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

2. OC-SEP041-CP01-01 Introduction Programmes and Courses  SEP – SBT041 – Unit 01  SEP – SBI041 – Unit 01  SEP – SGS041 – Unit 01

3. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Mrs. Rasika Bhore  M.sc (Microbiology) rasika.bhore@gmail.com

4. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 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.

5. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Discuss the two lives on Earth, Prokaryotes & Eukaryotes. Comparison between Prokaryotes & Eukaryotes.

6. School of Science and Technology, Online Counseling Resource… Introduction  According to the internal cell architecture cells are of two types, Prokaryotes & Eukaryotes.  Prokaryotes are unicellular organisms having simple structure.  Eukaryotes are multicellular organisms having various organs in their internal structure.  Both prokaryotes & eukaryotes together keep the balance of ecosystem. © 2007, YCMOU. All Rights Reserved.6

7. School of Science and Technology, Online Counseling Resource… Basic Structure of Prokaryotes  Prokaryotes are the single- celled organisms, such as bacteria, roughly one micrometer in diameter.  Five essential structural components: Nucleotide (DNA) Ribosomes Cell membrane Cell wall and Some sort of surface layer, which may or may not be an inherent part of the wall. © 2007, YCMOU. All Rights Reserved.7

8. School of Science and Technology, Online Counseling Resource… Architectural Regions  Structurally, there are three architectural regions: 1.Appendages (attachments to the cell surface) in the form of flagella and pili (or fimbriae). 2.Cell envelope consisting of a capsule, cell wall and plasma membrane. 3.Cytoplasmic region that contains the cell chromosome (DNA) and ribosomes and various sorts of inclusions. © 2007, YCMOU. All Rights Reserved.8

9. School of Science and Technology, Online Counseling Resource… Basic Structure of Eukaryotes  Eukaryotes include fungi, animals, and plants as well as some unicellular organisms.  Eukaryotic cells are 10 microns in diameter are about 10 times the size of a prokaryote and can be as much as 1000 times greater in volume than the prokaryote.  Eukaryotes possess several superior structures which provide the primary basis to distinguish them from prokaryotes.  These structures are Organelles, Nucleus with its nuclear membrane, Golgi apparatus, Mitochondria / Chloroplasts, and Cytoskeleton. © 2007, YCMOU. All Rights Reserved.9

10. School of Science and Technology, Online Counseling Resource… Structural Components of Eukaryotes © 2007, YCMOU. All Rights Reserved.10

11. School of Science and Technology, Online Counseling Resource… Comparison of Prokaryotes & Eukaryotes  Organelles : Organelles are independent, distinct, membrane- bounded structures or compartments within a eukaryotic cell which perform specific tasks for the overall success and well being of the cell. The specific functions of organelles vary widely and typically depend on their proximity within the cell as well as their physical characteristics. For example, specialized digestive organelles called lysosomes perform the digestive functions in many Eukaryotes. The absence of organelles greatly inhibited the Prokaryote's ability to evolve into more complex cells. © 2007, YCMOU. All Rights Reserved.11

12. School of Science and Technology, Online Counseling Resource… Nucleus & Chromosome Nucleus  In prokaryotic cells the nucleus is not bounded by nuclear envelope, so referred as Nucleoid.  In eukaryotic cells the nucleus is bounded by a definite double membraned nuclear envelope.  Nucleus represents the "control center" for the cell and includes 95% of its DNA. Chromosomes  Prokaryotes usually contain only one circular molecule of DNA, which represents its genome.  In eukaryotes, genome is structured into a number of linear chromosomes.  Each eukaryotic chromosome consists of a DNA complexed with basic proteins, Histones. © 2007, YCMOU. All Rights Reserved.12

13. School of Science and Technology, Online Counseling Resource… Cell Division  During the cell division of prokaryotic cell the DNA replicates, producing two nuclear bodies.  Eukaryotic cell divides by a complex process called ‘Mitosis’. © 2007, YCMOU. All Rights Reserved.13

14. School of Science and Technology, Online Counseling Resource… Cell Membranes  A plasma membrane surrounding the protoplasm is the only unit membrane in a great majority of prokaryotic cells.  Eukaryotic cell possess additional internal unit membrane system consisting of the endoplasmic reticulum, mitochondria, chloroplasts & lysosomes.  Eukaryotic cell membranes contain sterols which are not found significantly in prokaryotic cell membranes except in Mycoplasma group. © 2007, YCMOU. All Rights Reserved.14

