to hope99 - ptosis

[ArchivalUser]

need answers for these Qs plz

Q1
Bacterial strain X is resistant to ampicillin and sensitive to kanamycin. Bacterial strain Y is resistant to kanamycin and sensitive to ampicillin. Bacterial strains X and Y are grown in mixed culture in medium without antibiotics, then the culture is plated on medium containing both ampicillin and kanamycin. Bacterial colonies grow on the plates. In a second experiment, DNase is added to the mixed culture medium. When this mixed culture is plated on medium containing both antibiotics, no colonies grow. Assuming that bacterial cells are impermeable to DNase, which of the following processes best explains these observations?
A ) Conjugation
B ) Mutation
C ) Transduction
D ) Transformation
E ) Transposition


Q2

An 18-year-old woman who has hepatocellular carcinoma is treated with a new chemotherapeutic agent. One week after initiation of therapy, examination of tissue obtained on biopsy of the liver shows that many neoplastic cells have decreased in size. Many fragments of membrane-bound structures containing condensed nuclear chromatin and organelles are identified. Electrophoresis on agarose gel of DNA isolated from this tissue shows a "ladder" consisting of multiple regularly spaced DNA bands. Activation of which of the following enzymes is most likely to be responsible for the alterations in DNA?
A ) DNA ligase
B ) DNA polymerase
C ) Endonuclease
D ) Phospholipase A2
E ) Transglutaminase

[ArchivalUser]

Q1)D ) Transformation
Q2)C ) Endonuclease

[ArchivalUser]

1)restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the sugar-phosphate backbones (i.e., each strand) of the double helix without damaging the nitrogenous bases. They work with cutting up foreign DNA, a process called restriction. Restriction enzymes therefore are believed to be a mechanism evolved by bacteria to resist attack from viruses called bacteriophages and to help in the removal of viral sequences. They are part of what is called the restriction modification system.

The chemical bonds that the enzymes cleave can be reformed by other enzymes known as ligases, so that restriction fragments carved from different chromosomes or genes can be spliced together, provided their ends are complementary (more below). Many of the procedures of molecular biology and genetic engineering rely on restriction enzymes.

2)Transformation

Many bacteria can acquire new genes by taking up DNA molecules (e.g., a plasmid) from their surroundings. The ability to deliberately transform the bacterium E. coli has made possible the cloning of many genes ” including human genes ” and the development of the biotechnology industry.


http://users.rcn.com/jkimball.ma.ultrane...Avery.html

[ArchivalUser]

thanx hope 99
i sure u will get 99
Gl

[ArchivalUser]

sorry .................Assuming that bacterial cells are impermeable to DNase
it is A ) Conjugation