CytologyThe Study of Cells

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Chapter 2

• CytologyThe Study of Cells

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Microscopyparts of the microscope

• Eyepiece
• The lens one looks through on a microscope.
  Usually 10x.
• Objective lenses
• The lenses closes to the object one is viewing.
• Held in a revolving nosepiece.
• 4x (scanning) 10x (low power), 40-43x (high
  power), 100x (oil immersion)
• Stage
• The platform on which the slide is placed. Often
  fitted with a mechanical stage to hold the slide
  and move the slide using stage controls.
  (Alternatively, slide clips are used to hold the
  slide.)
• Arm
• Supports the lens systems.
• Iris diaphargm
• Controls the amount of light passing through the
  object.
• Condenser lens
• Focuses light under the object.
• Focusing knobs
• Coarse focusused for focusing under scanning and
  low powers only
• Fine focusused for focusing under high and oil
  powers primarily

http//www.hometrainingtools.com/misc/compound20p
arts.jpg
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MicroscopyCare of the Microscope

• Report any damage or malfunction immediately.
• Carry the microscope carefully with one hand
  under the base and the other around the arm.
• Do not remove lenses from the microscope. If
  they are dirty inside, advise the instructor.
• Clean the lenses with lens paper only. If gentle
  rubbing with lens paper does not adequately clean
  the lens, notify the instructor. Kim Wipes are
  never to be used as lens paper. They may be used
  to clean slides.

• If anything is spilled on the microscope, clean
  it off immediately if it is anything other than
  water, inform the instructor.
• Unwind just enough cord to reach the outlet.
• Before putting the microscope away, check for the
  following
• Are the lenses clean?
• Is the low-power lens in position?
• Is the coarse focus knob turned down to its lower
  limit?
• Is the stage bare?
• Is the dust cover in place?

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MicroscopyUse of the Compound Microscope

• Obtain a letter slide from your instructor.
  Clean and examine it visually to locate the
  position of the object.
• Position the slide on the stage of the microscope
  so the object is centered over the condenser.
• Check the following
• Light is on.
• Lowest power (scanning lens) is in position.
• Iris diaphragm set at a medium opening.
• Looking from the side of the microscope, lower
  the objective (or raise the stage) until the
  objective reaches its lower (or upper in the case
  of the stage) limit, or until the objective is
  just about to touch the slide.
• Now look through the ocular lens and focus by
  turning the coarse adjustment so that the slide
  and lens move away from each other. Stop when
  the object comes into focus. Adjust the iris
  diaphragm to achieve the best contrast and
  resolution.

• Move the slide to the left and then to the right.
  What do you observe?
• Move the slide toward you, then away from you.
  What do you observe?
• Compare the orientation of the image with the
  orientation of the object on the stage. What do
  you observe?
• With the object in focus and centered in the
  field of view, turn the nosepiece until the low
  power lens is in position. The object should
  remain in focus, or minor adjustments with the
  coarse focus may be needed.
• Repeat step 9 with the high power objective.
  This time use the fine adjustment only to
  fine-tune the focus.

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Microscope Review

• Identify the parts of the microscope shown to the
  right.
• When beginning to focus one should always use the
  ____ lens.
• During focusing the objective and the slide
  should initially be positioned
• A. as close as possible.
• B. as far apart as possible.
• C. it doesnt really matter.
• Name three things that should be checked before
  putting the microscope away.
• An object is being viewed with a 40x objective
  and a standard ocular lens. What is the total
  magnification of the image?

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CytologyThe Study of Cells

• The Cell Surface
• Plasma membrane
• Glycocalyx
• Microvilli, cilia, flagella
• The Cytoplasm
• Cytoskeleton
• Organelles

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CytologyLight Microscope

• Cheek epithelial cells
• Procedure
• Use the flat end of a clean toothpick to gently
  scrape the inside of your cheek. Swirl the
  scrapings in a drop of water on a slide.
• Cover with a coverslip as demonstrated by your
  instructor.
• Stain with a small drop of methylene blue stain.
• Observations
• Cytoplasmbulk of cells interior
• Plasma membraneouter boundary of the cell
• Nucleusdarkly stained structure in the interior
  of the cell. Genetic control center.

http//biology.northwestcollege.edu/biology/b1010l
ab/b1010lab.htm
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CytologyLight Microscope

• Spinal cord smear
• Procedure
• Examine a spinal cord smear. Look for
  star-shaped nerve cells.
• Observations
• Observe a dark dot in the center of the cell.
  This is the nucleolus. Active RNA synthesis for
  ribosome assembly.
• Nucleus is the lighter area around the nucleus.

