BOTANY - THE CELL
PART 3
- (UPSC,TNPSC,TRB Imporatant Notes)
NUCLEOID
• In some organisms like bacteria, the nuclear region of the cell may be poorly defined due to the absence of a nuclear membrane. Such an undefined nuclear region containing only nucleic acids is called a Nucleoid.
• In some organisms like bacteria, the nuclear region of the cell may be poorly defined due to the absence of a nuclear membrane. Such an undefined nuclear region containing only nucleic acids is called a Nucleoid.
VACUOLES
• Empty structure in the cytoplasm is called vacuole. It could be single and big as in an onion cell (plant cell). Cheek cells (animal cells) have smaller vacuoles.
• Large vacuoles are common in plant cells. Vacuoles in animal cells are much smaller.
• Vacuoles are storage sacs for solid or liquid contents.
• The central vacuole of some plant cells may occupy 50-90% of the cell volume.
• In plant cells vacuoles are full of cell sap and provide turgidity [swollen and distended or congested] and rigidity to the cell.
• Many substances of importance in the life of the plant cell are stored in vacuoles. These include amino acids, sugars, various organic acids and some proteins.
• In single-celled organisms like amoeba, the food vacuole contains the food items that the amoeba has consumed.
• In some unicellular organisms, specialized vacuoles also play important roles in expelling excess water and some wastes from the cell
ENDOPLASMIC RETICULUM (ER)
• The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or long bags (vesicles).
• The ER membrane is similar in structure to the plasma membrane.
• There are two types of ER –– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).
1. Rough Endoplasmic Reticulum RER – Ribosomes
• RER looks rough under a microscope because it has particles called ribosomes attached to its surface.
• The ribosomes, which are present in all active cells, are the sites of protein manufacture.
• The manufactured proteins are then sent to various places in the cell depending on need, using the ER.
• The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or long bags (vesicles).
• The ER membrane is similar in structure to the plasma membrane.
• There are two types of ER –– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).
1. Rough Endoplasmic Reticulum RER – Ribosomes
• RER looks rough under a microscope because it has particles called ribosomes attached to its surface.
• The ribosomes, which are present in all active cells, are the sites of protein manufacture.
• The manufactured proteins are then sent to various places in the cell depending on need, using the ER.
2. Smooth Endoplasmic Reticulum SER
• The SER helps in the manufacture of fat molecules, or lipids, important for cell function.
• The SER helps in the manufacture of fat molecules, or lipids, important for cell function.
3. Functions of Endoplasmic Reticulum (ER)
• Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis.
• Some other proteins and lipids function as enzymes and hormones.
• Although the ER varies greatly in appearance in different cells, it always forms a network system.
• Thus, one function of the ER is to serve as channels for the transport of materials (especially proteins) between various regions of the cytoplasm or between the cytoplasm and the nucleus.
• The ER also functions as a cytoplasmic framework providing a surface for some of the biochemical activities of the cell.
• In the liver cells of the group of animals called vertebrates, SER plays a crucial role in detoxifying many poisons and drugs.
GOLGI APPARATUS OR GOLGI COMPLEX
• The golgi apparatus consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.
• These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system.
• The material synthesized near the ER is packaged and dispatched to various targets inside and outside the cell through the golgi apparatus.
• Its functions include the storage, modification and packaging of products in vesicles.
• In some cases, complex sugars may be made from simple sugars in the golgi apparatus.
• The golgi apparatus is also involved in the formation of lysosomes.
1. Lysosomes
• Lysosomes are a kind of waste disposal system of the cell.
• Lysosomes help to keep the cell clean by digesting any foreign material as well as worn-out cell organelles.
• Foreign materials entering the cell, such as bacteria or food, as well as old organelles end up in the lysosomes, which break them up into small pieces. Lysosomes are able to do this because they contain powerful digestive enzymes capable of breaking down all organic material.
• During the disturbance in cellular metabolism, for example, when the cell gets damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are also known as the ‘suicide bags’ of a cell.
• Structurally, lysosomes are membrane-bound sacs filled with digestive enzymes. These enzymes are made by RER.
MITOCHONDRIA
• Mitochondria are known as the powerhouse of the cell.
• The energy required for various chemical activities needed for life is released by mitochondria in the form of ATP (Adenosine Triphosphate) molecules.
[If Mitochondria is the Power Plant. ATP is the Electricity].
• ATP is known as the energy currency of the cell.
• The body uses energy stored in ATP for making new chemical compounds and for mechanical work.
• Mitochondria have two membrane coverings instead of just one.
