AS Biology F211 Cells and Microscopes

AS Biology F211 Cells and Microscopes

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  • Created by: Pheebie
  • Created on: 24-09-11 08:16

Magnification

  • How much larger an image appears under a microscope.
  • Total magnification= eye piece x objective lens.

                                  (http://t1.gstatic.com/images?q=tbn:ANd9GcR1w8CuyP44gyUAXmpTBUIlfQE_zwgByjV7kk7N51vu0GG0CEQD)

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Resolution

  • The ability to distinguish between two close points on an image- the degree of detail we can see.
  • The shortest wave length give us the best resolution, 0.2 µm = light microscopes maximum resolution.

                              

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Stains

Stains are used to colour the part of a cell that you wish to see under a microscope e.g. Iodine or Methyl Blue. 

                                                   (http://t3.gstatic.com/images?q=tbn:ANd9GcRpLMs5f8ZYrpUpmfG39MB8oaV790j0nWR6zQkBO7JblMDqZi6xMA)

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Light Microscope

  • Light is used to pass through a thin specimen to produce an image.
  • Resolution= 0.2µ or 200nm.
  • Maximum magnification= x1500
  • 2D, colour image produced.
  • Liquid dye used e.g. Iodine or Methyl Blue.
  • Disadvantages- Low magnification and resolution. 
  • Advantages- In colour, cheap and easy.

                                  

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Transmission Electron Microscopes

  • Electrons are used to pass through a specimen.
  • Resolution= 0.1nm, 0.0001µ.
  • Maximum magnification= x500,000.
  • 2D black and white image produced
  • No stain needed.
  • Advantages:- High magnification and Resolution.
  • Disadvantages- Not in colour, expensive and you need training to use them.

                                 (http://t3.gstatic.com/images?q=tbn:ANd9GcQMkWs8egHH82qRdXOKOpfrAPzl_DX48kVY69KZwCZht36TSTiiOQ)

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Scanning Electron Microscope.

  • Electrons bounce off the specimen  to produce an image.
  • Resolution = 0.1nm, 0.0001µm.
  • Maximum Magnification= x100,000.
  • 3D black and white image.
  • Heavy metal stains used to bounce electrons off.
  • Advantages:- High magnification and resolution.
  • Disadvantages:- No colour, expensive, need to be trained to use it.

                            (http://t1.gstatic.com/images?q=tbn:ANd9GcSz65IDH4MK0_46AIdJdqWuvgHt7rPdApJzMP2v6kKM8fPdx6eL9A)

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Prokaryotic Cells

Prokaryotic are:- Simple cells, no true nucleus, no membrane bound organells.

They Include:-

  • Pili- Attachment to cell surfaces.
  • Capsule- Additional protection.
  • Cell Wall- Peptidoglycan and outer membrane.
  • Ribosome's.
  • Flagellum- For movement.
  • DNA- Chromosome information.
  • Plasmid- Small DNA loop.
  • Mesosome- Formation of new cell.

                     (http://t0.gstatic.com/images?q=tbn:ANd9GcT3brK15-ST7--PI7Ro646_UysiaJ6M1ZTA9AHXTjgTX6BweIVN)

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Eukaryotic Cells:

More complex cells.

Contain membrane organelles.

Plant, animal and fungi all have eukaryotic cells.

                                (http://t0.gstatic.com/images?q=tbn:ANd9GcT8ypRrJ62v6E5K0QkEi_d_OblUWYWVhV49tsyCNgvfvgAUXTgS1w)

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Animal Cells Include:-

  • Lysosomes.
  • Cytoplasm.
  • Nucleus.
  • Ribosome's.
  • Cell Membrane.
  • Mitochondria.
  • Centrioles.

                          (http://t0.gstatic.com/images?q=tbn:ANd9GcTIF15BNRFxEp4oXZr2QbkiT55D2WU-M-oiG65p9XoZlhZcIZkq)

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Plant Cells Include:-

  • Nucleus.
  • Ribosome's.
  • Chloroplasts.
  • Plasmodesma.
  • Vacuole.
  • Cell membrane.
  • Cell Wall.
  • Mitochondria.

                        (http://t0.gstatic.com/images?q=tbn:ANd9GcQz45a5Th-i6szmoXYT3QhNMYudZzc5MnApxNcCikevoHbq_vS8)

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Rough Endoplasmic Reticulum.

Where proteins are made through protein-synthesis.

