Online Counseling Resource

YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – 422222, India

OC-SBT092-CP1-03

Introduction

Programmes and Courses  SEP – SBT092 – Unit 01 - 03

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Credits

 Academic Inputs by  Arun Punaji More.

 M.Sc. (Microbiology) Experience: 11 Years  [email protected]

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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:  

Describe

characteristics of prokaryotic chromosomes

Describe

chromosome walking © 2009, YCMOU. All Rights Reserved.

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Introduction

The prokaryotic chromosomes show remarkable differences in its organization that that of eukaryotic chromosomes.

The mechanism of stabilizing the DNA molecules and its protection from the adverse effects by harmful enzymes are also different for eukaryotic and prokaryotic chromosomes.

In this module students shall learn the characteristic organization and important physical properties of prokaryotic chromosome; Students shall also learn the characteristic differences between the organization of eukaryotic and prokaryotic chromosomes.

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Prokaryotic Chromosomes-1

      Morphology: The prokaryotic chromosome usually contain a single copy of DNA molecule.

However some bacteria such as

Borrelia burgdorferi

and

Vibrio cholerae

than one chromosome.

possess more The prokaryotic chromosome is circular, double stranded and located concentrated at a particular site called as nucleoid .

However some bacteria carry linear chromosome e.g. streptococci .

Just before the cell division of prokaryotic cell, two nucleoids are observed by a special staining method.

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Prokaryotic Chromosomes-2

Gentle lysis of prokaryotic cell releases Complete DNA moles in uncoiled form Showing that inside the cell the prokaryotic DNA must be tightly packed.

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Prokaryotic Chromosomes-3 Structure of prokaryotic chromosome:

Circular chromosome of bacterial cell © 2009, YCMOU. All Rights Reserved.

Super coiled chromosome 9

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Prokaryotic Chromosomes-4 Structure of prokaryotic chromosome:-

Prokaryotic DNA do not Contain introns as eukaryotic DNA Thus making the transcription of prokaryotic DNA comparatively simple © 2009, YCMOU. All Rights Reserved.

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Prokaryotic Chromosomes-5

Prokaryotic DNA have only one Origin of replication which initiate Bidirectional replication of the DNA.

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Prokaryotic Chromosomes-6

    

Characteristics of prokaryotic chromosome:-

Prokaryotic chromosome show co-linearity i.e. DNA sequences directly related to its corresponding amino acid sequence in the polypeptide chain.

Prokaryotic DNA has only one origin of replication.

Prokaryotic DNA contain very few number of repeated sequences.

Prokaryotic DNA is not contained by membrane system like that present in eukaryotic chromosome.

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Prokaryotic Chromosomes-7

    

Characteristics of prokaryotic chromosomes:-

Gene density of prokaryotic chromosome is much more higher than that of eukaryotic chromosomes.

Gene density of prokaryotic chromosome is 860 to 1060 genes/Mb (gene per size of DNA expressed in Mb) Prokaryotic chromosome is very simple.

Prokaryotic DNA contain approximately 500 to 6200 genes.

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Chromosome Walking-1

    Chromosome walking is technique by which clone contigs are assembled for construction of genetic map of eukaryotic chromosome.

Contigs assembly is done by finding out all the pairs of overlapping clones in the genome library.

For this any one clone is first selected radio labelled and used as hybridization probe to find out its overlapping clone.

Then another clone is selected and the procedure is repeated until all the pair of overlapping clones are found.

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Chromosome Walking-2

 Chromosome walking by clone contigs assembly method: © 2009, YCMOU. All Rights Reserved.

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What We Learn…..

   Characteristics of prokaryotic chromosomes Definition of chromosome walking Applications of chromosome walking © 2009, YCMOU. All Rights Reserved.

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Critical Thinking Question

 Why gene density is higher in prokaryotic chromosomes than eukaryotic chromosomes?

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Hints For Critical Thinking Question

 Absence of intergenic sequences in prokaryotic chromosome.

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Study Tips

 Book   

Title: Molecular Biology of the Gene Author:

Watson, baker et al.

Publication:

Pearson Education Ltd.

Book 

Title: Genetics

 

Author: C. B. Pawar Publication:

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End of the Presentation Thank You !

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