• The outer membrane is very porous while the inner membrane is deeply folded. These folds create a large surface area for ATP-generating chemical reactions.
• Mitochondria are strange organelles in the sense that they have their own DNA and ribosomes. Therefore, mitochondria are able to make some of their own proteins [ribosomes prepare proteins].
• Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis.
• Some other proteins and lipids function as enzymes and hormones.
• Although the ER varies greatly in appearance in different cells, it always forms a network system.
• Thus, one function of the ER is to serve as channels for the transport of materials (especially proteins) between various regions of the cytoplasm or between the cytoplasm and the nucleus.
• The ER also functions as a cytoplasmic framework providing a surface for some of the biochemical activities of the cell.
• In the liver cells of the group of animals called vertebrates, SER plays a crucial role in detoxifying many poisons and drugs.
GOLGI APPARATUS OR GOLGI COMPLEX
• The golgi apparatus consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.
• These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system.
• The material synthesized near the ER is packaged and dispatched to various targets inside and outside the cell through the golgi apparatus.
• Its functions include the storage, modification and packaging of products in vesicles.
• In some cases, complex sugars may be made from simple sugars in the golgi apparatus.
• The golgi apparatus is also involved in the formation of lysosomes.
1. Lysosomes
• Lysosomes are a kind of waste disposal system of the cell.
• Lysosomes help to keep the cell clean by digesting any foreign material as well as worn-out cell organelles.
• Foreign materials entering the cell, such as bacteria or food, as well as old organelles end up in the lysosomes, which break them up into small pieces. Lysosomes are able to do this because they contain powerful digestive enzymes capable of breaking down all organic material.
• During the disturbance in cellular metabolism, for example, when the cell gets damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are also known as the ‘suicide bags’ of a cell.
• Structurally, lysosomes are membrane-bound sacs filled with digestive enzymes. These enzymes are made by RER.
MITOCHONDRIA
• Mitochondria are known as the powerhouse of the cell.
• The energy required for various chemical activities needed for life is released by mitochondria in the form of ATP (Adenosine Triphosphate) molecules.
[If Mitochondria is the Power Plant. ATP is the Electricity].
• ATP is known as the energy currency of the cell.
• The body uses energy stored in ATP for making new chemical compounds and for mechanical work.
• Mitochondria have two membrane coverings instead of just one.
• The outer membrane is very porous while the inner membrane is deeply folded. These folds create a large surface area for ATP-generating chemical reactions.
• Mitochondria are strange organelles in the sense that they have their own DNA and ribosomes. Therefore, mitochondria are able to make some of their own proteins [ribosomes prepare proteins].
PLASTIDS
• You might have noticed several small colored bodies in the cytoplasm of the cells of Tradescantia leaf. They are scattered in the cytoplasm of the leaf cells. These are called plastids.
• They are of different colours. Some of them contain green pigment called chlorophyll. Green coloured plastids are called chloroplasts. They provide green colour to the leaves.
• Chloroplasts are important for photosynthesis in plants.
• Chloroplasts also contain various yellow or orange pigments in addition to chlorophyll.
• Plastids are present only in plant cells. There are two types of plastids – chromoplasts (coloured plastids) and leucoplasts (white or colourless plastids).
• Leucoplasts are primarily organelles in which materials such as starch, oils and protein granules are stored.
• The internal organization of the plastids consists of numerous membrane layers embedded in a material called the stroma.
• Plastids are similar to mitochondria in external structure. Like the mitochondria, plastids also have their own dna and ribosomes.
• You might have noticed several small colored bodies in the cytoplasm of the cells of Tradescantia leaf. They are scattered in the cytoplasm of the leaf cells. These are called plastids.
• They are of different colours. Some of them contain green pigment called chlorophyll. Green coloured plastids are called chloroplasts. They provide green colour to the leaves.
• Chloroplasts are important for photosynthesis in plants.
• Chloroplasts also contain various yellow or orange pigments in addition to chlorophyll.
• Plastids are present only in plant cells. There are two types of plastids – chromoplasts (coloured plastids) and leucoplasts (white or colourless plastids).
• Leucoplasts are primarily organelles in which materials such as starch, oils and protein granules are stored.
• The internal organization of the plastids consists of numerous membrane layers embedded in a material called the stroma.
• Plastids are similar to mitochondria in external structure. Like the mitochondria, plastids also have their own dna and ribosomes.
SUMMARY
• Each cell acquires its structure and ability to function because of the organization of its membrane and organelles in specific ways. The cell thus has a basic structural organization. This helps the cells to perform functions like respiration, obtaining nutrition, and clearing of waste material, or forming new proteins. Thus, the cell is the fundamental structural unit of living organisms. It is also the basic functional unit of life.
