The Cell

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The Cell

• The stuff that has been boring you for years!
• (Brought to you by the people who make learning
  mandatory so that we can keep our jobs and have
  summer off!)

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The Basics Prokaryote vs. Eukaryote

• Pro bacteria, archaebacteria, no true nucleus,
  lacks nuclear envelope, Genetic Material in
  nucleoid region, no membrane bound organelles,
  0.1-10 µm
• Euk Protista, Fungi, Plantae, Animalia, true
  nucleus, bounded by nuclear envelope, genetic
  material within nucleus, contains cytosol and
  membrane bound organelles, 10-100.0µm

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Membrane Structure

• Plasma membrane is boundary between living and
  nonliving, 8nm thick, controls chemical traffic,
  selectively permeable
• Made of amphipathic phospholipids, means
  hydrophilic and hyrdrophobic region present

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Fluid Mosaic Membrane

• Membrane held together by weak hydrophobic
  interactions
• lipids and proteins drift w/in membrane
• must be fluid to work properly, moderated by
  cholesterol

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• membrane less fluid at warmer T by restraining
  movement of phospholipids
• at low T, prevent packing of phospholipids
• Membrane is a mosaic of diff proteins embedded an
  dispersed in a phospholipid bilayer

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• Integral proteins transmembrane,
• peripheral proteins attached to membrane
  surface
• Protein functions channels, transport,
  recognition, adhesion, receptor, electron
  transport
• Distinct directional orientation
• Carbohydrates on exterior, proteins also have
  directional orientation

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• Cholesterol provide rigidity in animal cells,
  sterols in plants
• Glycolayx carbohydrate coat covering outer
  plasma membrane, markers for cell to cell
  recognition

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Organelles Cell Structures

• Know the following structures and organelles.
• Nucleus, nuclear envelope, ribosome, Endoplasmic
  reticulum, golgi apparatus, lysosome, peroxisome,
  mitochondria, chloroplast, cell walls, vacuoles,
  vessicles,

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Cytoskeleton

• Structural support for motility and regulation
• Allows cell to change shape
• mechanically transmits signals from surface to
  interior
• constructed from three types of fibers
• microtubules (thick)
• microfilaments(thin)

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• Intermediate fibers

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Microtubules

• Found in Eukaryotic Cells, hollow, straight,
  constructed of globular protein called tubulin,
  reinforce cell shape
• Tracks for organelle movement by motor molecules

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• Separate chromosomes during cell division
• Centrosomes, centrioles, cilia, flagella

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Centrosomes and Centrioles

• Centriole pair of cylindrical structures located
  in centrososme, composes of nine sets of triplet
  microtubules arranged in a ring, replicate during
  division

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Cilia and Flagella

• May propel, or draw fluid across membrane
• extension of plasma membrane with core of
  microtubules, 9 2 pattern, identical to
  centrioles, anchored by basal body
• Use ATP to power dynein movement

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Microfilaments

• Solid rods of globular protein (actin) wound into
  helix
• Provide cellular support, bear tension, aide in
  muscle contraction (myosin), cytoplasmic
  streaming, and localized contraction for the
  cleavage furrow during cell division

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Intermediate filaments

• Composed of Keratin, more permanent the
  microtubules and microfilaments
• Bear tension, framework for cytoskeleton, fix
  organelle position (nucleus)

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Cell Junctions

• Anchor cells to one another, provide passageway
  for exchange of nutrients and wastes
• Desmosomes protein attachments between animal
  cells, like a spot weld
• Tight Junctions stitched seams in animal cells,
  no movement between, digestive system

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Cell Junctions Continued

• Gap Junctions narrow tunnels, animal cells,
  consist of proteins called connexons, prevent
  cytoplasm from mixing, but allow ions to pass
• Plasmodesmata plant cells, desmotubule (from
  ER) surrounded by cytoplasm passes through

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Movement of Materials.Bio Again

• You need to know
• Selectively permeable membrane, osmosis,
  diffusion, facilitated diffusion, active
  transport, Endo and Exocytosis (including
  pinocytosis and phagocytosis), protein pumps
• New stuff I will teach you
• Dialysis diffusion of solutes across a
  selectively permeable membrane, passive transport

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Movement of Materials continued

• Plasmolysis the movement of water out of the a
  cell that results in the collapse of the cell,
  passive
• Countercurrent exchange diffusion between two
  regions, like gills and fish blood stream, heat
  in ducks in legs and body, passive
• Receptor-mediated endocytosis active, specific
  molecules bind to specialized receptors, form
  ligands in the pit. Proteins that transport
  cholesterol and hormones

