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unit 1.pptx
- 2. Observed and coined term “cell” Robert Hooke He observed cork cells
- 4. THE CELL THEORY 1. Cells are the smallest units of life. 2. Cells come only from existing cells 3. Cell is the unit of function of all living cells Theodor Schwann Matthais Schleidon Rudolf Virchow
- 5. Are there exceptions to the cell theory?? No protoplasm No definite nucleus One celled Many nuclei No nucleus
- 6. Can we see cells?
- 7. Why are cells so small? The functions of cell’s volume- – The rate of heat and waste production and – Rate of resource consumption. As the width increases the surface area also increases, but it is slower than the increase in volume. As a cell grows larger at some point its surface area becomes too small to allow these materials to enter the cell quickly enough to meet the cell's need. Rate of diffusion α Surface Area x Concentration Difference Distance
- 8. CELL SIZE 1. A few types of cells are large enough to be seen by the unaided eye. The human egg (ovum) is the largest cell in the body, and can (just) be seen without the aid of a microscope. 2. Most cells are small for two main reasons: a). The cell’s nucleus can only control a certain volume of active cytoplasm. b). Cells are limited in size by their surface area to volume ratio. A group of small cells has a relatively larger surface area than a single large cell of the same volume. This is important because the nutrients, oxygen, and other materials a cell requires must enter through it surface.
- 9. • Molecules of Biological significance are around 1 nm in size where as the cell membrane is about ten times thicker at 10nm. • Where as a virus is ten times larger again at around 100nm. • where as a bacteria is ten times larger again at around 1 um. • where as a eukaryotic animal cell is is ten time larger again at around 10 um. • where as a eukaryotic plant cell is ten times larger again at around 100 um. Relative sizes: 1. molecules (1nm). 2. cell membrane thickness (10nm). 3. virus (100nm). 4. bacteria (1um). 5. organelles (less 10um). 6. cells (<100 um). 7. generally plant cells are larger than animal cells.
- 10. Example of cell – increase the SA/V ratio
- 11. Simple and compound microscope. Simple microscopes: Consist of a single lens. Compound microscopes: Consist of more than one lens
- 12. MICROSCOPE • Two properties: 1. Magnification: the ability of the microscope to increase the size of the image of an object formed on the retina of the eye. 2. It can be represented as: MP =Size of retinal image formed with the microscope ( size of image) Size of retinal image formed with unaided normal eye (size of specimen) ________________________________________
- 13. TGES BIOLOGY IBDP Resolving power • The ability of a microscope or any magnifying instrument to separate or distinguish between two closely placed points. • This depends on the wave length and the light gathering capacity of the objective lens- numerical aperture.
- 14. Light microscope: The source of illumination is light. Electron microscope: The source of illumination is electron beam.
- 15. Compound microscope Compound microscope is a combination of two simple microscopes. Compound microscope has two lenses.
- 17. Light and electron microscope images Light microscope Electron microscope
- 18. How many types of cells are there? On what basis do we decide the type of cells?
- 19. Types of cell Prokaryotic cell Eukaryotic cell
- 21. Prokaryotic cell-drawing Pilus Flagellum Cell membrane Cell wall Nucleoid Storage granule Ribosome Plasmid Mesosome
- 22. TGESBIOLOGY ISC 11 Cell membrane Centriole Nucleus Nucleolus Lysosome Mitochondria Smooth Endoplasmic reticulum Rough Endoplasmic reticulum Golgi complex Secretory vesicles Eukaryotic cell- drawing
- 24. Components of a cell Cell boundaries Cytoplasm Nucleus Cell organelles (metabolically active) Cell inclusions (metabolically inactive) Membrane bound Non Membrane bound Storage products Secretory products Excertory products ER Mitochondria Plastids Golgi complex Lysosomes Ribosomes Cytoskeleton Centrioles Cell wall Cell membrane Protoplasm DNA/RNA proteins
- 25. CELL WALL • Thick, rigid protective envelope. • Present in plants, bacteria, fungi and algae. • Bacteria and fungi – proteins and non-cellulosic carbohydrates. • Algae and plant cells– cellulose • Mechanical support • Protects plasma membrane • Determines cell shape • Prevents water loss • Protects against pathogens Functions
- 26. Cell membrane Membrane made up of phospholipids and is semi permeable in nature
- 27. CYTOPLASM • Homogeneous translucent, jelly like part of the protoplasm after the cell organelles are removed. Functions- • Intracellular distribution of substances • Exchange of materials between organelles
- 29. ENDOPLASMIC RETICULUM • All cells except RBC, eggs, embryonic cells & resting cells • Made up of – – Cisternae, – tubules and – vesicles • Types– • SER –makes lipids modifies proteins.(adipose, liver cell) • RER- studded with ribosomes and makes proteins
- 30. MITOCHONDRIA • Absent in prokaryotes, lost in RBC. Outer chamber or perichondrial space Algae with one mitochondria Microsterias Highest number of mitochondria in insect flight muscles.
- 31. MITOCHONDRIA Ultra structure • Outer mitochondrial membrane. • Inner membrane– • Inner membrane has folds– cristae– studded knob-like particles called elementary particles or oxysomes. Outer chamber or perichondrial space
- 32. PLASTIDS • Chloroplast, chromoplast and leucoplast.
- 33. Chloroplast • Occurrence • Shape • Size • Number (20-40 per cell) • Ultra structure a) Envelope b) Stroma c) Grana
- 34. Chloroplast • Structure: – Double membrane envelope-peri- plastid space – The stroma or matrix – Grana –contains sac like thylakoids
- 35. CHLOROPLASTS: AUTONOMY AND FUNCTION • Manufacture some proteins • New arise from division of older ones Functions: • Photosynthesis • Oxygen supply • Storage of starch temporarily • Fixation of CO2 • Greenery • Chromoplasts
- 36. LEUCOPLASTS Colourless plastids No grana and photosynthetic pigments. They are of three types ■ Amyloplasts – starch containing ■ Proteoplasts- stores proteins ■ Elaioplasts-fat storing
- 37. CHROMOPLAST Chromoplast • Coloured plastids • Contain –carotenoids • Functions ■ Impart colours to flowers ■ Bright colour to fruits ■ When green carry out photosynthesis ■ Sites of synthesis of membrane lipids
- 38. Golgi complex
- 40. LYSOSOMES • LYSOSOMES • Rounded or spherical with single membrane containing acid hydrolases. ■ Structure: Two subunits- Large subunit and small subunit ■ Present freely in the cytoplasm. ■ FUNCTION- SITE OF PROTEIN SYNTHESIS RIBOSOMES
- 41. Centrioles • Non membranous cell organelle. • Occur in pairs- diplosome • Occur at right angles to each other in the cytoplasm –centrosphere. • Centriole and centrosphere- centrosome • Function- initiates cell division
- 42. VACUOLES • Sap filled vesicles in the cytoplasm • Bounded by tonoplast, fluid- cell sap
- 43. NUCLEUS Structure: • 1. Nuclear envelope or karyotheca • 2. Nucleoplasm -karyolymph • 3. Chromatin net • 4. Nucleolus Occurrence: • Absent in bacteria, BGA (prokaryotes) • Present in all eukaryotes
- 47. Functions • Regulates all cell activity • Contains chromosomes that is responsible for heredity.
- 48. • All images have been downloaded from Google images for educational purpose only.