How to measure quality and quantity of DNA while doing experiments.?

One  can run your DNA sample on agarose gel to see, whether you have significant degradation.

If you are interested in contamination, you can make a standard photometric analysis to assess the 260/280 and 260/230 ratios and absorbance at 320 nm on NanoDrop or even something similar to Eppendorf's BioPhotometer.

BioPhotometer 

In case RNA may be an obstacle for some down-stream procedures, with Qubit one  can also measure separately DNA and RNA concentrations and then decide if you have too much RNA and it's worth treating your sample with RNase.

Read More

Unknown Wednesday, April 02, 2014  No comment

How do prokaryotes produce ribosomes without a nucleus?

Prokaryotes have 70S(it is measure in centrifuge) ribosomes, each consisting of a small (30S) and a large (50S) subunit and each sub-units have different proteins and RNA's in too groups

In the nuclear region they contain their own circular shaped DNA and RNA segments called "bacterial chromosomes". This contains instructions on how to make essential ribosomes. The ribosomes float freely in the cytoplasm of the prokaryotic cell.

They  reproduce by a process that is called binary fission. The  DNA in such cells is contained in a single circular chromosome called a plasmid within the cytoplasm. The reproductive process starts with the replication of the chromosome. The new chromosome attaches itself to the plasma membrane and the two chromosomes migrate to opposite ends of the cell. The plasma membrane in the middle of the cell grows inward until it closes to separate the cell into two compartments, each with a full complement of genetic material. The cell then "fission" at the center, forming two new daughter cells.

Read More

Unknown Tuesday, February 25, 2014  No comment

How to explain temperature-sensitive mutation,what exactly it is ?

In  temperature sensitive mutation is it lowers the critical melting temperature for the protein, so making it denature at a lower temperature than the normal gene product.Therefore when the temp changes from the 37 to 30 degree there is alterations.These alterations in key portions of a protein may lead to changes in the specificities of the protein.

This is a kind of loss of phenotype phenomena,heat-sensitive mutations, traditionally known as temperature-sensitive (TS) mutations, are powerful tools for studying the functions of all genes.TS mutations are functional at low temperatures, yet nonfunctional at high temperatures, and thus a rise in temperature quickly ablates protein function.

Temperature sensitive mutations are typically missense mutations, which retain the function of a specific essential gene at standard low temperature, lack that function at a defined high temperature, and exhibit partial function at an intermediate temperature

Mutations are ususally found which resulted in a preferential loss of ability to carry out protein synthesis, RNA synthesis, DNA synthesis, cell division, or cell-wall formation.So it depends on the kind of strain you have isolated

Read More

Unknown Monday, December 23, 2013  No comment