ALLEN BIOLOGY MODULES : CELL UNIT MBBS Notes | EduRev

MBBS : ALLEN BIOLOGY MODULES : CELL UNIT MBBS Notes | EduRev

 Page 1


Session 2019-20
ALLEN
S.No.                CONTENTS Page
1. What is cell ? and cell theory 179
2. Cell membrane 182
3. Cell wall 185
4. Endomembranous system 187
(i) Endoplasmic reticulum 187
(ii) Golgi apparatus 189
(iii) Lysosome 190
(iv) Vacuole 192
5. Mitochondria 193
6. Plastid 195
7. Ribosome 198
8. Cytoskeleton 199
(i) Microtubules 199
(ii) Micro filament 199
(iii) Intermediate filament 199
9. Cilia and flagella 199
10. Centrosome and centriole 200
11. Microbodies 201
12. Nucleus 202
13. Chromosome 204
14. Exercise-I (Conceptual Questions) 209
15. Exercise-II (Previous Y ears Questions) 216
16. Exercise-III (Analytical Questions) 223
17. Exercise-IV (Assertion & Reason) 226
18. Cell cycle, Mitosis 228
19. Meiosis 235
20. Exercise-I (Conceptual Questions) 242
21. Exercise-II (Previous Y ears Questions) 247
22. Exercise-III (Analytical Questions) 251
23. Exercise-IV (Assertion & Reason) 253
CELL BIOLOGY
E
NEET SYLLABUS
CELL STRUCTURE AND FUNCTION : Cell theory and cell as the basic unit of life; Structure of prokaryotic and
eukaryotic cell; Plant cell and animal cell; Cell envelope, cell membrane, cell wall; Cell organelles-structure and
function; Endomembrane system-endoplasmic reticulum, Golgi bodies, lysosomes, vacuoles; mitochondria, ribosomes,
plastids, micro bodies; Cytoskeleton, cilia, flagella, centrioles (ultra structure and function); Nucleus-nuclear
membrane, chromatin, nucleolus.
CELL DIVISION : Cell cycle, mitosis, meiosis and their significance.
Page 2


Session 2019-20
ALLEN
S.No.                CONTENTS Page
1. What is cell ? and cell theory 179
2. Cell membrane 182
3. Cell wall 185
4. Endomembranous system 187
(i) Endoplasmic reticulum 187
(ii) Golgi apparatus 189
(iii) Lysosome 190
(iv) Vacuole 192
5. Mitochondria 193
6. Plastid 195
7. Ribosome 198
8. Cytoskeleton 199
(i) Microtubules 199
(ii) Micro filament 199
(iii) Intermediate filament 199
9. Cilia and flagella 199
10. Centrosome and centriole 200
11. Microbodies 201
12. Nucleus 202
13. Chromosome 204
14. Exercise-I (Conceptual Questions) 209
15. Exercise-II (Previous Y ears Questions) 216
16. Exercise-III (Analytical Questions) 223
17. Exercise-IV (Assertion & Reason) 226
18. Cell cycle, Mitosis 228
19. Meiosis 235
20. Exercise-I (Conceptual Questions) 242
21. Exercise-II (Previous Y ears Questions) 247
22. Exercise-III (Analytical Questions) 251
23. Exercise-IV (Assertion & Reason) 253
CELL BIOLOGY
E
NEET SYLLABUS
CELL STRUCTURE AND FUNCTION : Cell theory and cell as the basic unit of life; Structure of prokaryotic and
eukaryotic cell; Plant cell and animal cell; Cell envelope, cell membrane, cell wall; Cell organelles-structure and
function; Endomembrane system-endoplasmic reticulum, Golgi bodies, lysosomes, vacuoles; mitochondria, ribosomes,
plastids, micro bodies; Cytoskeleton, cilia, flagella, centrioles (ultra structure and function); Nucleus-nuclear
membrane, chromatin, nucleolus.
CELL DIVISION : Cell cycle, mitosis, meiosis and their significance.
Session 2019-20
ALLEN
In 1837, Matthias Jakob Schleiden viewed and stated that new plant cells are formed
from the nuclei of old plant cells. While dining that year with Schwann, the conversation turned on
the nuclei of plant and animal cells. Schwann remembered seeing similar structures (nuclei) in the
cells of the notochord and instantly realized the importance of connecting the two phenomena
(presence of nuclei and new cell formation). The resemblance was confirmed without delay by both
observers, and the results soon appeared in Schwann's famous microscopic investigations on the
accordance in the structure and growth of plants and animals, in which he declared that "All
living things are composed of cells and cell products". This became cell theory.
