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Online Counseling Resource
YCMOU ELearning Drive…
School of Architecture, Science and Technology
Yashwantrao Chavan Maharashtra
Open University, Nashik – 422222, India
OC-SEP041-CP01-04
Introduction
Programmes and Courses
 SEP – SBT041 – Unit 01
 SEP – SBI041 – Unit 01
 SEP – SGS041 – Unit 01
School of Science and Technology, Online Counseling Resource…
Credits
 Academic Inputs by
 Mrs. Rasika Bhore
 M.sc (Microbiology)
 [email protected]
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School of Science and Technology, Online Counseling Resource…
How to Use This Resource

Counselor at each study center should use this presentation to deliver
lecture of 40-60 minutes during Face-To-Face counseling.

Discussion about students difficulties or tutorial with assignments should
follow the lecture for about 40-60 minutes.

Handouts (with 6 slides on each A4 size page) of this presentation should
be provided to each student.

Each student should discuss on the discussion forum all the terms which
could not be understood. This will improve his writing skills and enhance
knowledge level about topics, which shall be immensely useful for end
exam.

Appear several times, for all the Self-Tests, available for this course.

Student can use handouts for last minutes preparation just before end
exam.
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Learning Objectives
 After studying this module, you should be able to:
 Discuss the content of cytoplasm of bacteria.
 Describe the bacterial genome.
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Introduction
 The cytoplasm of bacterial cells consists of an aqueous
solution of three groups of molecules:
 Macromolecules such as proteins (enzymes).
 mRNA and tRNA.
 Small molecules that are energy sources, precursors of
macromolecules, metabolites or vitamins; and various
inorganic ions and cofactors.
 The primary structural components found in the cytoplasm are
the nucleoid and ribosomes, and possibly some type of
inclusion.
 The cytoplasm of prokaryotes is more gel-like than that of
eukaryotes.
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Contents Of Cytoplasm
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Ribosomes
 The distinct granular appearance of prokaryotic cytoplasm is
due to the presence and distribution of ribosomes.
 Ribosomes are composed of proteins and RNA.
 The ribosomes of prokaryotes are smaller than cytoplasmic
ribosomes of eukaryotes.
 Prokaryotic ribosomes are 70S in size, being composed of 30S
and 50S subunits.
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School of Science and Technology, Online Counseling Resource…
Function Of Ribosomes
 Ribosomes are involved in the process of translation (protein
synthesis), but some of their activities differ in eukaryotes,
bacteria and archaea.
 Ribosomes do this by catalyzing the assembly of individual
amino acids into polypeptide chains; this involves binding a
messenger RNA and then using this as a template to join
together the correct sequence of amino acids.
 This reaction uses adapters called transfer RNA molecules,
which read the sequence of the messenger RNA and are
attached to the amino acids.
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School of Science and Technology, Online Counseling Resource…
Effect of Antibiotics On Ribosomes
 The differences between the bacterial and
eukaryotic ribosomes are exploited to create
antibiotics that can destroy a bacterial infection
without harming the cells of the infected person.
 Due to the differences in their structures, the
bacterial 70S ribosomes are vulnerable to these
antibiotics while the eukaryotic 80S ribosomes are
not.
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School of Science and Technology, Online Counseling Resource…
Bacterial Chromosome
 The bacterial chromosome (nucleoid) is typically one large
circular molecule of DNA, more or less free in the cytoplasm,
although coiled and supercoiled and anchored by proteins.
 The total DNA content of a prokaryote is referred to as the cell
genome.
 The cell chromosome is the genetic control center of the cell
which determines all the properties and functions of the
bacterium.
 During cell growth and division, the prokaryotic chromosome
is replicated in a semiconservative fashion to make an exact
copy of the molecule for distribution to progeny cells.
 Replication and segregation of prokaryotic DNA is coordinated
by the membrane and various proteins in the cytoplasm.
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School of Science and Technology, Online Counseling Resource…
Function of Bacterial Chromosome
 The nucleoid is the genetic material of the
bacterium.
 Genes located along the DNA are transcribed into
RNA that, in the case of mRNA, is then translated
