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Area IB - Molecules and Cells: Cells (10%)

Chapter 4: Cell Structure and Function (Main ideas from Biology, 9th Edition, by Sylvia S. Mader)

4.1 Cellular Level of Organization
  • All organisms are made up of cells, and a cell is the structural and functional unit of organs and, ultimately, of organisms. Cells are capable of self-reproduction, and cells come only from preexisting cells. (Page 58)
  • A cell needs a surface area that can adequately exchange materials with the environment. Surface-area-to-volume considerations require that cells stay small. (Page 59)
4.2 Prokaryotic Cells
  • Bacteria and archaea are prokaryotic cells. Bacterial cells have these features:
    Cell envelope
    • Glycocalyx
    • Cell wall
    • Plasma membrane
    • Nucleoid
    • Ribosomes
    • Thylakoids (cyanobacteria)
    • Flagella
    • Sex pili
    • Fimbriae (Page 63)
4.3 Eukaryotic Cells
  • Compartmentalization is seen in eukaryotic cells, and they are larger than prokaryotic cells. We will discuss the nucleus and ribosomes; the organelles of the endomembrane system; the energy-related organelles; and the cytoskeleton. Each of these has a specific structure and function. (Page 65)
  • The nucleus is in constant communication with the cytoplasm. The nucleus is the command center of the cell because it contains DNA, the genetic material. DNA, which is located in the chromosomes, specifies the sequence of amino acids in a protein through an intermediary called mRNA. Protein synthesis occurs in the cytoplasm, at the ribosomes, whose subunits are made in the nucleolus. Ribosomes occur singly and in groups (i.e., polyribosomes). Numerous ribosomes become attached to the endoplasmic reticulum. (Page 69)
  • The organelles of the endomembrane system are as follows:
    Endoplasmic reticulum (ER): series of tubules and saccules
    Rough ER: ribosomes are present
    Smooth ER: ribosomes are not present
    Golgi apparatus: stack of curved saccules
    Lysosomes: specialized vesicles
    Vesicles: membranous sacs (Page 72)
  • Chloroplasts and mitochondria are organelles that transform energy. Chloroplasts capture solar energy and produce carbohydrates. Mitochondria convert the energy within carbohydrates to that of ATP molecules. (Page 75)
  • The cytoskeleton is an internal skeleton composed of actin filaments, intermediate filaments, and microtubules that maintain the shape of the cell and assist movement of its parts. (Page 77)
  • Centrioles, which are short cylinders with a 9 + 0 pattern of microtubule triplets, may give rise to the basal bodies of cilia and flagella. (Page 78)
  • Cilia and flagella, which have a 9 + 2 pattern of microtubules, are involved in the movement of cells. (Page 78)


Chapter 4 Animation
Click the link to see the animation full size.

Chapter 5: Membrane Structure and Function (Main ideas from Biology, 9th Edition, by Sylvia S. Mader)

5.1 Membrane Models
  • The fluid-mosaic model of membrane structure consists of a fluid phospholipids bilayer in which embedded proteins form a mosaic pattern. (Page 84)
5.2 Plasma Membrane Structure and Function
  • The plasma membrane consists of a phospholipids bilayer that has the consistency of olive oil and accounts for the fluidity of the membrane. The integral proteins, which are either partially or wholly embedded in the membrane, have specific function. Some are involved in the passage of molecules through the membrane, others are receptors for signal molecules, and still others play an enzymatic role. (Page 87)
5.3 Permeability of the Plasma Membrane
  • The plasma membrane is differentially permeable. Certain substances can freely pass through the membrane, and others cannot. Those that cannot freely cross the membrane may be transported across either by carrier proteins or by vesicle formation. (Page 88)
  • Molecules diffuse down their concentration gradients. A few types of small molecules can simply diffuse through the plasma membrane. (Page 89)
  • In an isotonic solution, a cell neither gains nor loses water. In a hypotonic solution, a cell gains water. In a hypertonic solution, a cell loses water and the cytoplasm shrinks. (Page 91)
  • Some of the proteins in the plasma membrane are carriers. They transport biologically useful molecules into and out of the cell. (Page 92)
  • During facilitated transport, small molecules follow their concentration gradient. During active transport, small molecules and ions move against their concentration gradient. (Page 93)
  • Substances are secreted from a cell by exocytosis. Substances enter a cell by Endocytosis. Receptor-mediated Endocytosis allows cells to take up specific kinds of molecules and then they are released within the cell. (Page 95)
5.4 Modification of Cell Surfaces


Chapter 5 Animations
Click the links to see the animations full size.
How Diffusion Works

How Facilitated Diffusion Works

How Osmosis Works

How the Sodium-Potassium Pump Works

Endocytosis and Exocytosis

Chapter 9: The Cell Cycle and Cellular Reproduction (Main ideas from Biology, 9th Edition, by Sylvia S. Mader)

9.1 The Cell Cycle
  • The cell cycle consists of interphase (G1, S, and G2) plus cell division (mitosis and cytokinesis). During the life of an organism, both cell division and apoptosis occur. (Page 151)
9.2 Mitosis and Cytokinesis
  • Each type of eukaryote has a characteristic number of chromosomes in the nucleus of each cell. The chromosomes duplicate prior to mitosis, and this allows the chromosome number to stay constant despite nuclear division. (Page 153)
  • During mitosis, daughter chromosomes go into daughter nuclei by a mechanism that ensures each daughter nucleus has a full set of chromosomes. (Page 156)
  • Cytokinesis in animal cells is accomplished by a furrowing process. Cytokinesis in animal cells begins with the formation of a cell plate, which eventually becomes new plasma membrane between the daughter cells. (Page 157)
  • Mitosis is critical to the development and repair of organisms. The meristem cells of flowering plants and the stem cells of human tissues are capable of dividing throughout the lifetime of the individual. (Page 157)
9.3 The Cell Cycle and Cancer
  • Cancer cells grow and divide uncontrollably, and then they metastasize, forming new tumors wherever they relocate. (Page 159)
  • When a proto-oncogene mutates and becomes an oncogene, or if a tumor suppressor gene mutates, the cell cycle is not properly regulated, and tumor formation is more likely to occur. (Page 160)
9.4 Prokaryotic Cell Division
  • Prokaryotes reproduce asexually by binary fission. DNA replicates, and the two resulting chromosomes separate as the cell elongates. (Page 162)
  • Due to binary fission and mitosis, daughter cells are genetically identical to the parent cell. Cell division allows unicellular organisms to reproduce and is necessary to growth and repair in multicellular organisms. (Page 163)


Chapter 9 Animations
Click the links to see the animations full size.
How the Cell Cycle Works

Mitosis and Cytokinesis

Control of the Cell Cycle

Stimulation of Cell Replication

How Tumor Suppressor Genes Block Cell Division