8B Genome Projects and Gene Technologies Flashcards
Genome
The entire set of DNA
Proteome
All the proteins that are made by an organism
Why is it easy to determine the proteome of a simple organism?
They don’t have any introns that have to be removed
Recombinant DNA
The name for DNA formed by joining together DNA from different organisms
What are the three methods of making DNA fragments?
Use reverse transcriptase. use restriction endonuclease, use a gene machine
How is reverse transcriptase used to make a DNA fragment?
The mRNA molecules are used as template, and reverse transcriptase makes DNA from this mRNA template.
mRNA is mixed with free DNA nucleotides and reverse transcriptase. These make single strands of cDNA
What is the DNA that is produced by using mRNA and reverse transcriptase called?
cDNA (complementary DNA)
Why is mRNA used with reverse transcriptase?
There’s only two copies of each gene, so it is difficult to obtain a DNA fragment from the actual DNA. There are lots of copies of mRNA that are used to code for proteins, so mRNA is easier to obtain
How are restriction endonuclease enzymes used to make a DNA fragment
Restriction endonuclease enzymes recognise specific palindromic sequences and cut the DNA at these sequences, because the shape of the recognition sequence is complementary to the enzymes active site
Palindromic sequences
Sequence that consist of antiparallel base pairs (base pairs that read the same in opposite directions)
How can DNA fragments cut with restriction endonuclease enzymes be joined together?
If cut with the same restriction endonuclease, it will create sticky ends. The complementary sticky ends of the DNA fragments can anneal
Sticky end
A small tail of unpaired DNA bases at the end of a DNA fragment
How are DNA fragments made using a gene machine?
DNA synthesised from scratch. Sequence that is needed is designed on the computer. The first nucleotide is fixed to a support e.g a bead. Nucleotides are added. Oligonucleotides (twenty nucleotides long). Oligonucleotides are joined together
What are the two ways of amplifying DNA fragments?
In vivo and in vitro
What is the first step in in vivo cloning?
To insert the DNA fragment into a vector’s DNA
vector
Something used to transfer DNA into a cell (e.g a plasmid)
Describe the process of in vivo cloning
The vector is isolated
The vector is cut open using the same restriction endonuclease that was used to isolate the DNA fragment of the target gene
Vector and DNA fragment are mixed together with DNA ligase
The vector DNA and the DNA fragment have now been added together, and are a recombinant DNA
What is the purpose of DNA ligase?
To anneal the sticky ends together
Ligation
The use of DNA ligase to anneal the sticky ends
Transforming cells
Inserting the vector with the recombinant DNA into a cell
How do you get cells to take up the recombinant DNA?
Place bacterial cells in an ice cold calcium chloride solution to make the cell walls more permeable. Then heat shock (42 degrees c for 1-2 mins)
How do you identify transformed cells?
Use marker genes.
Insert marker gene at same time as inserting the DNA fragment into the vector DNA
Host cells grown on agar jelly. Shows evidence of marker gene also such as antibiotic resistance or fluorescence
If you want the transformed cells to produce proteins what do you have to make sure?
The vector contains specific promoter and terminator regions