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![SPECIALIZED PLANT ORGANELLES
Chloroplast and other plastids:
Membrane-bound organelles that only occur in plants
and photosynthetic eukaryotes.
Are the sites of photosynthesis.
They contain chlorophyll, the green pigment necessary
for photosynthesis in membranous sacs, thylakoids.
A stack of thylakoids are a granum [plural = grana])
floating in a fluid termed the stroma.
•
chlorophyll
Carbon Dioxide + Water ---------------> Glucose + Oxygen
radiant energy (food)](https://image.slidesharecdn.com/7ew27d3wswu8epcwvebl-3-220614151019-4fd088ff/75/3-_Cell_structure_and_function-pdf-43-2048.jpg)
3._Cell_structure_and_function.pdf
- 2. Was proposed bySchleidan and Schwann. The cell theory is… 1. All living organisms are made up of cells. (may be single celled or multi celled). 2. Cells are the smallest or basic unit of life having the properties of life and forms the structural and functional unit of all organisms. 3. All cells come from cells that already exist (pre existing). CELL THEORY
- 3. BASIC ASPECTS OFCELL STRUCTURE AND FUNCTION
- 4. ALL CELLS HAVE: Plasmamembrane Have regions of DNA (nucleiod or nucleus) Cytoplasm. However most of the cells differ in size, shape, functions and complexity
- 5. Cell shape depends onwhat functions they perform Majority of cells have a fixed shape except Amoeba which change shape
- 6. Based on cellsize organisms can be Small cell cannot be seen with naked eye. Measured in micron. (1 micron = 1/1000mm). Need microscope Ex: Bacteria, virus MICROSCOPIC MACROSCOPIC Large cells, can be seen with eyes. Measured in millimeters No need for microscope. Ostrich egg, hens egg
- 7. Based on cellnumber organisms can be UNICELLULAR MULTICELLULAR Organism has only one cell. Single cell performs all life activities. Bacteria, virus Organism made of many cells. Cells get specialized to perform different functions. Muscle, nerve cell etc Shape of cell depends on what function it performs; majority of cells have fixed shape except amoeba which can change shape
- 8. Based on celltypes organisms can be Prokaryotic Gr: Pro = early; karyon = nucleus Eukaryotic Gr: Eu =good; karyon = nucleus Unicellular, small in size, simple. Cell without definite nucleus. Presence of nucleiod No nuclear membrane Naked DNA: DNA not associated with proteins. No membrane bound organelles Cell divides by binary fission, budding Cell wall present Ribosomes are of 70s type. Ex: Bacteria. Mostly multi cellular, complex . Cell with definite clear nucleus. Absence of nucleiod Has a well developed nuclear membrane. DNA associated with proteins (histones). Has organelles like golgi, chloroplast etc. Cell divides by mitosis, meiosis. Cell wall is present in plant but absent in animal cell. Ribosomes are of 80s type. Ex: Plant and animal cell.
- 9. Major similarities between(prokaryote and eukaryote) are: They both have DNA as their genetic material. They are both membrane bound. They both have ribosomes . They have similar basic metabolism
- 10. Why most cellsare small and have different shapes? Why should an egg after fertilization undergo division ?
- 11. The surface ofa cell, its membrane, is the site of exchange between its interior and its external environment. This surface must allow sufficient exchange to support the contents of the cell. As an object increases in size its volume increases as the cube of its linear dimensions while surface area increases as the square. As these cubes illustrate the surface area to volume ratio of a small object is larger than that of a large object of similar shape. This ratio limits how large cells can be.
- 12. Surface to volumeratio explains: Different cell shape ( small, round or elongated). Cell Size: In small cells, all parts of the cell are near the cell membrane, so that nutrients can easily reach any part of the cells interior. However, in the larger cell, the less surface area when compared to its volume means nutrients cannot rapidly diffuse to all interior parts of the cell.. That is why eukaryotic cells have specialized internal organelles to carry out metabolism, provide energy, and transport chemicals throughout the cell. With increasing cell size or body length, the surface/volume ratio decreases
- 13. PROKARYOTIC CELL Examples ofProkaryotic cell
- 14. PROKARYOTIC CELLS very, verysmall, simple structure Plasma (cell) membrane = encloses cytoplasm of cell Nucleoid Region = is where DNA is present .(not a nucleus) Ribosomes = assembles proteins with information from DNA Bacterial Cell Wall = a rigid outer layer that surrounds the cell membrane, protects the cell, maintains shape Capsule = a sticky outer layer over cell wall Pili and Fimbriae = numerous short projections that help with adherence Prokaryotic Flagella = longer projections that help with motility (movement) Plasmids = extra-chromosomal pieces of DNA
- 15. A PROKARYOTIC CELL REASONSFOR IDENTIFICATION Presence of cell wall. Presence of plasma membrane. Presence of a nucleiod : DNA in an irregular shaped region of cytoplasm called nucleiod . Absence of well defined cytoplasmic organelles like ER, golgi bodies, mitochondria. Respiratory enzymes attached to plasma membrane. Example: Bacteria.
