prokaryotic and eukaryotic cell

Prokaryotic and eukaryotic cells characteristics have been discussed in this presentation.

1. Prokaryotic and Eukaryotic Cell : Structure and Functions SUBMITTED BY :- GUIDED BY :- ADITI CHANDRAKAR DR. JAISHANKAR PAUL M.SC. 1 st SEMESTER BIOTECHNOLOGY SCHOOL OF STUDIES BIOTECHNOLOGY PT. RAVISHANKAR SHUKLA UNIVERSITY 1

2. CONTENT Introduction Prokaryotic cell: characteristics Structure & functions of Prokaryotic cell Eukaryotic cell: characteristics Structure & functions of Eukaryotic cell Difference between plant & animal cell Comparision of Prokaryotic & Eukaryotic cell Similarities between Prokaryotic & Eukaryotic cell References 2

3. INTROUCTION On the basis of presence or absence of nucleus the cell are classified into two main types: i ) Prokaryotic cell ii) Eukaryotic cell 3

4. Prokaryotic cell:- ( pro= before, karyon = nucleus) “Prokaryotic cells are the cells that do not have a true nucleus and membrne -bound organelles.” E.g. Bacterial cell, PPLO etc.. Eukaryotic cell:- ( Eu = true , karyon = nucleus ) “Eukaryotic cells are the cells that contain membrane-bound nucleus and organelles.” E.g. Protists , fungi, plants and animal cells 4

5. PROKARYOTIC CELL Prokaryotic cells are single-celled (unicellular) microorganisms known to be earliest on earth. Oldest type of prokaryotic cell appeared approximately 3.5 billion years ago. Prokaryotic cell are simplest type of cell. Prokaryotes are the largest group of organisms. They are found in all environments. Prokaryotes includes Eubacteria and Archaebacteria ( Halophiles , Thermophiles , Methanogens ). Photosynthetic prokaryotes includes Cyanobacteria that perform photosynthesis. 5

6. Characteristics of prokaryotic cells : Prokaryotic cell lack nuclear membrane, nucleolus, due to which DNA and RNA remain dispersed throughout the cytoplasm. Mitochondria, Golgi body, Chloroplasts, Endoplasmic reticulum and Lysosomes are absent. The genetic material is present on a single chromosome. The cell wall is made up of carbohydrate (polysaccharide) and amino acids. Ribosomes are 70S type (subunits 50S + 30S type) Nucleus is known as nucleoid 6

7. Prokaryotes are smaller in size when compared to eukaryotic cells. Infoldings of plasma membrane inside the cytoplasm is found which is known as mesosome and perform the function of mitochondria. They divide asexually by binary fission . 7

8. Prokaryotic cell: structure and their functions 1) Glycocalyx :- It is the outermost protective covering followed by cell wall and then plasma membrane. It could be loose sheath called slime layer in some, whereas in others it may be thick and tough called capsule. Functions : - It helps in moisture retention, protects the cell when engulfed ( phagocytosis ) and help in the attachment of cells to nutrients and surfaces . 8

9. 2) Cell wall :- Bacterial cell wall is rigid and strong structure. Functions :- Cell wall determines the shape of the cell and provide a strong structural support to prevent the bacterium from bursting or collapsing. 3) Cell membrane :- This layer is semi-permeable in nature and surrounds the cytoplasm . This membrane is similar structurally to that of the Eukaryotes. Functions: - It interacts with outside world and regulate the entry and exit of substances in the cell. 9

10. 4) MESOSOME: - It is formed by extension of plasma membrane into the cytoplasm. Mesosomes are analogus to mitochondria. Function :- It helps in cellular respiration. 5) CYTOPLASM :- It is a jelly like substance present inside the cell membrane. All the organelles are suspended in cytoplasm. 6) PILI: - These are hair-like outgrowths that help the bacterium to attach to the surface of other bacteria. 10

11. 7) FIMBRIAE:- are small bristle like fibres sprouting out of the cell. Function :- Help to attach the bacteria to the rocks in streams and also to the host tissues. 8) FLAGELLA: - are long filamentous appendages consisting of a hook, filament and basal body. Function :- Helps in locomotion 9) RIBOSOMES :- 70S ribosomes (two subunits 50S & 30S) are present in prokaryotic cell. Function :- Involve in protein synthesis. 11

