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Fundamental Unit of Life-Cell- II
The document discusses the fundamental unit of life - the cell. It describes the nucleus, which contains nucleolus and chromatin. Organisms are classified as prokaryotic or eukaryotic based on their nuclear organization. The cytoplasm contains organelles that perform specific functions for the cell, such as the endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, ribosomes, plastids, and vacuoles. The nucleolus controls metabolic activities and inheritance, while chromatin condenses into chromosomes during cell division. Prokaryotes lack membrane-bound organelles and have a single chromosome, while eukaryotes have multiple chromosomes and organelles.
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Fundamental Unit of Life-Cell- II
- 1. FUNDAMENTAL UNIT OFLIFE-II
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- 3. NUCLEUS It isthe dense spherical structure embedded in the cytoplasm. Nucleus has double membraned envelope called Nuclear envelope. Nuclear envelope encloses a ground substance called Nucleoplasm or Karyolymph. The nuclear envelope possess many pores called as Nuclear pores. The Nucleoplasm has two types of structures Nucleolus & Chromatin
- 4. NUCLEOLUS Spherical bodyrich in proteins and RNA. It is the site of ribosome formation. There may be one or more nucleoli in the nucleoplasm. Function of Nucleolus It controls all the metabolic activities of the cell. It controls the inheritance of characters from parents to the offspring. It controls cell division
- 5. CHROMATIN The chromatin isthe network of fine threads composed of genetic material DNA (Deoxyribo nucleic acid) and proteins. During cell division chromatin condenses into thick cord like structure called chromosomes.
- 6. PROKARYOTIC & EUKARYOTIC ORGANISMS Based on the complexity of the nuclear organisation the cells are classified into Prokaryotic organisms & Eukaryotic organisms
- 7. DIFFERENCE BETWEEN PROKARYOTIC& EUKARYOTIC ORGANISM PROKARYOTIC ORGANISM EUKARYOTIC ORGANISM Size generally small : 1-10M Size generally large (5-100M) Nuclear region : Not well defined and not surrounded by a nuclear membrane & known as Nucleoids. Nuclear region : Well defined and surrounded by a nuclear membrane Chromosome : single Chromosome : More than one Membrane bound organelles absent Membrane bound organelles present.
- 8. OTHER DIFFERENCES BETWEEN PROKARYOTIC& EUKARYOTIC ORGANISM
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- 10. CYTOPLASM The cytoplasmis the fluid content inside the plasma membrane. It also contains many specialised cell organelles. Each of these organelles performs a specific function for the cell. Cell organelles are enclosed by membranes Functions Cytoplasm helps in removal of waste material. Synthesis of different types of biomolecules such as proteins, fatty acids, etc occur in the cytoplasm. Helps in cell respiration, conversion of glucose into energy.
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- 12. CELL ORGANELLES Acell performs various functions such as Synthesis of complex molecules and their breakdown Production of energy Secretion of certain substances, etc These activities of the cell are performed within specialised cell organelles that are enclosed by membranes. The various cell organelles include- Endoplasmic reticulum (Smooth ER & Rough ER) Golgi complex ( Golgi apparatus) Lysosomes Ribosomes Vacuoles Mitochondria Plastids Centrosome.
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- 14. ENDOPLASMIC RETICULUM Theendoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags (vesicles). The ER membrane is similar in structure to the plasma membrane. It is spread throughout the cytoplasm and is continuous with the plasma membrane and nuclear membrane. There are two types of ER - rough endoplasmic reticulum (RER) and - smooth endoplasmic reticulum (SER).
- 15. ENDOPLASMIC RETICULUM Functions RER looksrough 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 SER helps in the manufacture of fat molecules, or lipids, important for cell function. 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.
