The Control of Gene Expression: Gene Technologies - Recombinant DNA Technology Flashcards
1
Q
What is recombinant DNA technology?
A
- Transferring a fragment of DNA from one organism to another
2
Q
Why does recombinant DNA technology work?
A
- Genetic code is universal, as are transcription and translation mechanisms
- So transferred DNA can be translated within cells of the recipient (transgenic) organism
3
Q
What is a transgenic organism?
A
- Organism that contains transferred DNA
4
Q
How can fragments of DNA be produced?
A
- Conversion of mRNA to complementary DNA (cDNA), using reverse transcriptase
- Using restriction endonucleases to cut a fragment containing the desired gene from DNA
- Creating the gene in a ‘gene machine’
5
Q
Reverse transcriptase
A
- Reverse transcriptase is only found in retroviruses and bacteria
- mRNA is isolated from cells and mixed with free DNA nucleotides and reverse transcriptase
- Reverse transcriptase makes complementary DNA (cDNA) from mRNA
6
Q
Restriction endonucleases
A
- Some sections of DNA have palindromic sequences of nucleotides with antiparallel base pairs (known as recognition sequences)
- Restriction endonucleases are enzymes that recognise specific recognition sequences and cut the DNA at these places
- Restriction endonucleases only cut at specific recognition sequences they are complementary with
• Sticky ends
- If recognition sequences are present at either side of DNA fragment, restriction endonucleases can separate it from the rest of DNA
- Sometimes cut leaves sticky ends
- Sticky ends can be used to bind to another complementary sticky end
- Both DNA fragments need to have been cut by same restriction endonuclease to form complementary sticky ends
7
Q
What are recognition sequences?
A
- Sections of DNA with palindromic sequences of nucleotides with antiparallel base pairs
8
Q
What are sticky ends?
A
- Staggered cuts of DNA fragments formed by cuts from restriction endonucleases
9
Q
Gene machines
A
- Any sequence can be made so DNA sequence doesn’t need to exist naturally
- Required sequence is designed if it doesn’t exist
- First nucleotide is attached to a support e.g a bead
- Nucleotides are added in correct order with use of protecting groups
- Oligonucleotides are produced
- Oligonucleotides are broken off from support and all protecting groups are removed
- Oligonucleotides can be joined to make longer DNA fragments
10
Q
What are protecting groups?
A
- Protecting groups prevent unwanted branching
11
Q
What are oligonucleotides?
A
- Short sections of DNA, roughly 20 nucleotides long
