Cell is the basic unit of the body and is composed primarily of water, proteins, lipids, and carbohydrates. The cell contains membrane-bound organelles that carry out specific functions. Mitochondria produce energy through ATP production. The endoplasmic reticulum and Golgi apparatus synthesize proteins and lipids. Lysosomes digest materials through hydrolytic enzymes. Cellular waste and debris are removed through autophagy and phagocytosis. Movement of the cell is achieved through ameboid movement and cilia/flagella.

1. The cell and its function
Cell is the basic unit of the body

2. Organization of the cell

3. Cell composition
• Water :70-85% ,
• Ions
• Proteins: 10-20% ,
• Lipids : 2-95%
• Carbohydrates : 1-6 %

4. 1-Water:
• The principal fluid medium of the cell
• present in most cells except fat cell

5. 2-protiens :
• divided into two types :
A- Structural proteins:
Present in the cell mainly in the form of long
filaments (mainly form microtubules that provide
the cytoskeletons of such cellular organelles.
b- functional proteins:
Composed of combination of few molecules in
tubular globular form (they are mainly the enzymes
of the cell)

6. • Lipids:
• Important lipids are : phospholipids and cholesterol
constitute only about 2% of the total cell mass, they
are mainly insoluble in water and therefore are used
to form the cell membrane and intracellular
membrane barriers that separate the different cell
compartments.
• Neutral fat (triglycerides): in fat cell triglycerides
account for 95% of the cell mass.
• The fat stored in theses cells represent the body’s
main storehouse of energy-giving nutrients

7. • Carbohydrates :
• Little structural function in the cell and play a
major role in nutrition of the cell .
• Most human cells do not maintain large stores
of carbohydrates , the amount usually
averages about 1% of their total mass but
increase to 3% in muscle cell and 6% in liver .

8. Membranous structure of the cell
• Cell membrane
• Nuclear membrane
• Membrane of the endoplasmic reticulum
• Membrane of mitochondria, lysosomes and
Golgi apparatus.

9. Cell membrane
• Thin ,pliable , elastic
structure
• 7.5 – 10 nanometers
thick
• Mainly composed of
proteins and lipids.
• Protein 55%
• Phospholipids 25%

10. Cell Membrane Components:
• barrier to water and water-soluble substances
• organized in a bilayer of phospholipid molecules
hydrophilic
“head”
hydrophobic
FA “tail”
ions H2O
urea
CO2
1 - LIPIDS:
O2
N2
halothane
glucose

11. • provide “specificity” to a membrane
• defined by mode of association with the lipid bilayer
– integral: channels, pores, carriers, enzymes, receptor,
etc.
– peripheral: enzymes, intracellular signal mediators,
controllers of transport of substances through pores
K+
2- Proteins:

12. • glycolipids (approximately 10%)
• glycoproteins (majority of integral proteins)
• proteoglycans (carbs bound to protein cores)
• Glycocalyx loose carbohydrate coat outside surface of the cell
GLYCOCALYX
3 - Carbohydrates:

13. • important function for it:
o negative charge of the carbo chains repels other
o negative charges
o involved in cell-cell attachments/interactions
o play a role in immune reactions
o Act as receptor substance for binding hormone such
as insulin
GLYCOCALYX
(-)
(-)
(-)
(-)
(-)
(-)
(-)
Carbohydrates (Cont.):

14. Cytoplasm and its organelles
• Cytosol :clear fluid portion of the cytoplasm in
which the particles are dispersed in .
• Particles Dispersed in cytoplasm are :
1- neutral fat globules
2-Glycogen granules
3-ribosomes
4-Secretory vesicles
5- the other organelles

15. Cell Organelles

16. 1 - The Endoplasmic Reticulum:
• Network of tubular and flat vesicular structures
• Membrane is similar to (and contiguous with) the plasma membrane
• Space inside the tubules is called the endoplasmic matrix

17. • outer membrane surface
covered with ribosomes
• newly synthesized
proteins are extruded into
the ER matrix
• proteins are “processed”
inside the matrix
- cross-linked
- folded
- glycosylated (N-linked)
- cleaved
Rough or Granular ER

18. •Part of ER has no
attached ribosomes.
• site of lipid synthesis
-phospholipids
- cholesterol
• growing ER membrane
buds continuously
forming transport
vesicles, most of which
migrate to the Golgi
apparatus
Smooth ER (a Granular ER)

19. The Golgi Apparatus:
• Membrane composition
similar to that of the
smooth ER and plasma
membrane
• Composed of 4 or more
stacked layers of flat
vesicular
Structures
• This apparatus is
prominent in secretory
cell, where its located
on the side of the cell
from which the
secretory substance
are extruded.

