Much larger than prokaryotic cells having two enveloped systems True cells occurring in plants and animals Though they have different shape size and physiology but all cells are typically composed of plasma membrane cytoplasm and its organelles ie mitochondria endoplasmic reticulum ID: 1026099
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1. Cell Biology
2. Eukaryotic CellMuch larger than prokaryotic cells having two enveloped systemsTrue cells occurring in plants and animals Though they have different shape size and physiology but all cells are typically composed of plasma membrane cytoplasm and its organelles i.e. mitochondria, endoplasmic reticulum golgi complex , ribosomes etc.Nuclear content such as DNA,RNA , nucleoprotein and nucleus remains separated from cytoplasm by thin perforated membrane.
3. Animal CellPlant Cell
4. Animal and Plant Cells Have More Similarities Than Differences
5. Eukaryotes and ProkaryotesDifferences
6. General features:Size: Cells are microscopic but larger than prokaryotic cells. Size varies from 1μ to 175000 μ(175 mm). E.g. Ostrich cell is usually considered as largest cell(175 mm diameter) but certain nerve cells have the length of 3 to 3.5 feet.Shape: irregular, triangular , tubular, cuboidal, polygonal, cylindrical, oval, rounded or elongatedStructure: 1. Cell wall and Plasma membrane2. Cytoplasm3. Nucleus
7. A. Cellwall and Plasma membraneCell wall : The protoplast of plant cell is separated from entire world by cell wall which is entirely lacking in animal cells.Semi rigid , laminated , external and non-living covering of cell.It contains a complex polysaccharide carbohydrate, the cellulose. Function: Provide protection and support to plasma membrane and cytoplasm.Has some canal like or pit like minute apertures by which the cell remains connected with adjacent cells.selectively permeable boundary between the cell and the external environment
8. Plasma Membrane :External covering of many plant and animal cells.Living , ultrathin, elastic , porous ,semi permeable membranous covering of cells.Provide mechanical support and external form to the protoplast (cytoplasm + nucleus), separate protoplasm from exterior, check the entry or exit of undesirable substancesTransmits necessary materials to and from the cell.Has outer and inner layer of protein and middle layer of lipids, consist of many pores through which exchange of molecules takes place.
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10. Cell MembraneStructure: phospholipid bilayer with proteins that function as channels, markers, and receptors-also contains cholesterol which provides rigidityFunction: selectively permeable boundary between the cell and the external environment
11. B. CytoplasmPlasma membrane is followed by cytoplasm which is distinguished into following structure: Cytoplasm 1.Cytoplasmic matrix 2. Cytoplasmic structure 1.) Cytoplasmic matrix: Present between plasma membrane and nucleus Amorphous ,translucent, homogeneous colloidal liquid.Consist of various inorganic molecules such as H2O , salts of Na, K and other metals and various organic compounds such as carbohydrate, lipids, proteins, nucleoproteins, nucleic acids and various enzymes.Outer Peripheral layer is non- granular , viscous, clear and rigid known as plasmagel or cortex or cortical layer or ectoplasm .Inner portion of cytoplasmic matrix is granular, less viscous , known as endopalsm.
12. 2.)Cytoplasmic Structure:In cytoplasmic matrix certain living and non-living structure remain suspended.Non-living structures are known as paraplasm, deutoplasm or inclusionLiving structures are membrane bounded known as organoids or organellesa.)Cytoplasmic Inclusionb.) OrganellesStored food and secretary substances of the cell remain suspended in the cytoplasmic matrix, in the form of refractile granulesLiving structures, performing various important biosynthetic and metabolic activities such as respiration, transportation , support, storage etc.2. Important organelles are microtubules, centrosomes, basal granules, cilia, flagella, endoplasmic reticulum, Golgi complex lysosomes, mitochondria etc.
13. Structure and Function of OrganellesThe Structure and Function of the following organelles will be discussed:Cell MembraneNucleusCell WallCytoplasmMicrotubules or microphilamentsRibosomesEndoplasmic ReticulumGolgi ApparatusMitochondriaLysosomesPeroxisomesCilia and FlagellaBasal BodiesCentriolesVacuolesPlastids
14. The Parts of the Cell
15. Organelles1. Microtubules and Microphilaments Microtubules :Ultrafine tubules of tubulin proteins . Function: Transportation of water , ions and small molecules , cytoplasmic streaming and formation fibers of the mitotic or meiotic spindle during cell division. Forms the structural units of the centrioles , basal granules, cilia and flagella. Microphilaments : Ultrafine proteinous solid maintaining the structure of cell and forms contractile component of muscle cells.