In 1855, pathologist Rudolf Virchow posed the maxim Omnis cellula e cellula that
every cell arises from pre-existing cells.
Theodore Schwann
(1810-1882)
Nationality : British
Matthias Jakob Schleiden
(1804-1881)
Nationality : German
Rudolf Carl Virchow
(1821-1902)
Nationality : Prussian (Germany)
Page 3


Session 2019-20
ALLEN
S.No.                CONTENTS Page
1. What is cell ? and cell theory 179
2. Cell membrane 182
3. Cell wall 185
4. Endomembranous system 187
(i) Endoplasmic reticulum 187
(ii) Golgi apparatus 189
(iii) Lysosome 190
(iv) Vacuole 192
5. Mitochondria 193
6. Plastid 195
7. Ribosome 198
8. Cytoskeleton 199
(i) Microtubules 199
(ii) Micro filament 199
(iii) Intermediate filament 199
9. Cilia and flagella 199
10. Centrosome and centriole 200
11. Microbodies 201
12. Nucleus 202
13. Chromosome 204
14. Exercise-I (Conceptual Questions) 209
15. Exercise-II (Previous Y ears Questions) 216
16. Exercise-III (Analytical Questions) 223
17. Exercise-IV (Assertion & Reason) 226
18. Cell cycle, Mitosis 228
19. Meiosis 235
20. Exercise-I (Conceptual Questions) 242
21. Exercise-II (Previous Y ears Questions) 247
22. Exercise-III (Analytical Questions) 251
23. Exercise-IV (Assertion & Reason) 253
CELL BIOLOGY
E
NEET SYLLABUS
CELL STRUCTURE AND FUNCTION : Cell theory and cell as the basic unit of life; Structure of prokaryotic and
eukaryotic cell; Plant cell and animal cell; Cell envelope, cell membrane, cell wall; Cell organelles-structure and
function; Endomembrane system-endoplasmic reticulum, Golgi bodies, lysosomes, vacuoles; mitochondria, ribosomes,
plastids, micro bodies; Cytoskeleton, cilia, flagella, centrioles (ultra structure and function); Nucleus-nuclear
membrane, chromatin, nucleolus.
CELL DIVISION : Cell cycle, mitosis, meiosis and their significance.
Session 2019-20
ALLEN
In 1837, Matthias Jakob Schleiden viewed and stated that new plant cells are formed
from the nuclei of old plant cells. While dining that year with Schwann, the conversation turned on
the nuclei of plant and animal cells. Schwann remembered seeing similar structures (nuclei) in the
cells of the notochord and instantly realized the importance of connecting the two phenomena
(presence of nuclei and new cell formation). The resemblance was confirmed without delay by both
observers, and the results soon appeared in Schwann's famous microscopic investigations on the
accordance in the structure and growth of plants and animals, in which he declared that "All
living things are composed of cells and cell products". This became cell theory.
In 1855, pathologist Rudolf Virchow posed the maxim Omnis cellula e cellula that
every cell arises from pre-existing cells.
Theodore Schwann
(1810-1882)
Nationality : British
Matthias Jakob Schleiden
(1804-1881)
Nationality : German
Rudolf Carl Virchow
(1821-1902)
Nationality : Prussian (Germany)
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
179 E
Pre-Medical : Biology
ALLE N
CELL : THE UNIT OF LIFE
WHAT IS A CELL?
* All organisms are composed of cells. Some are composed of a single cell and are called unicellular organisms
while others, like us, composed of many cells, are called multicellular organisms.
* Unicellular organisms are capable of (i)  independent existence and (ii) performing the essential functions of life.
Anything less than a complete structure of a cell does not ensure independent living. Hence, cell is the fundamental
structural and functional unit of all living organisms.
* First cell discovered by - Robert Hooke in Cork
* Anton Von Leeuwenhoek first saw and described a live cell. Robert Brown later discovered the nucleus.
The invention of the microscope and its improvement leading to the electron microscope revealed all the
structural details of the cell.
CELL THEORY
* In 1838, Matthias Schleiden, a botanist, examined a large number of plants and observed that all plants are
composed of different kinds of cells which form the tissues of the plant. At about the same time, Theodore.
Schwann (1839), Zoologist, studied different types of animal cells and reported that cells had a thin outer layer
which is today known as the ?plasma membrane?. He also concluded, based on his studies on plant tissues, that
the presence of cell wall is a unique character of the plant cells.
* Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products
of cells.
* Schleiden and Schwann together formulated the cell theory. This theory however, did not explain as to how
new cells were formed. Rudolf Virchow (1855) first explained that cells divided and new cells are formed
from pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of Schleiden and Schwann
to give the cell theory a final shape. Cell theory as understood today is:
(i) All living organisms are composed of cells and products of cells.
(ii) All cells arise from pre-existing cells.
AN OVERVIEW OF CELL
* The onion cell which is a typical plant cell, has a distinct cell wall as its outer boundary and just within it is the
cell membrane.
* Cells that have membrane bound nuclei are called eukaryotic whereas cells that lack a membrane bound
nucleus are prokaryotic.
* In both prokaryotic and eukaryotic cells, a semi-fluid matrix called cytoplasm occupies the volume of the cell.
* The cytoplasm is the main arena (zone) of cellular activities in both the plant and animal cells.
Various chemical reactions occur in it to keep the cell in the ?living state?.
* Besides the nucleus, the eukaryotic cells have other membrane bound distinct structures called
organelles like the endoplasmic reticulum (ER), the golgi complex, lysosomes, mitochondria,
microbodies. The prokaryotic cells lack such membrane bound organelles.
* Ribosomes are non-membrane bound organelles found in all cells both eukaryotic as well as prokaryotic
cell. Within the cell, ribosomes are found not only in the cytoplasm but also within the two organelles ?
chloroplasts (in plants) and mitochondria and on rough ER.
* Animal cells contain another non-membrane bound organelle called centriole which helps in cell division.
Page 4


Session 2019-20
ALLEN
S.No.                CONTENTS Page
1. What is cell ? and cell theory 179
2. Cell membrane 182
3. Cell wall 185
4. Endomembranous system 187
(i) Endoplasmic reticulum 187
(ii) Golgi apparatus 189
(iii) Lysosome 190
(iv) Vacuole 192
5. Mitochondria 193
6. Plastid 195
7. Ribosome 198
8. Cytoskeleton 199
(i) Microtubules 199
(ii) Micro filament 199
(iii) Intermediate filament 199
9. Cilia and flagella 199
10. Centrosome and centriole 200
11. Microbodies 201
12. Nucleus 202
13. Chromosome 204
14. Exercise-I (Conceptual Questions) 209
15. Exercise-II (Previous Y ears Questions) 216
16. Exercise-III (Analytical Questions) 223
17. Exercise-IV (Assertion & Reason) 226
18. Cell cycle, Mitosis 228
19. Meiosis 235
20. Exercise-I (Conceptual Questions) 242
21. Exercise-II (Previous Y ears Questions) 247
22. Exercise-III (Analytical Questions) 251
23. Exercise-IV (Assertion & Reason) 253
CELL BIOLOGY
E
NEET SYLLABUS
CELL STRUCTURE AND FUNCTION : Cell theory and cell as the basic unit of life; Structure of prokaryotic and
eukaryotic cell; Plant cell and animal cell; Cell envelope, cell membrane, cell wall; Cell organelles-structure and
function; Endomembrane system-endoplasmic reticulum, Golgi bodies, lysosomes, vacuoles; mitochondria, ribosomes,
plastids, micro bodies; Cytoskeleton, cilia, flagella, centrioles (ultra structure and function); Nucleus-nuclear
membrane, chromatin, nucleolus.
CELL DIVISION : Cell cycle, mitosis, meiosis and their significance.
Session 2019-20
ALLEN
In 1837, Matthias Jakob Schleiden viewed and stated that new plant cells are formed
from the nuclei of old plant cells. While dining that year with Schwann, the conversation turned on
the nuclei of plant and animal cells. Schwann remembered seeing similar structures (nuclei) in the
cells of the notochord and instantly realized the importance of connecting the two phenomena
(presence of nuclei and new cell formation). The resemblance was confirmed without delay by both
observers, and the results soon appeared in Schwann's famous microscopic investigations on the
accordance in the structure and growth of plants and animals, in which he declared that "All
living things are composed of cells and cell products". This became cell theory.
In 1855, pathologist Rudolf Virchow posed the maxim Omnis cellula e cellula that
every cell arises from pre-existing cells.
Theodore Schwann
(1810-1882)
Nationality : British
Matthias Jakob Schleiden
(1804-1881)
Nationality : German
Rudolf Carl Virchow
(1821-1902)
Nationality : Prussian (Germany)
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
179 E
Pre-Medical : Biology
ALLE N
CELL : THE UNIT OF LIFE
WHAT IS A CELL?
