histology 154 cell lecture 1 dr mathew

1. CELLCELL
STRUCTURESTRUCTURE
AND FUNCTIONAND FUNCTION

2. CellCell

3. PLASMA MEMBRANEPLASMA MEMBRANE

4. PLASMA MEMBRANEPLASMA MEMBRANE
It is necessary that for the proper
functioning the cells and cell
components should be separated from
the outside environment.

5. PLASMA MEMBRANEPLASMA MEMBRANE
A lipid/protein/carbohydrate complex.
Provides a barrier to the cell
Forms a boundary between the cell and its
environment
Contains transport and signaling systems
Membranes bound organelles
Segregation of biochemical activities within the cell

6. PLASMA MEMBRANEPLASMA MEMBRANE
The lipids have
hydrophilic polar heads
pointing out and the
hydrophobic portion
forming the core.

7. PLASMA MEMBRANEPLASMA MEMBRANE
Lipid bilayers are fluid.
Individual phospholipids diffuse rapidly throughout
the two dimensional surface of the membrane.
The Fluid Mosaic Model
This is known as the fluid mosaic model of biological
membranes (mosaic because it includes
molecules other than phospholipids, such as
proteins, cholesterol, and other types of
molecules).

8. PLASMA MEMBRANEPLASMA MEMBRANE

9. PLASMA MEMBRANEPLASMA MEMBRANE
APPEARS TRILAMINAR UNDER THE
TRANSMISSION ELECTRON MICROSCOPE
TWO DENSE LINES (2.5 – 3.0 nm)
A LESS DENSE INTERMEDIATE ZONE

10. PLASMA MEMBRANEPLASMA MEMBRANE

11. GLYCOCALYXGLYCOCALYX
THE CARBOHYDRATE MOLECULES
FORM A THIN OUTER LAYER
CALLED THE GLYCOCALYX

12. PLASMA MEMBRANEPLASMA MEMBRANE
Functions
1. Semi-permeable barrier
2. Regulate transport in and out of cell.
3. Communication
4. Adhesion

13. PLASMA MEMBRANEPLASMA MEMBRANE
Functions
5. Barrier Functions: The lipid bilayer accounts
for the basic barrier functions of the plasma
membrane. Permeable to water, O2 and small
hydrophobic molecules such as steroids, ethanol
Impermeable to highly charged molecules and
charged ions.
6. Transport in and out of the plasma membrane

14. NUCLEUSNUCLEUS

15. NUCLEUSNUCLEUS
The nucleus is the controlling station ofThe nucleus is the controlling station of
eukaryotic cell.eukaryotic cell.
Usually the nucleus is round and is theUsually the nucleus is round and is the
largest organelle in the cell.largest organelle in the cell.

16. NUCLEUSNUCLEUS
It is surrounded by a membrane, calledIt is surrounded by a membrane, called
the nuclear envelope, which is similar tothe nuclear envelope, which is similar to
the cell membrane that encloses thethe cell membrane that encloses the
entire cell.entire cell.

17. NUCLEUSNUCLEUS
Nuclear membrane possess specificNuclear membrane possess specific
openings called nuclear pores, that allowopenings called nuclear pores, that allow
specific materials to pass in and out ofspecific materials to pass in and out of
the nucleus.the nucleus.

18. NUCLEUSNUCLEUS
Attached to the nuclear envelope is theAttached to the nuclear envelope is the
endoplasmic reticulum.endoplasmic reticulum.
The nucleus is surrounded by theThe nucleus is surrounded by the
cytoplasm inside a cell.cytoplasm inside a cell.

19. NUCLEUSNUCLEUS
Structurally, the nucleus isStructurally, the nucleus is
composed of three main parts,composed of three main parts,
the nucleolus,the nucleolus,
the nuclear envelope, andthe nuclear envelope, and
the chromatin.the chromatin.

