The document summarizes the history and components of cells. It describes how early scientists like Van Leeuwenhoek, Hooke and Brown discovered cells and cell structures using microscopes. It then outlines the cell theory developed by Rudolf Virchow stating that cells are the basic unit of structure and function and that new cells are produced from existing cells. The summary then provides details on the generalized functions of cells and describes the structures and functions of key animal and plant cell organelles such as the nucleus, mitochondria, chloroplasts and cell membrane.

1. Chapter 2 Cell

2. History of Cytology Anton Van Leeuwenhoek – invented microscope – discovered the presence of cell while observing a drop of rainwater . Robert Hooke – invented a compound microscope – coined the word “cell” – Robert Brown - he discovered the nucleus of the cell. Matthias Scheiden ( Botanist ) & Theodore Schwann ( Zoologist ) concluded that plants and animals are made up of cells.

3. Rudolf Virchow – Considered cells as the basic units of structure and function – discovered the process of cell division – cells came from the division of pre-existing cells. Walter Fleming – he discovered aster formation and condensation of the chromatins Peirre-Joseph Van Beneden – he discovered meiosis . History of Cytology

4. Parts of the Cell Theory (Rudolf Virchow) The cell is the unit of structure in all living things. The cell is the unit of function in all living things. All cells come from preexisting cells.

5. Generalized Functions of the Cell Irritability – the ability to respond to stimuli. Contractility – the ability to change shape. Absorption – is the imbibitions of substances for assimilation by the cell

6. Secretion & Excretion – are processes involved when the cell excludes material. Respiration – the process involved in the release of energy through the biological oxidation of food. Reproduction – is the increase in the number of cells through cell division. Generalized Functions of the Cell

7. Cell Size Macroscopic – cells that are big enough to be seen by unaided eyes. Example Frog’s egg cell Chicken egg Microscopic - Example Liver cell – 7 microns Blood cell

8. Shape Spherical – round or oval Squamous – flat & tile-like Cuboidal – Square & equidimensional

9. Columnar – rectangular, upright Fusiform – Tapering at both ends Shape

10. Stellate – Star-like Spiderlike – oval shaped surrounded with cytoplasmic extensions Shape

11. Netlike –, Branching & interlacing Filamentous – Threadlike & long Amorphous – irregular, no definite shape Shape

12. Animal Cell Nuclear pore Nuclear Membrane Nucleolus Chromatins Nucleus Centriole Pinocytic Vesicle Lysosome Cytoplasm Cell Membrane Vacuole Ribosomes Mitochondrion Smooth Endoplasmic Reticulum Golgi Complex Rough Endoplasmic Reticulum Nucleoplasm

13. Cell membrane - selectively regulates the materials moving to and from the cell

14. Cell Wall – present only in plant cells Structure - a non-living secretion of the cell membrane, composed of cellulose - cellulose fibrils deposited in alternating layers for strength - contains pits (openings) that make it totally permeable Function - provides protection from physical injury - together with vacuole, provides skeletal support

15. Nucleus The nucleus consists of the nuclear envelope, nucleolus, chromatin, and nucleoplasm. Nuclear Envelope Structure -two unit membranes with a fluid-filled space - nuclear pores present -outer membrane may be continuous with endoplasmic reticulum Function -selectively permeable to control movement in or out -contains nuclear contents

16. Chromosomes Structure -composed of long thin strands of DNA Function -contains instructions that control cell metabolism and heredity

17. Nucleolus Structure -non-membraneous matrix of RNA (ribonucleic acid) and protein Function - instructions in DNA are copied here - works with ribosomes in the synthesis of protein

18. Centriole Structure - nine triplets of microtubules form one centriole - two centrioles form one centrosome Function - forms spindle fibres to separate chromosomes during cell division

19. Endoplasmic Reticulum (ER) Structure - sheets of unit membrane with ribosomes on the outside - forms a tubular network throughout the cell Function - transports chemicals between cells and within cells - provides a large surface area for the organization of chemical reactions and synthesis

20. Ribosome Structure - non-membraneous, spherical bodies composed of RNA (ribonucleic acid) and protein enzymes Function - site of protein synthesis

21. Golgi Apparatus Structure - stacks of flattened sacs of unit membrane - vesicles pinch off the edges Function - modifies chemicals to make them functional - secretes chemicals in tiny vesicles - stores chemicals - may produce endoplasmic reticulum

22. Mitochondrion Structure - composed of modified double unit membrane (protein, lipid) - inner membrane infolded to form cristae Function - site of cellular respiration ie. the release of chemical energy from food Glucose + Oxygen ------> Carbon Dioxide + Water + Energy (ATP)

23. Lysosome Structure - membrane bound bag containing hydrolytic enzymes - hydrolytic enzyme = (water split biological catalyst) i.e. using water to split chemical bonds Function - break large molecules into small molecules by inserting a molecule of water into the chemical bond

24. Microfilaments/Neurotubules - system of transport for materials within a neuron and may be used for structural support

25. Vacuole Structure - a single layer of unit membrane enclosing fluid in a sack Function - produces turgor pressure against cell wall for support - stores water and various chemicals - may store insoluble wastes food vacuole -stores and digests food contractile vacuole -pumps out wastes and excess water from the cell

26. Chloroplast Structure - composed of a double layer of modified membrane (protein, chlorophyll, lipid) - inner membrane invaginates to form layers called "grana" (sing., granum) where chlorophyll ( green ) is concentrated Function - site of photosynthesis chlorophyll Carbon Dioxide + Water -------------------> Glucose + Oxygen + radiant energy (food) Chromoplasts have carotenoids, which impart red -to- yellow colors to plant parts, but no chlorophyll. Amyloplasts have no pigments. They store starch grains in plant parts such as potato tubers.

27. Two Types of vacuole 1. Food vacuole -stores and digests food 2. Contractile vacuole -pumps out wastes and excess water from the cell

28. Nucleus control center of the cell contains DNA which directs the synthesis of proteins by the cell Mitochondrion carries on the process of cell respiration converting glucose to ATP energy the cell can use Endoplasmic Reticulum transport channels within the cell Ribosome found on the endoplasmic reticulum and free within the cell responsible for the synthesis of proteins for the cell cell membrane selectively regulates the materials moving to and from the cell

29. Food Vacuole stores and digests food Contractile vacuole pumps out wastes and excess water from the cell Chloroplast found in plant cells and algae carries on the process of photosynthesis Cell wall surrounds and supports plant cells

30. Some Cell Organelles Cell Organelle Function nucleus control center of the cell contains DNA which directs the synthesis of proteins by the cell mitochondrion carries on the process of cell respiration converting glucose to ATP energy the cell can use endoplasmic reticulum transport channels within the cell ribosome found on the endoplasmic reticulum and free within the cell responsible for the synthesis of proteins for the cell cell membrane selectively regulates the materials moving to and from the cell food vacuole stores and digests food contractile vacuole pumps out wastes and excess water from the cell chloroplast found in plant cells and algae carries on the process of photosynthesis cell wall surrounds and supports plant cells

31. Plant Cell Animal Cell

32. Vacuole Thylakoid membrane Starch grain Chloroplast Plasmodesmata Cell Wall

33. THE END NEXT MEETING - EXAM

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