A fluorescent molecule of 2000 daltons is microinjected into a single cell of an epithelial layer. When the layer is examined in a fluorescence microscope, the molecule remains confined to that cell. However, when a fluorescent molecule of 800 daltons is injected into a single cell of an epithelial layer, it quickly appears in the adjacent cells. Which of the following is responsible for the spread of the smaller molecule? 1. A) Desmosomes (maculae adherentes) 2. B) Focal contacts 3. C) Gap junctions 4. D) Intermediate junctions 5. E) Tight junctions (zonulae occludentes)

A fluorescent molecule of 2000 daltons is microinjected into a single cell of an epithelial layer. When the layer is examined in a fluorescence microscope, the molecule remains confined to that cell. However, when a fluorescent molecule of 800 daltons is injected into a single cell of an epithelial layer, it quickly appears in the adjacent cells. Which of the following is responsible for the spread of the smaller molecule? 1. A) Desmosomes (maculae adherentes) 2. B) Focal contacts 3. C) Gap junctions 4. D) Intermediate junctions 5. E) Tight junctions (zonulae occludentes)

Human Anatomy & Physiology (11th Edition)

11th Edition

ISBN:9780134580999

Author:Elaine N. Marieb, Katja N. Hoehn

Publisher:Elaine N. Marieb, Katja N. Hoehn

Chapter1: The Human Body: An Orientation

Section: Chapter Questions

Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...

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12) Match the cell-cell junction on the left with the appropriate function on the right. Note that more than one letter may apply for a particular function and that each letter may be used more than once or not at all. A) Gap junctions provides a very strong attachment point between cells B) Desmosomes allow easy movement of large amounts of substances between adjacent cells C) Plasmodesmata seals the plasma membranes of adjacent cells together, preventing the movement of molecules between them D) Tight junctions
List and describe the three main types of cytoskeleton. If you wanted to do immunocytochemistry to specifically stain each type of cytoskeleton, what is a protein that could be used for each cytoskeletal type (in other words, what is a unique protein for each cytoskeletal type)?
During a microscopy exercise in the anatomy laboratory,a student makes the following observations about a tissuesection: (1) The section contains some different types ofscattered protein fibers—that is, they exhibit differentwidths, some are branched, some are long and unbranched,and their staining characteristics differ (some are seenonly with specific stains). (2) Several cell types withdifferent morphologies are scattered throughout the section,but these cells are not grouped tightly together. (3) Theexamined section has some “open spaces”—that is, placesbetween cells and the observed fibers in the section thatappear clear with no recognizable features. What type oftissue is the student observing? Where might this tissue befound in the body?
List and describe the three main types of cytoskeleton. If you wanted to do immunocytochemistry to specifically stain each type of cytoskeleton, what is a protein that could be used for each cytoskeletal type (in other words, what is a unique protein for each cytoskeletal type)? What are three types of actin structures? Describe the involvement of actin structures in cell migration. How is the growth and shrinking of microtubules regulated? Then describe the roles of microtubules in: chromosomal separation during mitosis and the movement of organelles and vesicles within a cell. Describe a possible mechanism on how signaling pathways might impact the cytoskeleton, so that cell migration could be regulated in a localized manner within a multicellular organism. (hint: think about the possible transcriptional regulation of the G-protein regulators) What are 2 main challenges of protein targeting? Then describe one way these challenges are overcome during signal-based targeting and one way…
You are using fluorescence microscopy to study a plasma membrane protein that is fused to green fluorescent protein (GFP). Adding GFP to a protein allows us to monitor the protein in live cells using light microscopy without the need for any special stains. Under baseline conditions, the fusion protein is evenly distributed over the surface of the cell. You use the microscope software and laser to photobleach an ROI and watch for the recovery of fluorescence in real time. you have a control protein, a GFP fusion with the insulin receptor, where the ROI fully recovers from photobleaching in 10 min. However, when Protein X is fused with GFP, the fluorescence recovers only to 10% the starting levels in 10 min in the same cell type under the same experimental conditions. Provide two different, reasonable explanations for the different results with these two fusion proteins.
Let’s say you wanted to look at cells of Bacillus cereus, which are rod-shaped cells that are about 4 µm long. If you were observing B. cereus with a microscope using the high-power lens, how big would the cells appear to be when you look at them?
There are certain cells that are multinucleated (having more than one nucleus). Which of the following is a possible explanation for this occurrence? A) The cell underwent repeated cytokinesis but no mitosis. B) The cell underwent repeated mitosis with simultaneous cytokinesis. C) The cell underwent repeated mitosis, but cytokinesis did not occur. D) The cell had multiple S phases before it entered mitosis.
The inner nuclear membrane contains a) None of these choices are accurate b) proteins including chaperonins and translocon c) integral membrane proteins including emerin, the lamin B receptor (LBR), and the SUN proteins d) peripheral membrane proteins including KASH and SUN
Which of the following are binding/architectural proteins in the nucleus? a) U1 and U3 and H1, H2, and H3 b) cohesion, TFIIIC, CTCF
Which of the following regarding microtubules is LEAST correct? A)Microtubules do not have important functions in neurons B)Microtubules are important for anterograde axoplasmic transport C)No answer text provided. D)Microtubules are important for maintaining the structure of the neuron E)Microtubules are important for retrograde axoplasmic transport
1) All of the following are functions of proteins within a membrane except __________. A)Maintaining the fluidity of membranes B)transport ions and other polar substances C)receptors to bond molecules outside of the cell D)helping the body to recognize its own cells 2) Which of the following organelles is not part of the endomembrane system A)mitochondria B)golgi apparatus C)lysosomes D)rough endoplasmic reticulum 3) Which cytoskeletal element is composed of actin and is involved with muscle contraction and provided strength to cells during stretching and compression? A)Microfilimants B)Intermediate filaments C)Microtubules D)Flagella
(a) If you were to magnify a cell 10,000-fold (typical of the magnification achievedusing an electron microscope), how big would it appear? Assume you are viewing a“typical” eukaryotic cell with a cellular diameter of 50 μm.(b) If this cell were a muscle cell (myocyte), how many molecules of actin could ithold? Assume the cell is spherical and no other cellular components are present; actinmolecules are spherical, with a diameter of 3.6 nm. (c) If this were a liver cell (hepatocyte) of the same dimensions, how manymitochondria could it hold? Assume the cell is spherical; no other cellular components arepresent; and the mitochondria are spherical, with a diameter of 1.5 μm