21. The nuclear pore and envelope
Insures that the interior of the nucleus is isolated
from a cell's cytoplasm, allowing two different
environments to be maintained.
The membrane has two layers that enclose a
distinct space in between and marked by large
pores.

22. The nuclear pore and envelope
The membrane is very selective, permitting only
certain substances to enter or leave the nucleus.
In addition, the space contained within the
double-layered nuclear membrane is continuous
at points with the endoplasmic reticulum.

23. The nuclear pore and envelope

24. TRANSMISSIONTRANSMISSION
ELECTRONELECTRON
MICROGRAPHMICROGRAPH
OFOF
NUCLEAR PORENUCLEAR PORE

25. NUCLEOLUSNUCLEOLUS
Principal RNA containing structure of
the nucleus.
It is rich in protein
is surrounded by a ring of
heterochromatin which may penetrate
into the main body of the nucleolar
complex.

26. NUCLEOLUSNUCLEOLUS
The fine structure of the nucleolus
reveals the presence of a fibrillar and a
granular area, each composed of
ribonucleoproeins, and each is related
to the biogenesis of ribosomes.

29. CHROMATINCHROMATIN
Chromatin is the name that describes nuclear
material that contains the genetic code.
The chromatin (meaning "colored substance")
contains DNA and proteins.
Chromatin gives rise to chromosomes.

30. CHROMATINCHROMATIN
Two types of chromatin material
Heterochromatin and
Euchromatin.

31. HETEROCHROMATINHETEROCHROMATIN
 The darkly stained, condensed region of the chromatin is
known as heterochromatin.
 The heterochromatin occurs around the nucleolus and at
the periphery.
 It is supposed to be metabolically and genetically inert
because it contains comparatively small amount of DNA
and large amount of RNA.

32. EUCHROMATINEUCHROMATIN
The light stained and diffused region of
the chromatin is called euchromatin.
The euchromatin contains compatatively
large amount of DNA.

33. Nuclear poreNuclear pore
Nuclear envelopeNuclear envelope
EuchromatinEuchromatin
HeterochromatinHeterochromatin
NUCLEOLUSNUCLEOLUS
Pars granulosaPars granulosa
Pars fibrosaPars fibrosa
NucleolusNucleolus
organizing centreorganizing centre
Rough endoplasmicRough endoplasmic
reticulumreticulum

34. GOLGI APPARATUSGOLGI APPARATUS

35. GOLGI COMPLEXGOLGI COMPLEX
Golgi complex is a disc shaped
structure with central flattened,
plate like compartments or
cisternae, peripheral network of
interconnecting tubules and
peripherally occuring vesicles.

37. FUNCTIONS OF GOLGIFUNCTIONS OF GOLGI
COMPLEXCOMPLEX
Golgi complex is concerned
with the formation and
packaging of materials for
export from the cell

39. ENDOPLASMICENDOPLASMIC
RETICULUMRETICULUM

40. GRANULAR OR ROUGHGRANULAR OR ROUGH
ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM

41. GRANULAR OR ROUGHGRANULAR OR ROUGH
ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM
It possesses rough walls because the
ribosomes remain attached with its
membranes.
The granular or rough type of
endoplasmic reticulum is found
abundantly in those cells which are
active in protein synthesis.

42. FUNCTIONS OF GRANULAR OR ROUGHFUNCTIONS OF GRANULAR OR ROUGH
ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM
Rough ER is involved in protein synthesis.
The endoplasmic reticulum also functions as
a transport system.
Protein molecules move from the rough ER
into the smooth ER, which then sends them
enclosed within the vesicles usually to the
Golgi complex.

44. AGRANULAR OR SMOOTHAGRANULAR OR SMOOTH
ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM

45. FUNCTIONS OF AGRANULAR ORFUNCTIONS OF AGRANULAR OR
SMOOTHSMOOTH
ENDOPLASMIC RETICULUMENDOPLASMIC RETICULUM
The smooth type of endoplasmic reticulum
occurs mostly in those cells, which have no
active participation in the synthesis of
proteins.
It is involved in the synthesis of
LIPIDS, GLYCOGEN AND STEROIDS

47. RIBOSOMESRIBOSOMES
The ribosomes are small, dense, rounded
and granular particles of ribonucleoprotein.
They are found either freely in the matrix
of mitochondria, chloroplast and cytoplasm
or found attached on the surface of the
endoplasmic reticulum and nucleus.