• Cells are enclosed by a plasma membrane composed of lipids and proteins.
• The presence of the cell wall enables the cells of plants, fungi and bacteria to exist in hypotonic media without bursting.
• The ER functions both as a passage way for intracellular transport and as a manufacturing surface.
• The golgi apparatus consists of stacks of membrane-bound vesicles that function in the storage, modification and packaging of substances manufactured in the cell.
• Most plant cells have large membranous organelles called plastids, which are of two types – chromoplasts and leucoplasts.
• Chromoplasts that contain chlorophyll are called chloroplasts and they perform photosynthesis. Leucoplasts help in the storage of oils, starch and protein granules.
• Most mature plant cells have a large central vacuole that helps to maintain the turgidity of the cell and stores important substances including wastes.
• Prokaryotic cells have no membrane-bound organelles, their chromosomes are composed of only nucleic acid, and they have only very small ribosomes as organelles.
• A white blood cell (WBC) in human blood is an example of a single cell which can change its shape.
• Bacterial cell also has a cell wall.
• In egg white material is albumin which solidifies on boiling. The yellow part is yolk. It is part of the single cell.
• Valonia ventricosa, a species of algae with a diameter that ranges typically from 1 to 4 centimetres is among the largest unicellular species.
• Each cell acquires its structure and ability to function because of the organization of its membrane and organelles in specific ways. The cell thus has a basic structural organization. This helps the cells to perform functions like respiration, obtaining nutrition, and clearing of waste material, or forming new proteins. Thus, the cell is the fundamental structural unit of living organisms. It is also the basic functional unit of life.
• Cells are enclosed by a plasma membrane composed of lipids and proteins.
• The presence of the cell wall enables the cells of plants, fungi and bacteria to exist in hypotonic media without bursting.
• The ER functions both as a passage way for intracellular transport and as a manufacturing surface.
• The golgi apparatus consists of stacks of membrane-bound vesicles that function in the storage, modification and packaging of substances manufactured in the cell.
• Most plant cells have large membranous organelles called plastids, which are of two types – chromoplasts and leucoplasts.
• Chromoplasts that contain chlorophyll are called chloroplasts and they perform photosynthesis. Leucoplasts help in the storage of oils, starch and protein granules.
• Most mature plant cells have a large central vacuole that helps to maintain the turgidity of the cell and stores important substances including wastes.
• Prokaryotic cells have no membrane-bound organelles, their chromosomes are composed of only nucleic acid, and they have only very small ribosomes as organelles.
• A white blood cell (WBC) in human blood is an example of a single cell which can change its shape.
• Bacterial cell also has a cell wall.
• In egg white material is albumin which solidifies on boiling. The yellow part is yolk. It is part of the single cell.
• Valonia ventricosa, a species of algae with a diameter that ranges typically from 1 to 4 centimetres is among the largest unicellular species.
PLANT CELL vs ANIMAL CELL
Plant Cell :
Nucleus : Present
Cilia : Present
Shape : Round (irregular shape)
Chloroplast : Animal cells don’t have chloroplasts
Cytoplasm : Present
Endoplasmic Reticulum (Smooth and Rough) : Present
Ribosomes : Present
Mitochondria : Present
Vacuole : One or more small vacuoles (much smaller than plant cells).
Cilia : Present
Shape : Round (irregular shape)
Chloroplast : Animal cells don’t have chloroplasts
Cytoplasm : Present
Endoplasmic Reticulum (Smooth and Rough) : Present
Ribosomes : Present
Mitochondria : Present
Vacuole : One or more small vacuoles (much smaller than plant cells).
Animal Cell
Nucleus : Present
Cilia : It is very Rare
Shape : Rectangular (Fixed shape)
Chloroplast : Plant cells have chloroplasts because they make their own food
Cytoplasm : Present
Endoplasmic Reticulum (Smooth and Rough) : Present
Ribosomes : Present
Mitochondria : Present
Vacuole : One. large central vacuole taking up 90% of cell volume.
Nucleus : Present
Cilia : It is very Rare
Shape : Rectangular (Fixed shape)
Chloroplast : Plant cells have chloroplasts because they make their own food
Cytoplasm : Present
Endoplasmic Reticulum (Smooth and Rough) : Present
Ribosomes : Present
Mitochondria : Present
Vacuole : One. large central vacuole taking up 90% of cell volume.
Magme Guru is India's Biggest learning free App for Aspirants who are competing for all government exams with more than 2350+ Subjects and 523+ Exams.
No comments:
Post a Comment