Rudolf Virchow proposed – Theory of cell lineage, Omnis cellula–e cellulae (all cells living cells are arises from pre-existing cells)
The cell is the structural, functional, and fundamental unit of an organism.
Cell theory – A cell is a basic unit of life that arises from pre-existing cells.
· Viruses are the exception to the cell theory.
· Viruses are the exception to the cell theory.
Cellular totipotency
· Cellular totipotency given by Haberlandts and Experimentally proved by Stewart et all.
· Ability of a vegetative cell to grow into a new plant.
· True nucleus is absent.
· Nucleus is an incipient type called Nucleoid. i.e, that lacks Nuclear membrane, Nuceloplasm and Nucleolus.
Note: Chondroid – primitive mitochondria, Viroid – primitive virus. (Viroids are the smallest infectious agent made up of nucleic acid only)
· DNA is single circular, double-stranded, non-repetitive (Absence of non-sense codon) and without histone protein.
· Membrane bounded cell organelles as mitochondria, chloroplast, nucleus etc. are absent.
· Ribosome is 70S (50S + 30S) type.
· Cell division is amitotic type (mitosis and meiosis absent).
· Respiratory and Photosynthetic enzymes are present in the plasma membrane
· Cilia and flagella are present but they lack 9 + 2 arrangement and tubulin protein, but flagellin is present instead of tubulin.
· Is dead and permeable – 1st observed by Robert Hooke (1665)
· In bacteria and cyanobacteria, the cell wall is made up of Peptidoglycan or Murein or Mucopeptide or Muramic acid
· Bacteria is the smallest organism with cell wall
· In fungi, it is made up of chitin or fungal cellulose
· In higher plants, it primarily contains cellulose and pectin suberin, lignin, etc. are other components
II. Primary cell wall
· Composition: cellulose and hemicellulose.
III Secondary cell wall:
· It builds up by the addition of extra cellulose layers on the inside surface of the primary cell wall.
· Made up of cellulose and hemicelluloses
Chemical composition of Cell Wall:
a. Cellulose – Polymer of β - glucose.
· Dujardian used the term – Sarcode
· Term protoplasm – by Purkinje
· Huxley defined it as the Physical basis of life
· It mainly contains water (75 – 85%)
· It coagulates above 60 – 70°C.
· Cytoplasm = matrix + cell organelles
· Cytoplasm without cell organelles is Hyaloplasm or Cytosol
· Cytoplasm is the site for glycolysis, synthesis of fatty acids, nucleotide
(ii) Smooth ER (SER)
· Ribosome is absent.
· Helps in the synthesis of fat and lipids
Functions of ER:
· Forms intracellular transport system
· Protein synthesis (RER), lipid synthesis (SER)
· Formation of Golgi body
2. Golgi Bodies
· Also known as Dictyosome, the Traffic police of cell.
· Discovered by - Camilo Golgi
· Is absent in prokaryotes, RBCs, Sieve tube.
Consists of
(a) Cisternae
(b) Tubules
(c) Vesicles
· Vesicles of SER form Golgi body.
· It helps in, the formation of cell plates (Especially vesicles)
· During cytokinesis, spindle protein + vesicles of Golgi body forms phragmoplast, which later changes into cell plate
· Helps in acrosome formation in sperm.
· Secretion of mucilage in root tip region that acts as a lubricant for root penetration.
· Formation of Nissle's granules (In the cyton of a nerve cell)
5. Glyoxisome
· Contains enzyme of Glyoxalate cycle
· Glyoxalate cycle: Conversion of fatty acids into carbohydrates in plants.
· Glyoxalate cycle is an example of Glyconeogenesis
· Gluconeogenesis (formation of glucose from Non-carbohydrate source)
· They are found in only germinating seeds
c. Grana
· Unit structure of grana is thylakoid
· Thylakoids contains no of Quantasomes or photosynthetic unit.
· Thylakoid is the structural unit of the chloroplast.
· It is the site for light reaction in photosynthesis
· Quntasomes is the functional unit of the chloroplast.
· Each Quatasome contains 280 photosynthetic pigments
· Grana are interconnected by means of stroma lamella or fret membrane.
280 photosynthetic pigments include:
a) 50 carotenoids
b) 230 chlorophylls
i) 160 Chl. a
ii) 70 Chl. b
Various Pigments in Details:
1. Chlorophyll a
· C55H72O5N4Mg
· Functional group – CH3
· Molecular weight – 893
· Main or universal photosynthetic pigment
· Present in all except Bacteria.
2. Chlorophyll b
· C55H70O6N4Mg
· Molecular weight – 907
· Functional group – CHO
3. Carotenoids
a. Carotene – orange and red color
C40H56
E.g. Lycopene, Capsanthin
b. Xanthophylls- yellow coloured
C40H56O2
10. Ribosomes:
· Protein factory of the cell.
· Smallest non-membranous cytoplasmic organelle
· Made up of – rRNA and protein.
· They are formed inside Nucleolus.
· rRNA synthesized in the nucleus.
· They are isolated from other cell organelles by the process of fractionation and ultracentrifugation.
