Cell Signaling Part 1 Concept Review
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by John Lundy
| 10 Questions
Note from the author:
An assignment to insure understanding of key concept concerning cell signaling.
1
1 pt
Above is shown the 4 major types of cell communication. Match the following Biological events with the type of cell signaling that BEST matches what is happening in the organism.
  • Chemical Signals regulating rhythmic muscle contraction are propagated down the length of cardiac muscle fibers from one cell to the next.
  • T cells responding to the activated version of the antigun they produced and being stimulated to divide and reproduce more of the activated antigen type.
  • Mast cell in the respiratory system releasing histamine in response to the presence of an aborigine.
  • Bovine growth Hormone is released during development of a young calf.
  • autocrine signal
  • endocrine signal
  • paracrine signal
  • intercellular signaling
Figure 9.8 A receptor tyrosine kinase is an enzyme-linked receptor with a single transmembrane region, and
extracellular and intracellular domains. Binding of a signaling molecule to the extracellular domain causes the
receptor to dimerize. Tyrosine residues on the intracellular domain are then autophosphorylated, triggering a
downstream cellular response. The signal is terminated by a phosphatase that removes the phosphates from the
phosphotyrosine residues.
Figure 9.10 The epidermal growth factor (EGF) receptor (EGFR) is a receptor tyrosine kinase involved in
the regulation of cell growth, wound healing, and tissue repair. When EGF binds to the EGFR, a cascade of
downstream events causes the cell to grow and divide. If EGFR is activated at inappropriate times, uncontrolled
cell growth (cancer) may occur.
5
1 pt
What property prevents the ligands of cell-surface
receptors from entering the cell?
a. The molecules bind to the extracellular domain.
b. The molecules are hydrophilic and cannot
penetrate the hydrophobic interior of the plasma
membrane.
c. The molecules are attached to transport proteins
that deliver them through the bloodstream to
target cells.
d. The ligands are able to penetrate the membrane
and directly influence gene expression upon
receptor binding.
6
1 pt
The secretion of hormones by the pituitary gland is an
example of _______________.
a. autocrine signaling
b. paracrine signaling
c. endocrine signaling
d. direct signaling across gap junctions
7
1 pt
Why are ion channels necessary to transport ions into or
out of a cell?
a. Ions are too large to diffuse through the
membrane.
b. Ions are charged particles and cannot diffuse
through the hydrophobic interior of the
membrane.
c. Ions do not need ion channels to move through
the membrane.
c. Ions do not need ion channels to move through
the membrane.
d. Ions bind to carrier proteins in the bloodstream,
which must be removed before transport into the
cell.
8
1 pt
Endocrine signals are transmitted more slowly than
paracrine signals because ___________.

a. the ligands are transported through the
bloodstream and travel greater distances
b. the target and signaling cells are close together
c. the ligands are degraded rapidly
d. the ligands don't bind to carrier proteins during
transport
9
1 pt
What is the function of a phosphatase?
a. A phosphatase removes phosphorylated amino
acids from proteins.
b. A phosphatase removes the phosphate group
from phosphorylated amino acid residues in a
protein.
c. A phosphatase phosphorylates serine, threonine,
and tyrosine residues.
d. A phosphatase degrades second messengers in
the cell.
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