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LS 7C Animations (Weeks 1-4)
Terms in this set (65)
When cells communicate by the signaling process, one cell produces a _________________ that must be received by the ___________ on or in the responding cell.
signaling molecule; signal receptor
Signal molecules that are _______ usually have their corresponding receptor ______________ of the cell.
polar; on the surface
A receptor that is inside the cell would require a __________ signal molecule that can ____________________ the plasma membrane.
nonpolar; pass through
A _________ expresses a gene or genes that direct production of the signaling molecule, and the _______________ expresses a gene or genes that direct production of the _________________.
signaling cell; responding cell; receptor protein
One example of a cellular response to a signal is the triggering of cell division. If a mutation occurred in the gene for the signal receptor in this pathway that caused the receptor to reject binding of the signal, what response can be predicted?
The cell does not divide.
G protein-coupled receptors are found:
on the cell surface.
When an appropriate signal binds to a G protein-coupled receptor, what is the best description of how the information is passed across the plasma membrane?
Signal binding causes a conformational change in the cytoplasmic portion of receptor protein.
Which of the following statements best summarizes the function of G protein-coupled receptors?
A signal present on the outside of the cell leads to a change on the inside of the cell.
When a G protein-coupled receptor binds a signal molecule, it activates a G protein. The active G protein is bound to a molecule of _______, and in its active state can _________.
GTP; activate another target protein
If a mutation caused the G protein to become permanently bound to GTP, what result can be predicted?
It constantly signals its pathway to be "on."
The type of signaling cascade shown in the video directly affects which of these animal tissue types?
Adrenaline stimulates an increase in heart rate by binding to:
G-protein coupled receptors on the surface of cardiac muscle cells.
The alpha subunit of a G-protein is free to diffuse in the plane of the membrane when:
GDP is exchanged for GTP.
Termination of the adrenaline signal begins when:
GTP bound to the G-protein alpha subunit is hydrolyzed to GDP and Pi.
Arrange the events in the stimulation of heart muscle in order from earliest (1) to latest (5). Note that this question does not list every step in the pathway, but the steps presented should be arranged in order.
1. Activation of G-proteins
2. Activation of adenylyl cyclase
3. Conversion of ATP into cyclic AMP
4. Activation of protein kinase A
5. Phosphorylation of proteins that induce contraction in muscle cells
Which of the following could lead to a prolonged increase in heart rate, even in the absence of an external signal? Choose all that apply.
-An inability of a G-protein to hydrolyze GTP
-An inability to inactivate protein kinase A
The primary advantage of a signaling cascade is that it:
allows a large intracellular response from a small number of extracellular signal molecules.
In the example of adrenaline signaling, which steps represent an amplification of the signal?
activated receptor activates G proteins, activated adenylyl cyclase produces cAMP, active protein kinase A phosphorylates target proteins
Which of the following steps does not result in an amplification of the signal information?
activation of adenylyl cyclase by active G protein
In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. How many total modified protein target molecules result from a single activated signal receptor?
In the example of adrenaline signaling used in the animation, suppose each amplification step produces hundredfold active molecules. A signaling pathway resulting from a single activated signal receptor results in the consumption of _______ molecules of GTP and _______ molecules of ATP.
Which of the following is false?
High blood glucose levels can result from an overproduction of insulin.
High blood glucose stimulates the _________ cells in the pancreas to secrete _________.
Insulin injections are an important treatment for some diabetics. A serious potential side effect of insulin injections is hypoglycemia (low blood sugar). This would most likely occur under which of the following circumstances?
injecting too much insulin
Assume you haven't eaten in the last 24 hours. Which of the following would you predict?
Glucagon release from the pancreas will increase.
Muscle and liver cells respond to insulin by:
taking up glucose and storing it as glycogen.
Which of the following statements correctly describe(s) the relationship between the classes of hormones and their behavior or function? Select all that apply.
-how soluble the hormone is in water.
-whether the hormone will be able to move through the cell membrane.
-whether the hormone interacts with receptors on the cell membrane.
-whether the hormone interacts with receptors inside the cell.
Which of the following statements correctly describe(s) peptide hormones? Select all that apply.
-Most peptide hormones act on cells by binding to receptors on cell surfaces and triggering signaling cascades inside the cell.
-The action of peptide hormones can cause changes in gene expression or can affect the function of metabolic enzymes in cells.
Which of the following correctly describe(s) the functioning of steroid hormones in the animal endocrine system? Select all that apply.
-Steroid hormones can change which mRNAs are produced in a cell.
-Steroid hormones have their primary effects in the cell's nucleus.
You are working with a team of scientists who are investigating the biochemical control system involved in how animals digest fats in their meals. You have evidence that there must be a signal molecule involved that is released soon after the fats are consumed. When this signal molecule is present it triggers activation of appropriate digestive enzymes and cellular uptake transporters until the meal has been fully digested. Based on this information, what type of signal molecule would you predict is involved in this process?
peptide or amine hormone
Which of the following occurs when a neuron is depolarized?
