Hooke first observed cells in 1665 using a microscope to examine cork. Leeuwenhoek later observed living cells in pond water in 1673. In 1838, Schleiden concluded plants are made of cells, and in 1839 Schwann concluded animals are made of cells, laying the foundations for the cell theory. Virchow in 1855 observed cells dividing and proposed all cells come from pre-existing cells. The cell theory 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. Eukaryotic cells are more complex than prokaryotic cells, containing membrane-bound organelles. The cell membrane regulates what enters

1. Basic Structure of Cell
By
Sonika
1

2. 2
Basic Structure of a Cell

3. 3
History of Cells & theHistory of Cells & the
Cell TheoryCell Theory
Virchow
Cell
Specialization

4. 4
First to View CellsFirst to View Cells
• In 1665, Robert
Hooke used a
microscope to
examine a thin
slice of cork
(dead plant cells)
• What he saw
looked like small
boxes

5. 5
First to View CellsFirst to View Cells
• Hooke is
responsible for
naming cells
• Hooke called them
“CELLS” because
they looked like
the small rooms
that monks lived in
called Cells

6. 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

7. 7
Beginning of the Cell TheoryBeginning of the Cell Theory
• In 1838, a
German botanist
named Matthias
Schleiden
concluded that all
plants were made
of cells
• Schleiden is a
cofounder of the
cell theory

8. 8
Beginning of the Cell TheoryBeginning of the Cell Theory
• In 1839, a
German zoologist
named Theodore
Schwann
concluded that
all animals were
made of cells
• Schwann also
cofounded the
cell theory

9. 9
Beginning of the Cell TheoryBeginning 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

10. 10
CELL THEORY
• 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)

11. 11
DiscoveriesDiscoveries
SinceSince the Cellthe Cell
TheoryTheory

12. 12
Simple or ComplexSimple or Complex
CellsCells

13. 13
Prokaryotes – The first CellsProkaryotes – The first Cells
• Cells that lack a nucleus or
membrane-bound organelles
• Includes bacteria
• Simplest type of cell
• Single, circular chromosome

14. 14
ProkaryotesProkaryotes
• Nucleoid region
(center) contains
the DNA
• Surrounded by cell
membrane & cell
wall (peptidoglycan)
• Contain ribosomes
(no membrane) in
their cytoplasm to
make proteins

15. 15
Eukaryotes
• Cells that HAVE a
nucleus and membrane-
bound organelles
• Includes protists,
fungi, plants, and
animals
• More complex type of
cells

16. 16
Eukaryotic Cell
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles

17. 17
Two Main Types of
Eukaryotic Cells
Plant Cell Animal Cell

18. 18
OrganellesOrganelles

19. 19
OrganellesOrganelles
• Very small (Microscopic)
• Perform various functions for a
cell
• Found in the cytoplasm
• May or may not be membrane-
bound

20. 20
Cell or Plasma MembraneCell or Plasma Membrane
Outside
of cell
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

21. 21
PhospholipidsPhospholipids
• 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)

22. 22
The Cell Membrane is FluidThe Cell Membrane is Fluid
Molecules in cell membranes are constantly moving
and changing

23. 23
Cell Membrane ProteinsCell Membrane Proteins
• 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

24. 24
• Lies immediately
against the cell
wall in plant cells
• Pushes out
against the cell
wall to maintain
cell shape
Cell Membrane in PlantsCell Membrane in Plants
Cell membrane

25. 25
• Found outside of the cell
membrane
• Nonliving layer
• Supports and protects
cell
• Found in plants, fungi, &
bacteria
Cell wallCell WallCell Wall

26. 26
• Jelly-like
substance enclosed
by cell membrane
• Provides a medium
for chemical
reactions to take
place
Cytoplasm of a CellCytoplasm of a Cell
cytoplasm

27. 27
• Contains organelles
to carry out
specific jobs
More on CytoplasmMore on Cytoplasm
cytoplasm

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

29. 29
• Each cell has fixed
number of
chromosomes that
carry genes
• Genes control cell
Nucleus
More on the NucleusMore on the Nucleus

30. 30
Nuclear EnvelopeNuclear Envelope
• Double membrane surrounding
nucleus
• Also called nuclear membrane
• Contains nuclear pores for
materials to enter & leave
nucleus
Nuclear
pores

31. 31
Inside the Nucleus -
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

32. 32
What Does DNA do?What Does DNA do?
DNA is the hereditary
material of the cell
Genes that make up the DNA
molecule code for different
proteins

33. 33
Nucleolus
• Inside nucleusInside nucleus
• DisappearsDisappears whenwhen
cell dividescell divides
• Makes ribosomesMakes ribosomes
that makethat make
proteinsproteins

34. 34
CytoskeletonCytoskeleton
• 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

35. 35
CytoskeletonCytoskeleton
MICROTUBULES
MICROFILAMENTS

36. 36
CentriolesCentrioles
• 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

37. 37
MitochondrionMitochondrion
(plural = mitochondria)(plural = mitochondria)
• “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)

38. 38
MITOCHONDRIA
Surrounded by a DOUBLE
membrane
Folded inner membrane
called CRISTAE
(increases surface area
for more chemical
Reactions)
Has its own DNA
Interior called MATRIX

39. 39
Interesting Fact ---Interesting Fact ---
• Mitochondria
Come from
cytoplasm in the
EGG cell during
fertilization
Therefore …
• You inherit your
mitochondria
from your
mother!