· Measuring unit of the ribosome – Svedberg unit (s) to measure the sedimentation speed.
Various Type of Ribosomes:
A. 70s (50s + 30s)
· Found in prokaryotes mitochondria and chloroplast of eukaryotes
(ii) Euchromatin – lightly stained region of the chromosome which contains genetically active genes
· Each chromosome consists of an Arm and Centromere.
· Arm + Centromere = chromatid.
· Prophase and Metaphase stage of cell division, consists of two chromatids.
· At anaphase, each chromosome consists of one chromatid.
· Shape of the chromosome is studied during anaphase
· Number of chromosomes is studied during metaphase.
· Characteristics of chromosome (no, shape, the position of Centromere, size of arm) of an organism is karyotype.
· Diagrammatic representation of Karyotype in a sequence is known as idiogram.
· Cellular totipotency given by Haberlandts and Experimentally proved by Stewart et all.
· Ability of a vegetative cell to grow into a new plant.
Types of Cell
A. Prokaryotic cell: (Pro – Primitive, Karyon: nucleus)· True nucleus is absent.
· Nucleus is an incipient type called Nucleoid. i.e, that lacks Nuclear membrane, Nuceloplasm and Nucleolus.
Note: Chondroid – primitive mitochondria, Viroid – primitive virus. (Viroids are the smallest infectious agent made up of nucleic acid only)
· DNA is single circular, double-stranded, non-repetitive (Absence of non-sense codon) and without histone protein.
· Membrane bounded cell organelles as mitochondria, chloroplast, nucleus etc. are absent.
· Ribosome is 70S (50S + 30S) type.
· Cell division is amitotic type (mitosis and meiosis absent).
· Respiratory and Photosynthetic enzymes are present in the plasma membrane
· Cilia and flagella are present but they lack 9 + 2 arrangement and tubulin protein, but flagellin is present instead of tubulin.
E.g. Bacteria and Blue-green algae (Cyanobacteria)
B. Eukaryotic Cell
· True nucleus is present which contains nuclear membrane, nucleolus, and nucleoplasm.
· DNA is linear, double-stranded, repetitive (Presence of non-sense codon) with his tone protein
· Membrane bounded cell organelles like mitochondria; chloroplast, lysosome etc. are present.
NOTE: Ribosome is 70S (50S + 30S) type in mitochondria and chloroplast and 80S (60S + 40 S) type in the nucleus, 80S = cytoplasmic Ribosomes, 70S = organelles.
· Cell division – Mitosis and Meiosis type
· Respiratory and photosynthetic enzymes are located in mitochondria and chloroplast respectively.
C. Mesokaryotic Cell
B. Eukaryotic Cell
· True nucleus is present which contains nuclear membrane, nucleolus, and nucleoplasm.
· DNA is linear, double-stranded, repetitive (Presence of non-sense codon) with his tone protein
· Membrane bounded cell organelles like mitochondria; chloroplast, lysosome etc. are present.
NOTE: Ribosome is 70S (50S + 30S) type in mitochondria and chloroplast and 80S (60S + 40 S) type in the nucleus, 80S = cytoplasmic Ribosomes, 70S = organelles.
· Cell division – Mitosis and Meiosis type
· Respiratory and photosynthetic enzymes are located in mitochondria and chloroplast respectively.
C. Mesokaryotic Cell
· Behaving like both Prokaryotic and Eukaryotic cells.
· Nuclear membrane is present. (Eukaryotic)
· DNA is without Histone. (Prokaryotic)
· Nuclear membrane is present. (Eukaryotic)
· DNA is without Histone. (Prokaryotic)
E.g. class Dinophyceae of algae.
Difference Between Prokaryotic and Eukaryotic cell
| Characteristic | Prokaryotic Cells | Eukaryotic Cells |
|---|---|---|
| Nucleus | No | Yes |
| Membrane-Bound Organelles | No | Yes |
| Size of Ribosomes | 70s | 80s |
| Cell wall composition | Peptidoglycan is present | No peptidoglycan |
| Mitotic division | No | Yes |
| DNA associated with histones | No | Yes |
| Number of chromosomes | One | More than one |
| Cell membrane composition | No sterols (except in mycoplasmas) | Sterols present |
| Number of cells | Usually unicellular | Usually multicellular |
| Size of cell | Smaller (1-5 µm) | Larger (10 - 100 µm) |
Differences between Plant and Animal cells
| Animal cell | Plant cell |
|---|---|
| 1. Cell wall absent. Cellulose in any form is also absent. | Cellulose cell wall is present in plant cells. |
| 2. Cytoplasm is denser, more granular and occupies most of the space in the cell. | The cytoplasm is pushed to the periphery and forms a thin lining against the cell wall. |
| 3. Vacuoles absent. If present, they are small, temporary and concerned with excretion or secretion. | Vacuoles are large and prominent. Maybe one or more. |
| 4. Plastids are absent. | Plastids are generally present. |
| 5. Centrosome is present with one or two centrioles. | The centrosome is absent but two small clear areas called polar caps are present. These participate in cell division. |
| 6. Prominent and highly complex Golgi bodies present near the nucleus. | Several subunits of the Golgi apparatus called dictyosomes are present. |
| 7. Reserve food stored in the form of glycogen. | Reserve food stored in the form of starch. |
 |
| Fig: Showing plant cell structure |
1. Cell Wall
· Common in plants, bacteria, cyanobacteria and fungi· Is dead and permeable – 1st observed by Robert Hooke (1665)
· In bacteria and cyanobacteria, the cell wall is made up of Peptidoglycan or Murein or Mucopeptide or Muramic acid
· Bacteria is the smallest organism with cell wall
· In fungi, it is made up of chitin or fungal cellulose
· In higher plants, it primarily contains cellulose and pectin suberin, lignin, etc. are other components