48. RIBOSOMESRIBOSOMES
Ribosomes are present in most prokaryotic
and eukaryotic cells.
They are the sites of protein synthesis
where amino acids are assembled to
produce the polypeptide chain.

49. RIBOSOMESRIBOSOMES
Ribosomes are classified into two types,
based on the size and the sedimentation
coefficient (S).
They are:
1. 70S Ribosomes and
2. 80S Ribosomes

50. LYSOSOMESLYSOSOMES

51. The lysosomes are tiny, membrane
bounded, vesicular structures of the
cytoplasm which perform intracellular
digestion of the cell.
The term lysosome means digestive
body (Gr., lyso-digestive, soma-body).
LYSOSOMESLYSOSOMES

52. SUICIDE BAGS OF
THE CELL
FUNCTIONS OFFUNCTIONS OF
LYSOSOMESLYSOSOMES

53. Cytoplasm of some eukaryotic cells
contains two cylindrical, rod-shaped,
microtubular structures, called
centrioles, near the nucleus.
CENTRIOLESCENTRIOLES

54. Centrioles lack limiting membrane
and DNA or RNA.
It gives rise to the mitotic apparatus
during mitosis or meiosis.
CENTRIOLESCENTRIOLES

55. In flagellated or ciliated cells
centrioles are found arranged just
beneath the plasma membrane to
form and bear flagella or cilia.
When a centriole bears a flagellum
or cilium, it is called basal body.
BASAL BODIESBASAL BODIES

56. Peroxisomes are organelles that
resemble lysosomes.
They are present in many animal
and plant cells.
They contain oxidative enzymes.
PEROXISOMESPEROXISOMES

57. Peroxisomes are distinguished by a
crystalline structure inside a sac which
also contains amorphous gray material.
They are self replicating, like the
mitochondria.
They also enlarge and bud to produce
new peroxisomes.
PEROXISOMESPEROXISOMES

58. Peroxisomes protect the cells from
the action of toxic substances like
hydrogen peroxide, or other
metabolites.
PEROXISOMESPEROXISOMES

59. Morphologically they resemble
peroxisomes, but the crystalloid
core consists of dense rods.
GLYOXISOMESGLYOXISOMES

60. They have enzymes for fatty acid
metabolism and gluconeogenesis.
Glyoxisomes are present in yeast
and the oil rich seeds of many
plants.
GLYOXISOMESGLYOXISOMES

61. MITOCHONDRIAMITOCHONDRIA

62. MITOCHONDRIA
 Mitochondria contain two
membranes, separated by a space.
 Both are the typical "unit
membrane" in structure. Inside the
space enclosed by the inner
membrane is the matrix.

63. MITOCHONDRIA
 The mitochondrial matrix
contains lipids, proteins, circular
DNA molecules, 70S ribosomes
and certain granules which are
related to the ability of
mitochondria to accumulate
ions.

64. MITOCHONDRIAL CRESTS
OR CRISTAE
The inner mitochondrial membrane
increases its surface area by giving out
plate-like or tubular invaginations called
MITOCHONDRIAL CRESTS OR CRISTAE

66. MITOCHONDRIAL CRESTS
OR CRISTAE
 Mitochondria replicate much like bacterial cells.
 They undergo fission. This involves a furrowing of the inner
and then the outer membrane of the mitochondrion.
 Then the two daughter mitochondria split.
 Before the mitochondrion divides, the mitochondrial DNA
replication occurs.
 Sometimes new mitochondria are synthesized.

67. "POWER HOUSES" OF THE CELL.