nucleus
nucleolus
dendrites
http//biodidac.bio.uottawa.ca/thumbnails/images/1
9-64.gif
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CytologyLight Microscope

• Blood smear
• Procedure
• Examine a blood smear, first under low power,
  then under high power.
• Observations
• Biconcave red blood cells will be stained pink
  (a). The lighter area in the center is thinner
  as a result of the loss of the nucleus during
  cell development.
• White blood cells have a darkly stained nucleus.
  The nuclei have different shapes in different
  kinds of white blood cells (b-d).

http//upload.wikimedia.org/wikipedia/commons/9/93
/Blood_smear.jpg
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CytologyLight Microscope

• Amphiuma livermitochondria
• Procedure
• Examine a preparation of Amphiuma liver. Note
  the closely packed cells. Focus on one or two
  cells under high power.
• Observations
• Note the nucleus and one or more nucleoli.
• Dark pigment granules are usually present.
• Examine the very small dots that give the
  cytoplasm a pink tint. These dots are
  mitochondria that function in energy conversions.
  They are especially numerous in liver tissue.

http//biodidac.bio.uottawa.ca/thumbnails/histocat
query.htm?Histo_CategoryFTissu20conjonctifHisto
_CategoryEConnective20tissue
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CytologyElectron Microscope, Details of
Structure and Function

• Plasma membrane
• Phospholipid bilayer
• Outer boundary
• Limiting to water soluble materials (e.g.,
  glucose) but not fat soluble materials (e.g.,
  steroid hormones)
• Cholesterol
• Maintains fluid nature
• Glycolipids
• Cell identification
• Membrane proteins
• Cellular transport
• Receptor molecules
• Cell adhesion

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CytologyElectron Microscope, Details of
Structure and Function

• Microvilli
• Extensions of plasma membrane that increase
  surface area for absorption. Kidney tubules.
• Cilia
• Short hairlike processes
• Motilemove substances across cell surfaces
  (mucus in the trachea or eggs in the fallopian
  tube)
• Nonmotilevariety of sensory fuctions.
• Flagellum
• Long hairlike process for locomotion of human
  sperm.

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CytologyElectron Microscope, Details of
Structure and Function

• Cytoskeleton
• Network of protein filaments and tubules that
  support a cell

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CytologyElectron Microscope, Organelles

• Nucleusgenetic control center. DNA codes for
  protein that make up body structure and control
  cell functions.
• Endoplasmic reticulumtransport system,
  synthesizes steroids and other lipids, detoxifies
  alcohol.
• Ribosomesprotein synthesis.
• Golgi complexmodifies and packages proteins for
  secretion.
• Lysosomesbreak down used organelles and other
  substances. Involved in programmed cell death.
• Peroxisomesneutralize free radicles and
  detoxifiy drugs and toxins. Produce hydrogen
  peroxide used to oxidize other molecules.
• Mitochondriaenergy conversions within the cell.
• Centriolesparticipate in cell division.

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Protein synthesis, transport, and packaging for
secretion

• Nucleus
• The genetic (protein) code
• Ribosomes
• Located on ER (thus rough ER)
• The code is translated into protein
• Rough endoplasmic reticulum (ER)
• Modifies and transports protein to Golgi complex
• Golgi complex
• Further modifies proteins and packages them into
  secretory vessicles

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Cell Cycle and Stem Cells

• Cell cycle
• All cells come from preexisting cells.
• Series of events that occurs in the life of a
  cell that culminates in mitosis and cytokinesis.
  The division of the nucleus and cytoplasm of one
  cell to produce two daughter cells.
• Stem cells
• Immature cells with the ability to develop into
  one or more types of mature, specialized cells.
• Adult stem cellsmost body organs.
• Unipotent or mulitipotent
• Embryonic stem cellsembryos.
• Pluripotent

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Cytology Review

• Name two organelles that you observed in the
  laboratory using the compound microscope.
• Name the function of those two organelles.
• Name the organelle responsible for each of the
  following functions
• Energy processing.
• Synthesis of ribosomes.
• Translating the genetic code in DNA into a
  protein.
• Modifying a protein and packaging it into a
  secretory vesicle.
• Detoxifying drugs and toxins.
• Participates in programmed cell death

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Cytology Review--Answers

• Nucleus, nucleolus, mitochondrion.
• Genetic control, ribosome synthesis, energy
  conversions.
• The organelles
• Mitochondrion
• Nucleolus
• Ribosome
• Golgi complex
• Peroxisome
• Lysosome