Ch21 DNA technology

Question 1

conversion of cDNA

Answer 1

1. mRNA template for complementary nucleotides
2. reverse transcriptase bonds to form cDNA
3. cDNA hydrolysed and becomes single stranded
4. DNA polymerase forms double-strand

Question 2

isolation of gene

Answer 2

1. use restriction endonuclease
2. cut DNA at specific base sequence
3. sticky ends produced

Question 3

Sticky ends

Answer 3

1. Palindromic
2. Complementary base-pairing

Question 4

Advantage of reverse transcription

Answer 4

1. mRNA is single stranded
2. mRNA has no introns

Question 5

Vector

Answer 5

transfers genes from one organism into bacteria host cell

Question 6

Gene machine steps

Answer 6

1. identify amino acid sequence of desired protein
2. work out mRNA and DNA sequence
3. enter DNA sequenece into computer which checks biosafety
4. computer creates small sections of overlapping single strands of nucleotides(oligonucleotides)
5. each oligonucleotides join together to make gene

Question 7

Gene machine advantage

Answer 7

1. faster - only one step
2. accurate
3. no enzyme-catalysed reactions

Question 8

in Vivo DNA insertion

Answer 8

1. Restriction endonuclease cuts plasmid
2. Restriction endonuclease cuts and isolates desired gene
3. Same enzyme cuts at same base sequence
4. Plasmid and gene DNA fragments have complementary sticky end base sequences
5. DNA ligase anneals gene and plasmid together- forms phosphodiester bonds

Question 9

Reverse transcription advantage

Answer 9

cDNA is intron free because comes from mRNA

Question 10

Overall protein making process

Answer 10

1. isolate DNA fragment
2. insert into vector
3. transform DNA into host cell
4. identify host cell using gene marker
5. growth/cloning

Question 11

Pre-insertion

Answer 11

1. add promoter and terminator region
2. RNA polymerase knows when to begin and end transcription

Question 12

in Vivo cloning

Answer 12

1. add marker gene
2. mix plasmid and bacterial cells in calcium ion medium
3. bacteria becomes impermeable and takes up recombinant plasmid
4. put bacteria colony onto medium where marker gene expressed
5. purify and clone desired bacteria

Question 13

Marker genes

Answer 13

1. produce fluorescent protein
2. produce enzyme with particular action
3. antibiotic resistant

Question 14

Polymerase chain reaction

Answer 14

1. DNA heated to 95
2. strands separate
3. cooled to 55
4. primers anneal to complementary base pairs
5. nucleotides attach by complementary base pairing
6. temp raised to 75
7. DNA polymerase(binds to primers) and bonds nucleotides together
8. repeat the cycle

Question 15

Primer

Answer 15

1. short nucleotide sequence
2. complementary to bases at start of fragment

Question 16

in Vitro gene cloning advantage

Answer 16

1. rapid
2. creates large amount of DNA
3. doesn’t require living cells

Question 17

in Vivo cloning advantage

Answer 17

1. transformed bacteria produces large amount desired protein
2. no contamination risk
3. accurate
4. targets specific gene

Question 18

DNA probe

Answer 18

1. complementary base sequence to desired allele
2. allows allele to be identified
3. fluorescent after binding
4. radioactive under Xray

Question 19

DNA hybridisation

Answer 19

1. heat DNA until separates
2. cool
3. DNA probe anneals to complementary base sequence of allele
4. DNA cleaned
5. hybridised DNA labelled and identified

Question 20

Gel electrophoresis

Answer 20

1. DNA cut into fragments using restriction endonucleases
2. place DNA fragment sample into wells on gel plate
3. Apply electrical current
4. immerse gel in alkaline solution
5. DNA fragments travel towards positive charge
6. smaller fragments travel further

Question 21

Uses of genetic fingerprinting

Answer 21

1. medical diagnosis
2. breeding
3. genetic relationships
4. forensic science

Question 22

Variable number tandem repeats

Answer 22

1. repetitive non-coding bases of DNA
2. more identical sequences of VNTRs- closer related

Question 23

Somatic gene therapy

Answer 23

1. alters alleles in body cells
2. short-term
3. still inherited by offspring

Question 24

Germ line therapy

Answer 24

1. alters mutated allele in sex cell
2. long-term
3. affects all cells and offspring

Question 25

Gene therapy

Answer 25

1. Add dominant allele alongside mutated recessive allele
2. silence mutated dominant allele by added new DNA