1 / 144

Understanding Cells

Understanding Cells. A. History of the Microscope. microscopes : an object. anything that will magnify. Make objects larger than they are Allow us to see objects that can’t be seen with our eyes. 1845. the inventor of the first microscope is debatable.

ismail
Download Presentation

Understanding Cells

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Understanding Cells A. History of the Microscope • microscopes : an object anything that will magnify • Make objects larger than they are • Allow us to see objects that can’t be seen with our eyes 1845

  2. the inventor of the first microscope is debatable • – Zaccharias and Hans Janssen (Holland) 1595 • produced a crude microscope • used a 2 lens system • – Galileo (Italy) 1609 • built a crude compound microscope • – Anton Van Leeuwenhoek (Holland) 1600’s • built a simple single lens microscope • first person to see unicellular movement

  3. – Hooke (England) 1665 • built a compound microscope • 3 lens system • – Hillier and Prebus (U of T Canada) 1930’s • built first electron microscope 1940’s • – first scanning electron microscope

  4. B. Types of Microscopes 1. Simple Microscopes • Are early microscopes • Consist of a lens single 2. Compound Microscopes • are = still focused when objectives are switched parfocal There are 2 types of compound microscopes a. Research b. Dissecting

  5. 1. research microscope • Has one ocular • has a rotating nosepiece with 3 objective lenses • Uses transmitted light (passes through specimen • Creates an image • Are used to look at • specimens • magnifies up to inverted transparent 400 X

  6. 2. dissecting microscope • has two eyepieces ( binocular) • has 1 rotating objective • Has 2 light sources top & bottom • Uses incident light (light reflected off the specimen virtual • Creates a image • Are used to look at • Magnify specimens up to 30 X solid objects

  7. Parts of a Microscope

  8. Image Magnification • Is the magnification you are using when viewing a specimen • It is created by both the objective & ocular • Formula: • Image Magnification = ocular x objective 4 X 40 X low: 10 X  = medium: 10 X  = high: 10 X  = 10 X 100 X 400 X 40 X

  9. Example 1: A student is viewing a specimen on low power. What is the image magnification? • Ocular = 10 • Objective = 4 Image Magnification = Ocular x Objective Image Magnification = 10 x 4 = 40

  10. Example 2: A student is viewing a specimen on high power. What is the image magnification? Ocular = 10 Objective = 40 Image Magnification = Ocular x Objective Image Magnification = 10 x 40 = 400

  11. Image • It is what you see • Is created using light (transmitted or incident) • There are two types: • Virtual • Inverted

  12. A. Virtual • The the same • Produced by a • Created using incident light;reflects off the specimen image is as it really is dissecting microscope

  13. B. Inverted • The image is upside down & backwards • Produced by a research microscope • Created using transmitted light;passes through the specimen

  14. field of view Field of View • the of the specimen that you see amount micronsµ(1  106m) • measured in higher magnifications • It is less with Conversion: 1mm = 1000 µm

  15. the field of view as magnification decreases increases low power 4 X 4000 µm high power 40 X 400 µm medium power 10 X 1500 µm

  16. Drawing Size • 1. draw the specimen • 2. measure the widest part in mm • 3. convert mm to microns (1000 m = 1 mm) 45mm = 45000 

  17. Estimation of Actual Size • Estimate how manyspecimens fitacross the field • Divide the field of view by that number actual size = field diameter fit number = 4000 µ 4 = 1000 µ actual size

  18. Scale • used to compare diagram size with actual size of the specimen • measure drawing diameter with a ruler then convert to microns scale = actual size drawing size eg) 1 : 50 000 1 : 0.1 on diagram real life on diagram real life really big things really small things

  19. D. Electron Microscopes • too large, complex and expensive for a school to use beam of electrons • uses a instead of a light wave • focus by adjusting electromagnets • no images since color requires light color • able to see great detail • images are called micrographs termite head

  20. Transmission Electron Microscopes • beam of electrons stained tissue imbedded in plastic passes through • Advantages: and the internal detail of the cell can be seen very high magnification (100,000 to 1,500,000 X), high resolution • Disadvantages: and the specimen must be 2-D, black and white Ebola virus dead

  21. Scanning Electron Microscopes • scans the of the specimen surface • image is produced by the electrons being onto a screen which can be manipulated for a 3-D view reflected off the surface • often coats the specimen with gold for a sharper image human eyelashes

  22. Advantages: black and white image of the surface of a specimen high magnification (300,000 X), 3D • Disadvantages: specimen must be although recently there has been a form that uses living material dead

  23. E. Confocal Laser Scanning Microscope (CLSM) • in the 1980’s the use of a laser beam and computers made it easier to view specimens living, transparent • image is of a very thin section with high resolution which is stored in the computer and can be combined to produce a 3D image that can be manipulated in every direction

  24. F. Imaging and Staining Techniques • - essential to see details contrast • most cells are colourless when light passes directly through them in brightfield microscopy • can be used that attach to different parts of the cell, and therefore the image stains improving the contrast eg) iodine, methylene blue • unfortunately, stains kill the cells

