Cell is the Basic Unit of Life

The word cell is derived from the Latin word “cellula” which means “a little room”
It was the British botanist Robert Hooke who, in 1664, while examining a slice of bottle cork under a microscope, found its structure resembling the box-like living quarters of the monks in a monastery, and coined the word “cells”

1. CELL – BASIC UNIT OF LIFE Fundament unit of life

2. Cell – basic unit of life Prokaryotic and Eukaryotic Cells Multicellular Organisms Cell Membrane and Cell Wall Cell Organelles Chloroplast Mitochondria Vacuoles Endoplasmic Reticulum Golgi Apparatus Nucleus Chromosomes Basic Structure, Number

3. Discovery of Cell In 1665 Robert Hooke – an English Scientist, Saw Cells in a thin slice of cork with his crude microscope. He observed as “Honey – comb” like Structure and named them as CELLULAE or CELLS His discovery indicated for the first time that living organisms consisted of number of small structures or units. Microscope

4. 1665- Robert Hook discovery of cell 1674- A. Van Leeuwenhoek -studied living for the first time. 1831- Robert Brown discovery and named Nucleus in a cell 1838-39- M.J.Schleiden & Schwann formulated Cell Theory 1855- Rudolf Virchow , Stated “ Omnis cellula-e-cellula ” to know the history of cell? Robert Hook Leeuwenhoek Robert Brown M.J.Schleiden Schwann Rudolf Virchow

5. Just as a building is made up of bricks the body of all living organisms made up of cells. Basing on the cellular organization some organisms are made of single cells “ U nicellular Organisms ” e.g. Chlamydomonas, Amoeba, Paramecium Organisms which are made up of more than a cell “multicellular” Irrespective of unicellular or multicellular organisms the cells perform similar basic functions for their survival. What are living organisms made up of?

6. Cells are too small to be seen by necked eye. They are studied with the help of microscopes. Microscopes are high resolution instruments that are used for observing fine details of very small objects Two common types of microscopes Light microscope-magnification range from 100-1500 Electron microscope- magnification range from 1 lakh- 5 lakhs Gadgets to study cells

7. Shape and size of cells vary but all of these are ultimately determined by the specific function. Shape and Size of cells Some cell can change their shapes amoeba , WBC but plants and animals have almost fixed shapes. Smallest ell= PPLO( mycoplasma ) Largest Cell-Ostrich egg Longest animal cell-Nerve cell A micrometer ( μ m) or micron is one thousandth of a millimeter.

8. The Scale of Life

9. Unicellular Made of Single Cell Single cell able to perform all the life processes like obtaining food, respiration, excretion, growth and reproduction. Cannot be divided in to cells, they are also called acellular organisms Amoeba, paramecium Unicellular vs. Multicellular Multicellular Made up of many number of cells Cells have a similar basic structure and similar basic life activities Different shapes and aggregated to form different tissues Tissues form organs and organs give rise to organ system that perform special function. Plants, Animals and Fungi

10. It performs all life function like intake of food materials, excretion, metabolism, respiration, irritability, etc., Division of Labour – Cell usually possesses a number of components called cell organelles. Each cell organelle performs different functions Clearing waste material Protein synthesis Lipid synthesis Cell is basic unit of life

11. A cell is a tiny mass of protoplasm which is surrounded by a membrane and is capable of performing all function of life . A typical cell is formed of three parts Plasma membrane- to create separate environment Nucleus- for its control Cytoplasm- possessing metabolic machinery What is Cell made up of?

12. The outer most delicate elastic membranous covering of the cell that separates its contents from the external environment is called Plasma Membrane Plasma Membrane is Selectively Permeable (it allows entry of certain substance restricting others) It is made up of a bi-lipid layer and proteins are integrated in out and inside. Small carbohydrates are attached at placed to outer surface of lipids and proteins. Functions- Shape to contents of cell, Mechanical Barrier, Semi-Permeable, Endocytosis, Recognition Centres, Flow of Information, Osmosis, Cell Continuity, Modified to perform special functions like absorption in microvilli. Plasma Membrane-Cell Membrane

13. Plasma Membrane Plasma membrane SEM-Plasma membrane

14. Membranes act as physical barriers between the organelles of a cell and its cytoplasm and its surrounding environment. Impermeable – substances do not pass through the membrane Permeable – both solute and solvent can pass through Semipermeable – membrane permeable to solvent but prevents solutes passage Selectively Permeable – if membrane allows the passage of solvent and some selected solutes. Transport Across the Membrane

15. Substances may pass across the membrane without or with expenditure of energy- Active Transport - substances pass the membrane with consuming ATP Passive Transport- substances pass the membrane without consuming ATP Bulk Transport – Large amounts of substances and food particles across the plasma membrane The process of bringing the bulk of materials from outside by formation of endosomes is called endocytosis. Bulk expulsion of materials as in secretion and excretion is called exocytosis. Active & Passive Transport