20. • Receives transport vesicles from
smooth ER
• Substances formed in the ER are
“processed”
- phosphorylated
- glycosylated
• Substances are concentrated, sorted
and packaged for secretion.
•Transported substance are then
processed in Golgi apparatus to form :
- Lysosomes
- Secretory vesicle
- Cytoplasmic component

21. Lysosomes:
•Lysosome provide an intracellular digestive system that allows the cell to
digest:
-damaged cellular structure
-food particles that have been ingested by cell
-unwanted matter such as bacteria
• contain hydrolytic enzymes (acid hydrolases)
- phosphatases
- nucleases
- proteases
- lipid-degrading enzymes
- lysozymes digest bacteria
• vesicular organelle formed from budding Golgi
• fuse with pinocytotic or
phagocytotic vesicles to form
digestive vesicles

22. Peroxisomes:
• similar physically to lysosomes
• two major differences:
• formed by self-replication
• they contain oxidases (hydrogen peroxide and catalase)
Function: oxidize substances (e.g. alcohol) that
may be otherwise poisonous

23. Secretory Granules
Secretory vesicle in acinar cells of the pancreas

24. Secretion:
• secretory vesicles containing
proteins synthesized in the RER bud
from the Golgi apparatus
•These vesicle store protien
proenzyme (enzymes that are not yet
activated)
• fuse with plasma membrane to
release contents
- constitutive secretion -
happens randomly
- stimulated secretion - requires
trigger

25. Secretory vesicles diffuse
through the cytosol and
fuse to the plasma
membrane
Exocytosis:
Lysosomes fuse with
internal endocytotic
vesicles

26. Mitochondria (powerhouse) :
Primary function: extraction of energy from nutrients
Mitochondria are self-replicative
Matrix: contain large amount of dissolve enzymes

27. cytoskeleton
• Fibrillar protein originated as precursor
protein molecules synthesized by ribosomes in
the cytoplasm.
• The precursor molecules then polymerize to
form filaments
• The primary function of microtubules is to act
as cytoskeleton , providing rigid physical
structure

28. The Nucleus: “Control Center” of the Cell
Nucleus contains large quantities of DNA ,which
are the genes .

29. The Nucleus: “Control Center” of the Cell
• Nuclear membrane is two separated bilayer
membrane, the outer membrane is continuous with
the endoplasmic reticulum.
• Nuclear membrane penetrated by several thousand
nuclear pores

30. • 100 nm in diameter
• functional diameter
is ~9 nm
• (selectively)
permeable to
molecules of up to
44,000 MW
The nuclear membrane is permeated by
thousands of nuclear pores

31. Chromatin (condensed DNA) is found in the nucleoplasm
o Nucleolus
• one or more per nucleus
• contains RNA and proteins
• not membrane delimited
• functions to form the granular “subunits” of ribosomes

32. • molecules attach to
cell-surface receptors
concentrated in clathrin-
coated pits
• receptor binding
induces invagination
• also ATP-dependent
and involves
recruitment of actin and
myosin
Ingestion by the cell
Receptor-mediated endocytosis:
Pinocytosis and phagocytosis

33. Digestion of Substances in
Pinocytotic or Phagocytic Vesicles
Pinocytosis :
ingestion of
minute particles
that form vesicles
of extracellular
fluid in the
cytoplasm