16. CytoskeletonStructure: a network of thin, fibrous elements made up of microtubules (hollow tubes) and microfilaments (threads made out of actin)Function: -acts as a support system for organelles-maintains cell shape
17. 2. Centrosomes or Centrioles: i) Contains dense cytoplasm , located near the nucleus of animal cells. ii) During cell division it contain two rod-shaped granules known as centrioles. iii) During cell division forms spindle of microtubules , helping in separation and movements of chromosomes .3. Basal Granules: i) Animal and plant cell having locomotory organelles(cilia & flagella) contain spherical bodies known as Basal granules ii) Remains embedded in the ectoplasm
18. RibosomesStructure: consist of two subunits made of protein and RNAFunction: location of protein synthesis
19. Endoplasmic ReticulumStructure: a system of membranous tubules and sacsFunction: intercellular highway (a path along which molecules move from one part of the cell to another)Two types:Rough Endoplasmic ReticulumSmooth Endoplasmic Reticulum
20. Rough Endoplasmic ReticulumRough Endoplasmic Reticulum (rER): prominent in cells that make large amounts of proteins to be exported from the cell or inserted into the cell membraneCovered with ribosomes
21. Smooth Endoplasmic ReticulumSmooth Endoplasmic Reticulum (sER): involved in the synthesis of lipids and breakdown of toxic substancesNot covered with ribosomes
22. Golgi ApparatusConcern with formation and packaging of materials for export from cell across the plasma membraneStructure: stacked flat sacsFunction: i) receives proteins from the rER and distributes them to other organelles or out of the cell (receiving, processing, packaging, and shipping) ii) Formation of secretory vesicles, plasma membrane , cell wall of plant cell etc.
23. MitochondriaLarge size , rounded or rod like structure, occurring singly or in a group.Size:.0.2 μ to 2μ in diameter and 0.3 μ to 40 μ in length Chemical composition: (i) 65 – 70% protein (ii) 25 – 30 % lipid (iii) 0.5 % RNA and small amount of DNA Lipid content includes 90% phospholipids (lecithin and cephalin), 5% or less cholesterol & 5% free fatty acid s and triglycerides. Outer mitochondria membrane contains large amount of phospholipids and cardilipin proteins.Structure: folded membrane within an outer membraneThe folds of the inner membrane are called cristae Function: - converts energy stored in food into usable energy for work , known as the power house of the cellcellular respiration
24. Energy liberation in mitochondria and its utilization in various cellular function
25. LysosomesTiny membrane bounded vesiclesStructure: spherical organelles that contain hydrolytic enzymes within single membranesFunction: breaks down food particles, invading objects, or worn out cell partsTypes: i) Primary lysosomes ii) Secondary lysosomes iii) Residual bodies iv) Autophagic vacuole or cytolysosomes
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27. PeroxisomesStructure: spherical organelles that contain enzymes within single membranesFunction: Degrade hydrogen peroxide, a toxic compound that can be produced during metabolism.
28. Cilia and FlagellaStructure: hair-like organelles that extend from the surface of cellsWhen they are present in large numbers on a cell they are called ciliaWhen they are less numerous and longer they are called flagellaBoth organelles are composed of nine pairs of microtubules arranged around a central pair.Function: cell motility
29. Cillia and Flagella
30. VacuolesStructure: a sac of fluid surrounded by a membraneVery large in plantsFunction: used for temporary storage of wastes, nutrients, and water
31. PlastidsPresent in plant cell, may be colorless or coloredThere are three types of plastids in plant cells:Chloroplasts (discussed on next slide)Chromoplasts: synthesize and store pigmentsLeucoplasts: colorless, store food such as starches, proteins, and lipids, also known as amyloplast or lipoplastChromoplastsRed PepperFlowerLeucoplasts
32. ChloroplastsStructure: stacked sacs (thylakoids) that contain chlorophyll surrounded by a double membraneFunction: photosynthesis (conversion of light energy to chemical energy stored in the bonds of glucose)
33. Nucleuslarge organelle which protects the majority of the DNA within each cell. The nucleus also produces the necessary precursors for protein synthesis. The DNA housed within the cell nucleus contains the information necessary for the creation of the majority of the proteins needed to keep a cell functional. nucleus has a variety of important structures to help maintain, process, and protect the DNA.Nucleus consists of three structures: i) Nuclear membrane ii) Nucleoplasm and chromosomes iii) Nucleolus