Robert Hooke first observed cells in 1665 using a microscope and named them for their resemblance to monks' rooms called cells. Anton van Leeuwenhoek was the first to observe living cells in 1673 using a simple microscope. In the 1830s, botanist Matthias Schleiden and zoologist Theodore Schwann developed the cell theory which states that all living things are made of cells, cells are the basic unit of structure and function, and new cells are produced from existing cells. Rudolf Virchow later added that cells divide by cell division. The cell contains organelles that perform various functions and is enclosed by a cell membrane that regulates what enters and leaves the cell.

1. Basic Structure of Cell 1
Dr.Devi

2. History 2
• In 1665, Robert
Hooke used a
microscope to
examine a thin
slice dead plant
cells
• What he saw
looked like small
boxes

3. First to View Cells 3
• Hooke is
responsible for
naming cells
• Hooke called them
“CELLS” because
they looked like
the small rooms
that monks lived in
called Cells

4. 6
Anton van Leeuwenhoek
• In 1673,
Leeuwenhoek (a
Dutch microscope
maker), was first to
view organism (living
things)
• Leeuwenhoek used a
simple, handheld
microscope to view
pond water &
scrapings from his
teeth

5. Beginning of the Cell Theory 5
• In 1838, a
German botanist
named Matthias
Schleiden
concluded that all
plants were made
of cells
• Schleiden is a
cofounder of the
cell theory

6. Beginning of the Cell Theory 6
• In 1839, a
German zoologist
named Theodore
Schwann
concluded that
all animals were
made of cells
• Schwann also
cofounded the
cell theory

7. Beginning of the Cell Theory
• In 1855, a German
medical doctor named
Rudolph Virchow
observed, under the
microscope, cells
dividing
• He reasoned that all
cells come from other
pre-existing cells by
cell division
9

8. CELL THEORY 8
• All living things are
made of cells
• Cells are the basic unit
of structure and
function in an organism
(basic unit of life)
• Cells come from the
reproduction of existing
cells (cell division)

9. Prokaryotes – The first Cells 9
• Cells that lack a nucleus or
membrane-bound organelles
• Includes bacteria
• Simplest type of cell
• Single, circular chromosome

10. Prokaryotes 10
• Nucleoid region
(center) contains
the DNA
• Surrounded by cell
membrane & cell
wall (peptidoglycan)
• Contain ribosomes
(no membrane) in
their cytoplasm to
make proteins

11. Eukaryotes 11
• Cells that HAVE a
nucleus and membrane-
bound organelles
• Includes protists,
fungi, plants, and
animals
• More complex type of
cells

12. Eukaryotic Cell 12
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles

13. • Unit of protoplasm
• Shapes
• 5-50 um
• Involved all vital functions

14. Organelles
14

15. Organelles 15
• Very small (Microscopic)
• Perform various functions for a
cell
• Found in the cytoplasm
• May or may not be membrane-
bound
• Membrane bound differ in their
thickness and protein contents

16. 20
Cell or Plasma Membrane
Inside
of cell
(cytoplasm)
Cell
membrane
Proteins
Protein
channel Lipid bilayer
Carbohydrate
chains
• Composed of double layer of phospholipids and
proteins
• Surrounds outside of ALL cells
• Controls what enters or leaves the cell
• Living layer
Outside
of cell

17. • 8 to 10 nm
• Trilaminar (electron microscope)
• Two dark lines separated by a
clear unstained intermediate zone
• This appearance is due to the
arrangement of phospholipid
molecules in two different
directions

18. Phospholipids 18
• Heads contain glycerol & phosphate
and are hydrophilic (attract water)
• Tails are made of fatty acids and
are hydrophobic (repel water)
• Make up a bilayer where tails point
inward toward each other
• Can move laterally to allow small
molecules (O2, CO2, & H2O to enter)

19. 19
Molecules in cell membranes are constantly moving
and changing

20. Cell Membrane Proteins 20
• Proteins help move large
molecules or aid in cell
recognition
• Peripheral proteins are
attached on the surface
(inner or outer)
• Integral proteins are
embedded completely
through the membrane

21. • Carbohydrate
may attach to proteins/lipids –
glycoproteins/glycolipids
• Present only on the outer surface
Cell coat/ glycocalyx
• Cholesterol
• Bilayer behaves like a fluid within
• Fluid mosaic model

22. Cytoplasm
• Cytosol
• Ground substance –fluid base
• Organelles
• Cytoskeleton- microtubules &
microfilament
• Inclusions –nonfunctioning
elements

23. 28
• Controls the normal
activities of the cell
• Contains the DNA in
chromosomes
• Bounded by a
nuclear envelope
The Control Organelle - Nucleus

24. 29
• Each cell has fixed
number of
chromosomes that
carry genes
• Genes control cell
Nucleus

25. Nuclear Envelope 25
• Double membrane surrounding
nucleus
• Also called nuclear membrane
• Outer membrane – rough ER
• Contains nuclear pores for
materials to enter & leave
nucleus
Nuclear
pores

26. Inside the Nucleus - 26
The genetic material (DNA) is found
DNA is spread out
And appears as
CHROMATIN
in non-dividing cells
DNA is condensed &
wrapped around proteins
forming
as CHROMOSOMES
in dividing cells