16. Active Transport

17. Passive Transport is of two types Diffusion Osmosis Diffusion – The process of movement of substances (solid, Liquid or Gas)from the region of higher concentration to the region of its lower concentration till spread uniformly in the given space is called diffusion . Passive Transport Diffusion – Demonstration

18. Helps in spread of different substances throughout cytoplasm of cell. Osmosis is a type of diffusion where only solvent is allowed to diffuse. Diffusion helps in exchange of respiratory gases between the cells and their environment. Transpiration is diffusion process Flowers spread aroma through diffusion to attract insects and other animals for pollination. Importance of Diffusion

19. Defined as the diffusion of water or solvent across a semipermeable membrane from a region of its higher concentration to region of its lower concentration. Plasma membrane functions as semipermeable membrane. Osmosis Osmosis Osmosis - demonstration

20. Diffusion It can take place in solid, liquid and gases. It does not involve any semi permeable membrane. It equalizes the concentration of substances. Different substances diffuse independent of one another Diffusion is not much influenced by the presence of other substances How Diffusion differs from Osmosis ? Osmosis It takes place only in liquid medium It requires semi-permeable membrane. It does not equalize the concentration of solvent on the two sides of the membrane Only solvent undergoes diffusion It is influenced by the concentration and type of solute particles.

21. Osmotic solutions are those solutions which can cause osmosis They are three types Hypotonic Solution, Isotonic Solution and Hypertonic Solution Hypotonic – which has an osmotic concentration lower than another solution. Isotonic – The solution has an osmotic concentration similar to another solution. Hypertonic – which has an osmotic concentration higher than that of another solution. Types of Osmotic Solutions

22. Osmosis is of two types Endosmosis Exosmosis Endosmosis – Osmotic entry of water in to the cell or system Exosmosis – Osmotic withdrawal of water from a cell or system When we place the cell in higher concentration the water comes out of the cell by a process called exosmosis. When we place the cell in lower concentration the water enters in to the cell by a process called endosmosis. Types of Osmosis Endosmosis Exosmosis

23. Rigid, semi elastic, semi transparent and protective covering present outside the plasma membrane in plant cells, fungi and prokaryotes. Made up of Cellulose in plants, Fungal cellulose and Chitin in fungi Extra deposition of lignin, suberin and cutin may be present during secondary thickening A cementing layer called middle lamella is present between the walls of two adjacent cells Cell wall possesses small pores through which adjacent cells remain connected called Plasmodesmata. Cell Wall Plasmodesmata. Middle lamella.

24. It provides shape to the cells It provides mechanical strength to plants Protects against pathogens and mechanical injury Growth of the cell wall determines the growth of the cell Cell wall prevents bursting of cell on endosmosis Ability to withstand a lot of variation in nature. What is the role of cell wall?

25. Does cell wall & Plasma membrane are similar in function? Cell Wall occurs in plant cells lies on the outside of the cell Rigid and thick Cell wall is permeable Formed of Cellulose, Hemi cellulose and Pectin. Provide protection and strength to the cell Plasma Membrane Occurs in plant & animal cells Lies on the outside of animal cells and inside in plants Flexible and thin Selectively Permeable Lipids and Proteins with small number of carbohydrates Hold cellular contents and control of passage materials

26. Nucleus – The Cell B rain Dense protoplasmic body that contains hereditary information controlling cell activities as well as for transfer to next generation It lies in median or central position In mature plant cell it lies towards periphery In prokaryotes nuclear membrane is absent It is called Nucleoid. Cells like RBC, Sieve Elements lack Nucleus Cells without Nucleus cannot survive for longtime One nucleus (uninucleate) is present in most of cells but some cells may have more than one (multi nucleate)

27. Nuclear Envelop is a double membrane covering which separates the nucleus from the cytoplasm. It contains many Nuclear pores. Nuclear pores allow exchange of materials between the nucleus and cytoplasm Nucleoplasm – It is colorless, dense sap found inside the nucleus in which chromatin and nucleolus are suspended. Nucleolus – a round structure found in side the nucleus, it is rich in RNA and protein. It is site of ribosome formation. What is Nucleus made up of? Nuclear Envelop Nucleoplasm Nucleolus

28. The Nucleus is Enclosed by a Double Membrane

29. Nuclear Pore Complex-Diagram

30. Does cell wall & Plasma membrane are similar in function? Nucleus It represent the whole eukaryotic complex that contains genetic information It is covered by a two membrane envelop It controls the structure and working of cells Nucleolus It is a component of nucleus It is without a covering membrane It synthesizes ribosomal subunits Chromatin Material – An intervened mass of thread-like structure made of DNA and Proteins. During Cell Division, Chromatin becomes highly condensed, thick and rod like structures, Known as Chromosomes.

