Test 2 Study Guide Flashcards
study of energy flowing through living systems
Bioenergetics
all the chemical reactions that take place inside cells, including anabolism and catabolism
Metabolism
pathways that require an energy input to synthesize complex molecules from simpler ones
Anabolic
pathways in which complex molecules break down into simpler ones
Catabolic
adenosine triphosphate, the cell’s energy currency
ATP
process during which energy released by one reaction is used to drive another reaction
Energy coupling
bonds that connect phosphates in an ATP molecule
Phosphoanhydride bonds
communication between a cell
Intercellular signaling
communication within cells
Intracellular signaling
cell that releases signal molecules allow communication with another cell
Signaling cells
molecule produced by a signaling cell that binds with a specific receptor, delivering a signal in the process
Ligand
cell that has a receptor for a signal or ligand from a signaling cell
Target cells
protein in or on a target cell that binds to ligands
Receptors
signal that is sent and received by the same or similar nearby cells
Autocrine signaling
A cell targets a cell connected by gap junctions
Direct (juxtracrine) signaling
Small molecule that transmits signals within a cell
Intracellular mediators
signal between nearby cells that is delivered by ligands traveling in the liquid medium in the space between cells
Paracrine signaling
chemical signal (neurotransmitter) that travels between nerve cells
Synaptic signal
chemical ligand that carries a signal from one nerve cell to the next
Neurotransmitters
small space between axon terminals and dendrites of nerve cells where neurotransmitter’s function
Chemical synapses
long-distance signal that is delivered by ligands (hormones) traveling through an organism’s circulatory system from the signaling cell to the target cell
Endocrine signals
cell that releases ligands involved in endocrine signaling (hormones)
Endocrine cells
receptor protein that is located in the cytosol of a cell and binds to ligands that pass through the plasma membrane
Internal receptors
cell-surface protein that transmits a signal from the exterior of the cell to the interior, even though the ligand does not enter the cell
Cell surface receptors
region of a cell-surface receptor that is located on the cell surface
Extracellular domain
bind a ligand and open a channel through the membrane that allows specific ions to pass through
Ion channel linked receptors
cell-surface receptor that activates membrane-bound G-proteins to transmit a signal from the receptor to nearby membrane components
G-protein linked receptors
cell-surface receptor with intracellular domains that are associated with membrane-bound enzymes
Enzyme-linked receptors
propagation of the signal through the cytoplasm (and sometimes also the nucleus) of the cell
Signal transduction
(of receptor proteins) interaction of two receptor proteins to form a functional complex called a dimer
Dimerization
chemical compound formed when two molecules join together
Dimer
chain of events that occurs in the cytoplasm of the cell to propagate the signal from the plasma membrane to produce a response
Signaling pathway
integration of signals from two or more different cell-surface receptors that merge to activate the same response in the cell
Signal integration
enzyme that catalyzes the transfer of a phosphate group from ATP to another molecule
second messengers: small, non-protein molecule that propagates a signal within the cell after activation of a receptor causes its release
Kinase
second messenger that is derived from ATP
Cyclic AMP
PKA, kinase that is activated by binding to cAMP
cAMP dependent kinase
lipid present at small concentrations in the plasma membrane that is converted into a second messenger; it has inositol (a carbohydrate) as its hydrophilic head group
Inositol phospholipids
cleavage product of PIP2 that is used for signaling within the plasma membrane
Diacylglycerol (DAG)
cleavage product of PIP2 that is used for signaling within the cell
Inositol triphosphate (IP3)
programmed cell death
Apoptosis
enzyme that removes the phosphate group from a molecule that has been previously phosphorylated
Phosphatases
enzyme that degrades cAMP, producing AMP, to terminate signaling
Phosphodiesterase
ligand that binds to cell-surface receptors and stimulates cell growth
inhibitor
Growth factors
specialized cell that can receive and transmit electrical and chemical signals
Neurons
cells that provide support functions for neurons
Glia
structure that extends away from the cell body to receive messages from other neurons
Dendrites
junction between two neurons where neuronal signals are communicated
Synapses
electrically sensitive structure on the cell body of a neuron that integrates signals from multiple neuronal connections
Axon hillock
tube-like structure that propagates a signal from a neuron’s cell body to axon terminals
Axon
structure on the end of an axon that can form a synapse with another neuron
Axon terminal
fatty substance produced by glia that insulates axons
Myelin
gaps in the myelin sheath where the signal is recharged
Nodes of ranvier
glial cell in the central nervous system that provide nutrients, extracellular buffering, and structural support for neurons; also makes up the blood-brain barrier
Astrocytes
glia that scavenge and degrade dead cells and protect the brain from invading microorganisms
Microglia
glial cell that provides nutrients and structural support for neurons in the peripheral nervous system
Satellite cell
