cell,subcellular organelles,and transport

2. Cell
and
Sub-cellular Structures
Dr.GANESH

3. Cell
Cell
is the
Basic Structural and Functional Unit
of all Living Organisms
• Therefore,
Evolution of cell
is a crucial milestone
in the
evolution of life.

4. Cell structure
•A
eukaryotic
cell
contains
a)plasma
membrane, b)cytosol and c)subcellular organelles.
• Cell is a closed compartment containing aqueous
fluid called –
cytosol
surrounded
by
cell
membrane
plasma membrane
called
–

5. Cell
• Subcellular organelles are bathed by cytosol
and include –
nucleus, mitochondria,
endoplasmic reticulum, ribosomes
golgi apparatus (golgi complex),
lysosomes, peroxisomes,
and cytoskeleton.

6. Cell
• Cell = Plasma membrane + cytoplasm
• Cytoplasm = Cytosol + Subcellular organelles

7. Cell
All subcellular organelles,
except
ribosomes and cytoskeleton,
are compartments within the cell,
surrounded by cell membrane
and
containing their own aqueous fluid

22. Cell
• Diversity of cell types serves the function of
the particular tissues and organs in which they
are present.
• Depending on the function,
different cell types
differ in their organelle content,
or
their organelles may contain
different amounts of
particular enzymes or structural molecules.

23. Cell Membrane
Contents:
• Structure
• Function
• Transport Across Cell Membrane

24. Cell Membrane
• thin hydrophobic sheet
in fluid state which envelopes the cell
• made up of lipid bilayer (two layers)
• containing also proteins
• Lipid and Protein molecules are bound to
each other by non-covalent bonds
• Carbohydrates, found in lesser amounts
are bound to lipid and protein molecules
by covalent bonds

25. Cell Membrane
Membranes
• Define the external boundaries of
cells and organelles
• Maintain their integrity
and
• Serve to compartmentalize functions within the
cells.

26. Salient features of Cell Membrane
• Membranes are
flexible (because they are fluid),
elastic
and
self-sealing
• flexibility
permits the shape changes that accompany cell
growth and movement of cells, gives stability
Also enables the cell to perform exocytosis and
endocytosis

27. • Membranes are selectively permeable to
molecules.
-Being hydrophobic membranes are permeable to
only lipid soluble/hydrophobic substances and
impermeable to hydrophilic/polar substances.
-However, membranes have transport systems
(made of proteins) to permit and regulate the
movement of polar compounds across its
thickness.

28. Functions of Cell Membrane
1. Cell Membranes maintain the shape and size
of the cells.
2. Protects the cytoplasm and the cell
organelles from the external environment
3. The intracellular membranes serve to
compartmentalize functions within the cells.
4. Membranes regulate the transport of
substances like
nutrients, ions, gases, water, various
products, wastes into and out of cells and
their organelles.

29. 5.Membranes bound enzymes carry out metabolic
reactions near the inner surface of the cell
membrane. Egs:Succinate dehydrogenase .
6.Membranes are involved in signal transduction;
i.e. proteins in membranes detect specific
signals
transmit such signals to the cell interior by
specific chemical events.
7. Membrane mediates cell-to-cell communication
between adjacent cells by gap-junctions.
8. Membrane regulates the flow of information
between cell and its environment

30. Structure of Cell Membrane
Membranes are
sheet-like complex structures
composed of • Lipids
• Proteins
and
• Carbohydrates

31. Structure of Cell Membrane
• Lipid bilayer conformation
is the basic structure of all biological
membranes.
• lipid bilayer
is made up of
amphipathic lipid molecules
(having both hydrophilic or polar part and a hydrophobic or
non-polar part)
crucial in the formation of membrane structure

32. Structure of Cell Membrane
Fluid Mosaic Model
proposed by Singer and Nicolson
to explain the structure of cell membrane
According to this,
• membrane is a
fluid lipid bilayer
with
a mosaic of embedded proteins

33. Membrane Components
Phospholipids
Proteins (peripheral and integral)
Cholesterol
Carbohydrates

34.  In 1972, S.J. Singer & G. Nicolson
proposed that membrane proteins are
inserted into the phospholipid bilayer
It’s like a fluid…
It’s like a mosaic…
It’s the
Fluid Mosaic Model!
AP Biology

35. Structure of Cell Membrane
In other words,
the model is compared to
icebergs (membrane proteins)
floating in a sea ( predominantly
phospholipid molecules)