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Veggin Out Photosynthesis

• Photosynthesis transforms solar light energy
  trapped by chloroplasts into chemical bond energy
  stored in sugar and other organic molecules,
  exergonic redox reaction
• Autotrophic nutrition making organic molecules
  from inorganic raw materials, called producers,
• Photoautotrophs Use light as E source
• Chemoautotrophs use the oxidation of inorganics
  (S or Ammonia) as source, bacteria

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Choloroplast

• Where light dependent and independent take place
• Chlorophyll green pigment, color and
  absorption, in mesophyll, in thylakoid membranes
• Stroma fluid outside thylakoid

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Noncyclic Photophosphorylation

• Photophosphorylation process of making ATP using
  E from light (the light dependant reaction)
• Check the diagram and try to remember.

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Calvin- Benson Cycle

• Uses ATP and NADPH to reduce CO2 to sugar
• Light Independent

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The Production of ATP

• Chemiosmotic Theory mechanism by which ADP is
  phosphorylated to ATP
• Specifically coupling of exergonic electron
  flow down electron transport chain to endergonic
  AP production by the creation of a proton
  gradient across a membrane. Proton gradient
  drives ATP synthesis as protons diffuse back
  across membrane.

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Chemiosmotic Theory

• H protons accumulate inside thylakoids
• ETC in a membrane translocate protons across the
  membrane as electrons pass through a series of
  carriers that are progressively more
  electronegative
• ATP Synthase generate ATP

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C4 Photosynthesis

• Higher rate than C3, less water loss, for plants
  in hot, dry climates. Sugarcane and crab grass
• Instead of PGA, form OAA (oxaloacetate), a 4
  carbon atom, converted to malate, then to
  pyruvate

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CAM Photosynthesis

• Crassulacean acid metabolism (CAM), similar to C4
• Happens during day when stomata closed, low water
  loss, succulents like cacti
• OAA to malic acid, back to OAA, then finishes
  Calvin cycle

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The ultimate movement of materialsCellular
Respiration

• Extracting stored E from glucose to form ATP,
  called aerobic respiration
• Glycolysis, Krebs cycle, and oxidative
  phosphorylation
• Production of 36 ATP from one glucose
• Anaerobic respiration without oxygen, Alcoholic
  fermentation, lactic acid fermentation

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Cell-Cell Recognition

• Basis for
• sorting of embryos cells into tissues and organs
• rejection of foreign cells by immune system
• Recognize by carbs
• branched oligosaccharides bonded covalently to
  lipids and proteins

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Cell Communication

• Communicating cells may be close or far apart,
  communicate by local regulators or hormones
• Three stages of cell signaling
• Reception
• Transduction
• Response

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Signal Reception

• Chemical signals bind to specific receptors
  (receptor protein)
• Signal molecules complement to specific region or
  receptor protein
• signal behaves as ligand (small molecule to large
  molecule)
• Signal receptors are plasma mem. proteins

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Signal Transduction Pathways

• Pathways relay signals from receptors to cellular
  responses
• Chain of reactions
• Information is passed along, passes along info
  not molecule
• second messengers Cyclic AMP, Ca ions

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Cellular Responses to Signals

• In response to signal, cell may regulate activity
  in cyto or transcription in nucleus
• Pathways amplify and specify responses
• cAMP few to many
• target cells with receptor bind to specific
  signaling molecule

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Regulation of Cell Cycle

• Controlled by a clock-
• Internal and external cues regulate
• Chemical-nutrients, growth factors
• Physical-density-dependent inhibition

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• Cancer cells have escaped from cycle controls

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Cancer

• Do not stop due to density inhibition
• Make growth factors themselves, is abnormal
  signal
• Divide indefinitely as long as nutrients are
  available, normal 20-50 times
• Stop dividing at random points
• Immune system normally recognizes

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• If avoid regulation, from tumor, unregulated mass
  of normal tissue
• Benign tumor remain at this original site and
  can be completely removed
• Malignant tumor invasive, impair normal function
  of organs, cancer

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Properties of Malignant tumors

• Anomalous cell cycle,
• Unusual chromosome
• Lost attachment to neighboring cells, may cause
  separation from original tumor
• Migrating cells invade other parts of body, form
  more tumors
• Spread is call metastasis