40. 40
Endoplasmic Reticulum - EREndoplasmic 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

41. 41
Rough Endoplasmic Reticulum (RoughRough Endoplasmic Reticulum (Rough
ER)ER)
• Has ribosomes
on its surface
• Makes
membrane
proteins and
proteins for
export out of
cell

42. 42
Rough Endoplasmic ReticulumRough Endoplasmic Reticulum
(Rough ER)(Rough ER)
• Proteins are made
by ribosomes on ER
surface
• They are then
threaded into the
interior of the
Rough ER to be
modified and
transported

43. 43
Functions of the Smooth ERFunctions of the Smooth ER
• Makes membrane
lipids (steroids)
• Regulates calcium
(muscle cells)
• Destroys toxic
substances
(Liver)

44. 44
Endomembrane System
Includes nuclear membrane connected to ER connected
to cell membrane (transport)

45. 45
RibosomesRibosomes
• Made of PROTEINS and rRNA
• “Protein factories” for cell
• Join amino acids to make proteins through
protein synthesis


46. 46
RibosomesRibosomes
Can be attached to
Rough ER
OR
Be free
(unattached)
in the
cytoplasm

47. 47
Golgi BodiesGolgi Bodies
• Stacks ofStacks of flattenedflattened
sacssacs
• Have a shippingHave a shipping
side (side (cis facecis face) & a) & a
receiving sidereceiving side
((trans facetrans face))
• ReceiveReceive proteinsproteins
made by ERmade by ER
• Transport vesiclesTransport vesicles
with modifiedwith modified
proteins pinch offproteins pinch off
the endsthe ends
Transport
vesicle
CIS
TRANS

48. 48
Golgi BodiesGolgi Bodies
Look like a stack of pancakes
Modify, sort, & package
molecules from ER
for storage OR
transport out of cell

49. 49
Golgi AnimationGolgi Animation
Materials are transported from Rough ER
to Golgi to the cell membrane by VESICLES

50. 50
LysosomesLysosomes
• ContainContain digestivedigestive
enzymesenzymes
• Break downBreak down food,food,
bacteria,bacteria, andand worn outworn out
cell partscell parts for cellsfor cells
• Programmed forProgrammed for cellcell
death (APOPTOSIS)death (APOPTOSIS)
• Lyse &Lyse & releaserelease
enzymesenzymes to break downto break down
& recycle cell parts)& recycle cell parts)

51. 51
Lysosome DigestionLysosome Digestion
• Cells take in
food by
phagocytosis
• Lysosomes
digest the food
& get rid of
wastes

52. 52
Cilia & FlagellaCilia & Flagella
• Function in moving
cells, in moving fluids,
or in small particles
across the cell surface

53. 53
Cilia & FlagellaCilia & Flagella
• Cilia are
shorter and
more numerous
on cells
• Flagella are
longer and
fewer (usually
1-3) on cells

54. 54
Cell Movement with Cilia &Cell Movement with Cilia &
FlagellaFlagella

55. 55
Cilia Moving Away Dust ParticlesCilia Moving Away Dust Particles
from the Lungsfrom the Lungs

56. 56
VacuolesVacuoles
• Fluid filled
sacks for
storage
• Small or absent
in animal cells
• Plant cells have
a large Central
Vacuole

57. 57
VacuolesVacuoles
• In plants, they store
Cell Sap
• Includes storage of
sugars, proteins,
minerals, lipids,
wastes, salts, water,
and enzymes

58. 58
ChloroplastsChloroplasts
• Found only in producers
(organisms containing
chlorophyll)
• Use energy from
sunlight to make own
food (glucose)
• Energy from sun
stored in the Chemical
Bonds of Sugars

59. 59
ChloroplastsChloroplasts
• Surrounded by DOUBLE
membrane
• Outer membrane smooth
• Inner membrane modified
into sacs called
Thylakoids
• Thylakoids in stacks
called Grana &
interconnected
• Stroma – gel like material
surrounding thylakoids

60. Reference
• Google
• NCERT Books
• UGC Books
• PPTs from google
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61. Thank You
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