1. The document discusses the cell as the basic unit of life and provides a detailed overview of cell theory and cell structure. It describes key discoveries in cell biology including Hooke's observation of cells in cork and van Leeuwenhoek's discovery of single-celled organisms under the microscope. 2. The three main points of cell theory are presented: all living things are made of cells, the cell is the basic unit of structure and function, and cells only come from pre-existing cells. Common features of cells like the cell membrane, cytoplasm, DNA, and organelles are also outlined. 3. Modern additions to cell theory are noted including that cells contain DNA, have similar composition and metabolism, and function

1. CellCell as basic unit of lifeas basic unit of life
Course: B.Tech Biotech
Subject: Basic of Life Science
Unit: II

2. What is the definition of a cell?
The basic unit of life.
Cells Make up Plants
Cells make up all living things.
Can you think of reasons why cells need nutrition
and a good environment?

3.  CellsCells represent the basic structural andrepresent the basic structural and
functional unit of life.functional unit of life.
 Important unifying concept in biology.Important unifying concept in biology.
 All organisms are composed of one or more cells.All organisms are composed of one or more cells.
 All tissues & organs are composed of cells.All tissues & organs are composed of cells.
 There is no life without cells!There is no life without cells!

4. Cells produce tissues
Tissues produce organs
Organs produce organ systems
Organs systems produce organisms

5. Some Random Cell FactsSome Random Cell Facts
 The average human being is composedThe average human being is composed
of around 100 Trillion individual cells!!!of around 100 Trillion individual cells!!!
 It would take as many as 50 cells toIt would take as many as 50 cells to
cover the area of a dot on the letter “cover the area of a dot on the letter “ii””
WOW!!!WOW!!!

6. Discovery of CellsDiscovery of Cells
 1665- English Scientist,1665- English Scientist, Robert Hooke,Robert Hooke, discovereddiscovered
cells while looking at a thin slice of cork.cells while looking at a thin slice of cork.
 He described the cells as tiny boxes or a honeycombHe described the cells as tiny boxes or a honeycomb
 He thought that cells only existed in plants and fungiHe thought that cells only existed in plants and fungi
1.

7. Anton van LeuwenhoekAnton van Leuwenhoek
 1673- Used a handmade microscope to observe1673- Used a handmade microscope to observe
pond scum & discovered single-celled organismspond scum & discovered single-celled organisms
 He called them “animalcules”He called them “animalcules”
 He also observed blood cells from fish, birds, frogs,He also observed blood cells from fish, birds, frogs,
dogs, and humansdogs, and humans
 Therefore, it was known that cells are found inTherefore, it was known that cells are found in
animals as well as plantsanimals as well as plants
2.

8. = Three part theory about cells
1. All living things are made of cells.
(Schleiden & Schwann)(1838-39)
2. The cell is the basic structural and
functional unit of life. (Schleiden &
Schwann)(1838-39)
3. All cells come from pre-existing
cells. (Virchow)(1858)
Cell theory

9. How big are cells?
Smallest free-living cell =
Mycoplasma genitalium
Size = 0.2 to 0.3 µm
3.

10. How big are cells?
• Bacteria e.g. Eschericia coli (aka E.coli)
• Size=1 µm by 3 µm
4.

11. How big are cells?
• Human red blood cell = 8 µm in diameter
5.

12. How big are cells?
• Largest cell on
the human
body =
ovum
• Size=
• 1000 µm in
diameter
(1 mm) 6.

13. How big are cells?
• Smallest cell in the human body =
sperm cell.
7.

14. How big are cells?
• Largest cell = yolk of an ostrich egg
9.8.

15. Modern Cell TheoryModern Cell Theory
 Modern Cell Theory contains 4 statements, inModern Cell Theory contains 4 statements, in
addition to the original Cell Theory:addition to the original Cell Theory:
 The cell contains hereditary information(DNA) whichThe cell contains hereditary information(DNA) which
is passed on from cell to cell during cell division.is passed on from cell to cell during cell division.
 All cells are basically the same in chemicalAll cells are basically the same in chemical
composition and metabolic activities.composition and metabolic activities.
 All basic chemical & physiological functions areAll basic chemical & physiological functions are
carried out inside the cells.(movement, digestion,etc)carried out inside the cells.(movement, digestion,etc)
 Cell activity depends on the activities of sub-cellularCell activity depends on the activities of sub-cellular
structures within the cell(organelles, nucleus, plasmastructures within the cell(organelles, nucleus, plasma
membrane)membrane)

16. How Has The Cell Theory Been Used?How Has The Cell Theory Been Used?
 The basic discovered truths about cells, listedThe basic discovered truths about cells, listed
in the Cell Theory, are the basis for thingsin the Cell Theory, are the basis for things
such as:such as:
 Disease/Health/Medical Research and Cures(AIDS,Disease/Health/Medical Research and Cures(AIDS,
Cancer, Vaccines, Cloning, Stem Cell Research, etc.)Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

17. Common features of all cells
1. Cell Membrane –
selectively/differentially
permeable (lets some things in
and out)
10.

