Tour Of The Cell

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Tour Of The Cell

• Chapter 6

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Microscopy

• What is the difference between magnification and
  resolving power?
• Magnification is how much larger the object can
  now appear
• Resolving power is the ability to distinguish
  between two points It is limited by the
  wavelength of visible light

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The different microscopes

• Light microscope - resolving power is limited by
  the wavelengths of light
• Specimen should be stained, but can be alive
• compound microscope
• stereomicroscope
• Electron microscope - resolving power is greater
  since wavelengths of electrons are smaller than
  those of light
• SEM - 3D image
• TEM - flat image
• electron microscopes cannot use live specimens

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How did scientists first discover the different
cell parts?
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As organisms get larger, why do they become
multicellular?
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Its all about the surface area to volume ratio!
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Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells
• Bacteria, Archaea
• genetic material not in a nucleus
• no membrane bound organelles

• Eukaryotic cells
• Protists, Plants, Fungi and Animals
• true nucleus with genetic material
• has membrane bound organelles

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The Prokaryotic Cell
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The Plasma Membrane
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General Eukaryotic Cells
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Two Areas of the Eukaryotic Cell

• What is the space between the cell membrane and
  the nucleus called?
• The cytoplasm. This includes the organelles and
  the cytosol
• The cytosol is the fluid medium found in the
  cytoplasm

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The nucleus
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Nuclear Components

• Envelope double layered membrane that has pores
  for molecular transport
• Chromatin DNA protein complex of threadlike
  fibers that make up the eukaryotic chromosome
• Chromosome Chromatin fibers condense into
  visible chromosomes during cell division

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Ribosomes

• Prokaryotic ribosomes differ from eukaryotic
  ribosomes
• Function Site of protein synthesis

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The Endomembrane system

• Related through direct continuity or by transfer
  on membrane segments through vesicles
• Structure of membranes is not identical
• Includes
• Nuclear envelope --gt Endoplasmic reticulum --gt
  Golgi apparatus --gt lysosomes --gt vacuoles
  --gtplasma membrane

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Transport vesicle from ER
New vesicle forming
Transport vesicle from Golgi
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Functions of Golgi apparatus

• Modifies stores and routes products of ER
• Alters membrane phospholipids
• Targets products for parts of the cell

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Vacuoles

• Larger than vesicles
• food vacuoles formed by phagocytosis
• contractile vacuole found in fresh water
  protozoans, keeps water balance
• central vacuole found in most plant cells
  stores organic compounds, has enzymes to break
  macromolecules, has poisonous and unpalatable
  compounds, etc.

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Mitochondria and Chloroplasts

• not part of endomembrane system
• their membrane proteins are made by free
  ribosomes and their own ribosomes
• both have small amount of DNA
• grow and reproduce on their own within the cell
• involved in energy transformation

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Plastids

• amyloplasts - store starch, in roots and tubers
• chromoplasts - non-chlorophyll pigments
  responsible for non-green colors
• chloroplasts - chlorophyll containing plastids

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Peroxisome

• Contains enzymes that transfer hydrogen from
  substrates to oxygen producing hydrogen peroxide
• Some use oxygen to fuel the breakdown of fatty
  acids to smaller molecules that can be used in
  the mitochondrion
• In liver they detoxify alcohol and other poisons
  by transferring hydrogen from poison to oxygen
• Hydrogen peroxide is toxic. What enzyme can be
  used to break this down?

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Cytoskeleton

• Provides structural support
• Functions in motility and motion

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Microtubules

• cellular support
• provides tracks for movement within the cell
  e.g. transport vesicles
• composes cilia and flagella, locomotive
  appendages of certain cells
• separation of chromosomes during cell division
  (spindle fiber)
• composes centrioles in animal cells

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Microfilaments

• smaller than microtublues
• participates in muscle contraction
• support
• localized cell contractions

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The Cell Surface

• cell walls in plant cells
• membrane linked channel - plasmodesmata that
  connects cytoplasm between cells

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Animal Cell Surfaces

• glycocalyx - strengthens cell surface, helps glue
  animal cells together
• tight junctions - holds cells together to block
  transport
• desmosomes - rivets cells together into strong
  sheets but permits transport
• gap junctions - analogous to plasmodesmata in
  plant cells

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Lets Review

• Name the cell structure and its function
• Be able to tell if this structure is found in
  prokaryote, eukaryote, plant and/or animal cells

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