  25. – ability to distinguish between that are very close together, in other words, of the image resolution two structures clarity • for a standard light microscope 0.2 µm • light microscopes have limited resolution because when light is focused into smaller diameters, the image becomes blurred

  26. – a technique used to localize substances in cells fluorescence microscopy • fluorescent substances are attached to molecules in cells glow • they then in the presence of ultraviolet light Cell during mitosis

  27. G. Cell Research at the Molecular Level • due to advances in technology, we are able to see great detail at the molecular level of cells • now have other microscopes that can see in even more detail than the SEM and TEM: • atomic force microscope (AFM) surface of a plastic ID card • scanning tunneling microscope (STM) silicon atoms magnified 1 000 000 000 X

  28. Gene Mapping • DNA found on the chromosomes within the nucleus of the cell directs the activities of the cell • the produced a so that all gene locations are known…this may allow scientists to manage such as Human Genome Project genetic map of humans disease-causing abnormalities cancer • can also use to manipulate plant genes to produce plants that are (many ethical issues involved) pest and drought resistant

  29. Cell Communication • cells are ( both move into and out of the cell) open systems matter and energy • from one cell travels through the and attaches to specific receptors on other cells (like a lock and key) messenger molecules bloodstream receptors • the then change shape and allows functions to occur

  30. H. Development of Cell Theory Spontaneous generation that life can emerge • is the idea spontaneously from non-living matter • It was an idea that continued to thrive from 1500s to the mid 1800s • It was disproved by: • 1. Francesco Redi • 2. Louis Pasteur

  31. 1. Francesco Redi - 1668 • Questioned the idea that maggots could appear spontaneously from raw meat • Had 3 jars that contained raw meat: • 1 open to the air • 1 completely sealed • 1 covered with gauze (contains tiny holes) • Result = Only the one did have flies not closed

  32. Needlham’s Experiment • Belief: boiling destroyed microorganisms • Needham’s Experiment: put boiled chicken broth into a sealed flask • In theory, no microorganisms should exist • But …microorganisms still appeared?!? • Spontaneous generation remained popular… they ignored contact with air

  33. Spallanzani’s Work • Spallanzani’s belief: microbes in the air inside the flask got into the broth • The test: remove the air from the flask and then seal in the boiled chicken broth • Result: nothing grew in the chicken broth! • Why is Spontaneous generation is still popular?!?

  34. 2. Louis Pasteur - 1864 S shaped • Conducted experiment using broth and flasks • He boiled the broth & put it in an s-shaped flask • After some time he removed the s-shaped flask • Result = Swan neck let in & there was growth but removal of neck produced mould no air no mould

  35. S - s haped neck a ll ows a i r but s t op s mi c r oo r gan i s m and dus t

  36. Variables in Experiments Represent conditions that occur in an experiment There are 3: • Controlled variable • Manipulated variable • Responding variable

  37. conditions remain the same 1. Controlled Variable • Are the in an experiment that for each trial • E.g. the temperature in the room

  38. condition(s) that are changed 2.Manipulated Variable • Are the in the experiment • E.g. amount of light

  39. 3. Responding Variable • Is (what happens) • E.g. the plant with no light dies the response

  40. The Cell Theory • the cell was discovered by while he was examining under his microscope Robert Hooke cork • the (which disproves spontaneous generation) proposed by in says that: Cell Theory Schleiden and Schwann 1839 1. all living things are made of cells 2. all life functions takes place in cells, making them the smallest unit of life 3. all cells come from pre-existing cells NOTE: do not fit this category, they are not considered living or non-living viruses

  41. I. The Cell • cells carry on all life processes including: 1. intake of nutrients 2. movement 3. growth 4. response to stimuli 5. exchange of gases 6. waste removal 7. reproduction

  42. Nucleus • control centre of the cell • surrounded by nuclear envelope (semipermeable double membrane) • the nuclear envelope is perforated by pores which allow the entry and exit of certain large macromolecules and particles • contains DNA (deoxyribonucleic acid), which is found in chromosomes and carries genetic information

  43. nucleolus is a small part that stores ribosomal RNA

  44. Cell Membrane • protective barrier for the cell • semipermeable (allows needed materials into the cell and waste materials out) • not rigid; very fluid • type of protein molecule varies with the membrane

  45. Cytoplasm • gel-like substance (mostly water) • includes everything between the nuclear membrane and the cell membrane • contains nutrients needed for cellular activities • has specialized organelles with specific functions

  46. Cytoskeleton • network of fibres extending throughout the cytoplasm • used for support, motility and regulation • contain microtubules, microfilaments and intermediate filaments

  47. Mitochondria • provide the cell with energy (ATP) • called the “Power house” of the cell • sugar is burned and O2 is used up • number of mitochondria in a cell is directly related to its level of metabolic activity ex. muscle cells have lots of mitochondria • contain some DNA and can divide

More Related