34. Digestion of Substances in
Phagocytosis Phagocytic Vesicles
• Phagocytosis: the same as pinocytosis except that it involve large
particles rather than molecule like macrophages and WBC.
• Phagocytosis occur in the following steps :
1- the cell membrane receptors attach to the surface ligands of
the particles.
2- the edge of the membrane around the points of attachment
evaginate outward within a fraction of a second to surround the entire
particle, all this occurs suddenly in a zipper like manner to form a
closed phagocytic vesicle.
3- action and other contractile fibrils in the cytoplasm surround
the phagocytic vesicle and contract around its outer edge , pushing the
vesicle to the interior.
4- the contractile proteins then pinch the stem of the vesicle so
completely that the vesicle separates from the cell membrane , leaving
the vesicle in the cell interior in the same way that pinocytosis vesicle
are formed.

35. Digestion of pinocytosis and phagocytic foreign
substance inside the cell
• Function of the lysosomes:
-lysosome attached to the vesicle and empty their acid
hydrolases to the inside of the vesicle
-digestive vesicle is formed inside the cell cytoplasm and
hydrolyzing just begin, the products of digestion are small
molecules of amino acid , glucose, phosphate, then diffuse
through membrane of the vesicle into the cytoplasm.
Residual body is left from digestive vesicle which represent
indigestible substances, and this is excreted by exocytosis.
Digestive organ is Pinocytic and phagocytic vesicle containing
lysosomes.

36. Regression of the tissue and autolysis
of cells
• Tissue of the body often regress to a smaller size and
the lysosomes are responsible for much of this
regression
• Lysosomes also remove damaged cells (autolysis) or
damaged portion of cells from tissues
• Lysosomes also contain bactericidal agents that can kill
phagocytized bacteria before they can cause cellular
damage.
-lysozyme: dissolve the bacterial cell membrane
-Lysoferrin : bind iron and before they can promote
bacterial growth
-acid at a PH 5 , which activate the hydrolase and
inactivate bacterial metabolic system.

37. Syntheses and formation of cellular
structure by endoplasmic reticulum and
Golgi apparatus
• Proteins are formed by the granular endoplasmic
reticulum within the structure of the ribosomes
• Lipids are formed by the smooth endoplasmic
reticulum especially (phospholipids and
cholesterol).
-this process cause the ER to grow more extensive
and to keep it normal small vesicle called ER
vesicles continually break away from the smooth
reticulum and then migrate to Golgi apparatus.

38. Other function of the endoplasmic
reticulum
• It provides the enzyme that control glycogen
break down when glycogen is to be used for
energy
• It provides a vast number of enzymes that are
capable of detoxifying substances such as
drugs .detoxification achieved by coagulation
,oxidation , hydrolysis , conjugation with
glycoronic acid.

39. Specific function of the Golgi
apparatus
• Synthetic function of the Golgi apparatus:
1-provide additional processing of substances
already formed in the ER.
2-cabibility of synthesizing certain
carbohydrates that cannot be formed in the ER .
-especially the formation of large saccharide
polymers bound with small amounts of protein
(hyaluronic acid and chondroitin sulfate)

40. • A few of the many function of hyaluronic and
chondroitin sulfate in the body are :
1-they are the major components of proteoglycans
secreted in mucus and other glandular secretion.
2- they are the major components of the ground
substance outside the cells in the interstitial spaces
acting as fillers between collagen fibers and cells
3- they are principal components of the organic
matrix in both cartilage and bone
4- they are important in many cell activities
including migration and proliferation.

41. Step 1.
• Carbohydrates are converted
into glucose
• Proteins are converted into
amino acids
• Fats are converted into
fatty acids
Step 2.
• Glucose, AA, and FA are
processed into Acetyl-CoA
Step 3.
• Acetyl-CoA reacts with O2 to
produce ATP
A maximum of 38 molecules of ATP
are formed per molecule of glucose
degraded.
ATP production (function of the mitochondria)

42. Step 1.
• glucose converted to pyruvic
(glycolysis)
amino acids and fatty acids and
pyruvic acid converted into the
compound acytel-Coa in the
matrix of the mitochondrion
Citric acid cycle or Krebs cycle :
chemical reaction in
mitochondrion for further
dissolution.
In this cycle the acytel-Coa is
split into hydrogen atoms and
carbon dioxide
ATP production (function of the mitochondria)