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- 17. Defining features ofEukaryotic cell Presence of true nucleus: Nucleus with nuclear membrane and nucleolus. Compartmentalization: Partitioning the cell interior into organelles. Allows large number of activities to occur simultaneously in very limited space.
- 18. A typical eukaryoticcell Structure Nucleus Localizing the cells DNA Endoplasmic reticulum Routing and modifying newly formed polypeptides chains and synthesizing lipids. Golgi bodies Modifying polypeptide chains to mature proteins, sorting, shipping proteins and lipids for secretion or use inside cell. Various vesicles Transporting or storing a variety of substances, in cell Mitochondria Producing ATP molecules Non membraneous structures and function Ribosomes Assembling polypeptide chains Cytoskeleton Giving shape and internal organization to cell; moving cell and internal structures However, there are also some important differences between animal cells and plant cells.
- 19. Eukaryotic cell Plant cellAnimal cell Larger in size Presence of cell wall (cellulose) Large central vacuole Presence of chloroplast No centrioles; only centrosome Smaller in size Absence of cell wall Small vacuoles Absence of chloroplast Presence of centrioles
- 20. The Cell Membrane Functionsas a semi-permeable barrier, allowing only selected molecules to enter the cell. Structural molecule of cell membrane is a phospholipid molecule . Structure is explained by the lipid bi layer model in which proteins are embedded (fluid mosaic model). Outer most limiting membrane in animal cell and cell wall in plant cells
- 21. CYTOPLASM CYTOPLASMIC ORGENELLES CYTOSKELETON CYTOSOL Cytoplasmis a clear jelly. It is 70% water in most cells. Nucleus, Endoplasmic reticulum, golgi etc Microtubules, cilia and flagella
- 22. ORGANELLES AND THEIRMAIN FUNCTIONS Organelle = "small organ", membrane enclosed structures found inside the cell, each for a specialized function. All chemical activities of the cell occur within organelles. Benefits of Organelles: Separate environments for chemical reactions Increased membrane surface area This image cannot currently be displayed.
- 23. The Nucleus -THE BRAIN OF EUKARYOTIC CELLS The nucleus occurs only in eukaryotic cells It has double membrane that contain DNA of a eukaryotic cell. The nucleus consists of the: Nuclear envelope Nucleolus Chromatin And nucleoplasm
- 24. • The nuclearenvelope is a double-membrane structure. • Numerous nuclear pores occur in the envelope, allowing RNA and other chemicals to pass. • Outer membrane may be continuous with ribosomes attached to endoplasmic reticulum. Function • Selectively permeable to control movement of substance in or out NUCLEAR ENVELOPE
- 25. NUCLEOLUS Is a non-membranebound structure . It is composed of protein and nucleic acids found within the nucleus. The ribosomal RNA is transcribed within the nucleolus. Round, irregular darkly stained structure within nucleus. It has RNA (ribonucleic acid) and protein Function – Protein and RNA subunits of ribosomes (ribosomal sub units )are assembled here. Nucleolus
- 26. NUCLEOPLASM Semi Fluid foundinside portion of nucleus and has enzymes and chemicals for synthesis of DNA and RNA.
- 27. CHROMATIN : The chromatin(meaning "colored substance") contains DNA and proteins. Total collection of all DNA molecules and their associated proteins in the nucleus.
- 28. CHROMOSOME : One DNAmolecule and many proteins that are intimately associated with it. Remember that chromosomes are condensed chromatin (DNA plus histone proteins). Transcription Translation Protein synthesis
- 29. Endoplasmic reticulum- (ER) Meaningof the term: ENDO = within the cell PLASM = cytoplasm RETICULUM = network. Structure: ER starts with nucleus and branches throughout cytoplasm. It is stacked , flattened membrane sacs. Found throughout cytoplasm from plasma membrane to nuclear membrane. Types: Rough and smooth endoplasmic reticulum Functions: RER helps in protein synthesis so rich in pancreatic cells producing enzymes and peptide hormones . SER is the main site for lipid synthesis.
