1. What is/are diff between chromosomal DNA and plasmid DNA?
2. WHAT are 3 steps for DNA extraction?
1. A plasmid is an extra-chromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA. In many cases, it is circular and double-stranded. Plasmids usually occur naturally in bacteria, but are sometimes found in eukaryotic organisms. Plasmids are considered transferable genetic elements, or "replicons", capable of autonomous replication within a suitable host.
A chromosome is an organized structure of DNA and protein that is found in cells. A chromosome is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.
The major general differences include:
- Plasmids have much less base pairs than chromosomes
- Plasmids are rarely organized by chaperone proteins
- Plasmids are easily transferred
- Plasmids usually contain non-essential genes
- Plasmids function can be lost or gained without harming the organism
- Plasmids are usually found in "lower" organisms
2.
1. Break open the cells.
2. Remove large junk from the mix (organelles, stuff like that).
3. Get the DNA to form a solid (to precipitate) to remove most other contaminants.
There are a lot of other procedures out there, but many follow these basic steps. The biggest difference is in how pure you want the DNA to be. Many use a size-exclusion column to remove other contaminants (RNA is often removed in this manner). This sort of column is just a tube with a filter at the bottom. This holds in a bunch of small grains that have tiny holes in them. Small molecules (RNA from cells is generally smaller than the DNA) travel through the holes to get to the bottom, and big molecules (like the DNA) travel around the grains. The shortest path is the one the big molecules take, so they come out the bottom first.
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