18. Common features of all cells
2. Cytoplasm – semi-fluid
material in which cell
organelles float
11.

19. Common features of all cells
3. Nucleic acid
containing genetic
code :
Which nucleic acid?
DNA
12.

20. Common features of all cells
4. Cytoskeleton
– proteins that
support the cell
(Microtubules &
microfilaments)
13.

21. Common features of all cells
5. Ribosomes
– make
proteins
14.

22. Some Parting ThoughtsSome Parting Thoughts
 It is amazing to think that the cells that makeIt is amazing to think that the cells that make
up our bodies are just as alive as we are.up our bodies are just as alive as we are.
Humans are just an intricately designedHumans are just an intricately designed
community of cells, which must work togethercommunity of cells, which must work together
to survive.to survive.
 Cells, in my opinion, are one of the strongestCells, in my opinion, are one of the strongest
cases for intelligent design by our Creatorcases for intelligent design by our Creator
God!God!

23. Web and Books referencesWeb and Books references
 Book Name : AlbertBook Name : Albert
 http://en.wikipedia.org/wiki/Cell_theoryhttp://en.wikipedia.org/wiki/Cell_theory
 http://www.edu.pe.ca/gray/class_pages/smaccormachttp://www.edu.pe.ca/gray/class_pages/smaccormac
k/topic_2_1_celltheory.pdfk/topic_2_1_celltheory.pdf
 http://www.princeton.edu/~achaney/tmve/wiki100k/dohttp://www.princeton.edu/~achaney/tmve/wiki100k/do
cs/Cell_theory.htmlcs/Cell_theory.html
 http://www.uic.edu/classes/bios/bios100/lecturesf04ahttp://www.uic.edu/classes/bios/bios100/lecturesf04a
m/lect06.htmm/lect06.htm
23

24. Images ReferencesImages References
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k/pE33sBBi90E/s1600/Robert+Hooke+and+the+microscope+use+to+ak/pE33sBBi90E/s1600/Robert+Hooke+and+the+microscope+use+to+a
nalyze+cork+cell.PNGnalyze+cork+cell.PNG
 2.http://www.masslocalinstitute.org/onlinecourses/publichealthhistory/va2.http://www.masslocalinstitute.org/onlinecourses/publichealthhistory/va
nLeeuwenhoek.jpgnLeeuwenhoek.jpg
 3.http://wishart.biology.ualberta.ca/BacMap/includes/species/Mycoplas3.http://wishart.biology.ualberta.ca/BacMap/includes/species/Mycoplas
ma_genitalium.pngma_genitalium.png
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blr_inline_nc5kjt5EeG1t196up.gifblr_inline_nc5kjt5EeG1t196up.gif
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 6. http://img.tfd.com/mk/O/X2604-O-20A.png6. http://img.tfd.com/mk/O/X2604-O-20A.png
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1100063/23843295-human-fertility-questions-and-reproductive-health-1100063/23843295-human-fertility-questions-and-reproductive-health-
confusion-and-uncertainty-as-a-male-sperm-cell-and.jpgconfusion-and-uncertainty-as-a-male-sperm-cell-and.jpg

25.  8.http://www.thehindu.com/multimedia/dynamic/01426/HY13_W8.http://www.thehindu.com/multimedia/dynamic/01426/HY13_W
LG_OSTRIC_HY_1426652f.jpgLG_OSTRIC_HY_1426652f.jpg
 9.http://suzyssitcom.com/wp-content/uploads/2012/02/Ostrich-9.http://suzyssitcom.com/wp-content/uploads/2012/02/Ostrich-
Egg-200x150.jpgEgg-200x150.jpg
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ne.gifne.gif
 11. http://www.medfriendly.com/images/cytoplasm.jpg11. http://www.medfriendly.com/images/cytoplasm.jpg
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.png.png
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q=tbn:ANd9GcQS1FuhaOk6JfcrDPI1cugdw52uxfCMJB153xeigq=tbn:ANd9GcQS1FuhaOk6JfcrDPI1cugdw52uxfCMJB153xeig
mTQVt95MHahmTQVt95MHah
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