15. School of Science and Technology, Online Counseling Resource… Cell Wall prokaryotes  A thick cell wall encloses the cell of prokaryotes, exception is Mycoplasma group.  The cell wall contains amino sugars & muramic acid.  Presence of cell wall halts the activities like endocytosis & exocytosis. Eukaryotes  Cell walls are absent in most of the animals.  When present, consists of relatively simple substances like cellulose, mannans & xylans. © 2007, YCMOU. All Rights Reserved.15

16. School of Science and Technology, Online Counseling Resource… Appendages  Bacteria can have two types of appendages: pili & flagella.  A bacterium may have one, both or neither of these.  The presence or absence of appendages depends on the species & the conditions under which it is cultivated.  Bacterial flagella is responsible for its mobility.  Some eukaryotes have flagella on their outer surface.  Flagella serve the same function of motility but their structure & movement are completely different.  Eukaryotic flagella are 100-200 µm long.  They are more complex than prokaryotic flagella & do not turn.  They are membrane bound having 9+2 microtubules arrangement.

17. School of Science and Technology, Online Counseling Resource… Ribosomes  In prokaryotes the ribosomes occur in the free form or are associated with mRNA.  These are of 70s types having 30s & 50s subunits.  In eukaryotes the ribosomes are associated with the membranes of the endoplasmic reticulum.  Eukaryotic cytoplasmic ribosomes are of 80s types having 40s & 60s subunits. © 2007, YCMOU. All Rights Reserved.17

18. School of Science and Technology, Online Counseling Resource… Respiration  The cell membrane of prokaryotes plays a role in this energy yielding process.  E.g. the respiratory electron transport system is located in the cell membrane in aerobic bacteria.  In eukaryotes, respiration is performed in the mitochondria.  Inner mitochondrial membrane contains the enzyme that participate in electron transport. © 2007, YCMOU. All Rights Reserved.18

19. School of Science and Technology, Online Counseling Resource… Photosynthesis  In photosynthetic bacteria photosynthesis takes place in chromatophores that may be in the form of vesicles & tubules or parallel tubes.  In photosynthetic blue green bacteria it takes place in lamellar leaf like plates thylakoids, distributed throughout the cytoplasm.  Green plants contain complicated structures called chloroplasts which consist of parallel layers of lamellae, enclosed within a double membraned sac.  Chloroplasts contain chlorophyll & caratenoid photosynthetic pigments & enzymes for CO 2 fixation.  Prokaryotes lack the enzyme for fixing CO 2. © 2007, YCMOU. All Rights Reserved.19

20. School of Science and Technology, Online Counseling Resource… Protein Synthesis  Eukaryotic polypeptides have methionine as the starting amino acid.  mRNAs are largely monocistronic, means having only a single functional site for the initiation of protein synthesis.  In prokaryotes the starting amino acid is N-formylmethionine.  Bacterial mRNAs are polycistronic & contain several initiation & termination sites.  There is also difference in initiation, elongation & release factors of prokaryotes & eukaryotes. © 2007, YCMOU. All Rights Reserved.20

21. School of Science and Technology, Online Counseling Resource… Reproduction  Sexual reproduction is common in eukaryotes.  It is the only method of reproduction in vertebrates & many invertebrates.  Since sexual reproduction results in doubling of chromosome number, meiosis take place at some stage of life cycle before the formation of gametes.  In prokaryotes sexual reproduction is rare & fragmentary.  Usually asexual reproduction take place by which bacterial DNA produce exact copy of itself. © 2007, YCMOU. All Rights Reserved.21

22. School of Science and Technology, Online Counseling Resource… What We Learn………….  Prokaryotes include single celled bacteria 1 micrometer in diameter.  Eukaryotes include plants, animals & fungi & 10 times larger than prokaryotes.  Prokaryotes have no different organelles as that of eukaryotes.  Nuclear envelope is absent in prokaryotes.  Prokaryotic genome is a single circular DNA while eukaryotic genome is made from chromosomes.  Cell wall & cell membrane generally present in prokaryotes & in some eukaryotes.  Cell division is different in both classes.

23. School of Science and Technology, Online Counseling Resource… Critical Thinking Questions  Why prokaryotic cells meet their needs for nutrients quickly & grow rapidly? © 2007, YCMOU. All Rights Reserved.23

24. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved. Hints For Critical Thinking Questions  Surface to volume ratio.

25. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.25 Study Tips  Book Title: General microbiology Vol I Author: Powar & Daginawala  Book Title: Microbiology Author: Michael J. Pelczar

26. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.26 Study Tips www.facstaff.gpc.edu Prokaryotes & eukaryotes www.wikepedia.org

27. End of the Presentation Thank You !