Wednesday, October 8, 2008

Lyon’s Den Blog

Unit One Review: Chapters 3 and 6




Chapter 3: Water and the Fitness of the Environment

  1. Section 3.1 The polarity of water molecules results in hydrogen bonding
    1. Water is made of 2 hydrogen atoms joined to one oxygen atom by single covalent bonds
    2. Water is a polar molecule meaning that opposite ends of the molecule have opposite charges
  2. Section 3.2 Four emergent properties of water contribute to Earth's fitness for life
    1. Cohesion
      1. The binding together of like molecules- often by hydrogen bonds
      2. Water molecules stick together by cohesion
    2. Adhesion
      1. The clinging of one substance to another
      2. This property allows the water to counter the pull of gravity during transpiration
    3. Surface Tension
      1. A measure of how difficult it is to stretch or break the surface of a liquid
      2. Water has a higher surface tension to most other molecules
    4. Moderation of Temperature
      1. Water has a very high specific heat
        1. The amount of heat required to raise or lower the temperature of a substance by 1 degree C.
        2. Water's high specific heat is essential to our survival and maintaining a relatively moderate climate
      2. Evaporative cooling
        1. The property of a liquid whereby the surface becomes cooler during evaporation owing a loss of highly kinetic molecules to the gaseous state
        2. Contributes to the stability of the temperature in lakes and ponds
        3. Provides a mechanism that prevents terrestrial organisms from overheating
        4. Ice helps keep organisms in bodies of water from freezing, it works like an insulator
    5. The Solvent of Life
      1. An aqueous solution is one in which water is the solvent
      2. Water is the closest thing to a universal solvent
    6. Hydrophilic substances
      1. Any substance that has an affinity for water
      2. Can be hydrophilic and not dissolve
      3. i.e. glucose
    7. Hydrophobic substances
      1. Any substance that does NOT have an affinity for water
      2. Are nonionic and nonpolar substances
      3. i.e. vegetable oil
    8. molarity
      1. the number of moles of solute per liter of solution
  3. Section 3.3 Dissociation of water molecules leads to acidic and basic conditions that affect living organisms
    1. ocassionally a hydrogen ion that is participating in a hydrogen bond between two water molecules shifts from one molecule to another
      1. an acid is a substance that is increases the hydrogen ion concentration of a solution
      2. a substance that reduces the hydrogen concentration is a base

      3. Buffers are substances that minimize changes in the concentrations of H+ and OH-
    2. Review Questions
      1. The bonds that are broken when water vaporizes are:
        1. Ionic bonds
        2. Bonds between water molecules
        3. Bonds between atoms within individual water molecules
        4. Polar covalent bonds
        5. Nonpolar covalent bonds
      2. Which of the following is an example of a hydrophobic material?
        1. Paper
        2. Table salt
        3. Wax
        4. Sugar
        5. Pasta


Chapter 6: A Tour of the Cell

  1. Section 6.1 to study the cells, biologists use microscopes and the tools of biochemistry
    1. Light microscopes
      1. Visible light is passed through the specimen and then passed through the specimen or onto the surface
    2. Electron microscope
      1. Focuses a beam of electrons through the specimen or onto its surface
      2. Two basic types of electron microscopes
        1. Sacanning electron microscope
        2. Transmission electron microscope
  2. Section 6.2/ 6.3
    1. Comparing prokaryotic and eukaryotic cells