43. The Use of ATP for Cellular Function
1. Membrane transport
2. Synthesis of chemical
compounds
3. Mechanical work
(muscle contraction,
by ciliary and ameboid
motion)
• ATP concentration is ~10x that of ADP

44. Locomotion of cell
1-ameboid movement
2-cilia and ciliary movements (cilium and
flagellum)

45. Ameboid movement
• It is the movement of an entire
cell in relation to its
surroundings.
• It begins with protrusion of
pseudopodium from one end
of the cell ,then projects far
out from the cell body and
partially secure itself in a new
tissue area
• Then the remainder of the cell
is pulled toward the
pseudopodium.

46. Ameboid Locomotion:
• Mechanism is result from continual formation of new cell membrane at the
leading edge of the pseudopodium and continual absorption of the
membrane in mid and rear portion of the cell.
• continual endocytosis at the “tail "and exocytosis at the leading edge
of the pseudopodium
• attachment of the pseudopodium is facilitated by receptor proteins
carried by vesicles
• forward movement
results through
interaction of actin
and myosin (ATP-
dependent)

47. Ameboid locomotion
• Types of cells exhibits ameboid locomotion:
1-WBCs
2-fibroblast which move into damaged area
3- its especially important in development of the
embryo and fetus after fertilization of an ovum.

48. chemotaxis is the most important initiator of
ameboid locomotion by chemotactic substance
Cell movement is influenced by chemical substances…
high concentration
(positive)
Low concentration
(negative)
Chemotaxis

49. Cilia and Ciliary Movements:
• Each cilium is an outgrowth of
the basal body and is covered by
an outcropping of the plasma
membrane.
• Occurs only on the inside surfaces of the human
airway (cause a layer of mucus to move at a rate of
about 1cmmin toward the pharynx) and fallopian
tubes(to transport the ovum from ovary to uterus)
• Each cilium is comprised of
11 microtubules
• 9 double tubules
• 2 single tubules
axoneme
• Ciliary movement is ATP-dependent
(also requires Ca2+ and Mg2+)

50. Cilia and ciliary movement
Mechanism of ciliary movement:
1-The 9 double tubules and the two single tubule are all linked to one another
by a complex of protein cross-linkage this is called the axoneme
2-after removal of membrane and destruction of other elements of the cilium
,the cilium can still beat under appropriate condition
3-there are two necessary condition for continued beating of the axoneme after
removal of the other structure of the cilium:
A- the availability of the ATP
B-appropriate ionic condition especially (Mg and Ca)
4-during forward motion of the cilium the double tubules on the front edge of
the cilium slide outward toward the tip of the cilium, while those on the back
remain in place.
5-multiple protein arms composed of the protein dynein ,which has ATPase
enzymatic activity ,project from each double tubule toward an adjacent double
tubule.

51. flagellum
• Is much longer than cilium and its moves in
quasi-sinusoidal waves instead of whip like
movements.

52. TRANSPORT ACROSS CELL
MEMBRANES
1-simple diffusion
2-carrier mediated transport
3-Facilated diffusion
4-primary active transport
5-co transport
6-counter transport

53. TRANSPORT ACROSS CELL
MEMBRANES
• A. Simple diffusion
1. Characteristics of simple diffusion
■ is the only form of transport that is not carrier-
mediated.
■ occurs down an electrochemical gradient
(“downhill”).
■ does not require metabolic energy and therefore
is passive.
J=-PA(C1-C2)

54. Permeability
• is the P in the equation for diffusion.
• describes the ease with which a solute diffuses through a
membrane.
• depends on the characteristics of the solute and the
membrane.
A- Factors that increase permeability:
• ↑ Oil/water partition coefficient of the solute increases
solubility in the lipid of the membrane.
• ↓ Radius (size) of the solute increases the diffusion
coefficient and speed of diffusion.
• ↓ Membrane thickness decreases the diffusion distance.