36. Structure of Cell Membrane
Membranes are
5-8 nm thick
and
appear trilaminar
when viewed through an electron
microscope

37. Structure of Cell Membrane
• Different membranes within the cell
and between cells have different
compositions
• This difference reflects the diversity
of biological roles of these
membranes

38. Structure of Cell Membrane
For e.g.
• myelin sheath of neurons,
which acts as an electrical insulator,
is rich in lipids
whereas
• inner mitochondrial membrane
in which many enzyme-catalyzed processes take place
contains
more proteins than lipids

39. Lipids
All Lipids present in cell membrane are –
Amphipathic Lipids
Compound Lipids and
Cholesterol (Free Cholesterol)
Phospholipids Glycolipids
conceived as having a –
polar head
and a
non-polar tail.

40. Amphipathic Lipid
Polar Head
Non-polar Tails

41. Lipids
Amphipathic lipids
self-assemble in aqueous medium
into bilayer sheets (lipid bilayer)
with their hydrophobic parts (non-polar tails) of each
layer
facing and interacting with each other forming a
hydrophobic membrane core
and
hydrophilic parts (polar heads)
facing towards the two surfaces
interacting with the aqueous medium

42. Lipid Monolayer
Aqueous Medium
Non-polar Medium

43. Lipid Bilayer
Aqueous Medium
Aqueous Medium
Hydrophobic Core

44. Lipids of cell membrane
Ampipathic lipids such as
• phospholipids
(e.g. lecithin,cephalin,sphingomyelin)
• glycolipids and
• cholesterol.

45. Lipids
Specific type of lipid
may be present in particular tissues
Example:
• Nerve tissues
have large quantity of
glycolipids and sphingomyelins.
• Mitochondrial membrane
rich in cardiolipin.

46. Proteins
• Make up about 50% of total membrane mass
In a typical cell
• Distributed
Asymmetrically
in the
lipid bilayer

47. Proteins
• Membrane proteins are of 2 types.
1.Peripheral membrane proteins
attached to the lipid bilayer on either surface
E.g.
succinate dehydrogenase (TCA Cycle),
endoplasmic reticulum enzymes, etc
2. Integral membrane proteins
deeply embedded in the lipid bilayer.
– Some integral membrane proteins may completely
span the lipid bilayer –
–transmembrane proteins
e.g. receptor proteins, transport proteins, channel
proteins, etc).

48. Cell Membrane proteins
Peripheral
membrane proteins
Integral
Transmembrane proteins
membrane proteins
Examples
Integral membrane proteins
•Receptor proteins
• Transport proteins
• Channel proteins

49. Many Functions of Membrane Proteins
Outside
Plasma
membrane
Inside
Transporter
AP Biology
Enzyme
activity
Cell surface
receptor
Cell surface
identity marker
Cell adhesion
Attachment to the
cytoskeleton

50. Membrane Carbohydrates
• relatively minor components
5-8% of the total membrane mass.
• covalently linked to lipids and proteins as
glycolipids and glycoproteins.
• Located on the extra cellular side of the
membrane, which forms a loose outer
carbohydrate coat called Glycocalyx

51. Functions of Glycocalyx
• Gives a net negative surface charge
and repel from other electrically negative
particles.
• Cell to cell attachment is possible.
• Part of receptor substances for binding
hormones such as insulin
• Some of the carbohydrate moieties
enter into immune reaction.

52. Cell Membrane Carbohydrates
Glycolipid
Glyccalyx
Glycoprotein

58. Oligosaccharide
Peripheral Membrane Protein
Glycolipid
Glycoprotein
Integral Membrane Proteins

59. Cell Membrane Structure
Glycolipid
Lipid
Bilayer
Peripheral
membrane proteins
Glycoprotein
Polar head
Non polar tail
Integral Transmembrane proteins
membrane proteins

60. Membrane Components
Phospholipids
Proteins (peripheral and integral)
Cholesterol
Carbohydrates

62. Fluidity of Membranes
Membrane consists of
a mosaic of lipids and proteins
that can move laterally (so fluid)
in the plane of the membrane.
fluidity makes the membrane
• flexible (which in turn permits the shape changes that
accompany cell growth and cell movements),
• increases permeability ,gives stability
and
enables them to
• invaginate or evaginate
allowing them to ingest or to expel materials.

