Download LESSON—19 THE EXTERIOR OP THE CELL. A. Objectives

LESSON—19
THE EXTERIOR OP THE CELL.
A. Objectives
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Provide a general structure of a membrane receptor; explain the importance of
receptors.
Discuss why cells need identification markers; list specific examples of identification
markers; predict under which circumstances the presence of identification markers on
your cells becomes of practical importance.
Discuss how many cells cooperate to form tissues; compare adhering, organizing and
communicating junctions; define desmosomes, tight junctions and gap junctions.
Discuss the role of the glycocalyx in the functions of the cells; describe the cell wall
structure of plants.
B.
Lecture outline
1.
COMMUNICATION BETWEEN CELLS.
Read:
Cell Junctions (SBM p127-130).
a. receptors.
b. identification numbers.
c. junctions between cells:
anchoring junctions: desmosomes, hemidesmosomes, and adherens junctions
organizing junctions: tight junctions.
communicating junctions: gap junctions connexins
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2.
CELL COAT OR GLYCOCALYX IN ANIMAL CELLS.
3.
CELL WALL IN PLANT CELLS.
C. Study Questions.
1.
What is a typical molecule that would bind to a cell receptor?
A.
ATP.
B.
DNA.
C.
glycolipids.
D.
hormones.
E.
surface markers.
2.
Examples of molecules to which cell surface receptors respond include all of the following EXCEPT
A.
adrenalin.
B.
thyroxine.
C.
insulin.
D. acetylcholine.
E.
water.
3.
What is the role of MHC molecules?
A.
transport of glucose by facilitated diffusion.
B.
recognition of the hormone insulin.
C.
recognition of self.
D. recognition of a particle to be phagocytized.
E.
transport of glycine through a coupled channel.
4.
Desmosomes that hold cells tight together under stress are
A.
adhering junctions.
B.
communicating junctions.
C.
ordinary junctions.
D. organizing junctions.
E.
matrimonial junctions.
5.
Small molecules sometimes pass from one cell to another through
A.
adhering junctions.
B.
communicating junctions.
C.
ordinary junctions.
D. organizing junctions.
E.
matrimonial junctions.
6.
The polar character of the eptithelial cells of the gut are maintained because of the presence of
A.
adhering junctions.
B.
communicating junctions.
C.
ordinary junctions.
D. organizing junctions.
E.
matrimonial junctions.
7.
Plant cells communicate with each other by cytoplasmic strands that extend through pores of the cell wall.
The cytoplasmic extensions are called
A.
adhering junctions.
B.
communicating junctions.
C.
ordinary junctions.
D. organizing junctions.
E.
plasmodesmata..
8.
Anchoring junctions that hold cells together at one point as a spot weld does are
A.
tight junctions
B.
C.
D.
E.
adhering junctions
desmosomes
gap junctions
plasmodesmata
9.
Junctions that permit the transfer of water, ions, and molecules between adjacent plants cells are
A.
tight junctions
B.
adhering junctions
C.
desmosomes
D.
gap junctions
E.
plasmodesmata
10.
Junctions that help form the blood-brain barrier are
A.
tight junctions
B.
adhering junctions
C.
desmosomes
D.
gap junctions
E.
plasmodesmata
11.
One difference between tight junctions and dermatomes is that tight junctions:
A.
B.
C.
D.
E.
12.
are regions where the plasma membrane from two neighboring cells are in actual contact.
occur only in plants.
involve connective microfilaments that traverse the space between adjacent cells.
are anchored by microfilaments on the insides of the cell membranes of adjacent cells.
contain a 24 nm space between two adjacent membranes.
The structures in this figure:
A.
B.
C.
D.
E.
provide anchorage points between adjacent cells.
allow the transport of small molecules and ions between adjacent cells.
allow passage of materials through intercellular spaces.
prevent the passage of materials through intercellular spaces.
can only be found in plants.
13. Plasmodesmata of plant cells are functionally equivalent to ________ of animal cells.
A.
gap junctions
B.
dermatomes
C.
tight junctions
D.
cell surface receptors
E.
microvillus