* All organisms are composed of cells. Some are composed of a single cell and are called unicellular organisms
while others, like us, composed of many cells, are called multicellular organisms.
* Unicellular organisms are capable of (i)  independent existence and (ii) performing the essential functions of life.
Anything less than a complete structure of a cell does not ensure independent living. Hence, cell is the fundamental
structural and functional unit of all living organisms.
* First cell discovered by - Robert Hooke in Cork
* Anton Von Leeuwenhoek first saw and described a live cell. Robert Brown later discovered the nucleus.
The invention of the microscope and its improvement leading to the electron microscope revealed all the
structural details of the cell.
CELL THEORY
* In 1838, Matthias Schleiden, a botanist, examined a large number of plants and observed that all plants are
composed of different kinds of cells which form the tissues of the plant. At about the same time, Theodore.
Schwann (1839), Zoologist, studied different types of animal cells and reported that cells had a thin outer layer
which is today known as the ?plasma membrane?. He also concluded, based on his studies on plant tissues, that
the presence of cell wall is a unique character of the plant cells.
* Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products
of cells.
* Schleiden and Schwann together formulated the cell theory. This theory however, did not explain as to how
new cells were formed. Rudolf Virchow (1855) first explained that cells divided and new cells are formed
from pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of Schleiden and Schwann
to give the cell theory a final shape. Cell theory as understood today is:
(i) All living organisms are composed of cells and products of cells.
(ii) All cells arise from pre-existing cells.
AN OVERVIEW OF CELL
* The onion cell which is a typical plant cell, has a distinct cell wall as its outer boundary and just within it is the
cell membrane.
* Cells that have membrane bound nuclei are called eukaryotic whereas cells that lack a membrane bound
nucleus are prokaryotic.
* In both prokaryotic and eukaryotic cells, a semi-fluid matrix called cytoplasm occupies the volume of the cell.
* The cytoplasm is the main arena (zone) of cellular activities in both the plant and animal cells.
Various chemical reactions occur in it to keep the cell in the ?living state?.
* Besides the nucleus, the eukaryotic cells have other membrane bound distinct structures called
organelles like the endoplasmic reticulum (ER), the golgi complex, lysosomes, mitochondria,
microbodies. The prokaryotic cells lack such membrane bound organelles.
* Ribosomes are non-membrane bound organelles found in all cells both eukaryotic as well as prokaryotic
cell. Within the cell, ribosomes are found not only in the cytoplasm but also within the two organelles ?
chloroplasts (in plants) and mitochondria and on rough ER.
* Animal cells contain another non-membrane bound organelle called centriole which helps in cell division.
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
180 E
Pre-Medical : Biology
ALLE N
SIZE AND SHAPE OF CELL
Size :
 Cell differ greatly in size, shape and activites.
 Mycoplasma (Smallest cells) : Only 0.3 mm in length
 Bacteria = 3 to 5 mm
 Largest isolated single cell = egg of an ostrich.
 Human red blood cell » 7.0 mm in diameter
 Nerve cell = longest cell
Shape :
 The shape of the cell may vary with the function they perform.
 They may be disc-like, polygonal, columnar, cuboid, thread like or even irregular.
Red blood cells
(round and biconcave
White blood cells
(amoeboid)
Columnar epithelial cells
(long and narrow)
Nerve cell
Branched and 
long)
A tracheid
(elongated)
Mesophyll cells
(round and oval)
Typical bacteria
(1-2 µ)
PPLO
(about 0.1 µ)
Viruses
(0.02-0.2 µ)
A typical eukaryotic cell
(10-20 µ)
PROKARYOTIC CELLS
 The prokaryotic cells are represented by bacteria, blue-green algae, mycoplasma or PPLO (Pleuro Pneumonia
Like Organisms). They are generally smaller and multiply more rapidly than the eukaryotic cells.
 The organisation of the prokaryotic cell is fundamentally similar even though prikaryotes exhibit a wide variety
of shapes and functions.
EUKARYOTIC CELLS
 The eukaryotes include all the protists, plants, animals and fungi. In eukaryotic cells there is an
extensive compartmentalisation of cytoplasm through the presence of membrane bound organelles.
 Eukaryotic cells possess an organised nucleus with a nuclear envelope. In addition, eukaryotic cells have a
variety of complex locomotory and cytoskeletal structures. Their genetic material is organised into
chromosomes.