In higher plants, the cell wall consists of
I. Middle lamellae.
· Common wall between adjacent cells.
· Made up of calcium pectate (mainly) and magnesium pectate
· It holds the neighbouring cell walls together.
I. Middle lamellae.
· Common wall between adjacent cells.
· Made up of calcium pectate (mainly) and magnesium pectate
· It holds the neighbouring cell walls together.
II. Primary cell wall
· Composition: cellulose and hemicellulose.
· lies inside middle lamellae
· Meristematic and parenchymatous cells have this type of wall only
· Meristematic and parenchymatous cells have this type of wall only
III Secondary cell wall:
· It builds up by the addition of extra cellulose layers on the inside surface of the primary cell wall.
· Made up of cellulose and hemicelluloses
 |
| Fig: Cell wall |
IV. Plasmodesmata
· Reported by Strasburger (1901 A.D)
· Intercom of cell
· Protoplasmic connection or cytoplasmic bridge between two adjacent cells.
· Exchange of materials takes place through it.
· Modification of cell membrane
Note: Dead cells are interconnected by pits.
· Reported by Strasburger (1901 A.D)
· Intercom of cell
· Protoplasmic connection or cytoplasmic bridge between two adjacent cells.
· Exchange of materials takes place through it.
· Modification of cell membrane
Note: Dead cells are interconnected by pits.
Chemical composition of Cell Wall:
a. Cellulose – Polymer of β - glucose.
· Cellulose – most abundant carbohydrate in the biosphere
· Rubisco – the most abundant protein in the biosphere
· Structural unit of the cell wall is cellulose
b. Hemicellulose – Binding material in cell wall
c. Pectin – in collenchyma
d. Cuticle
· Found in the exposed part of the plants
· Thick layered in Xerophytes
· Thin layer or absence in Hydrophytes
e. Suberin – in endodermal cells and in cork cell
f. Lignin
· Provided tensile strength
· Found in Sclerenchymatous cells, Tracheids, and vessels.
g. Silica – Leaf cell of grasses
· Nature of cell wall is fully permeable except cork cell wall, which is impermeable due to the deposition of suberin.
Function – Gives mechanical support i.e. exoskeleton of the cell.
· Made up of phospholipids and proteins.
· Often called a biological membrane.
· Rubisco – the most abundant protein in the biosphere
· Structural unit of the cell wall is cellulose
b. Hemicellulose – Binding material in cell wall
c. Pectin – in collenchyma
d. Cuticle
· Found in the exposed part of the plants
· Thick layered in Xerophytes
· Thin layer or absence in Hydrophytes
e. Suberin – in endodermal cells and in cork cell
f. Lignin
· Provided tensile strength
· Found in Sclerenchymatous cells, Tracheids, and vessels.
g. Silica – Leaf cell of grasses
· Nature of cell wall is fully permeable except cork cell wall, which is impermeable due to the deposition of suberin.
Function – Gives mechanical support i.e. exoskeleton of the cell.
2. Cell membrane / Plasma membrane
· Forms outermost boundary of animal cells· Made up of phospholipids and proteins.
· Often called a biological membrane.
Different models proposed are
1. Unit Membrane model- By Robertson
2. Trilaminar or Sandwich model- By Danillae and Davson
3. Fluid mosaic model - By Singer and Nicholson
· Cell membrane is modified into Mesosome in bacteria
· Mesosome – A finger like the one project found in bacteria that helps in respiration
· Semi-permeable in nature
· Size of the molecule that can pass through the membrane is 1 – 15 Ã…
· It shows Bulk transport
1. Unit Membrane model- By Robertson
2. Trilaminar or Sandwich model- By Danillae and Davson
3. Fluid mosaic model - By Singer and Nicholson
· Cell membrane is modified into Mesosome in bacteria
· Mesosome – A finger like the one project found in bacteria that helps in respiration
· Semi-permeable in nature
· Size of the molecule that can pass through the membrane is 1 – 15 Ã…
· It shows Bulk transport
Bulk transport
(a) Exocytosis
· Removal of materials from cell to outside
· It is also called the cell-vomiting phenomenon
(a) Exocytosis
· Removal of materials from cell to outside
· It is also called the cell-vomiting phenomenon
(b) Endocytosis
Entry of materials from outside the cell
(i) Phagocytosis
· Entry of solid food
· It is also called the cell-eating process
(ii) Pinocytosis
· Entry of liquids
· It is also called the cell-drinking process
Entry of materials from outside the cell
(i) Phagocytosis
· Entry of solid food
· It is also called the cell-eating process
(ii) Pinocytosis
· Entry of liquids
· It is also called the cell-drinking process
3. Protoplasm
· Protoplasm = Cytoplasm + Nucleoplasm· Dujardian used the term – Sarcode
· Term protoplasm – by Purkinje
· Huxley defined it as the Physical basis of life
· It mainly contains water (75 – 85%)
· It coagulates above 60 – 70°C.