31. Thread like structures which are formed by condensation of chromatin during cell division are called chromosomes they referred as hereditary vehicles Chromosomes are made of DNA & Proteins A chromosome consists of two similar threads called Chromatids Two chromatids are attached at the center by a centromere On either side of centromere chromatids are called arms Chromosomes

32. Chromosome number is fixed for each species In most organisms they occur in homologous pair In each pair, one chromosome belongs to father parent while other belongs to mother parent Presence of two sets of chromosomes is called Diploid 2n=46 ( in human) Presence of singe set of chromosomes is called Haploid n=23 (in human) Chromosomes-Number

33. Nucleus contains all the genetic information not only for the cell but also the whole organism It functions as control centre of the cell as it controls cell metabolism and cell activities Ribosomes are formed by nucleolus part of nucleus Nucleus us brings about cell differentiation by which a cell attains a specific structure and function. Division of nucleus is essential for cell division Reshuffling of chromosomes and changes in genes produce variations Role of Nucleus in a Cell

34. Prokaryotes (singular ) are a group of organisms that lack a cell nucleus or any other membrane-bound organelles. They differ from the eukaryotes, which have a cell nucleus. Prokaryotes are the single-celled organisms, such as bacteria, and are roughly one micrometre in diameter . A eukaryote is an organism whose cells contain complex structures inside the membranes. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear envelope, within which the genetic material is carried Prokaryotes & Eukaryotes Bacteria Plant Cell

35. Prokaryotes do not have a nucleus that houses its genetic material. Prokaryote cell consists of a large DNA molecule compacted in an area of cytoplasm called the nucleoid region.   The nucleoid region is protected and encased by the cell wall, or cell membrane, the outer layering of the cell (similar to human's skin).  Finally, Flagellum a rudder-like device, affords the prokaryote the luxury of mobility.   Prokaryotes & Eukaryotes

36. Prokaryotes & Eukaryotes Prokaryotes Small in size, 1-10 μ m. Organized nucleus is absent. A single DNA molecule is present suspended in cytoplasm, nucleolus is absent Membrane bound cell organelles are absent Typical vacuoles are absent Mitosis is absent Bacteria, Cyanobacteria Eukaryotes Larger in size, 5-100 μ m Organized nucleus is present with nuclear envelop, Nucleolus is present, several DNA molecules are present Membrane bound cell organelles are present Typical vacuoles are present Mitosis is present Plants, Animals, Fungi

37. Eukaryotic (Animal ) Cell

38. The contents of a cell except for the nucleus. It includes cytosol, organelles, vesicles, and the cytoskeleton Cytoplasm has two parts, cytosol and cell organelles Cytosol – is the fluid part of cytoplasm, homogeneous and crystallocolloidal liquid that contains substances water, ions, enzymes, vitamins, amino acids, carbohydrates, lipids, proteins etc., Cell Organelles – Submicroscopic structure which are specialized to perform specific cellular functions. Cell organelles may be bounded by a membrane as in Eukaryotes but prokaryotes lack membrane bound organelles Virus lack cytoplasm as well as membrane Cytoplasm

39. The endoplasmic reticulum (ER) is a network of interconnecting membranes distributed throughout the cytoplasm. The internal compartment, called the lumen, is a separate part of the cell with a distinct protein and ion composition. The ER’s folding generates a surface area much greater than that of the plasma membrane. At certain sites, the ER membrane is continuous with the outer nuclear envelope membrane . Depending upon the presence or absence of ribosomes on the surface, there are two types of E.R. Rough E.R. – Characterized by the presence of ribosomes on its surface Smooth E.R. – Devoid of ribosomes on its surface Endoplasmic Reticulum

40. Endoplasmic Reticulum

41. Protein Synthesis – Rough E.R. is the site of Protein synthesis Lipid Synthesis – Smooth E.R. helps in lipid synthesis Proteins and lipids synthesized on E.R. are used for making cell membrane Transport – helps in intercellular and intracellular transport of substances Support – it gives internal support to the cytoplasm SER in liver cells takes part in detoxifying many poisons and drugs Functions of E.R. SER Ribosomes are absent Synthesize lipids and steroids Mainly formed of vesicles and tubules RER Ribosomes are present Synthesize proteins Formed by cisternae

42. Golgi complex is an organelle of membrane bound sacs, tubules and vesicles secrete complex biochemical Golgi is a single complex in animal cells. In plants they form separate units called dictyosomes. Membrane bound sacs of Golgi are called cisternae. Cisternae occurs in stacks, tubes and vesicles occur on their periphery Golgi Complex