69. CYTOSKELETON
 MICROFILAMENTS:
Stabilize cell shape
Cell motility
 MICROTUBULES:
Serve as tracks along which
materials are moved in the cell

70. CELL DIVISION
MITOSIS
AND
MEIOSIS

71. CELL DIVISION
 MITOSIS VS MEIOSIS
 purpose produces somatic cells produces reproductive
cells (body, growth)
 process cell duplication reduction division
(diploid -> diploid) (diploid -> haploid)
 number of 1 cell division 2 cell divisions
divisions
 product 1 -> 2 daughter cells 1 -> 4 cells (gametes)
daughter cells identical daughter cells different
(to each other & mother cell)

72. CELL CYCLE
 DIFFERENT PHASES OF CELL CYCLE
 DNA synthesis occurs only during one phase of the cell cycle
called the S (synthetic) phase.
 A gap of time occurs between the synthetic phase and the cell
division (Mitosis)
 and another gap occurs after division and the next S phase.
 Thus the cell cycle in eukaryotes may be divided into the mitotic
phase (M phase), G1 phase (the first gap) the S phase and the
G2 phase (the second gap).
 Many cell types which are said to be in the resting stage,
suspend cell cycle after mitosis and just prior to the S phase,
such cells are said to be in the G0 state.

73. MICROSCOPYMICROSCOPY

76. CellCell

79. IMMUNO HISTO CHEMISTRY

80. CELL CULTURE

81. CELL DIVISION- MITOSIS
 A. Interphase.
 1. This phase includes gap 1, S and gap 2 periods of
cell cycle.
 2. Since the replication of DNA occurs in the S
phase, the nucleus has twice the diploid amount of
DNA.
 3. As the cell prepares to divide, the chromosome
condense and become visible.

82. CELL DIVISION- MITOSIS
 B. Prophase.
 1. Chromosomes become visible, Each
chromosome consists of a pair of long parallel
strands (sister chromatids), which are held together
at the centromere.
 2. Crossing over between the sister chromatids
may occur at this stage.
 3. The nuclear membrane and the nucleolus
disappears.
 4. The centrioles divide and the daughter centrioles
migrate towards the opposite poles of the cell.

83. CELL DIVISION- MITOSIS
 C. Metaphase
 1. In this stage the chromosomes have
reached the maximum level of
contraction.
 2. The spindle fibers form and
chromosomes move to the equatorial
plate of the cell.

84. CELL DIVISION- MITOSIS
 D. Anaphase
 1. In anaphase the centromere divides
and the paired chromatids separate.
 2. The spindle fibre contracts, bringing
the daughter chromosomes to the two
poles of the cell.

85. CELL DIVISION- MITOSIS
 E. Telophase
 1. As the daughter chromosomes
reach the cell, the cytoplasm divides, and
the cell plate forms.
 2. The chromosomes start to
unwind.
 3. The nuclear membrane reforms.

86. SAMPLE PREPARATIONSAMPLE PREPARATION
FOR LIGHTFOR LIGHT
MICROSCOPYMICROSCOPY

87. SAMPLE PREPARATION:
i) Fixation: stabilizes cellular constituents
(proteins and polymeric nucleic acids)
ii) dehydrate/embed: infiltrate tissue with
solid material to allow for cutting
-dehydrate in ethanol/xylene (removes
lipids)
-infiltrate with paraffin or plastic
-can freeze to solidify tissue for sectioning
(cryosectioning)

88. iii) Microtomy: cut tissue very thin
-typically 1 - 10 micrometers thick
-paraffin/plastic embedded tissue
sectioned with micro tome
-frozen samples sectioned with
cryostat (microtome within a
freezer)

90. iv) stain specimen with dyes (classical
histology):
paraffin is removed from section then
section is re- hydrated and stained
Routine stain
-hematoxylin: basic dye –STAINS
NUCLEUS
-eosin: acid dye STAINS
CYTOPLASM

92. THANK YOUTHANK YOU