MOLECULAR BIOLOGY OF THE CELL: SIXTH EDITION
CHAPTER 19: CELL JUNCTIONS AND THE
EXTRACELLULAR MATRIX
© Garland Science 2015
1 Indicate whether each of the following descriptions better applies to connective (C) or
epithelial (E) tissues. Your answer would be a four-letter string composed of letters C and E only,
e.g. EEEE.
( ) Cells are usually distributed sparsely in the extracellular matrix.
( ) Gap junctions are rarely found.
( ) Direct cell–cell attachments are common.
( ) Cells are tightly associated into sheets.
2 In the following schematic diagram of a simple columnar epithelium lining the digestive
tract, indicate which position (A to F) along the basal–apical axis better corresponds to each of
the following features. Your answer would be a six-letter string composed of letters A to F only,
e.g. FEDABC.
A B C D E F
Gut Connective
lumen tissue
( ) Basal lamina
( ) Cell apex
, ( ) Adherens junctions
( ) Gap junctions
( ) Hemidesmosomes
( ) Tight junctions
3 Which of the following cell junctions uses cadherin cell adhesion molecules to anchor the
actin cytoskeleton?
A. Tight junction
B. Adherens junction
C. Desmosome
D. Hemidesmosome
E. Gap junction
4 Which of the following is NOT an anchoring junction?
A. Adherens junction
B. Desmosome
C. Actin-linked cell–matrix junction
D. Hemidesmosome
E. Tight junction
5 Indicate true (T) and false (F) statements below regarding cadherins. Your answer would
be a four-letter string composed of letters T and F only, e.g. TFTT.
( ) Cadherins are present in all multicellular organisms.
( ) Adhesion by cadherins is dependent on Ca2+ ions.
( ) In contrast to nonclassical cadherins, classical cadherins are more closely related in
sequence.
( ) E, N, and P cadherins are mainly found in desmosomes.
6 You have isolated epithelial cells from mouse mammary glands and have grown them in a
three-dimensional gelatinous matrix in the presence or absence of a specific inhibitor that targets a
transmembrane metalloprotease. The protease is capable of cleaving cadherin near the base of its
extracellular domain to release an N-terminal fragment containing the extracellular cadherin
domains. The distribution of the cells in the matrix, as seen under a light microscope, one day
after the transplantation of the isolated tissue is presented in the following schematic drawings.
Which condition (1 or 2) do you think corresponds to the presence of the protease inhibitor?
Write down 1 or 2 as your answer.
, 1 2
7 Cadherin molecules at the cell surface are often clustered side-to-side to create a
molecular Velcro that attaches the cell to another cell or to the extracellular matrix. In the
following simplified drawings, two cells are initially attached via such a Velcro. When one of the
cells moves in either of three different ways (A to C), it is faced with a mechanical resistance from
the cadherin interactions. The resistance against which type of movement do you think is the
weakest? Write down A, B, or C as your answer.
Two A B C
neighboring The cell moves The cell slides The cell rolls
cells away from its past its over its
neighbor neighbor neighbor
8 Cells expressing either N-cadherin (A), high levels of E-cadherin (B), or low levels of E-
cadherin (C) have sorted themselves out on a substratum in a cadherin-dependent manner as
shown in the schematic drawing below. Which cells (A to C) would you expect to correspond to
white, gray, and black in the drawing, respectively? Your answer would be a three-letter string
composed of letters A to C only, e.g. CAB.
CHAPTER 19: CELL JUNCTIONS AND THE
EXTRACELLULAR MATRIX
© Garland Science 2015
1 Indicate whether each of the following descriptions better applies to connective (C) or
epithelial (E) tissues. Your answer would be a four-letter string composed of letters C and E only,
e.g. EEEE.
( ) Cells are usually distributed sparsely in the extracellular matrix.
( ) Gap junctions are rarely found.
( ) Direct cell–cell attachments are common.
( ) Cells are tightly associated into sheets.
2 In the following schematic diagram of a simple columnar epithelium lining the digestive
tract, indicate which position (A to F) along the basal–apical axis better corresponds to each of
the following features. Your answer would be a six-letter string composed of letters A to F only,
e.g. FEDABC.
A B C D E F
Gut Connective
lumen tissue
( ) Basal lamina
( ) Cell apex
, ( ) Adherens junctions
( ) Gap junctions
( ) Hemidesmosomes
( ) Tight junctions
3 Which of the following cell junctions uses cadherin cell adhesion molecules to anchor the
actin cytoskeleton?
A. Tight junction
B. Adherens junction
C. Desmosome
D. Hemidesmosome
E. Gap junction
4 Which of the following is NOT an anchoring junction?
A. Adherens junction
B. Desmosome
C. Actin-linked cell–matrix junction
D. Hemidesmosome
E. Tight junction
5 Indicate true (T) and false (F) statements below regarding cadherins. Your answer would
be a four-letter string composed of letters T and F only, e.g. TFTT.
( ) Cadherins are present in all multicellular organisms.
( ) Adhesion by cadherins is dependent on Ca2+ ions.
( ) In contrast to nonclassical cadherins, classical cadherins are more closely related in
sequence.
( ) E, N, and P cadherins are mainly found in desmosomes.
6 You have isolated epithelial cells from mouse mammary glands and have grown them in a
three-dimensional gelatinous matrix in the presence or absence of a specific inhibitor that targets a
transmembrane metalloprotease. The protease is capable of cleaving cadherin near the base of its
extracellular domain to release an N-terminal fragment containing the extracellular cadherin
domains. The distribution of the cells in the matrix, as seen under a light microscope, one day
after the transplantation of the isolated tissue is presented in the following schematic drawings.
Which condition (1 or 2) do you think corresponds to the presence of the protease inhibitor?
Write down 1 or 2 as your answer.
, 1 2
7 Cadherin molecules at the cell surface are often clustered side-to-side to create a
molecular Velcro that attaches the cell to another cell or to the extracellular matrix. In the
following simplified drawings, two cells are initially attached via such a Velcro. When one of the
cells moves in either of three different ways (A to C), it is faced with a mechanical resistance from
the cadherin interactions. The resistance against which type of movement do you think is the
weakest? Write down A, B, or C as your answer.
Two A B C
neighboring The cell moves The cell slides The cell rolls
cells away from its past its over its
neighbor neighbor neighbor
8 Cells expressing either N-cadherin (A), high levels of E-cadherin (B), or low levels of E-
cadherin (C) have sorted themselves out on a substratum in a cadherin-dependent manner as
shown in the schematic drawing below. Which cells (A to C) would you expect to correspond to
white, gray, and black in the drawing, respectively? Your answer would be a three-letter string
composed of letters A to C only, e.g. CAB.
