Structure and functions of cell organelles
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The document discusses the structure and functions of cell organelles, highlighting the difference between prokaryotic and eukaryotic cells. It describes various organelles including the cell membrane, cytoplasm, mitochondria, nucleus, nucleolus, vacuoles, endoplasmic reticulum, golgi apparatus, ribosomes, lysosomes, cell wall, and plastids, detailing their functions and importance in cellular processes. Key functions include energy production, protein synthesis, storage, and roles in photosynthesis and cell protection.
Structure and functions of cell organelles
- 1. PRINCEPRINCE SAINISAINI CLASS-CLASS-IXIX ‘A’‘A’ SUB-SUB-SCIENCESCIENCE TOPIC-TOPIC-STRUCTURE ANDSTRUCTURE AND FUNCTIONS OF CELL ORGANELLESFUNCTIONS OF CELL ORGANELLES
- 2. 1. Cells • Cells are the basic unit of all living things. • Cell Theory: •All organisms are made up of one or more cells. •The cell is the basic unit of all organisms.
- 3. 2. Two Types of Cells Eukaryotic cell Prokaryotic cell
- 4. 2.1 Prokaryotic cell • It is a single celled organism that does not have a nucleus or membrane bound organelles.
- 5. 2.2 Eukaryotic Cells • There are 4 classes of eukaryotic cells. • We will discuss only 2; Plant & Animal cells - Plant Cell Animal Cell
- 7. 3.1 Cell Membrane • The outermost covering of the cell that separates the contents of the cell from its external environment is known as cell membrane. It is selectively permeable and is made up of bilayer of lipoprotein. • The cell membrane holds the cell together and allows nutrients into the cell.
- 8. 3.2 Cytoplasm • The fluid or matrix content inside the plasma membrane of a cell along with the cell organelles is known as cytoplasm.
- 9. 3.3 Mitochondria • It is an cell organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner part being folded inwards to form layers (cristae).
- 10. 3.3.1 Functions of Mitochondria • It is the site for respiration. • The energy required for various chemical activities needed for life is released by mitochondria in the form of ATP molecules. • They have their DNA and ribosomes due to which they are able to make some of their own proteins. Thus, they are regarded as semiautonomous organelles.
- 11. 3.4 Nucleus •The nucleus controls the cell. •It is the largest organelle in the cell and contains the cell’s DNA.
- 12. 3.4.1 Functions of Nucleus • It helps in inheritance of features from parents to next generation in the form of DNA molecules present in chromosomes which are present in it. • It controls which protein and what amount of it will be synthesized in the cell. • It plays a central role in the cell division. • It plays a crucial part, along with the environment, in determining the way the cell will develop and what form it will exhibit at maturity and what function it will do, by directing the chemical activities of the cell.
- 13. 3.5 Nucleolus •Inside the nucleus, there is another organelle called the nucleolus. •It is responsible for making ribosomes.
- 14. 3.6 Vacuoles •They are storage sacs for solid or liquid contents bounded by a unit membrane. •In animals they are present in large number but their size is small. •While plants have very few vacuoles but their size is large.
- 15. 3.6.1 Functions of Vacuoles • They are storage sacs of the cells. • Many important substances like amino acids, sugars, various organic acids and some proteins are present in the vacuoles of plants. • In single celled organisms like Amoeba, food vacuoles contains the food items that the Amoeba has consumed. • In some unicellular organisms, specialised vacuoles also play important roles in expelling excess water and wastes from the cell.
- 16. 3.7 Endoplasmic Reticulum • It is a large network of membrane bound tubes and sheets. It looks like long tubules or round or oblong bags(vesicles). • There are two types of endoplasmic reticulum: 1. Rough Endoplasmic Reticulum: It has particles called ribosomes attached to its surface. Thus, it looks rough under a microscope and is known as rough endoplasmic reticulum. 2. Smooth Endoplasmic Reticulum: It looks smooth because it doesn’t have ribosomes on its surface and is known as smooth endoplasmic reticulum.
- 17. 3.7.1 Functions of Endoplasmic Reticulum • Rough Endoplasmic Reticulum is a site for protein synthesis. • Smooth Endoplasmic Reticulum is a site for lipid synthesis. • Some of these proteins and lipids synthesized by RER and SER respectively help in the process of building the cell membrane which is known as membrane biogenesis. • It serves as channels for the transport of materials from nucleoplasm to cytoplasm or from one part of the cytoplasm to the another part of the cytoplasm. • SER in the liver cells of the group of animals called vertebrates plays a crucial role in detoxifying many poisons and drugs.
- 18. 3.8 Golgi apparatus • It is organelle in the cell that is responsible for sorting and correctly shipping the proteins produced in the ER. • Golgi Apparatus is made up of membrane bound vesicles present in the form of stacks. Such structures are called cisterns. • It was discovered by Camillo Golgi.
- 19. 3.8.1 Functions of Golgi Apparatus • Storage, packaging and dispatching of the substances formed by SER and RER. • Formation of complex sugars from simple sugars. • Formation of lysosomes.
- 20. 3.9 Ribosomes and Its Functions • These are tiny particles present in all active cells and act as the active sites for protein synthesis. • Organelles that help in the synthesis of proteins. • Some ribosomes are found in the cytoplasm, but most are attached to the endoplasmic reticulum.
- 21. 3.10 Lysosomes and Its Functions • These are membrane bound cell organelle that contains digestive enzymes. • When the cell gets fully damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are also known as suicide bags of cell. • Lysosomes function as the cell's recycling compartment.
- 22. 3.11 Cell Wall •Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. It lies outside the plasma membrane. •Cell walls are only present in plants, fungi and bacteria. •Cell wall is mainly composed of cellulose which is a type of complex carbohydrate.
- 23. 3.11.1 Functions of Cell Wall •Cell wall permit the cells of plants, fungi and bacteria to withstand very dilute(hypotonic) external media without bursting. •It has narrow pores through which fine strands of cytoplasm are able to cross the cell walls. •Because of cell wall, cells can withstand changes in the external environment, protecting the constituents of cell.
- 24. 3.12 Plastids • These are found only in plant cell. They are double layered and contain their own DNA and ribosomes. • Plastids are of three types: 1.Chloroplasts: These are the plastids containing chlorophyll which gives green colour to the plant. It is also a semiautonomous organelle. 2.Leucoplasts: These are the white or colourless plastids. They can change to other types of plastids. 3.Chromoplasts: These are coloured plastids.
- 25. 3.12.1 Functions of Plastids 1) Chloroplasts: These are important for photosynthesis in plants. 2) Leucoplasts: These store materials like starch, oils and protein granules. 3) Chromoplasts: These impart colour to flowers and fruits. They are rich in carotenoid pigments and lipids.