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Bio 1201 Final, quizzes 20-25
Terms in this set (45)
at the average depth of the ocean, the hydrostatic pressure is :
the color of bioluminescent light is typically :
volume changes in metabolic biochemical reactions may result from changes in the organization of water (true or false?)
metabolic rates in the deep ocean are typically slower than in comparable shallow-living organisms with similar body temps (true or false?)
in deep-living angler fish, the female is a parasite on the male (true or false?)
phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because..
they amplify the original signal manyfold
binding of a signal molecule to which type of receptor leads directly to a change in the distribution of anions and/or cations on opposite sides of the membrane?
ligand-gated ion channel
amplification of a chemical signal occurs when?
a receptor in the plasma membrane activates several G-protein molecules while a signal molecule is bound to it
signal transduction pathway benefit cells because..
-they help cells respond to signal molecules that are too large or too polar to cross the plasma membrane
-they enable different cells to respond appropriately to the same signal
-variations in the signal transduction pathways can enhance response specificity
-they can amplify a signal
consider this pathway:
epinephrine, G-protein-linked receptor, G protein, adenylyl cyclase, cAMP
(identify the second messenger)
the activation of receptor tyrosine kinases is always characterized by :
dimerization and phosphorylation
lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because..
intracellular receptors are present only in target cells
G protein subunit with an intrinsic GTPase activity
put these in the order for the activity cycle of a G protein:
a hormone binds to a GPCR
GTP replaces GDP
1. a hormone binds to a GPCR
2. GTP replaces GDP
3. subunits dissociate
4. GTP hydrolyzed
protein Kinase A consists of two regulatory and two catalytic subunits. cAMP binds to the regulatory subunit, causing the protein to dissociate into a regulatory dimer and two catalytic subunits
(True or False?)
info about hormones
-hormones often regulate homeostasis through antagonistic functions
-hormones are often regulated through feedback loops
hormones are chemical messengers that travel to target cells through the circulatory system
-hormones are secreted by specialized cells usually located in endocrine glands
a distinctive feature of the mechanism of action of thyroid hormones and steroid hormones is that:
these hormones bind to receptors inside cells
an example of antagonistic hormones controlling homeostasis is:
insulin and glucagon in glucose metabolism
because most chemical signals are unable to pass through the plasma membrane, the cellular action they initiate results from
the activation of a signal transduction pathway
what is the role of a second messenger in hormone action?
it relays a hormone's message inside a target cell
which of the following statements about hormones is incorrect?
-they are produced by endocrine glands
-they are used to communicate between different organisms
-they are carried by the circulatory system
-they elicit specific biological responses from target cells
-they are modified amino acids, peptides, or steroid molecules
they are used to communicate between different organisms
why is it that some body cells respond differently to the same peptide hormones?
a target cell's response is determined by the product of a signal transduction pathway
how is a cell's response to a water-soluble hormone amplified?
regulatory proteins present inside of the cell
frequently, very few molecules of a hormone are required to affect changes in a target cell. This is because..
the mechanism of hormonal action involves an enzyme cascade that amplifies the response to a hormone
hormone X produces its effect in its target cells via the cAMP second messenger system. Which of the following will produce the greatest effect in the cell?
a molecule of hormone X applied to the extracellular fluid surrounding the cell
where is it likely that you will find the receptor molecules for chemical signals?
in the cell membrane of target cells
how does parathyroid hormone affect levels of Ca2+ in the blood?
when Ca2+ levels fall, PTH stimulates bone cells to decompose the matrix of bone and stimulates reabsorption of Ca2+ in the renal tubules
every time you eat a cookie or candy bar, your blood sugar increases. This triggers an increase in the hormone ________
hormones that have antagonistic effects:
insulin and glucagon
type 1 diabetes mellitus is :
an autoimmune disease in which the immune system attacks beta cells in the pancreas
a problem with the long-term use of glucocorticoids, such as cortisone, to treat inflammation is :
suppression of the immune system
the fundamental cell type in a nervous system is a
neurons consist of
a cell body, dendrites, and an axon
what maintains the resting potential (the difference in the electrical charge inside and outside a neuron membrane that enables the cell to transmit a signal)
the transport of sodium and potassium ions by the sodium/potassium pump
a stimulus triggers an action potential by
causing sodium ions to enter the neuron
descrive a nerve signal
the sequential depolarization of the membrane of a neuron
Acetylcholinesterase is the enzyme that degrades acetylcholine. What effect on nerve transmission would occur following the administration of a chemical that inhibited acetylcholinesterase?
extra excitatory postsysynaptic potentials would occur in the postsysynaptic neuron
a neuron that transmits an impulse to the central nervous system after the neuron is stimulated by the environment is called a
Schwann cells make up the
the sodium-potassium pump
expels sodium from the cell
the period in which an axon membrane cannot act is called
the refractory period
"Saltatory conduction" means that the membrane potential changes
only at the nodes of Ranvier
action potentials are generated along a neuron because
depolarization of the membrane at one point causes an increase of permeability to sodium at the next point
how are neurons structurally adapted to chemically transmit impulses to neighboring neurons?
axon terminals contain neurotransmitter substances within synaptic vesicles
info about the transmission across a typical chemical synapse
-the binding of neurotransmitter molecules to receptors transmits an impulse across a synapse
-neurotransmitter molecules are stored in vesicles in the synaptic terminal
-neurotransmitter molecules bind to receptors in the receiving cell's plasma membrane
-action potentials trigger chemical changes that make the neurotransmitter vesicles fuse with the plasma membrane of the transmitting cell
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