63. Factors Affecting the Fluidity
• Unsaturated cis-fatty acids
• Short chain fatty acids and
• High temperature
Increase the membrane fluidity.
Whereas,
Cholesterol
decreases
the
membrane fluidity

65. Specialised Membrane Structures
• Tight Junction
• seen in epithelial cells, where the lateral membrane
of a cell is fused with lateral membrane of adjacent
cell. This prevents the movement of molecules
through the gap between the cells. This ensures
that, molecules move only through the luminal side
to the serosal side.
E.g.: Seen in gastrointestinal epithelial cells.
• Myelin Sheath
Specialized structure for the conduction of nerve
impulse, rich in lipids.

66. Specialised Membrane Structures
• Synaptic membranes:
Cell membranes associated with synapses.
Required for the release or reception of
neurotransmitters.
• Microvilli:
Hair like projections produced by the membrane
evagination, which increases absorptive surface
area.
Eg: intestinal epithelial cells.

67. Specialized Membrane Structures
Tight Junction
Tight Junction
Eg: gastrointestinal epithelial cells
For cell to cell communication
Microvilli
Eg: gastrointestinal epithelial cells
Enhance absorption of food
Myelin sheath
Myelin Sheath
Eg: neurons
For conduction of nerve
impulse
Synaptic membrane
Eg: neurons
Transmit information between
neurones

68. Any Questions??
AP Biology

69.  Cell membrane is the boundary between
inside & outside…

separates cell from its environment
Can it be an impenetrable boundary?
NO!
OUT
IN
food
carbohydrates
sugars, proteins
amino acids
lipids
salts, O2, H2O
AP Biology
OUT
IN
waste
ammonia
salts
CO2
H2O
products
cell needs materials in & products or waste out

70. Transport Across
Cell Membrane
• Membranes act as effective barrier for the passage of
molecules,
thereby keeping some substances inside the cell and
others out.
• Yet they also contain transport systems
which confer on membranes the important property of
selective permeability
by allowing specific molecules to be taken up
and
unwanted compounds to be removed from the cell

71. Transport Across
Cell Membrane
•
As the membrane core is hydrophobic in
nature
hydrophobic molecules move more readily
across the membrane
than hydrophilic ones.
• As the membrane fluidity increases,
permeability to hydrophilic substances also
increases

72. Transport across cell membrane
 What molecules can get through directly?

fats & other lipids
inside cell
NH3
 What molecules can
lipid
salt
NOT get through
directly?

polar molecules
 H 2O

outside cell
sugar aa
H 2O
ions
 salts, ammonia

large molecules
 starches, proteins
AP Biology

73. Transport across cell membrane
 Membrane becomes semi-permeable
with protein channels

specific channels allow specific material
across cell membrane
inside cell
NH3
AP Biology
salt
H 2O
aa
sugar
outside cell

74. Classification of Transport Across Cell Membrane
Membrane Transport
Small Molecules
Passive transport
(Energy independent)
Simple Diffusion
Macromolecules & Particles
Active transport
(Energy dependent, Carrier mediated)
Facilitated Transport
(Carrier mediated)
Ion-channels
Endocytosis
Eocytosis

75. Another Way to Classify
Transport of Small Molecules
Non-mediated transport
(no carrier proteins)
Simple Diffusion
Facilitated Transport
(Passive transport)
Carrier mediated
Ion-channels
Active transport
(Energy dependent,)

76. Contents
•Transport of Small Molecules
o Non-mediated transport (no carrier proteins)
-- Simple Diffusion
-- Ion-channels
o Carrier mediated
-- Facilitated Transport(Passive)
-- Active transport(Energy dependent)
•Macromolecules & Particles

77. Non-mediated Transport
(no carrier proteins)
Simple Diffusion
Very Small molecules (like water) and gases (CO2,O2)
enter the cell by this method.
It is a very slow process.
Doesn’t require energy (energy independent/passive).
It is a non-mediated transport
(no carrier proteins involved).
Molecules diffuse from
a region of higher concentration
to a region of lower concentration
(down the concentration gradient)
diffusion occurs through a membrane opening or through
intermolecular spaces.

78. Simple diffusion
Eg:
a) Respiratory exchange of gases between
pulmonary alveolar membrane
and
tissue capillary wall
b) Intestinal absorption of
pentoses, some mineral ions and water-soluble
vitamins
and
c) renal reabsorption of urea

79. Ion-channels
• specialized protein molecules
that span the membranes
& permit the rapid transport of ions such as
Na+, K+, Cl-.
• The channels generally remain closed
but in response to stimulus,
open allowing rapid flux of ions
down the gradient

80. Carrier Mediated Transport
• specific carrier molecules are required
• protein in nature.
• Have specific binding sites
for the molecules to be transported
• Transport is dependent on
availability of free binding sites on the carrier
protein
• more rapid than simple diffusion.