· Cytoplasm = matrix + cell organelles
· Cytoplasm without cell organelles is Hyaloplasm or Cytosol
· Cytoplasm is the site for glycolysis, synthesis of fatty acids, nucleotide
Largest Component of the Cell – Nucleus
Largest Cell organelles in Plants – Chloroplast
Largest Cell organelles in Animals – Mitochondria
Smallest cell organelles – Ribosome
Largest Cell organelles in Plants – Chloroplast
Largest Cell organelles in Animals – Mitochondria
Smallest cell organelles – Ribosome
Membranes present in the Cell organelles:
A. The membrane is absent in
· Ribosomes
· Centrioles (Microtubules + Microfilament)
· Nucleolus
B. Double membrane is found in
1. Mitochondria
2. Chloroplast
3. Nucleolus
C. Single membrane-bounded organelles
a. Endoplasmic Reticulum (ER)
b. Golgi body
c. Lysosome
d. Peroxisomes
e. Glyoxisome
f. Sphaerosomes, etc
The vacuole is also a single membrane-bounded but sometimes it is not considered a cell organelle.
· Ribosomes
· Centrioles (Microtubules + Microfilament)
· Nucleolus
B. Double membrane is found in
1. Mitochondria
2. Chloroplast
3. Nucleolus
C. Single membrane-bounded organelles
a. Endoplasmic Reticulum (ER)
b. Golgi body
c. Lysosome
d. Peroxisomes
e. Glyoxisome
f. Sphaerosomes, etc
The vacuole is also a single membrane-bounded but sometimes it is not considered a cell organelle.
Cell organelles
1. ER (Endoplasmic Reticulum):· Cytoskeleton or Endoskeleton of a cell
· 1st observed by Porter
Consists of
(a) Cisternae – are not parallel to each other
(b) Tubules
(c) Vesicles
· It is a continuous structure between Nuclear membrane and Cell membrane
· ER continue from one cell to another cell by means of a pore called Desmotubules
· 1st observed by Porter
Consists of
(a) Cisternae – are not parallel to each other
(b) Tubules
(c) Vesicles
· It is a continuous structure between Nuclear membrane and Cell membrane
· ER continue from one cell to another cell by means of a pore called Desmotubules
Types of ER
(i) Rough ER (RER)
· Ribosome is attached to ER
· Helps in protein synthesis
(i) Rough ER (RER)
· Ribosome is attached to ER
· Helps in protein synthesis
(ii) Smooth ER (SER)
· Ribosome is absent.
· Helps in the synthesis of fat and lipids
Functions of ER:
· Forms intracellular transport system
· Protein synthesis (RER), lipid synthesis (SER)
· Formation of Golgi body
 |
| Fig: Showing endoplasmic reticulum |
2. Golgi Bodies
· Also known as Dictyosome, the Traffic police of cell.
· Discovered by - Camilo Golgi
· Is absent in prokaryotes, RBCs, Sieve tube.
Consists of
(a) Cisternae
(b) Tubules
(c) Vesicles
· Vesicles of SER form Golgi body.
· It helps in, the formation of cell plates (Especially vesicles)
· During cytokinesis, spindle protein + vesicles of Golgi body forms phragmoplast, which later changes into cell plate
· Helps in acrosome formation in sperm.
· Secretion of mucilage in root tip region that acts as a lubricant for root penetration.
· Formation of Nissle's granules (In the cyton of a nerve cell)
 |
| Fig: Golgi apparatus |
3. Lysosomes
· Discovered by C. De Duve
· Formed from Golgi body
· Also called suicidal bag of the cell
· Rich in hydrolytic enzyme, contains about 50 types of hydrolytic enzymes.
· Hydrolytic enzyme helps in hydrolysis i.e., digestion
· Common in animals
- Primary lysosome – formed from Golgi body.
- Secondary lysosome – primary lysosome + food vacuole
- Autophagic vacuole – when a lysosome contains a part of its own cell (generally unwanted structure) and digests it, it is called the Autophagic vacuole
- Residual body – Lysosome with indigestible materials which, helps in exo-cytosis.
· Discovered by C. De Duve
· Formed from Golgi body
· Also called suicidal bag of the cell
· Rich in hydrolytic enzyme, contains about 50 types of hydrolytic enzymes.
· Hydrolytic enzyme helps in hydrolysis i.e., digestion
· Common in animals
- Primary lysosome – formed from Golgi body.
- Secondary lysosome – primary lysosome + food vacuole
- Autophagic vacuole – when a lysosome contains a part of its own cell (generally unwanted structure) and digests it, it is called the Autophagic vacuole
- Residual body – Lysosome with indigestible materials which, helps in exo-cytosis.
