21.1 - Producing DNA Fragments

Question 1

What is genetic engineering?

Answer 1

Manipulation of genetic material to modify characteristics

Question 2

What is recombinant DNA?

Answer 2

DNA altered to contain nucleotides from two organisms
(Has taken in the desired gene)

Question 3

What are transgenic organisms?

Answer 3

Organisms that receive transferred (recombinant) DNA fragments

Question 4

What are the key stages in gene transfer?

Answer 4

1. The desired gene is identified and isolated.
2. Multiple copies of the gene are made using the polymerase chain reaction (PCR).
3. The gene is inserted into a vector.
4. The vector delivers the gene into cells in a different organism.
5. Cells with the new gene are identified, such as by using marker genes.
6. Cells with the new gene are cloned.

Question 5

Why can transgenic organisms express new genes?

Why is it possible for the DNA from one organism to function in another

Answer 5

Universal genetic code

Question 6

What are the 3 main methods to produce DNA fragments?

Answer 6

1. Making complementary DNA (cDNA) using reverse transcriptase and mRNA.
2. Cleaving DNA from a donor organism with restriction endonucleases (enzymes).
3. Synthesising new custom DNA sequences from nucleotides using a gene machine.

Question 7

How does reverse transcriptase produce DNA fragments?

Answer 7

1. mRNA is extracted from cells.
2. mRNA is reverse transcribed using the reverse transcriptase enzyme and DNA nucleotides.
3. This makes a cDNA strand identical to the original DNA strand, and cDNA is isolated from the mRNA strand.
4. cDNA, free nucleotides, and DNA polymerase can then be used to form the other strand of DNA, reforming the desired gene.

Question 8

What are restriction endonuclease’s (enzymes)?

Answer 8

Enzymes that cut DNA at specific palindromic sequences

Question 9

How do restriction enzymes cut DNA?

Answer 9

Incubate DNA

Question 10

What are sticky ends?

Answer 10

Short overhanging sequences of unpaired bases

Question 11

How does a gene machine synthesise new DNA?

Answer 11

Choose codons

Question 12

What are the advantages of gene machines?

Answer 12

Produces custom DNA without a template