81. Classification of
Carrier Mediated Transport
There are 2 Ways of Classification
1. Depending upon
Number of Molecules Transported
and
Direction of Transport
2. Depending upon
Whether Energy is Required or not

82. Classification of
Carrier Mediated Transport
1.
• Uniport
• Co-transport
- Symport
and
- Antiport
2.
• Facilitated Transport(Passive)
• Active transport(Energy dependent)

83. Carrier Mediated Transport
• Uniport
Movement of one molecule from one side to another
E.g.: movement of glucose from the cells of GIT to ECF.
• Co-transport
Movement of one molecule depends on
simultaneous or sequential transfer of another molecule
Co-transport may be
- Symport
Two molecules move in the same direction
E.g.: Na+/Glucose transport.
-Anti-port
Two molecules move in opposite directions
E.g.: Cl- – HCO3- exchange in RBCs

95. end

110. end

120. end

121. Carrier Mediated Transport
• Based on energy need,
carrier-mediated transport are of
two types:
--Facilitated Transport (energy independent/passive)
and
-- Active transport (energy independent/active)

122. Facilitated Transport
• It is passive transport and carrier mediated.
• Here transport is down the concentration gradient.
• Once the molecule binds to the biding site,
a conformational change occurs in the carrier
making the binding site exposed to the opposite direction
Now the molecule is released from the carrier.
Another conformational change in the carrier
leads to the exposure of the binding site to the region
where free molecules to be transported are present.
• Structurally similar solutes can
inhibit the entry of one another by competitive inhibition.
E.g. There are four different facilitated carrier systems for
carbohydrates and five for amino acids.

123. Facilitated transport
 Diffusion through protein channels


channels move specific molecules across
cell membrane
facilitated = with help
no energy needed
open channel = fast transport
high
low
AP Biology
“The Bouncer”

124. Transport Across Cell Membrane
Facilitated transport
Mechanism : Ping pong model

125. Active Transport
• Transport is
carrier mediated
against the concentration gradient
and hence
energy-dependent.
• Transport occurs only in one way,
against the concentration gradient.
• The energy comes usually from
hydrolysis of ATP molecules
• About 40% of the total energy of the cell is used for
the active transport.

126. Active Transport
 Cells may need to move molecules against
concentration gradient



shape change transports solute from
one side of membrane to other
protein “pump”
conformational change
“costs” energy = ATP
low
ATP
high
AP Biology
“The Doorman”

127. Active Transport
E.g.
• Na+–K+ pump or Na+-K+ ATPase
is the best example for active transport
because virtually all cells have it.
Other examples
• Ca+–dependent ATPase
(in sarcoplasmic reticulum of skeletal muscles),
• H+–dependent ATPase
located in the membrane of epithelial cell lining the
stomach
and has the function of acid (H+) secretion

128. Na+-K+ ATPase
• Na+-K+ ATPase establishes and maintains
a high intracellular K+ concentration
and
a low Na+ concentration
compared to their concentrations in ECF.
• The Na+ – K+ ATPase,
expels 3 Na+ ions
and
brings 2K+ ions from outside to inside
with a concomitant hydrolysis of ATP.
Drugs like digitalis (a cardiac glycoside)
and ouabain inhibit Na+ – K+ ATPase.

129. Active Transport
ATP
2 K+
2 K+
Na+-K+ ATPase
3 Na+
ADP + Pi
3 Na+

130. Sodium pump or Na+-K+ ATPase

131. Classification of active transport
• based on the source of energy
1. Primary active transport - Transport of
molecules is directly linked to the hydrolysis of
ATP, which provides energy.
E.g. Na+–K+ pump or Na+-K+ ATPase
2.Secondary active transport- Transport of
molecules is indirectly linked to the hydrolysis of ATP.
Eg: Glucose and galactose are absorbed from the
intestine by secondary active transport.
Concentration gradient of Na+ is maintained by Na+ – K+
ATPase.

132. Physiological importance of active
transport
• -Responsible for the generation of the resting membrane
potential, basis for excitability in nerve and transmission of
nerve impulse
• -Na+ pump is driving force for several secondary active
transport of nutrients into the cell. For example, glucose is cotransported with sodium into the cell
• -Calcium pump (Ca++ dependent ATPase): found in
sarcoplasmic reticulum of skeletal muscles. It transports
calcium from the cytosol to the sarcoplasmic reticulum. It
regulates muscle contraction
• -Proton pump (H+ dependent ATPase): located in the parietal
cells of the stomach . It is responsible for the secretion of Hcl
into stomach lumen, to maintain the highly acidic pH essential
for gastric digestion.

