Cell Organelles Campbell BIO Textbook Supplementary

• Cell motility - includes both changes in cell location and movement of cell parts
• Motor proteins attach to a receptor on a vesicle which can "walk" the vesicle along a microtubule or microfilament
• A cilium may also act as a "signal receiving antenna" for the cell
• In vertebrate animals, almost all cells have a cilium which is called primary cilium that transmit molecular signals from cell's environment to interior, which lead to changes in the cell's activities
• Nonmotile primary cilia have "9+0" pattern in which the microtubule assembly of a cilium or flagellum is anchored in the cell by a basal body
• Bending movements of the flagella and motile cilia involve motor proteins called dyneins that are attached along each microtubule doublet
• The outer doublets and two central microtubules are held together by flexible-linking proteins
• Which type of cell does cytoplasmic streaming occur and what element of the cytoskeleton is involved?

  plant cells; microfilaments
• A 3D network formed by microfilaments just to the inside of the plasma membrane, cortical microfilaments, help support the cell's shape
• The network of microfilaments gives rise to what outer cytoplasmic layer with a semisolid consistency of a gel?

  Cortex
• What makes up the core of microvilli in some intestinal cells?

  microfilaments
• Actin interacts with a thicker microfilament called myosin to cause contraction of muscle cells
• For instance, dead skin cells are full of keratin. Therefore what element of the cytoskeleton remains after cell death?

  Intermediate filaments
• Endosymbiont theory - theory states that an early ancestor of eukaryotic cells (a host cell) engulfed an oxygen-using nonphotosynthetic prokaryotic cell.
• Over the course of evolution the endosymbiont will become what organelle in the host cell ?

  Mitochondria
• Besides the nucleus surrounded by a double membrane, what are the other organelles that have a double membrane?

  Mitochondria and chloroplasts.
• Each of the two membranes enclosing the mitochondrion is a phospholipid bilayer
• Chloroplasts convert light to chemical energy since the membranes are divided into what components?

  intermembrane space, stroma, thylakoid space
• What do some peroxisomes use when breaking down fatty acids into smaller molecules?

  Oxygen
• What are the specialized peroxisomes found in fat-storing tissues of plant seeds that help convert fatty acids to sugar?

  Glyoxysomes
• In smooth ER, detoxification usually involves adding hydroxyl groups to drug molecules, making them more water-soluble and easier to flush the body.
• Secretory proteins depart from ER wrapped in the membranes of vesicles that bud in which specialized region of the ER?

  Transitional ER
• As polypeptides destined to be membrane proteins grow from ribosomes, they are inserted into the ER membrane itself and anchored there by their hydrophobic portions
• Cisternal maturation model - proposes that the Golgi cisternae themselves "mature," moving from the cis to the trans face while carrying some proteins along
• Molecular identification tags - Phosphate groups added to the Golgi products, aid in sorting by acting like zip codes on mailing labels
• If leakage occurs in a lysosome, the released enzymes are not very active since the cytosol has what pH?

  Neutral pH
• What protects the proteins of the inner surface of lysosomal membrane if the lumen is filled with hydrolytic enzymes?

  3D shapes of proteins
• What do lysosomal enzymes dismantle during autophagy when the damaged organelle or cytosol is surround by a double membrane?

  inner membrane and the enclosed material
• What is the main solution inside the central vacuole?

  cell sap
• All three types of cell junctions are especially common in what kind of tissue?

  Epithelial tissue
• Microfibrils of the polysaccharide cellulose are synthesized by what enzyme?

  cellulose synthase
• In the extracellular matrix, what are the cell-surface receptor proteins embedded in the plasma membrane?

  Integrins
• What is a nonmotile cilia, also known as signal-receiving "antenna," that is found only one per cell in vertebrate animals?

  primary cilium
• Pore complex - intricate protein structures that lines each pore and plays an important in regulating entry and exits of proteins and RNAs
• What intercellular junction of intestinal lining attaches muscle cells to each other?

  Desmosomes