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- 17. GOLGI BODIES Discovered byCamillo Golgi. It consists of saucer like compartments called cisternae, network of interconnecting tubules, vesicles and vacuoles at the peripheral regions. In the plant cells, golgi apparatus are called as dictyosomes. Functions : It is involved in the formation of lysosomes. It is also responsible for the synthesis of cell membrane and cell wall
- 18. TRANSPORT OF PROTEINS Theproteins that are synthesized in the Rough endoplasmic reticulum are loaded on transport vesicle and leave the Endoplasmic reticulum for Golgi apparatus. The cis face ( side facing the ER is called cis face) receives the protein which is then modified inside the Golgi bodies. The modified proteins are then sent to their target destination through the trans face (side facing the plasma membrane) of Golgi apparatus by the secretory vesicles.
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- 20. LYSOSOMES Lysosomes are membranebound vesicles that contain various types of enzymes. These enzymes are made by RER. They are also called as digestive bags. They are produced jointly by the Endoplasmic reticulum & Golgi apparatus. If the membrane of the lysosome ruptures the digestive enzymes are released into the cell and the cell is destroyed. Hence they are also called as “Suicide bags’’. Function Lysosomes are involved in intracellular digestion of particles ingested by the cell through endocytosis. The lysosomes of WBC’s (White Blood Cells) destroy the pathogen that are ingested through endocytosis.
- 21. RIBOSOMES They aresmall granular structures that occur in cytoplasm. They are made up of RNA and proteins. They occur freely into the cytoplasm or are attached to the Endoplasmic Reticulum. It consists of two Subunits A large subunit A small subunit. Function. They are responsible for protein synthesis in the cytoplasm and the RER.
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- 23. MITOCHONDRIA Globular orcylindrical organelles. Mitochondria has its own DNA called as Mitochondrial DNA. Contain two membranes Outer membrane Inner membrane (which have finger like projections called as Cristae). The cristae contain F0-F1 particles which play important role in cellular respiration The inner chamber is filled with homogenous dense material called Matrix.
- 24. MITOCHONDRIA Functions : Theysynthesize energy rich compounds such as ATP. (hence are called as Power house of the Cell). ATP- Adenosine Tri Phosphate They provide important intermediates for the synthesis of biomolecules like Chlorophyll, Amino acids etc.
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- 26. PLASTIDS Disc shapedor oval organelles which occur only in plant cells. Plastids are of three types Leucoplasts : These are colourless plastids which store food in the form of starch, lipids and proteins. Chromoplasts : These are yellow or reddish in colour due to presence of pigments other than chlorophyll. They provide colour to flowers and fruits. Chloroplasts : These are the green colour plastids that contain chlorophyll and are responsible for Photosynthesis.
- 27. CHLOROPLAST Chloroplasts Location- Chloroplasts are the small disc- like/oval plastids/ cell organelles present in the green parts of plants. Membranes – double membrane (outer and inner) Stroma – Liquid matrix containing grana Grana – Stack of Thylakoids carrying pigments chlorophylls Stroma lamellae/Fret – Grana are joined by fret Pigments – Helps in harvesting light Starch – stored food.
- 28. HOWTO DRAW CHLOROPLAST…..? ULTRASTRUCTURE OF CHLOROPLAST Which part of chloroplast give the different colours to leaf …..?
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- 30. VACUOLES They arefluid filled sacs bound by a single membrane and are present in plants as well as in certain protozoans as food vacuoles and contractile vacuoles. In plant cell, major portion of the cell is occupied by vacuole that are bound by membrane called as tonoplast. Vacuoles are plants are filled with cell sap containing minerals, sugars, amino acids and dissolved waste materials. Functions : They maintain proper osmotic pressure in the cell for its turgidity and absorption of water. In single-celled organisms like Amoeba, the food vacuole contains the food items that the Amoeba has consumed. In some unicellular organisms, specialised vacuoles also play important roles in expelling excess water and some wastes from the cell.
- 32. SUMMARY Nucleus Nucleolus Chromatin Based onthe Nuclear Organisation organism are classified as Prokaryotic & Eukaryotic Organisms Cytoplasm : The jelly like matrix found inside the Cell/Plasma membrane is called cytoplasm. It contains several cell organelles such as Endoplasmic Reticulum Golgi Apparatus Mitochondria Lysosomes Plastids Ribosomes Vacuoles
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