133. • Clinical application:
Cardiotonic rugs like digitalis (a
cardiac glycoside) and ouabain
inhibit Na+ – K+ ATPase. They are
used in treatment of heart
failure.

134. Transport of
Macromolecules & Particles
-transported by
Endocytosis
and
Exocytosis
-Macromolecules such as
proteins, polysaccharides, hormones and
particles like viruses, bacteria etc are
transported by these mechanisms.

135. Endocytosis
-internalize extra-cellular macromolecules by
invagination of cell membrane
- Endocytosis may be either
Phagocytosis
or
Pinocytosis.

136. Transport Across Cell Membrane
Endocytosis: Process by which cells take up the large
molecules

137. Phagocytosis (Gk: Phagein = to eat)
•
•
•
•
Occurs in specialized cells such as macrophages
and
granulocytes.
ingestion of large particles such as
viruses, bacteria, cells or debris.
• endocytic vesicle (phagosome)
fuses with the lysosome.
hydrolytic enzymes of lysosomes
break down the macromolecular contents
released in to the cytosol
reused or further catabolized

138. Pinocytosis(cell drinking)
•
Cellular uptake of fluid and fluid contents
containing small particles.
E.g.: -Intake of chylomicron
by the hepatocytes;
-internalization of LDL by LDL receptor

139. Exocytosis
extrusion of particulate or macromolecular
materials,
which can’t pass out through the intact membrane.
• secretory vesicle is pinched off from the Golgi
apparatus;
• moves towards and fuses with the plasma
membrane.
• E.g. a) Release of Trypsinogen by pancreatic
acinar cells.
b) Release of Insulin by -cells of Langerhans.
• c) Release of acetylcholine by pre-synaptic
cholinergic nerves.

140. Transport Across Cell Membrane
Exocytosis: Process of extrusion of a macromolecule
from the cell

141. Disorders of
Membrane Structure and Transport
Abnormality in membrane structure or transport
can cause diseases.
• Respiratory distress syndrome
Defect in biosynthesis of dipalmitoyl lecithin
(lung surfactant)
• Familial hypercholesterolemia
Mutations in the gene encoding LDL receptor
Cystic fibrosis
Mutations in the gene encoding Cl- transporter

142. Sub-cellular Organelles
include
-- nucleus,
Ribosomes
endoplasmic reticulum,
golgi apparatus/complex,
mitochondria,
lysosomes,
peroxisomes
and
cytoskeleton.

143. Sub-cellular Organelles
All eukaryotic cells contain
all these organelles
RBC is not a true cell and
contain only the
plasma membrane and
cytoskeleton

144. Nucleus
• largest sub-cellular organelle.
• double membrane –
nuclear membrane,
surrounds it.
• At intervals nuclear membrane has
nuclear pores,
permit the passage of molecules
in and out of the nucleus.
• nucleus of eukaryotic cell contains
a dense body known as
nucleolus
rich in rRNA.

145. Nucleus
• Nucleoplasm
– ground material of nucleus
rich in enzymes such as,
DNA polymerases, RNA polymerases, etc.
• Nucleus of an interphase (non-dividing) cell filled
with a diffuse material
– chromatin.
– During the cell division, chromatin condenses to form
chromosomes.
– Humans have 23 pairs of chromosomes compactly
packed in the nucleus.

146. Nucleus –Functions
• Nuclear DNA --the repository of genetic information
serves two purposes -i) By DNA replication
provides genetic information to
offspring or daughter cells
during cell division., thus it is blue print of life.
ii) By transcription (RNA synthesis)
provides information for the synthesis of all
protein molecules of the cell.
Both replication and transcription
take place in the nucleus.
Function of nucleolus:
-Synthesis of rRNA and ribosomes

147. Mitochondria
spherical, oval or rod like bodies.
have two membranes –
outer and inner membrane.
outer membrane is smooth
while the inner membrane is for folded to form
cristae
components of
electron transport chain (ETC) and
oxidative phosphorylation
buried in the inner mitochondrial membrane.

148. Mitochondria-structure

149. Mitochondria
• The central cavity of the mitochondrion
contains
the matrix
• Matrix contains enzymes and chemical
intermediates of -TCA cycle
Heme synthesis
Urea cycle, etc.
Also present in the matrix are, mitochondrial
DNA, RNA and ribosomes.