Function of Lysosomes:
· Extracellular and intracellular digestion.
· Digestion of harmful substances.
· Involves in Autolysis
Autolysis: self-destruction during starvation
· Extracellular and intracellular digestion.
· Digestion of harmful substances.
· Involves in Autolysis
Autolysis: self-destruction during starvation
4. Peroxisome/Microbodies
Contains enzyme Peroxidase and Catalase
Peroxidase: Helps in H2O2 formation.
Catalase: Helps in breakdown of H2O2
· Catalases are the fastest acting enzyme.
· In plants peroxisomes are involved in photorespiration.
· In animals, they involve in β - oxidation of fatty acid.
Note: β- oxidation of fatty acid means conversion of fatty acids into acetyl COA.
Contains enzyme Peroxidase and Catalase
Peroxidase: Helps in H2O2 formation.
Catalase: Helps in breakdown of H2O2
· Catalases are the fastest acting enzyme.
· In plants peroxisomes are involved in photorespiration.
· In animals, they involve in β - oxidation of fatty acid.
Note: β- oxidation of fatty acid means conversion of fatty acids into acetyl COA.
5. Glyoxisome
· Contains enzyme of Glyoxalate cycle
· Glyoxalate cycle: Conversion of fatty acids into carbohydrates in plants.
· Glyoxalate cycle is an example of Glyconeogenesis
· Gluconeogenesis (formation of glucose from Non-carbohydrate source)
· They are found in only germinating seeds
6. Sphaerosome
· Commonly called plant lysosome.
· Helps in synthesis and storage of lipids.
· They are common in cotyledons and endosperm of oily seeds.
· Commonly called plant lysosome.
· Helps in synthesis and storage of lipids.
· They are common in cotyledons and endosperm of oily seeds.
7. Vacuole
· common in plants.
· Vacuolar membrane is called Tonoplast (Semipermiable)
· Vacuolar sap, present in the vacuole, is called cell sap
Cell sap contains
(a) Water and minerals
(b) Pigments
· Anthocyanin is found in vacuole which is water-soluble
· Anthocyanin pigment is also called a vegetable chameleon.
· Different colours (Red, Blue, and Purple) of flower are due to Anthocyanin pigment)
· Red colour of Beetroot (Beta vulgaris) is due to anthocyanin
· It helps in Osmoregulation (water regulation) in protozoans. It contains the waste product or acts as food reserves
· common in plants.
· Vacuolar membrane is called Tonoplast (Semipermiable)
· Vacuolar sap, present in the vacuole, is called cell sap
Cell sap contains
(a) Water and minerals
(b) Pigments
· Anthocyanin is found in vacuole which is water-soluble
· Anthocyanin pigment is also called a vegetable chameleon.
· Different colours (Red, Blue, and Purple) of flower are due to Anthocyanin pigment)
· Red colour of Beetroot (Beta vulgaris) is due to anthocyanin
· It helps in Osmoregulation (water regulation) in protozoans. It contains the waste product or acts as food reserves
8. Plastid
· Discovered by Haeckel
· Found in plant cell only
· Is the semi-autonomous unit
· Develops from pro plastid found in meristematic regions.
· Discovered by Haeckel
· Found in plant cell only
· Is the semi-autonomous unit
· Develops from pro plastid found in meristematic regions.
A. Chloroplast
Common in almost all photosynthetic organisms except blue-green algae and photosynthetic bacteria.
In the case of photosynthetic bacteria and cyanobacteria, pigments are found in chromatophores or photosynthetic lamella.
· Chloroplast contains chlorophyll and carotenoid pigments.
Common in almost all photosynthetic organisms except blue-green algae and photosynthetic bacteria.
In the case of photosynthetic bacteria and cyanobacteria, pigments are found in chromatophores or photosynthetic lamella.
· Chloroplast contains chlorophyll and carotenoid pigments.
Various Shape of Chloroplast
a. Cup-shaped – in Chlamydomonas
b. Spiral (Ribbon shaped) – in Spirogyra
c. Reticulate (Net shaped) – in Oedogonium
d. Star-shaped – in Zygnema
e. Girdle shaped or Horseshoe-shaped – in Ulothrix
f. Spherical chloroplast – in Chlorella
a. Cup-shaped – in Chlamydomonas
b. Spiral (Ribbon shaped) – in Spirogyra
c. Reticulate (Net shaped) – in Oedogonium
d. Star-shaped – in Zygnema
e. Girdle shaped or Horseshoe-shaped – in Ulothrix
f. Spherical chloroplast – in Chlorella
Number of Chloroplast Present:
· Internal structure consists of grana, stroma, inter-granal lamellae/stroma lamellae etc.
- Single in – Chlamydomonas
- Maximum in – mesophyll cell of the leaf
· Internal structure consists of grana, stroma, inter-granal lamellae/stroma lamellae etc.
b. Stroma
· All enzymes of dark reactions are found in stroma.
