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Cells

Cells. Cell. Definition 1. The structural, functional and biological unit of all organisms .

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Cells

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  1. Cells

  2. Cell • Definition • 1. The structural, functional and biological unit of all organisms. • 2. An autonomous self-replicating unit that may exist as functional independent unit of life (as in the case of unicellularorganism), or as sub-unit in a multicellularorganism (such as in plants and animals) that is specialized into carrying out particular functions towards the cause of the organism as a whole. • 3. A membrane bound structure containing biomolecules, such as nucleic acids, proteins, and polysaccharides. (Science: Cell Biology)

  3. Eukaryotic and Prokaryotic • Animals & Plants (as well as Protocistsand many Algae) have cells that contain membrane bound organelles: nucleus, mitochondria, chloroplasts etc. • These are Eukaryotes • Karyote from Greek karyonEu- meaning true (meaning kernal or nucleus) • Prokaryotes do not have these internal membranes (Pro- meaning before)

  4. Eukaryotic Cells

  5. Organelles you need to know: • Nucleus • Chromatin • Nuclear envelope • Nucleolus • Mitochondria • Endoplasmic reticulum Rough and smooth • Ribosomes • Golgi Body • Lysosomes • Centrioles • Chloroplasts • Vacuoles • Plasmodesmata

  6. Nucleus • Largest Organelle (10-20μm) • Double membrane contains pores (nuclear envelope) • Contains nucleic acids and proteins • When not dividing, DNA bonded to protein forming chromatin • Nucleolus dense area, produces ribosomes

  7. Mitochondria • Rod like structures (1μm wide x 10μm long) • Powerhouse of the cell • Undertake Respiration • Produce ATP • Symbiotic evolution

  8. Centrioles • Usually a pair • Near the nucleus • Involved in cell division

  9. Network of cavities bound by membranes Transport system Synthesis of chemicals RER – ribosomes, protein synthesis/transport SER - synthesis of steroids and lipids Endoplasmic Reticulum

  10. Ribosomes • Small at ~20nm • Made of a combination of RNA and Protein (65%:35%) • Involved in protein synthesis • DNARNAProtein

  11. Golgi Body • Took ages for science to discover what this did • Used radioactive tracers • Proteins transported there in vesicles, fuse and pass thru’ • Proteins altered (carbohydrates added etc.) • Put into vesicles which bud off

  12. Digestive enzymes packaged into a vescicle Fuse with food vacuoles taken in by endocytosis by single celled animals or with damaged organelles Can rupture and destroy the whole cell apoptosis Lysosomes

  13. Chloroplasts • Large 4-10μm x 2-3 μm • Chlorophyll • Photosynthesis

  14. Vacuoles • Any fluid filled, membrane bound, space • Animal cells have temporary ones • Plant cells vac. is surrounded by a membrane called the tonoplast • Filled with cell sap • Osmosis keeps it ‘inflated’

  15. Plasmodesmata

  16. Cytoskeleton • 3D, “web-like” structure filling the cytoplasm • Microfilaments (protein fibres) • Microtubules (protein tubes 20nm diameter) • Gives cytoplasm structure • Holds organelles in place • Linked to: cell movements transport

  17. Prokaryotes

  18. Bacteria • Cause diseases • good bacteria • very very small (0.5 uM to 1 um in size) 1 cm . 1 mm 1 uM (a bacteria)

  19. Rod shaped Coccus shaped (round)

  20. ‘BAD’ bacteria – cause diseases Bacteria (E. coli) • meningitis • tuberculosis • anthrax • the plague • gonorrhoea • diarrhoea and vomiting Human intestinal cell Bacteria ‘FIGHT’ with the human cells and immune system to survive and cause disease

  21. syphilis gangrene leprosy Stomach ulcers Stomach ulcers Stomach ulcers Tooth decay plague

  22. Escherichia coli (E. coli) • Rod shaped bacteria • causes vomiting and diarrhoea • can cause kidney failure and DEATH E. coli 1 E. coli 2 E. coli 3 E. coli 4 E. coli

  23. flagella Outer membrane Cell wall Glycogen granule Plasma membrane Lipid droplet ribosome Circular chromosome

  24. flagella Outer membrane Cell wall Glycogen granule Plasma membrane Lipid droplet ribosome Circular chromosome

  25. Viruses

  26. Viruses Smallest of the microorganisms 0.002 – 0.3 µm (50x smaller than bacteria) Viruses are not cells Merely arrangements of genetic material and protein

  27. Electron Micrographs of Viruses A. Bacteriophage T4 B. Potato virus X C. Adenovirus D. Influenza virus

  28. Structure of viruses

  29. Viruses are geometric in shape Considerable variation in the genetic material they have, structure of their protein coat (capsid) or whether they have an envelope

  30. Cellular Organisation

  31. Cells  Tissues • Cells (basic units) • Organisms either unicellular or multi-cellular • Aggregations of Cells • Colonies show little co-ordination • More complex organisms show specialisation • If perform similar function organised into tissues

  32. Tissues • 4 main types in the human: • Epithelial tissues (lining of surfaces) • Connective tissue • Muscle tissue • Nervous tissue

  33. Tissues  Organs • Organs are made up of a group of tissues together in one structure so that they can work effectively.

  34. Plant leaf as an Organ Tissues: • Epidermal • Palisade mesophyll • Spongy mesophyll • Vascular tissue (inc. phloem and xylem tissues)

  35. Organs  Systems • When a number of organs work together to carry out a large scale function it is known as a system.

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