into protein at the ribosomes.
 In other words, DNA determines what proteins and
enzymes an organism can synthesize and,
therefore, what chemical reactions it is able to
carry out.
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School of Science and Technology, Online Counseling Resource…
Genome In Defense Mechanism
 In order to protect against infection, the body must detect the
presence of microorganisms.
 The body does this by recognizing molecules unique to
microorganisms that are not associated with human cells.
 These unique molecules are called pathogen-associated
molecular patterns or PAMPS.
 Bacterial and viral genomes contain a high frequency of
unmethylated cytosine-guanine dinucleotide sequences.
 Mammalian DNA has a low frequency of cytosine-guanine
dinucleotides and most are methylated.
 These unmethylated cytosine-guanine dinucleotide sequences
in bacterial DNA are PAMPS that bind to pattern-recognition
receptors on a variety of defense cells of the body and
triggers innate immune defenses such as inflammation, fever,
and phagocytosis.
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School of Science and Technology, Online Counseling Resource…
Plasmids
 Many bacteria possess extrachromosomal DNA known as
plasmids, which exist and replicate independently of the
chromosome.
 They are 2- to 30 times smaller than chromosome, but their
structure is same.
 Plasmids have relatively few genes (fewer than 30).
 The genetic information of the plasmid is usually not essential
to survival of the host bacteria.
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‘F’ Plasmid
 A special plasmid called a fertility (F) factor plays
an important role in conjugation.
 The F factor contains genes that encourage cellular
attachment during conjugation and accelerate
plasmid transfer between conjugating bacterial
cells.
 Those cells contributing DNA are called F+ (donor)
cells , while those receiving DNA are the F(recipient) cells.
 The F factor can exist outside the bacterial
chromosome or may be integrated into the
chromosome.
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School of Science and Technology, Online Counseling Resource…
‘R’ Plasmid
 Plasmids that encode enzymes that make a bacterium
resistant to antibiotics are called R (resistance) factors.
 Some R factors confers resistance to only a single antibiotic,
other to several antibiotics.
 Strains that carry R factors have multiple drug resistance.
 Genes that encode a series of bacteriocins are also found on
plasmids.
 Bacteriocins are bacterial proteins capable of destroying other
bacteria.
 Still other plasmids increase the pathogenicity of their host
bacteria because the plasmid contains genes for toxin
synthesis.
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School of Science and Technology, Online Counseling Resource…
What We Learn……
 Cytoplasm is a complex water solution consists of
nucleoid & ribosomes.
 Ribosomes are 70s type made up of 30s & 50s subunits.
 Ribosomes functions in protein synthesis.
 Bacterial chromosome is one long, single molecule of
double stranded, helical, supercoiled DNA.
 It decides which proteins & enzymes should synthesize
in cell.
 Plasmid is extrachromosomal DNA not necessary for cell
functioning.
 ‘F’ plasmid acts in conjugation while ‘R’ plasmid act as
antibiotic resistant marker.
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School of Science and Technology, Online Counseling Resource…
Critical Thinking Questions
1. How can we produce the penicillin
resistant strain of E.coli?
2. Mitochondria of eukaryotes possess same
70s ribosome as that found in
prokaryotes. Does it affected by
antibiotics? How?
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Tips For Critical Thinking Questions
1. By transferring R plasmids.
2. No it is not affected, because of the
double membrane covering of
mitochondria, antibiotics can not enter.
© 2007, YCMOU. All Rights Reserved.
School of Science and Technology, Online Counseling Resource…
Study Tips
 Lipps G (editor). (2008). Plasmids: Current Research and
Future Trends. Caister Academic Press. ISBN 978-1-90445535-6.
 Russell, David W.; Sambrook, Joseph (2001). Molecular
cloning: a laboratory manual. Cold Spring Harbor, N.Y: Cold
Spring Harbor Laboratory.
 LEDERBERG J (1952). "Cell genetics and hereditary
symbiosis". Physiol. Rev. 32 (4): 403–30.
 Kandavelou K; Chandrasegaran S (2008). "Plasmids for Gene
Therapy", Plasmids: Current Research and Future Trends.
Caister Academic Press.
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School of Science and Technology, Online Counseling Resource…
Study Tips
www.en.wikipedia.org
Plasmids
www.cliffsnotes.com
Bacterial chromosome & plasmid
www.students.ccbcmd.edu
Bacterial chromosome
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End of the Presentation
Thank You !