8B - Genome Projects and Gene Technologies Flashcards
What is a genome?
An entire set of an organism’s DNA, including all of the genes.
How does sequencing of an entire genome work and why?
- DNA is cut up into small sections, which are then sequenced and assembled again
- This is because sequencing methods only work on small sections
What was the Human Genome Project?
A project to map the entire sequence of the human genome.
What is a proteome?
All the proteins produced by an organism.
How and why does sequencing the genome of simple organisms help work out their proteome?
They don’t have much non-coding DNA, so the proteome can easily be determined.
When is proteomics useful?
Medical research (e.g. when identifying the antigens on the surface of disease-causing bacteria for vaccine creation)
Why is it hard to work out the proteome from the genome of complex organisms?
- They contain large sections of non-coding DNA and regulatory genes
- These do not code for particular proteins, so it is difficult to translate the genome into a proteome
How many human proteins have been identified so far?
30,000
Give some ways in which sequencing technologies are advancing.
- Automation
- Cost efficiency
- Large scale
Give an example of a development in DNA sequencing.
Pyrosequencing -> Allows 400 million bass to be sequenced in a 10 hour period
What does recombinant DNA technology involve?
Transferring a fragment of DNA from one organism to another.
How does recombinant DNA technology work and why?
- Genetic code is universal and transcription and translation mechanisms are similar too
- So DNA transferred to a different organism can be used to produce the same proteins (even in a different species)
What are organisms that contain transferred DNA called?
Transgenic organisms
Before DNA is inserted into another organism, what must first be done?
DNA fragment must be obtained containing the target gene
What are the 3 ways of producing gene fragments?
1) Reverse transcriptase
2) Restriction endonucleases
3) Gene machine
Describe how reverse transcriptase can be used to make a DNA fragment containing the target gene.
- mRNA is isolated from cells.
- Free DNA nucleotides and reverse transcriptase are added.
- The mRNA molecules can be used as templates for reverse transcriptase to make complementary DNA (cDNA).
What is the advantage of using reverse transcriptase to make DNA fragments containing a target gene?
mRNA created by the target gene is often more abundant than the two copies of the gene itself, so it is easier to obtain
What enzyme can be used to make a complementary DNA strand from mRNA?
Reverse transcriptase
What is the name for DNA produced by reverse transcriptase acting on mRNA?
Complementary DNA (cDNA)
Describe how restriction endonucleases can be used to make a DNA fragment containing the target gene.
- Some genes have a palindromic sequence of nucleotides either side. These are called recognition sequences.
- Restriction endonuclease is chosen that has an active site complementary to the recognition sequences.
- The sample is incubated with the restriction endonuclease, which causes the enzymes to cut the DNA via a hydrolysis reaction.
- This leaves the DNA segment with sticky ends.
What is the name for the place where a restriction endonuclease binds?
Recognition sequence
What makes a recognition sequence characteristic?
Have a palindromic sequence of nucleotides (i.e. with antiparallel base pairs)
Are there multiple different restriction endonucleases?
Yes, each one cuts at a different base sequence.
What type of reaction is a restriction endonuclease cutting DNA?
Hydrolysis