150. Functions
• ETC and oxidative phosphorylation-- situated in
inner mitochondrial membrane are involved in ATP
synthesis, hence mitochondria are regarded as
‘powerhouse of the cell’
• Some of the major pathways operate in the
mitochondria. They are, TCA cycle, -Oxidation of
fatty acid, ketone bodies
formation, gluconeogenesis (partly), urea cycle
(partly), heme synthesis (partly), pyrimidine
synthesis (partly) .
• Mitochondrial DNA codes for some of the
mitochondrial proteins involved in oxidative

151. Endoplasmic Reticulum (ER)
network of membrane-enclosed spaces
extends throughout the cytoplasm.
• classified into
rough and
smooth ER
rough appearance (when observed under electron
microscope) is
due to ribosomes attached to the cytoplasmic
side of the membrane.
smooth ER does not have ribosomes.

153. Functions of ER
• Rough ER : involved in synthesis of proteins
(lipoproteins, glycoproteins)
• Smooth ER:
I. Metabolism of drugs and toxic compounds
(cyt P450 monooxygenases are present in
liver cell smooth ER)
II. Synthesis of lipids
(TAG, phospholipids, cholesterol) and
III. Ca2+ storage in skeletal and cardiac
muscle.(note- sarcoplasmic reticulum of
muscle is a modified ER)

154. Golgi Complex/Golgi Apparatus
• group of membrane bound
flattened tubes or sacs
placed one over another
in a pile or stack.

156. Golgi Apparatus - Functions
Main functions of Golgi apparatus are
protein sorting, packaging and secretion.
• newly synthesized proteins are
handed over to the Golgi apparatus, which
catalyze the addition of
carbohydrates, lipids or sulfate moieties
to the proteins.

157. Lysosomes
membrane bound vesicle
containing various hydrolytic enzymes
(hydrolases.
• Lysosomal enzymes
are capable of digesting
proteins, carbohydrates, lipids and nucleic acids
• pH inside the lysosomes is less than that of
cytosol necessary for its digestivse function

159. Lysosomes -Functions
• hydrolases breakdown complex molecules
brought into the cell by
endocytosis, phagocytosis or
worn-out organelles from the cells own
cytoplasm. Lysosomes - termed as ‘suicide-bags’
as their lysis can lesad to
digestion and death of the cell
Sphingolipidosis –
group of disorders in which
excess of sphingolipids accumulates in lysosomes

160. Peroxisome
small spherical or oval membranous bodies
• contain enzymes -peroxidases and catalase

161. Peroxisome - Functions
Free radicals
formed by peroxidation of PUFA
capable of damaging
cell membranes, tissues, and genes
Such reactions are implicated in
inflammatory diseases, ageing process
malignant transformation.
and
• Catalase and peroxidase enzymes destroy such
unwanted peroxides and other free radicals

162. Ribosomes:
nucleoproteins
present either freely in cytosol or
bound to ER
• Function:
provide necessary infrastructure for
mRNA, tRNA & amino acid
to interact with each other for
translation process.

163. Cyto skeleton
Made up of
microtubules and actin filaments
role in maintaining the
cellular structure,
mobility and
cell division.
Hereditary spherocytosis
due to mutations in
genes encoding
spectrin or other structural proteins in
red blood cell membrane,
leading to excessive hemolysis

164. Organelle
Nucleus
Function
Provides genetic information to offspring
RNA transcription, directs protein
synthesis
Mitochondria Energy production from the oxidation of
food substances and the release of
adenosine triphosphate
Endoplasmic Translation and folding of new proteins
reticulum
(rough endoplasmic reticulum), synthesis
of lipids (smooth endoplasmic reticulum)

165. Golgi
appartus
Sorting, packaging, and modification of
proteins
Endoplasmic Translation and folding of new proteins
reticulum
(rough endoplasmic reticulum), synthesis
of lipids (smooth endoplasmic reticulum)
Lysosome
Breakdown of large molecules
Peroxisome
breakdown of metabolic hydrogen
peroxide and free radicals

166. Organelle
Function
Ribosome
Translation of RNA to
form proteins
Cytoskeleton
Maintaining
the
cellular, shape, motility
and
cell division.

167. Sub-Cellular Fractionation
isolation of an organelle
in a relatively pure form
in order to study its
functions
Cell membrane is disrupted usually by mechanical means
called
homogenization
• subcellular organelles
can then be separated from the homogenate by
differential centrifugation
using the instrument
ultracentrifuge

168. Thank u………!!
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