted and replicated. As a consequence, the opened up plasmids and the gene for cloning will have complementary base pairs exposed (______)………….
Extract taken from : Advanced Biology: Principles and Applications by Clegg and Mackean
Revision Puzzle
Across
2. Type of DNA vector used to transfer DNA from one cell to another
4. Type of enzyme used like a 'molecular scissors'
6. Genetic make-up of an organism
8. Another term for cutting of DNA
10. Alternative form of a gene
11. Type of bonding holding the bases together in DNA
Down
1. Single strand of DNA that contains a known series of bases
3. A purine base
5. Group of organisms capable of interbreeding successfully
6. A discreet piece of DNA
7. Site of protein synthesis in the cell
9. Contains uracil