27. What Does DNA do? 27
DNA is the hereditary
material of the cell
Genes that make up the DNA
molecule code for different
proteins

28. Nucleolus 28
• Inside nucleus
• Disappears when
cell divides
• Makes ribosomes
that make
proteins

29. Cytoskeleton 29
• Helps cell maintain cell
shape
• Also help move
organelles around
• Made of proteins
• Microfilaments are
threadlike & made of
ACTIN
• Microtubules are
tubelike & made of
TUBULIN
• Intermediate filaments

30. Cytoskeleton 30
MICROTUBULES
MICROFILAMENTS

31. Centrioles 31
• Found only in animal cells
• Paired structures near nucleus
• Made of bundle of microtubules
• Appear during cell division forming
mitotic spindle
• Help to pull chromosome pairs apart to
opposite ends of the cell

32. Mitochondrion (plural
= mitochondria)
32
• “Powerhouse” of the cell
• Generate cellular energy
(ATP)
• More active cells like
muscle cells have MORE
mitochondria
• Both plants & animal cells
have mitochondria
• Site of CELLULAR
RESPIRATION (burning
glucose)

33. MITOCHONDRIA 33
• Surrounded by a DOUBLE
membrane
• Has its own DNA
• Folded inner membrane
called CRISTAE
(increases surface area
for more chemical
Reactions)
• Elliptical, 0.5- 2um
• Interior called MATRIX

34. 39
• Mitochondria
Come from
cytoplasm in the
EGG cell during
fertilization
Therefore …
• You inherit your
mitochondria
from your
mother!
• Present in all
cells
• Number

35. 40
Endoplasmic Reticulum - ER
Two kinds of ER ---ROUGH & SMOOTH
• Network of hollow membrane tubules
• Connects to nuclear envelope & cell
membrane
• Functions in Synthesis of cell products &
Transport

36. Rough Endoplasmic Reticulum (Rough
ER)
36
• In the form of
flattened sacs
• Has ribosomes on
its surface
• Proteins
synthesized by
ribosomes enter
in the cavity of
RER for
processing and
storing

37. Rough Endoplasmic Reticulum
(Rough ER)
37
• Proteins are made by
ribosomes on ER
surface
• They are then
threaded into the
interior of the Rough
ER to be modified
and transported
• Synthesis of
phospholipids

38.  Protein combine with the
carbohydrates to form glycoprotein
 May combine with phospholipids
 Takes place under the influence of
enzymes present in RER
 Involved in synthesis of secretory
proteins and molecules used in the
formation of plasma membrane

39. Smooth endoplasmic
reticulum
 Consists of short anastomosing
tubules
 Ribosomes are not attached on
its surface

40. Functions of the Smooth ER 40
• Makes membrane
lipids (steroids)
• Regulates calcium
(muscle cells)
• Destroys toxic
substances
(Liver)

41. Endomembrane System 41
Includes nuclear membrane connected to ER connected
to cell membrane (transport)

42. Ribosomes
• 15-20 nm
• Made of PROTEINS and rRNA
• Made up f two subunits –produced in nucleolus
• “Protein factories” for cell
• make proteins through protein synthesis
• Polyribosomes
• Free ribosomes
•
42

43. Ribosomes 43
Can be attached to
Rough ER
OR
Be free
(unattached)
in the
cytoplasm

44. 47
Golgi Bodies
• Stacks of flattened
sacs; shallow cups
• Have a convex side
(cis face) & a
receiving side (trans
face)
• Receive proteins
made by ER
• Transport vesicles
with modified
proteins
Transport
vesicle
CIS
TRANS

45. Golgi Bodies 45
• Look like a stack of
pancakes
• Present between nucleus
and apex of the cell
Functions : Modify, sort, & package
molecules from ER for storage OR
transport out of cell
Membrane synthesis
Production of lysosomes

46. Golgi 46
Materials are transported from Rough ER
to Golgi to the cell membrane by VESICLES

47. Lysosomes 47
• Contain digestive enzymes, 0.2-
0.8um
• Formed in Golgi complex- primary
lysosomes
• Fuses with endocytic vesicle-
secondary lysosomes

48. • Powerful hydrolytic enzymes
• Break down food, bacteria, and worn out
cell parts for cells
• Programmed for cell death
(APOPTOSIS)
• Lyse & release enzymes to break down &
recycle cell parts)

49. Lysosome Digestion 49
•Lysosomes are involved
in the digestion of
substances or particles
that are brought on to
the cell by means of
endocytosis. This
process is called as
heterophagy

50.  Lysosomes are capable of
digesting the old organelles of
cytosol and return the digested
components again to the cytosol.
This process is called as
autophagy

51. Cilia & Flagella 51
• Function in moving
cells, in moving fluids,
or in small particles
across the cell surface

52. Cilia & Flagella 52
• Cilia are
shorter and
more numerous
on cells
• Flagella are
longer and
fewer (usually
1-3) on cells

53. Cell Movement with Cilia &
Flagella
53

54. Cilia Moving Away Dust Particles
from the Lungs
54

55. Vacuoles 55
• Fluid filled
sacks for
storage
• Small or absent
in animal cells
• Plant cells have
a large Central
Vacuole