Chapter 19: genetic technology

Question 1

define recombinant DNA

Answer 1

DNA made from joining pieces from 2 or more different sources

Question 2

give an overview of genetic engineering

Answer 2

1. ) required gene is obtained
2. ) gene is placed into vector
3. ) gene is inserted into recieving organism’s cell

Question 3

what is the role of restriction enzymes?

Answer 3

• cut through DNA at specific points

- catalyses the hydrolysis reaction that breaks the sugar-phosphate backbone to form sticky ends

Question 4

what is the role of DNA ligase?

Answer 4

• forms recombinant DNA

- catalyses the condensation reaction that joins the sugar-phosphate backbones of the plasmid and DNA

Question 5

define ‘transgenic bacteria’

Answer 5

bacteria that contains DNA that has been added to its cells following genetic engineering

Question 6

outline the steps of PCR

Answer 6

1. ) double stranded DNA sample is chosen
2. ) heated to 95 degrees, strands are separated
3. ) primers added, reduced to 55 degrees, primers anneal
4. ) temp raised to 72 degrees. DNA polymerase binds and extends primers using free nucleotides

Question 7

what is electrophoresis?

Answer 7

the process that separates DNA fragments based on size. It is used for identification and analyasis of DNA

Question 8

outline the steps of electrophoresis

Answer 8

1. ) DNA fragmented by restriction enzymes
2. ) DNA placed into wells. Gel put into buffer solution and an electric current passed through
3. ) DNA is stained

Question 9

what are DNA probes?

Answer 9

single-stranded DNA that is complementary to the DNA being investigated. It can be labelled with markers

Question 10

outline the steps involved in a microarray

Answer 10

1. ) test and reference single-stranded DNA identified
2. ) DNA labelled with fluorescent dyes
3. ) microarray with DNA probes

Question 11

why are promoters important for genetic engineering?

Answer 11

inserted alongside the gene so that RNA polymerase can bind to begin transcription

Question 12

what is the function of reverse transcriptase?

Answer 12

• mRNA is isolated
• reverse transcriptase makes the complementary DNA strand
• DNA ligase makes the c.DNA (complementary strand)

Question 13

define ‘gene therapy’

Answer 13

treating genetic disorders with genetic engineering

Question 14

give 3 disadvantages of somatic gene therapy

Answer 14

1. ) treatment is short-lived: the gene will not divide to pass on the allele
2. ) difficulty getting allele into genome. Genetically modified virus vectors mean the host becomes immune, and liposomes are also ineffective
3. ) genetic manipulations are restricted to the actual patient

Question 15

give an overview of SCID

Answer 15

• caused by the presence of defective gene for making adenosine deaminase enzyme
• a retrovirus was engineered to contain the normal ADA gene
• viral infection means ADA gene is taken up

Question 16

symptoms of SCID

Answer 16

• defective ADA causes the destruction of T-lymphocytes

Question 17

what is cystic fibrosis?

Answer 17

• caused by recessive allele of gene making CFTR
• CFTR acts as a chlorine ion transporter
• less H20 moves out of cell, so mucus is thicker

Question 18

disadvantages of genetic modification

Answer 18

• no long-lasting effects
• risk of immune response to transferred gene
• viruses may cause immune responses
• disorders caused by multiple alleles cannot be treated

Question 19

advantages of genetic modification

Answer 19

• can eliminate/ prevent hereditary conditions
• people born with conditions have a chance at life
• can eradicate diseases for future generations

Question 20

bioinformatics definition

Answer 20

the collection, processing and analyasis of biological information and data using computer software

Question 21

genetic screening definition

Answer 21

analysing someone’s DNA to check for the presence of a particular allele

Question 22

what are sticky ends?

Answer 22

unpaired bases

Question 23

give examples of vectors

Answer 23

plasmids, viruses and liposomes