In: Biology
1. Hershey and Chase conducted a classic experiment involving bacteriophages. What could they have concluded if they had found only 35S in their bacterial cells?
A. Protein and DNA together are the genetic material.
B. No conclusion is possible.
C. Protein is the genetic material.
D. DNA is the genetic material.
E. RNA is the genetic material.
2.
As unwinding of the helix occurs during DNA replication, tension referred to as ________ is created ahead of the replication fork. This tension is relieved by the action of ________.
A. supercoiling; DNA gyrase
B. processivity; primase
C. processivity; DNA gyrase
D. supercoiling; single-stranded binding proteins
E. supercoiling; DNA helicase
2. What is the reason for the difference in the synthesis of the leading and lagging strands of DNA molecules?
A. DNA polymerase can join new nucleotides only to the 3' end of
the growing strand.
B. One strand must be completely synthesized before synthesis of
the next can begin.
C. Helicase and SSB proteins work only at the 5' end of the
chromosome.
D. DNA ligase only works in the 3' to 5' direction
E. The origins of replication occur only at the 5' end of the
chromosome.
3. Which of the following can bind to the operator of the lac operon?
A. repressor
B. permease
C. activator
D. lactose
E. beta galactosidase
4. The first symptoms of Lesch-Nyhan syndrome begin to affect newborns at around six to eight months, whereas Huntington's s disease strikes in middle age. This illustrates differences in _________.
a. Penetrance
b. Expressivity
c. Epistasis
d. Age of onset
1. Protein is the genetic material.
If 35S protein found in the bacterial cells, may be they conclude protein is the genetic material so the bacteriophage inject the 35S in to the bacterial cells.
In other case in 1944 Avery, Macleod and Mcarty praposed transformation experiment to identify which component of the S-III cell is transformed live R-II cells in to live S-III cells. Finally they prove S-III cells DNA transform live R-II cells in to live S-III cells, thus they assumed DNA as genetic material.
If Hrshy and Chase follow transformation experiment. If 35S proteins found in infected bacterial cells they doesn't conclude which is genetic material either protein or DNA. If they are not follow the transformation experiment they may conclude protein is the genetic material.
2. Supercoiling ; DNA gyrase.
The molecule of DNA gyrase (DNA topoisomarase) binds in front of replicationfork to relieve the torsional stress generated during DNA unwinding by helicase.
2. DNA polymerase can join new nucleotides only to the 3' end of the growing strand.
DNA replication takes place from 5' to 3' direction.
3. Repressor
4. Age of onset