Chapter 7 A Tour of the Cell -- Part 1

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Chapter 7A Tour of the Cell -- Part 1

• TOPICS How to study cells
• Eukaryotic vs Prokaryotic
• Nucleus and Ribosomes
• Endomembrane system
• Other membranous organelles

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How do we study cells?

• Know the different microscopes and their
  purposes
• Light microscope (what we have at TPHS)
• Electron microscope
• SEM (scanning)surface scanning, the outside
  (see fig. 7.2, 7.9, or 7.23 b in the book)
• TEM (transmission)transmits through the
  specimen to see inside. (see fig. 7.2, 7.13 b, or
  7.18 in the book)
• Figure 7.1 size range in cells

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Figure 7.3cell fractionation, centrifuge
What are the largest
organelles/parts of a cell that fraction off into
the pellet first? What are the smallest? (last)
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Why are most cells so small?

• THIS IS REVIEW
• Prokaryotic (before, kernel aka nucleus)
• Archaea and Bacteria, no nucleus, no
  membrane-bound organelles, usually much smaller,
  figure 7.4, they have cytoplasm, cytosol, 1
  circular chromosome, plasma membrane, cell wall,
  ribosomes, nucleiod.
• Eukaryotic (true, kernel)
• Membrane-bound nucleus and other organelles,
  compartmentalized cells, animals, plants, fungi,
  protists. These cells are larger due to
  compartmentalization.

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Figures on pages 108 109.

• Know the names, identify the structures and know
  the functions of all of the organelles listed on
  these diagrams.
• Know major differences between the typical animal
  and typical plant cells.
• Animals centrioles,
• Plants (plastids) chloroplasts, cell wall,
  large central vacuole, tonoplast

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The Nucleus and Ribosomes

• Nucleus contains most of the genes that control
  a Eukaryotic cell.
• Nuclear envelope/nuclear lamina porous (why?)
  and double membrane
• Chromatin (46)/ tightly coiled chromosomes (46),
  genes
• Nucleolus, synthesizes ribosomes, in the nucleus
• Ribosomes site of protein synthesis
• Free ribosomesfor the production of proteins to
  be used in the cytosol and attached ribosomes on
  the ER for the production of proteins which are
  packaged or exported via the ER system.

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• Pores
• Lamina
• Outer andinner mem-branes
• Nucleolus
• Ribosomes
• Attachment site of ER

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Free and bound ribosomes, ER
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Endomembrane system

• Definition all of these structures have
  interchangeable membranes, they are all made of a
  phospholipid bilayer and are fusible with one
  another.
• Includes nuclear envelope (lamina) ER Golgi
  apparatus lysosomes vacuoles plasma membrane

See Figures 7.14, 7.16, 8.7 Why arent
mitochondria and chloroplasts in this group?
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The endomembrane systems interconnectedness.
All membranes are the same bilayer.
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Endoplasmic Reticulum

• Network of membranes within the cytoplasm
• (compartmentalization cisternal space)
• Rough ER network attached to the nucleus.
  Example proteins which are made from the attached
  ribosomes and then shipped via the ER insulin,
  glycoproteins, transport vesicles.
• Smooth ER conducts diverse processes
  synthesizes Lipids, detoxifies drugs, metabolizes
  carbos. ex glycogen hydrolysis (breakdown) in
  the liver.

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Golgi Apparatus / Bodies

• Modification and sorting of products from the
  ER.
• Secretion organelle
• Flattened sacs (cisternae), cis and trans faces,
  (receiving and shipping/transport sides of
  the golgi apparatus)
• Fusion of membranes (fig 7.14, 7.16, 8.7) is
  possible since the ER and the Golgi are both of
  the endomembrane system.
• Some vesicles have external identification
  molecules see fig. 8.7

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Fig. 7.14 Notice how the vesicle from the ER
fuses with the cis side of the golgi and then the
trans side of the golgi fuses with a food vacuole
to deliver digestive enzymes.
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Lysosomes Fig. 7.14

• Contains hydrolytic enzymes which digest
  macromolecules and recycle materials from the
  cell. (see fig 7.14)
• Usually maintains pH of 5 (acid)

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Vacuoles

• Many types
• Food vacuoles (in all cells)
• Contractile vacuoles, in protists like the
  paramecium (fig 8.12) for osmoregulation (water
  regulation).
• Plants large central vacuole (tonoplast)

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Mitochondria

• Energy transformation (from glucose to ATP)
• Cellular respiration and ATP generation
• Contain a small amount of their own DNA
  (semiautonomous) (Ch. 28), not of the
  endomembrane system.
• Double phospholipid bilayer. Cristae, large
  surface area. Inner membrane and Matrix.
• More to come stay tuned for Chapters 9-10

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Know the parts
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Chloroplasts (a type of plastid)

• Energy transformations (sun energy to ATP)
• Photosynthesis (CO2 and H2O to Glucose)
• Synthesize organic molecules from carbon dioxide
  and water.
• Contain a small amount of their own DNA
  (semiautonomous) (Ch 28)
• Double membrane, thylakoids, grana, stroma fluid

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Know the partsStroma fluidthylakoid
membranes are chlorophyll rich grana stacks
of many thylakoids, site of light reactions
(because of chlorophyll.)
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Peroxisomes

• Consume deadly free oxygen within the cell,
  transport it to mitochondria.
• Enzymes transfer hydrogen to oxygen, producing
  hydrogen peroxide (H2O2)
• H2O2 is also toxic to a cell, and an enzyme made
  by the peroxisome can break down H2O2

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• Fig. 7.19