· It is the ground substance of chloroplast
· It can synthesize a few proteins
· It contains DNA, RNA and ribosome (70S). This DNA helps in the division of chloroplast to some extent but not completely, so it is called a semi-autonomous unit.
· All enzymes of dark reactions are found in stroma.
· It is the ground substance of chloroplast
· It can synthesize a few proteins
· It contains DNA, RNA and ribosome (70S). This DNA helps in the division of chloroplast to some extent but not completely, so it is called a semi-autonomous unit.
c. Grana
· Unit structure of grana is thylakoid
· Thylakoids contains no of Quantasomes or photosynthetic unit.
· Thylakoid is the structural unit of the chloroplast.
· It is the site for light reaction in photosynthesis
· Quntasomes is the functional unit of the chloroplast.
· Each Quatasome contains 280 photosynthetic pigments
· Grana are interconnected by means of stroma lamella or fret membrane.
280 photosynthetic pigments include:
a) 50 carotenoids
b) 230 chlorophylls
i) 160 Chl. a
ii) 70 Chl. b
Various Pigments in Details:
1. Chlorophyll a
· C55H72O5N4Mg
· Functional group – CH3
· Molecular weight – 893
· Main or universal photosynthetic pigment
· Present in all except Bacteria.
2. Chlorophyll b
· C55H70O6N4Mg
· Molecular weight – 907
· Functional group – CHO
3. Carotenoids
a. Carotene – orange and red color
C40H56
E.g. Lycopene, Capsanthin
b. Xanthophylls- yellow coloured
C40H56O2
B. Chromoplast
· Colored plastid
· Formed either from chloroplast or from leucoplast.
· Conversion of chloroplast into chloroplast e.g., conversion of green tomatoes to red and green chillies to red
· Conversion of leucoplast into chromoplast. e.g. carrot
· Green chillies changed into red due to pigment capsanthin
· Green tomato changes into the red due to Pigment lycopene.
Other coloured plastids are
a. Phaeoplast- found in brown algae, main pigment phaeoxanthin
b. Rhodoplast – Red plastid found in Red algae. The main pigment is phycoerythrin.
c. Phycocyanin- Blue-green pigment in cyanobacteria (BGA)
· Colored plastid
· Formed either from chloroplast or from leucoplast.
· Conversion of chloroplast into chloroplast e.g., conversion of green tomatoes to red and green chillies to red
· Conversion of leucoplast into chromoplast. e.g. carrot
· Green chillies changed into red due to pigment capsanthin
· Green tomato changes into the red due to Pigment lycopene.
Other coloured plastids are
a. Phaeoplast- found in brown algae, main pigment phaeoxanthin
b. Rhodoplast – Red plastid found in Red algae. The main pigment is phycoerythrin.
c. Phycocyanin- Blue-green pigment in cyanobacteria (BGA)
C. Leucoplast
· Colorless plastid
· Stores reserve food materials.
· Usually found in underground parts of plants.
Types of Leucoplast:
i) Amyloplast- stores carbohydrates or starch egg. i.e. Rice, wheat, potato etc.
ii) Protinoplast or Aleuronoplast - stores protein - e.g. maize grains
· Colorless plastid
· Stores reserve food materials.
· Usually found in underground parts of plants.
Types of Leucoplast:
i) Amyloplast- stores carbohydrates or starch egg. i.e. Rice, wheat, potato etc.
ii) Protinoplast or Aleuronoplast - stores protein - e.g. maize grains
iii) Elaioplast (or oleosomes): stores lipids coil) as in cells of endosperm in caster.
 |
| Fig: Showing plastid |
9. Mitochondria
· Powerhouse of the cell
· Semi-Autonomous unit
· Autonomous unit – Nucleus
· Semi-Autonomous unit – Mitochondria and Chloroplast
· Altman named them as Biplasts.
· Powerhouse of the cell
· Semi-Autonomous unit
· Autonomous unit – Nucleus
· Semi-Autonomous unit – Mitochondria and Chloroplast
· Altman named them as Biplasts.
· Discovered by Kolliker
· Benda gave the name mitochondria.
· DNA is circular and double-stranded & Ribosomes are 70s type
· Found in all except RBCS and prokaryotes.
· Double membranous structure consists of two chambers i.e., outer chamber, and inner chamber
· Inner membrane projected into the central space in the form of a finger-like projection called cristae. This membrane contains enzymes of the electron transport chain.
· Each crista contains elementary particles or oxysomes.
· Oxisomes are called the functional unit of mitochondria
· Oxisomes contains
a) Head
b) stalk
c) Base
a. Head:
· Contains F1 particles site for ETS (electron transport system)
· Inner membrane encloses inner chamber, which is called matrix. Which is filled with DNA, ribosomes (70S) most of the catabolic enzymes controlling the Krebs cycle and fatty acid oxidation.
· Matrix is the site for Krebs cycle.
· About 70% of the total cell enzymes are found in mitochondria.
· Metabolically most active cell organelle is mitochondria.
· Mitochondria involves in cellular respiration
· All the mitochondria present in the cell are collectively called Chondriome
Functions of Mitochondria:
· Site for Krebs cycle in respiration contains all the enzymes, which brings about oxidative phosphorylation (formation of ATP)
· Forms middle piece of sperm (the engine of sperm)
· Benda gave the name mitochondria.