- 30. Has ribosomes associatedwith the side that face cytoplasm. Function: Protein synthesis and modification. Two kinds of endoplasmic reticulum Rough endoplasmic reticulum (ER) Smooth endoplasmic reticulum (SER) Has no ribosomes Function : Main site for lipid synthesis and secretion of steroid hormones ; inactivate drugs, stores calcium .
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- 32. A non-membrane boundorganelle. The ribosomes of prokaryotes and eukaryotes vary slightly with regard to size and shape. Made in the nucleus and transported to cytoplasm of the cell. Structure: Spheroid shape composed of 2 subunits; constructed out of protein and RNA . Small and a large subunit, which facilitate the specific coupling of tRNA anticodons with mRNA codons during protein synthesis Location: Found in 3 different places in cells... 1. Free in cytoplasm, as individual subunits or dimers, 2. Membrane bound on outer surface of endoplasmic reticulum membranes, 3. Attached to mRNA molecule in POLYSOME or polyribosome. Function: Is the site of assembling polypeptide chains. (cellular protein synthesis). Every new polypeptide chain is synthesized on ribosomes. Ribosome The "factories" of the cell - involved in protein synthesis
- 33. Golgi apparatus -"shipping department"of the cell A part of the ENDOCYTOTIC pathway Are found near the nucleus . STRUCTURE: Consists of FLAT MEMBRANE STACKS ABOUT 3-20 slightly curved saccules. FUNCTION: Final modification of lipids and proteins. Storage and packaging of materials that will be exported from the cell.
- 34. • Golgi apparatusreceives protein-filled vesicles that bud from the ER. • Vesicle fuses with membrane of Golgi apparatus . • Vesicles formed from the Golgi apparatus then move to different locations in cell; at plasma membrane, they discharge their contents as secretions. Function of golgi apparatus
- 35. Lysosomes or suicidalbags LYS = Breakdown or digest ; SOME = Body. Therefore it is "digesting body". A cytoplasmic single membrane bound vesicle produced by golgi apparatus containing hydrolytic enzymes. Found only in animal cells. Have diverse shapes, mostly spherical* Functions: Mainly in intracellular digestion. Have 40 enzymes digesting polysaccharides, lipids and proteins. White blood cells that engulf bacteria, virus and foreign particles use lysosomes to digest. Autodigestion occurs when lysosomes digest parts of cells
- 36. Variety of VESICLES Manysmall fluid filled sac surrounded by a single membrane. Vesicles are found in cytoplasm. Transport vesicles: Carries proteins and lipids from er to golgi and other organelles. Exocytotic vesicles: Vesicles from golgi fuse with plasma membrane and send substance out of cell. Endocytotic vesicles: Those which bring material into the cell. Peroxisomes: Membrane bound vesicle given by smooth ER. Contain enzymes that break down some fatty acids, alcohol, etc into H2o2which is then changed to water.
- 37. The cyto membraneor endo system or GERL Is a series of organelles in which lipids and proteins are assembled and modified to final products. All the organelles are connected physically. Help in transfer of modified lipids and proteins. Function of this system begins with endoplasmic reticulum
- 38. Nuclear membrane Endoplasmic reticulum Golgiapparatus Lysosomes Vesicles The endomembrane system functions, in part, in protein synthesis, protein modification, protein sorting and protein transport. The cyto membrane system includes
- 39. MITOCHONDRIA Power house ofthe cell Are the primary energy producers in cells. Specialist in oxygen requiring energy reactions (aerobic respiration) and produce ATP
- 40. Mitochondria Number: They arevery abundant in cells that require lots of energy. Shape: Stubby cigars sometimes they are round. Size : roughly the size of a bacteria Function : the site of cellular respiration ie. The release of chemical energy from food. Glucose + Oxygen------> Carbon Dioxide + Water + ATP Structure : Double membrane structure. There is a single outer membrane and inner membrane folded to form cristae. It is on these cristae that food (sugar) is combined with oxygen to produce ATP - the primary energy source for the cell.
- 41. Mitochondria are veryunique in several regards Found in all eukaryotic cells . Site of aerobic respiration . When cell divides, mitochondria divides by a process similar to binary fission. Enclosed in a double membrane system . They have their own DNA and ribosomes. The DNA of mitochondria is similar to bacterial DNA. All the mitochondria in your body came from your mother.