12. 10) NUCLEOID :- It is the region in the cytoplasm where the genetic material is present. 11) DNA :- is the genetic material of the cell. Function : - It directs what protein should the cell create and regulates the action of cell. 12) PLASMID :- are self replicating , circular, extra chromosomal DNA structures. Plasmids are not involve in reproduction. 13) INCLUSION BODIES :- Reserve materials in prokaryotic cells are stored in the form of inclusion bodies e.g. phosphate granules, glycogen granules etc.. 12

13. Diagram of a typical prokaryotic cell: bacterial cell 13

14. EUKARYOTIC CELLS Eukaryotes arose from prokaryotes and developed into larger and more complex organisms. Eukaryotic cells appeared approximately one billion years ago. Eukaryotes include some unicellular protists to multicellular fungi, plants and animals. These have a nucleus enclosed within the nuclear membrane. Eukaryotic cells are generally more advance than prokaryotic cell. 14

15. CHARACTERISTICS OF EUKARYOTIC CELL :- Eukaryotic cells have complex internal structure. They have the nucleus enclosed within the nuclear membrane and nucleolus is also present in the nucleus. All the cell organelles (mitochondria, endoplasmic reticulum, ribosomes , golgi body, vacuoles etc..)are present in the cytoplasm. Flagella and cilia are the locomotory organs in a eukaryotic cell. Ribosomes are of 80S type (subunits 60S + 40S type) 15

16. Cell wall made up of cellulose is present in plant cells but completely lacking in animal cells. Cells contain a cytoskeletal structure. Eukaryotic cells divide by mitosis. 16

17. EUKARYOTIC CELL :- STRUCTURES AND THEIR FUNCTIONS Plasma membrane/cell membrane Plasma membrane is a thin, elastic, transparent semi-permeable membrane, found in all cells. Functions :- Transport of water, molecules and ions. It acts as a protective layer around the protoplasm of the cell 17

18. Cell wall Cell wall is the outermost rigid structure present outside the plant and fungal cells. It is absent in animal cells. Function: - It provide definite shape to a cell and helps in cell-to-cell interaction. It acts as a protective layer that protects the cell from any injury or pathogen attack. 18

19. Cytoskeleton In eukaryotic cell microfilaments and microtubules together constitute cytoskeleton which provide perfect shape to cell and also give mechanical support to the cell. Function :- Helps in cyclosis of protoplasm. Involved in movement of cell . 19

20. ENDOPLASMIC RETICULUM Endoplasmic reticulum is a complex network of tubular membranes exclusively present in the cytoplasm of the eukaryotic cell. Endoplasmic reticulum is of two types:- Rough endoplasmic reticulum:- contains ribosomes Smooth endoplasmic reticulum:- lacks ribosomes Functions :- Provide more surface for metabolism, helps in the transport and intracellular circulation. Also helps in protein synthesis. 20

21. Nucleus Nucleus is a double membrane bound organelle which directs and control all the cellular functions and also contain genetic material. Nucleus consists of :- Nuclear membrane Nucleoplasm Chromosomes Nucleolus 21

22. Golgi apparatus Golgi body is made up of flat disc-shaped structure called cisternae and are arranged parallel and concentrically near the nucleus. Functions :- Important site for the formation of glycoproteins and glycolipids . It is mainly involved in modifying, sorting and packaging of cell products into secretory vesicles. . 22

23. RIBOSOMES Ribosomes are tiny granules composed of mRNA and protein. Function: - Main site for protein synthesis 23

24. Lysosome Lysosomes are vesicular bodies filled with hydrolytic enzymes and are involved in digestion of protein, lipid, carbohydrate and nucleic acid. They are also called as “Suicidal bags ”. Functions :- Dead cells inside the body are removed by lysosomes . 24

25. Cytoplasm Cytoplasm consists of jelly-like homogenous ground substance. It contains cell organelles and inorganic material. 25