 All eukaryotic cells are not identical. Plant and animal cells are different as the former possess cell walls,
plastids and a large central vacuole which are absent in animal cells. On the other hand, animal cells
have centrioles which are absent in almost all higher plant cells.
Page 5


Session 2019-20
ALLEN
S.No.                CONTENTS Page
1. What is cell ? and cell theory 179
2. Cell membrane 182
3. Cell wall 185
4. Endomembranous system 187
(i) Endoplasmic reticulum 187
(ii) Golgi apparatus 189
(iii) Lysosome 190
(iv) Vacuole 192
5. Mitochondria 193
6. Plastid 195
7. Ribosome 198
8. Cytoskeleton 199
(i) Microtubules 199
(ii) Micro filament 199
(iii) Intermediate filament 199
9. Cilia and flagella 199
10. Centrosome and centriole 200
11. Microbodies 201
12. Nucleus 202
13. Chromosome 204
14. Exercise-I (Conceptual Questions) 209
15. Exercise-II (Previous Y ears Questions) 216
16. Exercise-III (Analytical Questions) 223
17. Exercise-IV (Assertion & Reason) 226
18. Cell cycle, Mitosis 228
19. Meiosis 235
20. Exercise-I (Conceptual Questions) 242
21. Exercise-II (Previous Y ears Questions) 247
22. Exercise-III (Analytical Questions) 251
23. Exercise-IV (Assertion & Reason) 253
CELL BIOLOGY
E
NEET SYLLABUS
CELL STRUCTURE AND FUNCTION : Cell theory and cell as the basic unit of life; Structure of prokaryotic and
eukaryotic cell; Plant cell and animal cell; Cell envelope, cell membrane, cell wall; Cell organelles-structure and
function; Endomembrane system-endoplasmic reticulum, Golgi bodies, lysosomes, vacuoles; mitochondria, ribosomes,
plastids, micro bodies; Cytoskeleton, cilia, flagella, centrioles (ultra structure and function); Nucleus-nuclear
membrane, chromatin, nucleolus.
CELL DIVISION : Cell cycle, mitosis, meiosis and their significance.
Session 2019-20
ALLEN
In 1837, Matthias Jakob Schleiden viewed and stated that new plant cells are formed
from the nuclei of old plant cells. While dining that year with Schwann, the conversation turned on
the nuclei of plant and animal cells. Schwann remembered seeing similar structures (nuclei) in the
cells of the notochord and instantly realized the importance of connecting the two phenomena
(presence of nuclei and new cell formation). The resemblance was confirmed without delay by both
observers, and the results soon appeared in Schwann's famous microscopic investigations on the
accordance in the structure and growth of plants and animals, in which he declared that "All
living things are composed of cells and cell products". This became cell theory.
In 1855, pathologist Rudolf Virchow posed the maxim Omnis cellula e cellula that
every cell arises from pre-existing cells.
Theodore Schwann
(1810-1882)
Nationality : British
Matthias Jakob Schleiden
(1804-1881)
Nationality : German
Rudolf Carl Virchow
(1821-1902)
Nationality : Prussian (Germany)
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
179 E
Pre-Medical : Biology
ALLE N
CELL : THE UNIT OF LIFE
WHAT IS A CELL?
* All organisms are composed of cells. Some are composed of a single cell and are called unicellular organisms
while others, like us, composed of many cells, are called multicellular organisms.
* Unicellular organisms are capable of (i)  independent existence and (ii) performing the essential functions of life.
Anything less than a complete structure of a cell does not ensure independent living. Hence, cell is the fundamental
structural and functional unit of all living organisms.
* First cell discovered by - Robert Hooke in Cork
* Anton Von Leeuwenhoek first saw and described a live cell. Robert Brown later discovered the nucleus.
The invention of the microscope and its improvement leading to the electron microscope revealed all the
structural details of the cell.
CELL THEORY
* In 1838, Matthias Schleiden, a botanist, examined a large number of plants and observed that all plants are
composed of different kinds of cells which form the tissues of the plant. At about the same time, Theodore.
Schwann (1839), Zoologist, studied different types of animal cells and reported that cells had a thin outer layer
which is today known as the ?plasma membrane?. He also concluded, based on his studies on plant tissues, that
the presence of cell wall is a unique character of the plant cells.
* Schwann proposed the hypothesis that the bodies of animals and plants are composed of cells and products
of cells.
