for HS & B.Sc level

1. STRUCTURAL ORGANIZATION
OF EUKARYOTIC CELLS AND
THEIR FUNCTION
Prepared by -
Dwijottam Sarma Bordoloi (17/BBT/20)
Bhargab Kumar Thakuria (17/BBT/06)
Ashish Pratim Mahanta (17/BBT/60)

2. CONTENTS
1. Introduction
2. Diagrammatic Representation
3. Types
4. Structural Overview
5. Functions
6. Differences
7. References

3. INTRODUCTION
 Contains a prominent nucleus surrounded by a
membrane.
 Contains numerous organelles unlike prokaryotic
cell.
 The word Eukaryote which refer to any organism
possessing eukaryotic cell is derived from the
Greek word “eu karyon” in which “eu” means
“true” and “karyon” means “nut/kernel” which is
the “nucleus”.
Eukaryotic Cell :

4. DIAGRAMMATIC REPRESENTATION
Fig - A Eukaryotic Cell

5. TYPES
EUKARYOTIC
CELL
PLANT CELL ANIMAL CELL

6. Fig – PLANT CELL

7. Fig – ANIMAL CELL

8. STRUCTURAL OVERVIEW
Eukaryotic Cell is an aqueous compartment surrounded
by plasma membrane and cell wall (in case of plants
only) and consists of protoplasm in which different types
of cell organelles get embedded such as:
i. Nucleus
ii. Endoplasmic Reticulum
iii. Golgi Bodies
iv. Ribosome
v. Mitochondria
vi. Peroxisome
vii. Vacuoles
viii. Lysosomes (in animal cells only)
ix. Centriole (in animal cells only)
x. Chloroplast (in plant cells only)

9. STRUCTURAL OVERVIEW (CONTD…)
The remaining structural components of eukaryotic
cells include :
Cytoskeleton
Cilia and Flagella (found in animal cells)

10. FUNCTIONS
Plasma Membrane
• A fluid-like bilipid
membranous layer
composed of
proteins and
carbohydrates.
• It separates the cell from its external environment, protects
the cell and provides shape, stability and integrity of the cell.
• It is selectively permeable i.e. it allows certain molecules or
ions to pass through it by means of active or passive
transport.
• The Fluid Mosaic Model of the plasma membrane
proposed by Singer and Nicholson in 1972 is the dominating
and mostly widely accepted model at present.

11. Cytoplasm
• Jelly-like substance composed of
mainly water and found between
the cell membrane and nucleus.
• Organelles are found here and
substances like salts may be
dissolved in the cytoplasm.
Nucleus
• Largest organelle of the cell and is
called the brain or control centre of the
cell.
• Dark, round and surrounded by a
nuclear membrane that has nuclear
pores on it.

12. Nucleus (contd…)
• It contains the genetic information (DNA) on special strands
called chromosomes and controls the functions of the entire cell
by regulating gene expression.
Endoplasmic Reticulum
• Network of membranous canals
filled with fluid, continuous with the
nuclear membrane.
• They carry materials throughout
the cell and is the “transport
system” of the cell.
• They are of two types – Rough ER (which is rough in appearance
and is lined with ribosomes ) and Smooth ER (which is smooth in
appearance and doesn’t contain ribosomes).

13. Golgi Bodies
• Stacks of flattened membranous stacks.
• Moves materials within or outside the cell.
• Temporarily stores proteins, modifies and
packs macromolecules into useable forms
called vesicles for cell secretion.
Mitochondria
• Round tube-like organelles that are
surrounded by a double membrane.
• Referred to as the powerhouse of the
cell.
• Releases food energy from food
molecules through respiration in the form
of ATP.
Chemical Equation -

14. Lysosomes
• Organelles containing digestive enzymes that
degrades worn out cell parts.
• Referred to as ”garbage collector” of the cell.
Chloroplasts
• Present in plants only, contains the green
pigment chlorophyll for absorbing light energy
from sunlight.
• Responsible for performing photosynthesis in
plants.

15. Ribosomes
• Small particles found individually in the
cytoplasm and also line the RER.
• They consist of RNA, synthesize proteins
and can be thought of as “factories” of the
cell.
• They consists of two subunits of unequal size – large and small
subunits. In eukaryotes, the overall ribosome has a size of 80S;
in dissociated form, the large subunit is 60S and the small
subunit is 40S in size.
Peroxisome
• Contains the reducing enzyme catalase and
usually some oxidases that oxidize certain organic
substances.
H O + H O 2H O + O
catalase
2 2 2 2 2 2

16. Centrioles
• Pair of cylindrical organelles near the nucleus
involved in the development of spindle fibers
that separate chromosomes during cycle
division.
• Made of microtubules.
Cell Wall
• Located outside the membrane only in
plant cells, made up of cellulose.
• Maintains the cell shape, provide
protection and controls the passage of
substances.
Vacuoles
• Fluid filled organelles enclosed by a membrane.
• Store materials such as food, water, sugar, minerals
and waste products.

17. Cytoskeleton
• Made up of microtubules, actin and
intermediate filaments.
• Gives the cell its shape and help
organize the cell’s parts and also help
the cell to move.
Cilia and Flagella
• Cilia are hair-like structures of size 1-10 micrometers in length
that move in waves. They can trap inhaled particles in the air and
sweep mucus and dirt out of the lungs in the lining of trachea.
• Flagella are like little tail 100-200 micrometers in length
present in some bacteria that helps them to move or propel.
Cilia Flagellum

18. DIFFERENCES
Plant Cell Animal Cell
1. Possess a cellulosic cell wall
which is the outermost
boundary.
1. Doesn’t possess cell wall
and outermost boundary is the
plasma membrane.
2. Possess chloroplasts which
perform photosynthesis.
2. Lacks chloroplasts.
3. Possess a big central
vacuole.
3. Vacuoles are smaller in size.
4. Centrioles are absent. 4. Centrioles are present.
5. Lysosomes are absent. 5. Lysosomes are present.
6. Usually larger in size. 6. Comparatively smaller.

19. DIFFERENCES CONTD…
Plant Cell Animal Cell
7. Reserve food is stored in the
form of starch.
7. Reserve food is usually
glycogen.
8. Nucleus lies on one side in
the peripheral cytoplasm.
8. Nucleus usually lies in the
centre.
9. Rectangular in shape. 9. Round in shape.
10. They have many simple
units of Golgi apparatus called
dictyosomes.
10. They have single highly
complex Golgi.
11. They cannot change their
shape.
11. They can change their
shape.

20. REFFERENCES
Websites –
 www.wikipedia.org/wiki/Eukaryote
 www.softschool.com/science/biology
 www.shmoop.com/biology-cells/all-eukaryotic-cells.html
www.edu.pe.ca/gray/class_pages/rcfleming/cells
 www.majordifferences.com/2013/10/difference-plant-
cell-vs-and-animal-cell.html?m=1
Books –
 Life Sciences, Fundamentals and Practice – I
(Fifth edition)
Pathfinder Publication, New Delhi, India
By Pranav Kumar and Usha Mina