55. CARRIER MEDIATED TRANSPORT
• includes facilitated diffusion and primary and secondary
active transport.
• The characteristics of carrier-mediated transport are:
1. Stereospecificity For example, D-glucose (the natural
isomer) is transported by facilitated diffusion, but the L-
isomer is not.
2. Saturation :the transport rate increases as the
concentration of the solute increases, until the carriers
are saturated.
3. Competition. Structurally related solutes compete for
transport sites on carrier molecules. ( galactose is a
competitive inhibitor of glucose transport in the small
intestine)

56. Facilitated diffusion
Characteristics of facilitated diffusion :
■ occurs down an electrochemical gradient (“downhill”), similar to
simple diffusion.
■ does not require metabolic energy and therefore is passive
■ is more rapid than simple diffusion.
■ is carrier-mediated and therefore exhibits Stereospecificity,
saturation, and competition.
Example of facilitated diffusion
■ Glucose transport in muscle and adipose cells is “downhill,” is
carrier-mediated, and is inhibited by sugars such as galactose;
therefore, it is categorized as facilitated diffusion. In diabetes mellitus,
glucose uptake by muscle and adipose cells is impaired because the
carriers for facilitated diffusion of glucose require insulin.

57. Primary active transport
Characteristics of primary active transport:
■ occurs against an electrochemical gradient (“uphill”).
■ requires direct input of metabolic energy in the form of
adenosine triphosphate (ATP) and therefore is active.
■ is carrier-mediated and therefore exhibits stereo
specificity, saturation, and competition.
Examples of primary active transport
a. Na+,K+-ATPase (or Na+–K+ pump) in cell membranes
transports Na+ from intracellular to extracellular fluid
and K+ from extracellular to intracellular fluid; it
maintains low intracellular [Na+] and high intracellular
[K+].

58. ■ Both Na+ and K+ are transported against their electrochemical
gradients.
■ Energy is provided from the terminal phosphate bond of ATP.
■ The usual stoichiometry is 3 Na+/2 K+.
■ Specific inhibitors of Na+,K+-ATPase are the cardiac glycoside
drugs ouabain and digitalis.
b. Ca2+-ATPase (or Ca2+ pump) in the sarcoplasmic reticulum
(SR) or cell membranes transports Ca2+ against an
electrochemical gradient.
■ Sarcoplasmic and endoplasmic reticulum Ca2+-ATPase is
called SERCA.
c. H+,K+-ATPase (or proton pump) in gastric parietal cells
transports H+ into the lumen of the stomach against its
electrochemical gradient.
■ It is inhibited by proton pump inhibitors, such as omeprazole

59. SECONDARY ACTIVE TRANSPORT
Characteristics of secondary active transport :
a. The transport of two or more solutes is coupled.
b. One of the solutes (usually Na+) is transported “downhill” and provides
energy for the “uphill” transport of the other solute(s).
c. Metabolic energy is not provided directly, but indirectly from the Na+
gradient that is maintained across cell membranes.(Thus, inhibition of
Na+,K+-ATPase will decrease transport of Na+ out of the cell, decrease the
transmembrane Na+ gradient, and eventually inhibit secondary active
transport).
d. If the solutes move in the same direction across the cell membrane, it is
called co-transport, or symport.
(Examples are Na+–glucose cotransport in the small intestine and Na+–K+–
2Cl– cotransport in the renal thick ascending limb)
e. If the solutes move in opposite directions across the cell membranes, it is
called counter-transport, exchange, or antiport (Na+–Ca2+ exchange and
Na+–H+ exchange)

60. SECONDARY ACTIVE TRANSPORT
Example of Na+–glucose co-transport
• a. The carrier for Na+–glucose co transport is located in the
luminal membrane of intestinal mucosal and renal proximal
tubule cells.
• b. Glucose is transported “uphill”; Na+ is transported
“downhill.”
• c. Energy is derived from the “downhill” movement of Na+.
The inwardly directed Na+ gradient is maintained by the
Na+–K+ pump on the basolateral (blood side) mem-brane.
• Poisoning the Na+–K+ pump decreases the transmembrane
Na+ gradient and consequently inhibits Na+–glucose
cotransport.