* Schleiden and Schwann together formulated the cell theory. This theory however, did not explain as to how
new cells were formed. Rudolf Virchow (1855) first explained that cells divided and new cells are formed
from pre-existing cells (Omnis cellula-e cellula). He modified the hypothesis of Schleiden and Schwann
to give the cell theory a final shape. Cell theory as understood today is:
(i) All living organisms are composed of cells and products of cells.
(ii) All cells arise from pre-existing cells.
AN OVERVIEW OF CELL
* The onion cell which is a typical plant cell, has a distinct cell wall as its outer boundary and just within it is the
cell membrane.
* Cells that have membrane bound nuclei are called eukaryotic whereas cells that lack a membrane bound
nucleus are prokaryotic.
* In both prokaryotic and eukaryotic cells, a semi-fluid matrix called cytoplasm occupies the volume of the cell.
* The cytoplasm is the main arena (zone) of cellular activities in both the plant and animal cells.
Various chemical reactions occur in it to keep the cell in the ?living state?.
* Besides the nucleus, the eukaryotic cells have other membrane bound distinct structures called
organelles like the endoplasmic reticulum (ER), the golgi complex, lysosomes, mitochondria,
microbodies. The prokaryotic cells lack such membrane bound organelles.
* Ribosomes are non-membrane bound organelles found in all cells both eukaryotic as well as prokaryotic
cell. Within the cell, ribosomes are found not only in the cytoplasm but also within the two organelles ?
chloroplasts (in plants) and mitochondria and on rough ER.
* Animal cells contain another non-membrane bound organelle called centriole which helps in cell division.
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
180 E
Pre-Medical : Biology
ALLE N
SIZE AND SHAPE OF CELL
Size :
 Cell differ greatly in size, shape and activites.
 Mycoplasma (Smallest cells) : Only 0.3 mm in length
 Bacteria = 3 to 5 mm
 Largest isolated single cell = egg of an ostrich.
 Human red blood cell » 7.0 mm in diameter
 Nerve cell = longest cell
Shape :
 The shape of the cell may vary with the function they perform.
 They may be disc-like, polygonal, columnar, cuboid, thread like or even irregular.
Red blood cells
(round and biconcave
White blood cells
(amoeboid)
Columnar epithelial cells
(long and narrow)
Nerve cell
Branched and 
long)
A tracheid
(elongated)
Mesophyll cells
(round and oval)
Typical bacteria
(1-2 µ)
PPLO
(about 0.1 µ)
Viruses
(0.02-0.2 µ)
A typical eukaryotic cell
(10-20 µ)
PROKARYOTIC CELLS
 The prokaryotic cells are represented by bacteria, blue-green algae, mycoplasma or PPLO (Pleuro Pneumonia
Like Organisms). They are generally smaller and multiply more rapidly than the eukaryotic cells.
 The organisation of the prokaryotic cell is fundamentally similar even though prikaryotes exhibit a wide variety
of shapes and functions.
EUKARYOTIC CELLS
 The eukaryotes include all the protists, plants, animals and fungi. In eukaryotic cells there is an
extensive compartmentalisation of cytoplasm through the presence of membrane bound organelles.
 Eukaryotic cells possess an organised nucleus with a nuclear envelope. In addition, eukaryotic cells have a
variety of complex locomotory and cytoskeletal structures. Their genetic material is organised into
chromosomes.
 All eukaryotic cells are not identical. Plant and animal cells are different as the former possess cell walls,
plastids and a large central vacuole which are absent in animal cells. On the other hand, animal cells
have centrioles which are absent in almost all higher plant cells.
Session 2019-20
ALLEN
Z:\NODE02\B0AI-B0\TARGET\BIO\ENG\MODULE_6\02-CELL-BIO\01-CELL-BIO.P65
181 E
Pre-Medical : Biology
ALLE N
Microvilli
Plasma
membrane
Centriole
Peroxisome
Lysosome
Ribosomes
Mitochondrion
Rough
endoplasmic
reticulum
Cytoplasm
Nucleus
Nucleolus
Nuclear
envelope
Smooth
endoplasmic
reticulum
Golgi
apparatus
Animal cell
Lysosome
Rough endoplasmic
reticulum
Nucleus
Nucleolus
Golgi
apparatus
Nuclear
envelope
Plasma
membrane
Vacuole
Middle lamella
Mitochondrion
Ribosomes
Chloroplast
Cytoplasm
Peroxisome
Microtubule
Plasmodesmata
Smooth
endoplasmic
reticulum
Cell wall
Plant cell
Read More
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