1. Write briefly on the occurrence of micro organisms.
Micro organisms are found everywhere. They are omnipresent in soil,
water, air, living organisms, food etc. Some of them are found in extreme
conditions like arctic snow, volcanic ash, hot water springs etc.
2. Define microbiology.
Microbiology is the branch of biology that deals with scientific study of
micro organisms that are not visible to the naked eye. It is also concerned
with structure, function and classification of microbes and using their
activities.
3. Name the bacterium which is common inhabitant of human intestine. How
is it used in biotechnology?
Escherichia coli. The plasmids of E.coli are used as vectors during genetic
engineering in biotechnology.
4. What are pleomorphic bacteria? Give an example.
The bacteria that change their shape depending upon the type of
environment and nutrients available are called pleomorphic bacteria. Ex:
Acetobacter.
5. What is sex pilus? What is its function?
The elongated tubules with hollow cores on the surface of bacteria which
help in conjugation are called sex pili. They act as conjugation tubes and
help to bind two conjugant bacteria during conjugation.
6. What is genophore?
Genophore is the bacterial chromosome.
7. What is plasmid? What is its significance?
Small circular double stranded DNA molecules in bacterial cells are called
plasmids. They contain few genes and confer resistance to drugs. They
also produce toxins and enzymes. As they can be readily manipulated and
transferred they are used in genetic engineering.
8. What is conjugation? Who discovered it and in which organism?
Conjugation is the direct transfer of DNA between the living donor and the
living recipient bacterial cells through a conjugation tube.
It was first discovered by Lederberg and Tatum in Escherichia coli.
9. What is transformation? Who discovered it and in which organism?
Transformation is the uptake of naked DNA fragments from the surrounding
environment and incorporation of DNA into the genome of a bacterial cell
and expression of that genetic information in it.
It was discovered by Frederick Griffith in Streptococcus pneumoniae.
10.What is transduction? Who discovered it and in which organism?
Transduction is the transfer of genetic material from one bacterium to
another through a bacteriophage virus.
It was discovered by Lederberg and Zinder in Salmonella typhimurium.
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