Sodium ions enter the neuron through voltage-gated sodium channels.
Transmission of impulses along a neuron in the vertebrate nervous system ordinarily occurs in only one direction because, following passage of an action potential, the neuron is temporarily in a refractory period or hyperpolarized. This is caused by which of the following?
the movement of potassium ions out of the axon
In vertebrates, the speed of transmission along a neuron can be increased by which of the following?
myelinating the axon
In vertebrates, the speed of transmission along neurons is much faster in myelinated neurons compared to unmyelinated neurons. Which of the following is not true of transmission along myelinated neurons?
Saltatory conduction in non-myelinated neurons slows the process of transmission.
Action potentials typically move in one direction along the neuron away from the cell body. This is due to which of the following?
the temporary hyperpolarization of the axon membrane following the action potential spike
When an action potential reaches the axon terminal:
neurotransmitter molecules are released from the axon terminal and bind to receptors on the postsynaptic neuron, causing either an inhibitory hyperpolarization or an excitatory depolarization.
What causes the increase in cytosolic calcium that triggers the fusion of secretory vesicles to the membrane and the release of neurotransmitters into the synaptic cleft?
the change in conformation of voltage-gated calcium channels in the axon terminal membrane
Which of the following determines whether or not an action potential is triggered in the postsynaptic neuron?
the overall net change in membrane potential caused by the combined EPSPs and IPSPs
Place the following events in the correct order. I. opening of voltage-gated calcium channels II. change in membrane potential of the postsynaptic neuron III. fusion of secretory vesicles with the plasma membrane of the axon terminal IV. binding of neurotransmitters to receptors on the postsynaptic neuron V. increase in cytosolic calcium levels in the presynaptic neuron VI. arrival of action potential at the axon terminal of the presynaptic neuron
VI, I, V, III, IV, II
Which of the following could be inhibited by greatly decreasing extracellular calcium?
the fusion of secretory vesicles with the presynaptic plasma membrane
Stretch receptors in the knee extensor muscles stimulated by the tap of a physician's reflex hammer just below the knee cap directly triggers a nerve impulse in which of the following?
a sensory neuron
Which of the following is inhibited following a tap of a physician's reflex hammer just below the knee cap?
motor neurons of the knee flexor muscles
The interneuron in the spinal cord triggers which of the following?
an inhibitory stimulus that prevents contraction of the knee flexor muscles
How many synapses are involved in the contraction of the knee extensor muscles in the knee-jerk reflex?
How many synapses in total are involved in the knee-jerk reflex?
Which of the following allows the determination of the strength of a signal?
the frequency of action potentials exhibited by the local sensory neurons
Over a period of time, the number of action potentials exhibited by a stimulated sensory neuron decreases. This is known as:
Which of the following describes the functional importance of lateral inhibition?
Lateral inhibition allows the determination of the location of the source of a stimulus.
Lateral inhibition is the result of a sensory neuron causing which of the following?
the direct inhibition of adjacent interneurons
We are not aware of the fact that we are wearing socks shortly after we put them on. This is due to which of the following?
Images that you see in your peripheral vision are not as sharp as those directly in front of you because:
there is a higher concentration of cone cells in the center of the retina in an area called the fovea.
Which of the following most likely happens if you shift your gaze from the TV on the other side of the room to look closely at a stain on the front of the shirt you are wearing?
Your lenses become more rounded.
Which photoreceptor cells are primarily responsible for allowing you to read a newspaper in a dimly lit room?
the rod cells in the retina
Which of the groups of vertebrates below has the greatest number of cone cell types?
In which of the groups of vertebrates listed below would you expect to find the fewest number of different photopigments?
What is required to separate actin and myosin during sarcomere contraction?
Place the following events in muscle contraction in the correct sequence from first to last. 1. ATP binds to myosin head. 2. Myosin head interacts with actin. 3. ATP is converted to ADP and Pi. 4. Myosin head is cocked back. 5. Myosin head pivots in the power stroke. 6. ADP and Pi are released from myosin.
1, 3, 4, 2, 6, 5
The force generated by a muscle depends on:
All of these responses are required for force generation.
Which of the following is referred to as the power stroke?
a conformational change in myosin
The force generated by a long muscle varies as it contracts through its range of movement. At which point is the greatest force generated?
in the middle of the contraction when the muscle is at an intermediate length.
The cells that make up skeletal muscles are called:
The functional unit of skeletal muscles are called:
Which of the following is not true of muscle fibers?
Many muscle fibers are packaged into a muscle fibril.
Thick filaments are made of ____________ and thin filaments are made of ____________.
Skeletal muscle appears striated with light and dark regions. Which of the following is found in the dark regions?
actin and myosin
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