8B- Genome Projects And Making DNA Fragments. Flashcards
What have sequencing projects done?
They have read our entire genome.
Gene sequencing methods only work on fragments of DNA. If you want to sequence the whole genome you need to chop it into smaller pieces.
The Human Genome Project in 2003.
How does the sequencing of the genome of simple organisms help identify their proteins?
The proteome is all the proteins the organism is made of.
Simple organisms have no introns so ever triplet codes for a protein, it’s easy to determine.
This is useful as we can identify protein antigens on the surface of disease-causing bacteria and viruses can help with the development of vaccines.
Why is it harder to translate the genome of complex organisms?
More complex organism’s DNA contain introns and regulatory genes which determines which proteins are turned on or off.
It’s more difficult to translate the genome because we can’t distinguish between the non-coding.
How are sequencing methods updated?
Old sequencing methods were:
Labour intensive
Expensive
Small scale
Now they’re the opposite as pyrosequencing that can sequence 40 m bases in 10 hours.
What does recombinant DNA technology involve?
Transferring a fragment of DNA from one organism to another.
Genetic code is universal so the DNA can be used to produce a protein in the cells of recipient organisms. They don’t have to be from the same species.
What’s a transgenic organism?
Organisms that contain transferred DNA.
How can DNA fragments be made?
Using Reverse Transcriptase
Or
Restriction Endonuclease Enzymes
Or
Using a gene machine
How do you use reverse transcriptase to create DNA fragments?
The mRNA molecules can be used as templates to make lots of DNA.
The enzyme, reverse transcriptase, make DNA from an RNA template.
The DNA produced is called complementary DNA (cDNA).
This can be used to produce insulin, it can be used to make cDNA from the insulin mRNA.
mRNA is isolated from the cells, mixed with free nucleotides and reverse transcriptase. This uses the mRNA as a template to synthesise a new strand of cDNA.
How do you use restriction endonuclease enzyme to produce DNA fragments?
Restriction endonuclease identifies specific palindromic sequences (recognition sequences) and cute the DNA at these places.
Different restriction endonuclease cuts at different specific regions, the shape of the recognition sequence is complementary to the active site.
If recognition sequences are present at either side of the DNA fragment, you can use the enzyme to separate it from the rest of the DNA.
The SNA sample is incubated with the specific restriction endonuclease, which cuts the DNA via a hydrolysis reaction.
Sticky ends anneal to the other organisms DNA as it has a complementary sequence.
What makes a gene machine different?
It can synthesise DNA from scratch, without the need for a pre existing DNA template.
It uses a database that contains the information for the wanted DNA fragment.
The DNA does not have to exist naturally.
How does the gene machine work?
The sequence is designed (if it doesn’t already exist).
The first nucleotide is fixed to a bead.
Nucleotides are added step by step in the correct order, including adding protecting groups. These groups make sure the nucleotides are at the right point.
Short sections of DNA, oligonucleotides, (20 nucleotides) are produced. These can be joined to make long chains.