61. Secondary active transport
Example of Na+–Ca2+ counter transport or exchange
a. Many cell membranes contain a Na+–Ca2+ exchanger
that transports Ca2+ “uphill” from low intracellular
[Ca2+] to high extracellular [Ca2+]
. Ca2+ and Na+ move in opposite directions across the
cell membrane
b. The energy is derived from the “downhill” movement
of Na+.As with cotransport, the inwardly directed Na+
gradient is maintained by the Na+–K+ pump.
Poisoning the Na+–K+
pump therefore
inhibits Na+–Ca2+
exchange

62. Osmosis
A. Osmolarity
■ is the concentration of osmotically active particles in a
solution.
■ is a colligative property that can be measured by
freezing point depression.
■ can be calculated using the following equation:
Osmolarity = g x C
where:
Osmolarity = concentration of particles (osm/L)
• g = number of particles in solution (osm/mol)
• C = concentration (mol/L)

63. ■ Two solutions that have the same calculated
osmolarity are isosmotic
■ If two solutions have different calculated
osmolarities, the solution with the higher
osmolarity is hyper-osmotic
■ the solution with the lower osmolarity is
hyposmotic.

64. ■ Osmosis is the flow of water across a
semipermeable membrane from a solution with
low solute concentration to a solution with high
solute concentration.

65. 1. Example of osmosis:
a. Solutions 1 and 2 are separated by a
semipermeable membrane. Solution 1
contains a solute that is too large to cross the
membrane. Solution 2 is pure water. The
presence of the solute in solution 1 produces
an osmotic pressure

66. b. The osmotic pressure difference across the
membrane causes water to flow from solution
2 (which has no solute and the lower osmotic
pressure) to solution 1 (which has the solute
and the higher osmotic pressure).
c. With time, the volume of solution 1 increases
and the volume of solution 2 decreases

67. Calculating osmotic pressure (van’t
Hoff’s law)
• a. The osmotic pressure of solution can be calculated by
van’t Hoff’s law,
• which states that osmotic pressure depends on the
concentration of osmotically active particles.
• The concentration of particles is converted to pressure
according to the following equation:
• π = g x c x RT
• π =osmotic pressure (mm Hg or atm)
• g = number of particles in solution (osm/mol)
• C = concentration (mol/L)
• R = gas constant (0.082 L—atm/mol—K)
• T = absolute temperature (K).

68. • b. The osmotic pressure increases when the solute
concentration increases
(A solution of 1 M CaCl2 has a higher osmotic pressure than a
solution of 1 M KCl because the concentration of particles is
higher)
c. The higher the osmotic pressure of a solution, the greater the
water flow into it.
d. Two solutions having the same effective osmotic pressure are
isotonic because no water flows across a semipermeable
membrane separating them. If two solutions sep-arated by a
semipermeable membrane have different effective osmotic
pressures, the solution with the higher effective osmotic
pressure is hypertonic and the solution with the lower
effective osmotic pressure is hypotonic, Water flows from the
hypotonic to the hypertonic solution.
• e. Colloidosmotic pressure, or oncotic pressure, is the
osmotic pressure created by proteins (e.g., plasma proteins).

69. Reflection coefficient (σ)
is a number between zero and one that describes the
ease with which a solute permeates a membrane.
a. If the reflection coefficient is one, the solute is
impermeable. Therefore, it is retained in the original
solution, it creates an osmotic pressure, and it causes
water flow. Serum albumin (a large solute) has a
reflection coefficient of nearly one.
b. If the reflection coefficient is zero, the solute is
completely permeable. Therefore, it will not exert any
osmotic effect, and it will not cause water flow. Urea (a
small solute) has a reflection coefficient of close to zero
and it is, therefore, an ineffective osmole.

70. • 4. Calculating effective osmotic pressure
■Effective osmotic pressure is the osmotic
pressure (calculated by van’t Hoff’s law)
multiplied by the reflection coefficient.
■ If the reflection coefficient is one, the solute
will exert maximal effective osmotic pres-sure.
If the reflection coefficient is zero, the solute
will exert no osmotic pressure.

71. Thank you