- 42. Which organelles aretypical of Plant cell Cell Wall: Found only in prokaryotic cells and plant cells Outermost layer of plant and prokaryotic cell Structure a non-living secretion of the cell membrane, made up of cellulose Function protection from physical injury Provides skeletal support Maintains the shape of cells
- 43. SPECIALIZED PLANT ORGANELLES Chloroplastand other plastids: Membrane-bound organelles that only occur in plants and photosynthetic eukaryotes. Are the sites of photosynthesis. They contain chlorophyll, the green pigment necessary for photosynthesis in membranous sacs, thylakoids. A stack of thylakoids are a granum [plural = grana]) floating in a fluid termed the stroma. • chlorophyll Carbon Dioxide + Water ---------------> Glucose + Oxygen radiant energy (food)
- 44. Central Vacuole The membraneenclosed space in the center of the cell is usually filled with fluid containg amino acid, sugars, ions etc. In plants, this vacuole is large and often is the largest structure inside the cell.
- 45. CYTOSKELETON Is a networkof protein elements that extend through the cytoplasm in eukaryotic cells. Maintains cell shape (as red blood cells, nerve cells ). Protects the cell Enables some cell motion (using flagella and cilia) Plays important role in eukaryotic cellular division It helps in movement of organelles, intra cellular transport of vesicles and in movement of cells (amoeboid movement). It is composed of three types of protein fibers: Microtubules : Help in movement (ex: cilia and flagella) Myo filaments : Present in muscle cells (actin and myosin) Intermediate filaments : They hold adjacent cells together.
- 46. Microtubules Made of aprotein called tubulin. The fibers are lengthened and shortened by tubulin dimers. The assembly of microtubules is controlled by an area near the nucleus called the centrosome or microtubule organizing area. Microtubules help in: chromosome movement, movement of organelles, movement of cellular appendages.
- 47. CENTROSOME the “Microtubule organizingcenter", Is an area near nucleus in the cell where microtubles are produced. In an animal cell inside the centrosome there is a pair of small organelles, the centrioles. Plant cells have centrosome but no centrioles. During animal cell division, the centrosome divides and the centrioles replicate .
- 48. Centriole Is a barrelshaped organelle Animal cells contain pairs of centrioles which lie at right angles to each other next to the nucleus. Found in most animal cells, but absent in plants and fungi. The walls of each centriole is composed of nine triplets of microtubules along the periphery but do not have central microtubules (9 + 0 triplet arrangement of microtubules). Play an important role in formation of spindle fibres during cell division. C.S of centriole or basal body (9 + 0 triplet arrangement of microtubules).
- 49. BASAL BODIES Cilia andflagella are organized from centrioles that move to the cell periphery. These are called "basal bodies. A basal body is like a centriole except that it is found at the base of a cilium or flagellum. Basal bodies control the direction of movement of the cilia. Both centrioles and basal bodies are similar in that they are composed of nine triplets of microtubules along the periphery but do not have central microtubules (9 + 0 triplet arrangement of microtubules). How the triplets in the basal body turn into the cilium doublet remains a mystery.
- 50. Cilia and Flagella Short usuallynumerous hair like projections e.g., Paramecium, lining of human upper respiratory tract Longer usually fewer whip-like projections e.g., sperm cells Cilia Flagella
- 51. STRUCTURE OF CILIAAND FLAGELLA Presence of 9 doublets (pairs) of microtubules arranged in a circle around 2 central microtubules. This 9 + 2 pattern is characteristic of all eukaryotic cilia and flagella. The pairs of microtubules are cross-linked. The shifting positions of the cross-links move the cilia or flagella. C.S of cilia and flagella (9 + 2 doublet arrangement of microtubules).
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- 53. Microtubules Microfilaments Intermediatefilaments Largest cytoskeletal element Thinnest cytoskeletal element Most stable cytoskeletal element Move materials within the cell Help in movement of orgenelles, vesicles from the Golgi complex to the plasma membrane. Move the cilia and flagella Help in movement of chromosomes during cell division. Can move the cell itself. Can change shape of cell. Provides mechanical strength Long, hollow,cylindrical Long, helically twisted Intermediate in length. Rope like structure Made of tubulin protein Made of protein actin Made of desmins,vimentins Present only in animal cells. CYTOSKELETAL ELEMENTS