                          (http://t1.gstatic.com/images?q=tbn:ANd9GcR45jfqoWK_7j03bnPL-k-RPW05EI1dnOeB9XLZ7axjAoTl9ilA)

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Smooth Endoplasmic Reticulum

Where hormones are produced and where toxins are broken down in the liver.

               (http://t3.gstatic.com/images?q=tbn:ANd9GcSZ35Crw5rIbRp3CuNGIWht2ke0QBqdm4ajDmrIsfIpGWr5HmO7)

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Golgi Apparatus

Used in secretion and endocytosis- where vesticles fuse to remove contents. It also process and packages protein.

                                    (http://t0.gstatic.com/images?q=tbn:ANd9GcQL4w_2cJB8e4sDth4d3PLNFUVG0mOzOQphvIOKSBR5B9U6qDZE5Q)

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Ribosomes

Tend to be attached to rough ER. They are the site of protein-synthesis. 

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Mitochondria

Site of aerobic respiration in cells.

                       (http://t2.gstatic.com/images?q=tbn:ANd9GcSK_q0LvkqUiPivdrjspuAh_WPiAx1mMsFTKZ7a4pMMyXhgsoUD)

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Lysosomes

Small bags of digestive enzymes that digest food that has been bought into the cell by endocytosis.

                                           

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Plasma Membrane

Every cell is surrounded by a plasma membrane, it's one thin layer of fat surrounding a cell. It controls what can enter and exit a cell.

                        (http://t0.gstatic.com/images?q=tbn:ANd9GcQXUcFwqIhkZvJ7ClP7rrsAkyf8-WXr4521DsRITbBc1BSeopEIKw)

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Centrioles

Coordinate nucleation and growth of microtubles in all eukaryotic cells except those in higher plants. Microtuble organization centre. 

                                     (http://t0.gstatic.com/images?q=tbn:ANd9GcR4Q3uodsFj1Jzw0rk-_8Qb5FQxtm0CtdSTSkaI7f-zH392uDWc)

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Nucleus

Carries DNA for the cell within chromosomes.

                             (http://t2.gstatic.com/images?q=tbn:ANd9GcQDAshcykry1HcGkLW-J1FVQ5CZraogn9GiCSgUxTHJ3jojPEez)

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Flagella

Extensions from cell surface to produce motility. They're made of microtubles.

                                          (http://t1.gstatic.com/images?q=tbn:ANd9GcQSE1HIyvnRd-cwUq1GFigBrc1E_om68KSYWN1cAr-3rl-zgA86)

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Microtubles

Microtubles form a spindle responsible for moving chromosomes around the cell.

                                            (http://t3.gstatic.com/images?q=tbn:ANd9GcROh7ihQq0vFMMpzxoI6H0zmFN8zsOaB8JTwF97x6wTLS030Gg7)

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Actin Fillaments

Work with microtubles to maintain or change the shape of a cell. It is a secondary element of a cytoskeleton. 

                             (http://t3.gstatic.com/images?q=tbn:ANd9GcQavg7J7Q-gbews2O8XBla1kFP-8EC-gMP2x9w4lA_HWFWZbcG2CA)

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Cila

Short (5-10µm) hair-like out growths on the surface of a cell. They beat to produce cell movement (e.g. white blood cells) or ,move fluid across the cells surface (e.g in the respiratory system.) They're made of microtubles.

                                (http://t1.gstatic.com/images?q=tbn:ANd9GcQkVspe8_pPU0bC9Peddm1WYPagXy4htxcrzRxNfW5gbbShvWkvFA)

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Cytoskeleton

Composed of actin filaments (proteins) and microtubles, they provide the cell with:-

  • Support.
  • Structure.
  • Strength.
  • 'Tracks' on which organelles can move.

                        (http://t2.gstatic.com/images?q=tbn:ANd9GcSbrZmn_v0dxXyHXs7aYlyOa0KZSwCiSaBTsq1CZ07BZe7YHrkbww)

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Protein-synthesis

Nucleus- DNA code for protein in a gene---> Transcription, DNA--> mRNA (single stranded messenger RNA template)

Rough ER---> The mRNA is translated into a cell where the ribosome make the protein and its gets put into a vesticle.

Golgi Apparatus---> Vesticle take protein to the Golgi apparatus where it's processed and packaged.

The vesticle then takes it to where it's needed, either in the cell, in the cell membrane or it leaves the cell by the process of exocytosis. 

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Comments

Didgez

very helpful :) Thanks

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