· DNA is circular and double-stranded & Ribosomes are 70s type
· Found in all except RBCS and prokaryotes.
· Double membranous structure consists of two chambers i.e., outer chamber, and inner chamber
· Inner membrane projected into the central space in the form of a finger-like projection called cristae. This membrane contains enzymes of the electron transport chain.
· Each crista contains elementary particles or oxysomes.
· Oxisomes are called the functional unit of mitochondria
· Oxisomes contains
a) Head
b) stalk
c) Base
a. Head:
· Contains F1 particles site for ETS (electron transport system)
· Inner membrane encloses inner chamber, which is called matrix. Which is filled with DNA, ribosomes (70S) most of the catabolic enzymes controlling the Krebs cycle and fatty acid oxidation.
· Matrix is the site for Krebs cycle.
· About 70% of the total cell enzymes are found in mitochondria.
· Metabolically most active cell organelle is mitochondria.
· Mitochondria involves in cellular respiration
· All the mitochondria present in the cell are collectively called Chondriome
Functions of Mitochondria:
· Site for Krebs cycle in respiration contains all the enzymes, which brings about oxidative phosphorylation (formation of ATP)
· Forms middle piece of sperm (the engine of sperm)
 |
| Fig: Mitochondria |
10. Ribosomes:
· Protein factory of the cell.
· Smallest non-membranous cytoplasmic organelle
· Made up of – rRNA and protein.
· They are formed inside Nucleolus.
· rRNA synthesized in the nucleus.
· They are isolated from other cell organelles by the process of fractionation and ultracentrifugation.
· Measuring unit of the ribosome – Svedberg unit (s) to measure the sedimentation speed.
Various Type of Ribosomes:
A. 70s (50s + 30s)
· Found in prokaryotes mitochondria and chloroplast of eukaryotes
B. 80s (60s + 40s )
· Found in Eukaryotic Nucleus
· Two ribosomal subunits are joined by Mg+2
· During protein synthesis a number of ribosomes are found to attach within RNA called polysome.
· Ribosome provides the site for protein synthesis.
· Found in Eukaryotic Nucleus
· Two ribosomal subunits are joined by Mg+2
· During protein synthesis a number of ribosomes are found to attach within RNA called polysome.
· Ribosome provides the site for protein synthesis.
 |
| Fig: Showing Ribosome |
11. Centrioles:
· Common in animals and lower plants but absent in higher plants.
· Always found in pair called Diplosome.
· Centrospheres and centrioles (perpendicular to each other) form centrosomes.
· They are made up of protein tubulin
· Centriole helps in spindle fibre and astral rays' formation during cell division.
· The cell of higher plants do not have centrioles but still form spindle fibres (microtubules are responsible for spindle fibre formation).
· Arrangement of microtubules in centriole and structure of the basal body is (9+0) arrangement
· Centrioles give rise to basal bodies, which give rise to cilia and flagella.
· Common in animals and lower plants but absent in higher plants.
· Always found in pair called Diplosome.
· Centrospheres and centrioles (perpendicular to each other) form centrosomes.
· They are made up of protein tubulin
· Centriole helps in spindle fibre and astral rays' formation during cell division.
· The cell of higher plants do not have centrioles but still form spindle fibres (microtubules are responsible for spindle fibre formation).
· Arrangement of microtubules in centriole and structure of the basal body is (9+0) arrangement
· Centrioles give rise to basal bodies, which give rise to cilia and flagella.
12. Cilia and Flagella:
· Eukaryotic cilia and flagella are made up of protein tubulin.
· Arrangement of microtubule: 9+2 in eukaryotes but in prokaryotes, they are made up of protein-flagellin so there are no microtubules and 9+2 arrangement.
· Eukaryotic cilia and flagella are made up of protein tubulin.
· Arrangement of microtubule: 9+2 in eukaryotes but in prokaryotes, they are made up of protein-flagellin so there are no microtubules and 9+2 arrangement.
13. Nucleus:
· Controlling the centre of the cell.
· Discovered by Robert Brown.
· In prokaryotes, the nucleus is without a distinct nuclear membrane.
· In eukaryotic cells except for mature phloem sieve tube elements and mature RBC of mammals.
· Controlling the centre of the cell.
· Discovered by Robert Brown.
· In prokaryotes, the nucleus is without a distinct nuclear membrane.
· In eukaryotic cells except for mature phloem sieve tube elements and mature RBC of mammals.
Made up of
(i) Nuclear membrane
· Often called Nuclear envelop or Karyotheca.
· It is a perforated double membranous structure that encloses nuclear content.
(i) Nuclear membrane
· Often called Nuclear envelop or Karyotheca.
· It is a perforated double membranous structure that encloses nuclear content.
(ii) Nucleoplasm
· Ground substance of Nucleus.
· Ground substance of Nucleus.
(iii) Nucleolus
· Membrane less structure.
· Also called ribosomal factory of the cell. however, protein synthesis occurs inside the nucleus.
· Made up of DNA, RNA and protein.