43. Golgi Apparatus

44. Golgi apparatus is involved in repair and synthesis of cell membranes Lysosomes are formed by Golgi apparatus All types of substances which are to be secreted or excreted are packed in vesicles by Golgi apparatus for passage to the outside Takes part in storage, modification and packaging of various biochemical produced by different components of the cell Components of cell wall are synthesized by Golgi apparatus Complex and special sugars are made by Golgi apparatus Functions of Golgi

45. Lysosomes

46. Lysosomes generally found in animal cells they lack in plant cell Are small spherical vesicles covered by single membrane contain digestive enzymes for intracellular digestion and waste disposal These enzyme are synthesized by R.E.R In damaged cell, lysosomes burst to release enzymes for digestion of cellular components Functions Destruction of foreign particles Intracellular Digestion Removal of cell debris Time of metamorphosis Organs are digested by Lysosomes Lysosomes-suicide bags Lysosomes- Kuffer cells

47. Mitochondria is rod-shaped cell organelles of aerobic eukaryotes which take part in the Krebs cycle. Commonly called “Power House of the Cell” because they contain enzymes necessary for the total oxidation of food and for release of high amount of energy in the form of ATP It is bounded by two membrane- outer membrane is smooth and porous while inner membrane is folded inwards to form Cristae Cristae contains oxysomes they are partially embedded in inner membrane Mitochondria enclose a matrix having DNA, ribosomes and enzymes. DNA and ribosomes make the mitochondria semi-autonomous as they are able to manufacture some of their own proteins and enzymes. Mitochondria (power House of a Cell)

48. Mitochondria

49. Lysosomes-suicide bags

50. Plastids are large cell organelles found only in plant cells which are specialized to synthesize and store organic substances. Plastids are classified on the basis of pigment present in them two types Leucoplasts – colorless plastids (amyloplasts, aleuroplast, elaioplasts Chromoplasts – Coloured Plastids. Green & Non green plastids Plastids Leucoplasts colorless Cylindrical to round in shape Found in un exposed cells Take part in storage of food Can change to other types Chromoplasts (non green) Brown or reddish in colour Irregular in shape in exposed & un exposed cell Do not storage food Provide coloration of organs

51. Bounded by two membranes. Inside of chloroplast is clearly marked into a colorless matrix called Stroma and Membranous system called Grana. Each granum consists of stack of membrane bounded, flattened sacs called thylakoids Thylakoids pigments like chlorophyll, carotenoids and phycobillins Stroma contains enzymes for dark reaction, DNA, RNA and ribosomes, latter make the chloroplasts semiautonomous . Chloroplast-kitchen of the cell Chloroplast Chloroplast

52. Lysosomes-suicide bags

53. Chromoplasts provide color to fruits and flowers and attract the animals to help in pollination and fruit dispersal Leucoplasts take part in storage of protein, starch and oil Chloroplasts trap solar energy to manufacture food through photosynthesis Oxygen is being consumed in combustion and respiration. Carbon dioxide is being produced inn the two process. Chloroplasts maintain the balance of the two gases by absorbing carbon dioxide and oxygen in photosynthesis . Plastids-functions

54. Ribosomes are small rounded bodies found either in free state in the cytoplasm or attached to the surface of Endoplasmic Reticulum They are composed of ribonucleic acid (RNA) and proteins They are not bounded by a membrane They are present in both prokaryotes (70s=50s+30s) eukaryotes (80s=60s+40s) Absent in mammalian R.B.Cs. Ribosomes are the site of protein synthesis in the cell Ribosomes-Translation factory

55. It is a small naked organelle present near the nucleus in the cells of animals and some lower plants. It has sheath of special cytoplasm called centrosphere. It encloses two micro cylinders called centrioles. Two centrioles like right angles to each other. It has nine triplet fibrils present obliquely on the periphery. They form astral spindle fibers and produce basal bodies that form cilia and flagella Centrosome-central apparatus

56. Membrane bound non-cytoplasmic sacs that contain non-living solid or liquid contents. They are of three types- sap vacuoles, food vacuoles and contractile vacuoles Covering membrane of sap vacuole is called tonoplast The fluid filled content of the vacuole is called cell sap or tonoplasm Recently digestive enzymes are reported in vacuole of plant cell Vacuoles-store house of the cell

57. Vacuoles-store house of the cell

58. Differences between Plant and Animal Cell Cell wall is present Plastids are present Centrioles and centrosomes are absent Vacuoles large and less Nucleus lie on one side Cell is rigid Golgi contains dictyosomes Larger in size Starch is stored absent absent Centrioles and centrosomes are present Vacuoles small and many Nucleus lies in the centre Cell is flexible In the form of vesicles Smaller in size Glycogen is stored

59. Plant and Animal Cell

60. R.V.Raghavendra Rao PGTBiology JNV Kiltampalem Vizianagaram [email protected] Phone-9490811620 Prepared by