2. Making DNA fragemnts

Question 1

what does creating DNA fragments involve?

Answer 1

• sequencing
• genetically modified organisms
• genetic fingerprinting

Question 2

name the three methods which are used to make DNA fragments

Answer 2

1. reverse transcriptase are used to convert mRNA into cDNA
2. restriction enzymes are used to cut out specific parts of the DNA from the genome
3. gene machines can form DNA fragments joining nucleotide bases together

Question 3

outline reverse transcriptase forming DNA fragments

Answer 3

• the target gene can be found inside the cells proteins which it created
• reverse transcriptase is then added, joining to a start codon which is complimentary to its active site
• it then joins specific free floating DNA nucleotides to the mRNA via complimentary base pairing
• this creates cDNA

Question 4

outline restriction enzymes as a method of forming DNA fragments

Answer 4

• restriction endonucleases cut the gene at recognition sites which are complimentary to their specific site
• the target gene can be cut out when there are recognition sites at either end of it
• restriction enzymes create sticky ends of the gene, which are single strands of exposed nucleotides, when hydrolysing recognition sites

Question 5

the restriction sequence is _____________

Answer 5

palindromic

Question 6

define restriction endonucleases

Answer 6

they are enzymes, which hydrolyse the hydrogen bonds at specific recognition sites within the DNA, forming sticky ends

Question 7

define sticky ends

Answer 7

they are single strands of exposed nucleotide bases at the end of a DNA fragment

Question 8

outline gene machines as a form of obtaining DNA fragments

Answer 8

• the DNA sequence is fed into a machine
• the first nucleotide has a bead attached
• nucleotides are fed through one at a time
• oligonucleotides are made, which are short sections of DNA, these can be joined together to form a larger DNA fragment