Pro cells

Eu cells

Plasma membrane 



Cytosol w/ organelles 










1-10 micrometers

10-100 micrometers 

Internal membranes 




  1. Prokaryotic cell
    1. Prokaryotic cells include bacteria and archaebacteria
    2. Details include:    
      1. No membrane bound nucleus
      2. No membrane bound organelles
      3. Smaller than eukaryotes
  2. Eukaryotic cells
    1. Eukaryotic cells are animal and plant cells
    2. Details include:
      1. Membrane bound organelles
      2. Membrane bound nucleus, which contains cell's chromosomes
      3. Much larger than prokaryotes
      4. Eukaryotic cells make up the kingdom's protista, fungi, plantae, and animalla
  3. The Nucleus: Genetic Library of the Cell
    1. Contains most of the genes in the eukaryotic cell
    2. Enclosed by the nuclear envelope which has a double membrane
      1. The nuclear side of the envelope is lined by the nuclear lamina
    3. Within the nucleus DNA is organized into discrete units called chromosomes
  4. Ribosomes: Protein Factories in the Cell
    1. A cytoplasmic organelle that is the site for protein synthesis
      1. Free ribosomes- ribosomes suspended in the cytosol
      2. Attatched ribosomes- attatched to the outside of the endoplasmic reticulum
  1. Section 6.4 the endomembrane system regulates protein traffic and performs metabolic functions in the cell
    1. The endomembrane system includes:
      1. Nuclear envelope
      2. Endoplasmic reticulum
      3. Golgi apparatus
      4. Lysosomes
      5. Vacuoles
      6. Plasma membrane (related)
    2. Endoplasmic reticulum (ER) extensive membraneous network of tubules and sacs (cisternae) which sequesters its internal lumen (cristernal space) from the cytosol
      1. Smooth ER- synthesis of lipids, phospholipids and steroids, carbohydrate metabolism, detoxify drugs and poisons, and stores calcium for muscle contraction
      2. Rough ER- continuous with outer membrane of the nuclear envelope, manufactures secretory proteins
    3. Golgi Apparatus
      1. An organelle that is made of flattened, stacked membranous sacs that modify, store, and route products of the cell
      2. It also has distinct polarity, the cis face receives and the trans face pinches off vesicles for transport to other sites
    4. Lysosomes
      1. An organelle that is a membrane-enclosed bag of hydrolytic enzymes that digest all major classes of macromolecules
      2. Optimal PH is about 5
      3. Enzymes include carbohydrases, proteases, and nucleases
      4. Lysosomes pinch off from the trans face of the golgi apparatus
    5. Vacuole
      1. An organelle which is a membrane- enclosed sac that is larger than a vesicle
        1. Contractile vacuole- vacuole formed by phagocytosis which is the site for cellular digestion in some plants and macrophages
        2. Food vacuole- large vacuole formed by phagocytosis which is the site for intracellular digestion in some protists and macrophages
        3. Central vacuole- large vacuole found in most mature plant cells
  2. Section 6.5 mitochondria and chloroplasts change energy from one form to another
    1. Mitochondria
      1. The sites of cellular respiration, a process that uses energy extracted from organic molecules to produce ATP
      2. Contains two layers
        1. Outer membrane- highly permeable to solutes, but it blocks the passage of proteins and other macromolecules
        2. Inner membrane- contains embedded enzymes that are involved in CR. The membrane's many infoldings or cristae increase the surface area available for these reactions to occur
      3. Chloroplasts
        1. The site of photosynthesis
        2. Divided into 3 functional compartments by a system of membranes
          1. Thylakoid space- segregates the interior of the chloroplast into two compartments
          2. Intermembrane space- seperates the double membrane
          3. Thylakoid- flattened membraneous sacs inside the chloroplast
      4. Plastids
        1. A group of plant and algal membrane bound organelles that include amyloplasts, chromoplasts, and chloroplasts
          1. Amyloplasts- colorless plastids that store starch; particularily in roots and tubers
          2. Chromolpasts- have pigments that give fruites and flowers their yellow and orange hues
          3. Chloroplasts- the sites of photosynthesis (see above)
            1. Contain chlorophyll
  3. Section 6.6 the cytoskeleton is a network of fibers that organize cell structures and activities in the cell
    1. The cytoskeleton
      1. A network of fibers that form a dynamic framework for movement, support, and regulation of the cell
        1. Give mechanical support to the cell and helps maintain its shape
        2. Mechanically transmits signals from the cell's surface to its interior
        3. Enables a cell to change shape
      2. Constructed by 3 types of fibers    
        1. Microtubules- straight hollow fibers that are about 25nm in diameter and 200nm in length, constructed from tubulin
        2. Microfilaments- 7nm, constructed from actin, provide cellular support, participate in muscle contraction, and help with elongation and contraction of pseudopodia during amoeboid movement
          1. Intermediate filaments- (8-12nm) between microtubules and microfilaments, are constructed from keratin subunits, fix organelle position, reinforce cell shape, bear tension
        3. Other types of fibers
          1. Centrioles- a pair of cylindrical structures that are located in the centrosome of an animal cell. Composed of 9 sets of triplet microtublues and arranged in a ring
          2. Cilla and flagella- locomotor organelles found in eukaryotic cells. Assist in movement. Cilla is more numerous than flagella
  4. Section 6.7 extracellular components and connections between cells help coordinate cellular activities
    1. Cell walls of plants
      1. Protect the plant cels and give support, contains 3 parts
        1. Primary cell wall- the first wall secreted by a young plant cell
        2. Middle lamella- a thin layer of polysaccharides that hold adjacent cells together
        3. Secondary cell wall- is secreted by a mature plant cell. It is strong and has a double matriz that affords the cell protection and support
    2. The extracellular matrix (ECM) of animal cells
      1. The fluid outside of animal cells, contains fibers of collagen, proteoglycans, fibronectin, and its proteins also bind to integrin
    3. Intercellular junctions
      1. Plant cells contain channels which perforate the cell walls called plsasmodesmata. Cytosol passes through the plasmodesmata and connects the chemical environments of adjacent cells
      2. Junctions in animals
        1. Tight junctions
          1. The membranes of neighboring cells are tightly pressed together by specific proteins. They prevent the leakage of extracellular fluid across a layer of epithelial cells
        2. Desosomes
          1. Contain intermediate filaments made of sturdy karatin proteins, they fasten adjacent cells together
        3. Gap junctions
          1. Provide cytoplasmic channels from one cell to an adjacent cell. Allows ions, sugars, amino acids, and other small molecules to pass
  5. Review Questions
    1. Which of the follow is present in a prokaryotic cell?
      1. Mitochondrion
      2. Ribosome
      3. Chloroplast
      4. ER
      5. Nuclear envelope
    2. Which of the following is NOT considered part of the endomembrane system?
      1. Nuclear envelope
      2. Chloroplast
      3. Golgi apparatus
      4. Plasma membrane
      5. ER

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