DNA Technology - 2. What are plasmids?. Small, circular DNA molecules. (Found in bacteria). They are separate from the bacterial chromosome. Why are plasmids useful?. They are used to manipulate genes in the lab. They are small. Contain genes useful to the bacteria.
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Small, circular DNA molecules
(Found in bacteria)
They are separate from the bacterial chromosome
They are used to manipulate genes in the lab
They are small
Contain genes useful to the bacteria
And, are easily taken up by bacterial cells
When they are taken up they are called vectors
What happens when the bacterial cell replicates its chromosome?
It also replicates the plasmid DNA
(including any foreign DNA as well)
vector A DNA carrier that move genes from one cell to another
e.g., A T C G
For cutting, what are they called?
They recognize specific sequence of: A T C G
Hundreds have been isolated from bacteria
For pasting, what are they called?
Its the last step to make recombinant DNA
They bind cut ends back together
(by covalent bonds between adjacent nucleotides)
Cut gene sequence of interest (e.g., from human DNA)
Cut a plasmid (from a bacterium)
Create a recombinant DNA molecule
By using the plasmid
And ‘pasting’ a human gene sequence into it
Why is it so important?
Use minute amounts of blood or other tissue
To generate enough DNA for analysis
e.g., DNA from the follicle of ONE stand of hair
Make a mixture of:
Treat the mixture to:
Allows separation of DNA strands
Allows DNA strands to re-form duplexes
DNA Replication occurs during cooling cycle
How many copies of DNA after each cycle?
How many copies after a 5th cycle?
Within a few hours:
PCR can generate billions of copies
From a SINGLE DNA molecule
Enough to do extensive analyses
1990 - 2003
What was the goal of HGP?
To determine the nucleotide sequence all the DNA
In any given human cell
To identify the location & sequence of every gene
What was discovered?
Our DNA contains ~ 2.9 billion nucleotide pairs
About 25,000 genes
There is a LOT of DNA that isn’t made up of genes
About 97% is non-coding DNA
1. Why is only the slightest trace of DNA at a crime scene often sufficient for forensic analysis?
2. A carrier that moves DNA from one cell to another, such as a plasmid, is called a ________
3. What features of a DNA fragment causes it to move through a gel during electrophoresis?
4. A paleontologist has recovered a bit of organic material from the 400 year old preserved skin of an extinct dodo. She would like to compare DNA from the sample with DNA from living birds. The most useful method for increasing the amount of dodo DNA available for testing is __________
5. Why is golden rice pale yellow in color?
What does each ‘band’ consist of?