26. MITOCHONDRIA Mitochondria is a double membrane bound organelle. It is also known as “ power house of the cell ” because they produce energy. Functions :- Principle organ for the cellular respiration. . Produce cellular energy in the form of ATP. 26

27. PLASTIDS Plastids are the double membrane bound organelle and are only found in plants. Based on the type of pigments, plastids are of three types:- ( i ) Chloroplast :- Greenish colour plastids containing chlorophyll. (ii) Chromoplast :- contains a pigment called carotene that provides plants yellow , red or orange colour . (iii) Leucoplast:- are colourless and store lipids, carbohydrate or protein. 27

28. Cilia and Flagella Cilia and Flagella :- Hair-like projections covered with plasma membrane with core of axoneme (9+2 array). Function: - Cilia and flagella helps in locomotion. 28

29. Centrioles are paired barrel -shaped cell organelle found in alI animal cells but absent in plant cells. Function :- They are involved in development of spindle fibres . Regulate cell division of cells. They also form basal body of cilia and flagella. CENTRIOLE 29

30. Vacuoles Vacuoles are non-living membrane bound structures of cytoplasm present in all eukaryotic cells. Functions :- Helps in the function of osmoregulation . Also helps in phagocytosis and pinocytosis . 30

31. Microbodies Many membrane bound minute vesicles called microbodies that contain various enzymes are present in both plants and animal cells. 31

32. Diagram of Eukaryotic cells:- (A)Plant cell (B)Animal cell 32

33. Difference between Plant cell and Animal cell Features Plant cell Animal cell Cell shape Plant cell is large and has a fixed rectangular shape Animal cell is small and irregular or round in shape Cell wall Present Absent Nucleus Present; nucleus lies on one side of cell Present; nucleus lies in the centre of the cell Mitochondria Present in fewer numbers Present in large numbers 33

34. Features Plant cell Animal cell Plastids Present Absent Centrosome Absent Present Vacuole One large central vacuole is present Many small vacuoles are present Lysosomes Present but very rare Present Mode of nutrition Primarily autotrophic Heterotrophic 34

35. Comparison of prokaryotic and eukaryotic cell Features Prokaryotic cell Eukaryotic cell Type of cell Always unicellular Unicellular and multicellular Cell wall Usually present, chemically complex in nature. Present in plant cell but absent in animal cell Cell size Cells are smaller in size Cells are larger in size nucleus Absent, instead they have a nucleoid region in the cell present 35

36. 36 Features prokaryotic cell Eukaryotic cell Ribosomes Present, 70S type (Subunits 50S & 30S) Present, 80S type (subunits 60S & 40S) DNA arrangement Circular Linear Mitochondria Absent Present Plasmids Present Very rarely found in eukaryotic cells Centriols Absent Present in animal cells Flagella Consists of a single fibril Consist of two central and nine peripheral (9+2) fibrils

37. Features Prokaryoti c cell Eukaryotic cell Cell division Amitosis and binary fission Through mitosis and meiosis Reproduction Asexual both asexual and sexual Respiration Takes place on plasma membrane Takes place inside the mitochondria DNA Never associated with histone protein Always associated with histone protein Golgi body Absent Present Lysosome Absent Present 37

38. Features Prokaryotic cell Eukaryotic cell Endoplasmic reticulum Absent Present Nucleolus Absent Present Cytoplasm Present, but cell organelles absent Present, containing cell organelles Example Bacteria and archaebacteria Plant cells and animal cells 38

39. Similarities between Prokaryotic and Eukaryotic cell Both types of cells have plasma membrane of similar construction. Both types of cells have genetic information encoded in DNA using identical genetic code. Both types of cells have similar mechanism for transcription and translation of genetic information, including similar ribosomes . Similar mechanism for synthesizing and inserting membrane protein. Similar apparatus for conservation of chemical energy as ATP (located in the plasma membrane of prokaryotes and the mitochondrial membrane of eukaryotes). Similar mechanism of photosynthesis. 39

40. REFERENCES Biology textbook of Class IX (N.C.E.R.T.) Cell and Molecular Biology- Concept and experiment by Gerald Karp (6 th Edition) 40

41. THANKYOU 41