· Formed spindle fibre during the cell division.
· Membrane less structure.
· Also called ribosomal factory of the cell. however, protein synthesis occurs inside the nucleus.
· Made up of DNA, RNA and protein.
· Formed spindle fibre during the cell division.
(iv) Chromatin
· Composed of coils of DNA bound to a basic protein called his tones.
· During cell division, Chromatin Network condenses into a thread or a rod-like structure called a chromosome.
· Waldeyer coined the term chromosome Johnson coined the term gene.
· Morgan: Discovered that genes are Linearly arranged in the chromosome
· Best stage for the study of chromosome – Metaphase.
· Interphase – is the best stage for the nuclear study.
· In ultrastructure – chromatin appears like beads on a string.
· Beaded structure is called Nucleosome. (DNA + histone)
· chromatin is the most stainable part of the nucleus, which is stained by Acetocarmine
· Composed of coils of DNA bound to a basic protein called his tones.
· During cell division, Chromatin Network condenses into a thread or a rod-like structure called a chromosome.
· Waldeyer coined the term chromosome Johnson coined the term gene.
· Morgan: Discovered that genes are Linearly arranged in the chromosome
· Best stage for the study of chromosome – Metaphase.
· Interphase – is the best stage for the nuclear study.
· In ultrastructure – chromatin appears like beads on a string.
· Beaded structure is called Nucleosome. (DNA + histone)
· chromatin is the most stainable part of the nucleus, which is stained by Acetocarmine
Types of Chromosomes:
(i) Heterochromatin – Dark stained chromatin.
· That contains genetically inactive genes.
(i) Heterochromatin – Dark stained chromatin.
· That contains genetically inactive genes.
(ii) Euchromatin – lightly stained region of the chromosome which contains genetically active genes
· Each chromosome consists of an Arm and Centromere.
· Arm + Centromere = chromatid.
· Prophase and Metaphase stage of cell division, consists of two chromatids.
· At anaphase, each chromosome consists of one chromatid.
· Shape of the chromosome is studied during anaphase
· Number of chromosomes is studied during metaphase.
· Characteristics of chromosome (no, shape, the position of Centromere, size of arm) of an organism is karyotype.
· Diagrammatic representation of Karyotype in a sequence is known as idiogram.
Structure of Chromosome:
1. Telomere – terminal non–sticky end of the chromosome.
2. Pellicle – the sheath of the chromosome.
3. Centromere - primary constriction.
· It is an unstained region of chromosome
· Has plate-like structure – kinetochore
· Spindle fibres are attached to the kinetochore.
4. Secondary constriction:
· Nucleolus is developed at this point.
· It is often called NOR (Nucleolar organizer Region)
5. Satellite:
· It is the knob like structure near secondary constriction.
6. Chromonemata – DNA fibre inside the chromosome.
· Genome – the total no. of chromosomes present in the haploid cell or haploid set of chromosomes.
1. Telomere – terminal non–sticky end of the chromosome.
2. Pellicle – the sheath of the chromosome.
3. Centromere - primary constriction.
· It is an unstained region of chromosome
· Has plate-like structure – kinetochore
· Spindle fibres are attached to the kinetochore.
4. Secondary constriction:
· Nucleolus is developed at this point.
· It is often called NOR (Nucleolar organizer Region)
5. Satellite:
· It is the knob like structure near secondary constriction.
6. Chromonemata – DNA fibre inside the chromosome.
· Genome – the total no. of chromosomes present in the haploid cell or haploid set of chromosomes.
Type of chromosome based on the position of Centromere:
(a) Telocentric.
· Centromere is terminal
· Chromosome with a single arm.
· "I" shaped or rod-shaped.
(b) Acrocentric
· Centromere is near the terminal end.
· 'j' shaped
(c) Sub metacentric
· Centromere near the centre
· 'L' shaped.
(d) Metacentric
· Centromere at the centre.
· Arms are equal-sized.
(e) Acentric
· Chromosome without centromere.
(a) Telocentric.
· Centromere is terminal
· Chromosome with a single arm.
· "I" shaped or rod-shaped.
(b) Acrocentric
· Centromere is near the terminal end.
· 'j' shaped
(c) Sub metacentric
· Centromere near the centre
· 'L' shaped.
(d) Metacentric
· Centromere at the centre.
· Arms are equal-sized.
(e) Acentric
· Chromosome without centromere.
· Autosome carries genes for the determination of somatic characters.
· 22 pairs of Autosomes in human
· 22 pairs of Autosomes in human
Sex chromosome or Heterosome or Allosome
· Takes part in sex determination.
· 1 pair of sex chromosomes in man.
· XX in female XY in male.
· Sex of the foetus is determined by 'Y' of sperm
· Takes part in sex determination.
· 1 pair of sex chromosomes in man.
· XX in female XY in male.
· Sex of the foetus is determined by 'Y' of sperm
· Holoandric gene: genes present in the 'Y' chromosome of male
E.g. gene of hypertrichosis (hair in-ear)
E.g. gene of hypertrichosis (hair in-ear)
Also, Read Notes of other Lessons in Botany: