Human Physiology: Cell Structure and Function

1. Human Physiology:Cell Structure and Function BY DR BOOMINATHAN Ph.D. M.Sc.,(Med. Bio, JIPMER), M.Sc.,(FGS, Israel), Ph.D (NUS, SINGAPORE) PONDICHERRY UNIVERSITY I Lecture 31/July/2012 Source: Collected from different sources on the internet-http://koning.ecsu.ctstateu.edu/cell/cell.html Collected from different sources, modified and presented by Dr Boominathan Ph.D.

2. Anatomy, physiology, … • Anatomy is the science of the structure • Physiology is the science of the function • Anatomy and physiology are closely linked, in particular physiology cannot be understood without anatomy • In many respects, both are ‘closed sciences’

3. Physiology • Some important moments: • 17th century: William Harvey first describes the closed circulation • 19th century: Claude Bernard formulates the modern version of homeostasis – the constancy of the internal milieu • 19th century: Johannes Muller formulates the ‘law of specific nerve energy’

4. Physiology • Some important moments: • 17th century: William Harvey first describes the closed circulation • 19th century: Claude Bernard formulates the modern version of homeostasis – the constancy of the internal milieu • 19th century: Johannes Muller formulates the ‘law of specific nerve energy’ • In general, a slow development of our modern view of the function of the body

5. Physiology: Missing from the scheme: Structure and motion: • Skeletal system • Muscles Integratory systems: • Nervous system • Hormones

6. Cell Structure & Function Source: http://koning.ecsu.ctstateu.edu/cell/cell.html

7. Unit-I Outline • Levels of Cellular Organization & function-Organelles, tissues, organs & systems. • Cell theory • Properties common to all cells • Cell size and shape – why are cells so small? • Prokaryotic cells • Eukaryotic cells • Organelles and structure in all eukaryotic cell • Organelles in plant cells but not animal • Cell junctions

8. History of Cell Theory • mid 1600s – Anton van Leeuwenhoek • Improved microscope, observed many living cells • mid 1600s – Robert Hooke • Observed many cells • 1850 – Rudolf Virchow • Proposed that all cells come from existing cells

9. Cell Theory Cells were discovered in 1665 by Robert Hooke. Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Schleiden and Schwann proposed the Cell Theory.

10. Cell Theory • All organisms consist of 1 or more cells. • Cell is the smallest unit of life. • All cells come from pre-existing cells.

11. Cell Theory • All living things are made up of cells. • Cells are the smallest working units of all living things. • All cells come from preexisting cells through cell division.

12. Cell Theory Cell Theory 1. All organisms are composed of cells. 2. Cells are the smallest living things. 3. Cells arise only from pre-existing cells. All cells today represent a continuous line of descent from the first living cells.

13. Cell Theory Cell size is limited. -As cell size increases, it takes longer for material to diffuse from the cell membrane to the interior of the cell. Surface area-to-volume ratio: as a cell increases in size, the volume increases 10x faster than the surface area

14. Cell Theory

15. Cell Theory Microscopes are required to visualize cells. Light microscopes can resolve structures that are 200nm apart. Electron microscopescan resolve structures that are 0.2nm apart.

16. Cell Theory All cells have certain structures in common. 1. genetic material – in a nucleoid or nucleus 2. cytoplasm – a semifluid matrix 3. plasma membrane – a phospholipid bilayer

17. Definition of Cell A cell is the smallest unit that is capable of performing life functions.

18. Observing Cells (4.1) • Light microscope • Can observe living cells in true color • Magnification of up to ~1000x • Resolution ~ 0.2 microns – 0.5 microns

19. Observing Cells (4.1) • Electron Microscopes • Images are black and white – may be colorized • Magnifcation up to ~100,000 • Transmission electron microscope (TEM) • 2-D image • Scanning electron microscope (SEM) • 3-D image

20. SEM TEM

21. Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

22. Two Types of Cells Prokaryotic Eukaryotic

23. Prokaryotic • Do not have structures surrounded by membranes • Few internal structures • One-celled organisms, Bacteria http://library.thinkquest.org/C004535/prokaryotic_cells.html

24. Prokaryotic Cells Prokaryotic cells lack a membrane-bound nucleus. -genetic material is present in the nucleoid Two types of prokaryotes: -archaea -bacteria

25. Prokaryotic Cells Prokaryotic cells possess -genetic material in the nucleoid -cytoplasm -plasma membrane -cell wall -ribosomes -no membrane-bound organelles

26. Prokaryotic Cells

27. Prokaryotic Cells Prokaryotic cell walls -protect the cell and maintain cell shape Bacterial cell walls -may be composed of peptidoglycan -may be Gram positive or Gram negative Archaeancell walls lack peptidoglycan.

28. Prokaryotic Cells Flagella -present in some prokaryotic cells -used for locomotion -rotary motion propels the cell

29. Prokaryotic Cell Structure • Prokaryotic Cells are smaller and simpler in structure than eukaryotic cells. • Typical prokaryotic cell is __________ • Prokaryotic cells do NOT have: • Nucleus • Membrane bound organelles

30. Prokaryotic Cell

32. TEM Prokaryotic Cell

33. Eukaryotic • Contain organelles surrounded by membranes • Most living organisms Plant Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html

34. “Typical” Animal Cell http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

35. Plant Cell http://waynesword.palomar.edu/images/plant3.gif

36. Eukaryotic Cells Eukaryotic cells -possess a membrane-bound nucleus -are more complex than prokaryotic cells -compartmentalize many cellular functions within organelles and the endomembrane system -possess a cytoskeleton for support and to maintain cellular structure

37. Eukaryotic Cells

38. Eukaryotic Cells

39. Eukaryotic Cells Nucleus -stores the genetic material of the cell in the form of multiple, linear chromosomes -surrounded by a nuclear envelope composed of 2 phospholipid bilayers -in chromosomes – DNA is organized with proteins to form chromatin

40. Eukaryotic Cells

41. Eukaryotic Cells Ribosomes -the site of protein synthesis in the cell -composed of ribosomal RNA and proteins -found within the cytosol of the cytoplasm and attached to internal membranes

42. Cell Structure • All Cells have: • an outermost plasma membrane • genetic material in the form of DNA • cytoplasm with ribosomes

43. Cell Parts Organelles

44. Surrounding the Cell

45. Cell Membrane • Outer membrane of cell that controls movement in and out of the cell • Double layer http://library.thinkquest.org/12413/structures.html

46. Cell Wall • Most commonly found in plant cells & bacteria • Supports & protects cells http://library.thinkquest.org/12413/structures.html

47. Inside the Cell

48. Nucleus • Directs cell activities • Separated from cytoplasm by nuclear membrane • Contains genetic material - DNA

49. Nuclear Membrane • Surrounds nucleus • Made of two layers • Openings allow material to enter and leave nucleus http://library.thinkquest.org/12413/structures.html

50. Chromosomes • In nucleus • Made of DNA • Contain instructions for traits & characteristics http://library.thinkquest.org/12413/structures.html