glial cell that myelinates central nervous system neuron axons
Oligodendrocytes
glial cell that creates myelin sheath around a peripheral nervous system neuron axon
Schwann cells
glia that serve as scaffolds for developing neurons as they migrate to their final destinations
Radial glia
cell that lines fluid-filled ventricles of the brain and the central canal of the spinal cord; involved in production of cerebrospinal fluid
Ependymal cell
Non-neuronal cells that are not electrically excitable
Neuroglia
Small protrusions off dendrites that serve as synaptic site
Spines
the ability to change
Plasticity
the cell body of a neuron, where the nucleus and organelles are located
Soma
a bundle of axons in the peripheral nervous system
Nerves
the electrical signal transmitted by the axon of a neuron
Action potential
the electrical charge of a neuron (measured in mV
Electrical potential
movement from the cell body to the axon terminals
Anterograde
movement from the axon terminals to the cell body
Retrograde
a motor protein that uses ATP in anterograde transport of materials
Kinesin
motor proteins that uses ATP in retrograde transport of materials
Dynein
synapse where the cytoplasm of two cells is physically shared
Electrical synapses
a synapse where two cells are separated by a synaptic cleft that chemical neurotransmitters must cross to signal between cells
Chemical synapses
the end of the axon furthest from the cell body
Presynaptic terminal
release neurotransmitters into the synapse
Presynaptic cell
cells that receive neurotransmitters
Postsynaptic cell
a diffusion barrier that prevents some of the substances circulating in the blood to pass brain tissue
Blood brain barrier
chemicals that promote the growth and development of cells
Trophic factors
cavities within the brain that are filled with cerebral spinal fluid
Ventricles
a clear fluid formed as an ultra-filtrate of blood plasma. CSF is present in both the intracranial and spinal compartments
Cerebral spinal fluid
transmembrane proteins that have a pore that allow for the passage of ions between the inside and the outside of the cell
Ion channels
ion channels that are always open
Leak channels
ion channels that open/close in response to changes in voltage (membrane charge)
Voltage-gated ion channels
Ion channels that open in response to the binding of a chemical ligand (such as a neurotransmitter)
Ligand-gated ion channels
ion channels that open in response to physical distortion
Mechanoreceptors
channels that open in response to light
Photoreceptors
does not allow passage
Impermeable
process by which a high concentration of a substance, given enough time, will eventually diffuse into a lower concentration and settle evenly over the space
Chemical gradient
passive process when substances move from a higher concentration to a lower concentration
Diffusion
electrical forces acting on charged molecules “pulling” opposite charges towards each other while also “pushing” like charges away from one another
Electrical gradient
the combination of electrical and chemical gradients
Electrochemical gradient
the difference in charge across the cell membrane (between the inside and outside of the cell)
Membrane potential
when the membrane potential gets closer to zero
Depolarization
when the membrane potential gets further away from zero
Hyperpolarization
the membrane potential at which the electrical and concentration gradients for a given ion are in balance
Equilibrium potential
allows for passage across the cell membrane
Permeable
used to calculate the equilibrium potential of an individual ion
Nernst equation
Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule.
a. ATP: glucose
b. an anabolic molecule: catabolic molecule
c. glucose: ATP
d. a catabolic molecule: anabolic molecule
C
The energy released by the hydrolysis of ATP is____
a. primarily stored between the alpha and beta phosphates
b. equal to −57 kcal/mol
c. harnessed as heat energy by the cell to perform work
d. providing energy to coupled reactions
D
Which of the following molecules is likely to have the most potential energy?
a. sucrose
b. ATP
c. glucose
d. ADP
A
Which of the following is not true about enzymes:
a. They increase ∆G of reactions.
b. They are usually made of amino acids.
c. They lower the activation energy of chemical reactions.
d. Each one is specific to the particular substrate(s) to which it binds.
A
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.
B
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
C
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.
d. Ions bind to carrier proteins in the bloodstream, which must be removed before transport into the cell.
B
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
A
A scientist notices that when she adds a small, water-soluble molecule to a dish of cells, the cells turn off transcription of a gene. She hypothesizes that the ligand she added binds to a(n) ______ receptor.
a. Intracellular
b. Hormone
c. Enzyme-linked
d. Gated ion channel-linked
C
Neurons contain ________, which can receive signals from other neurons.
a. axons
b. mitochondria
c. dendrites
d. Golgi bodies
C
A(n) ________ neuron has one axon and one dendrite extending directly from the cell body.
a. unipolar
b. bipolar
c. multipolar
d. pseudounipolar
B
Glia that provide myelin for neurons in the brain are called ________.
a. Schwann cells
b. oligodendrocytes
c. microglia
d. astrocytes
B
Meningitis is a viral or bacterial infection of the brain. Which cell type is the first to have its function disrupted during meningitis?
a. astrocytes
b. microglia
c. neurons
d. satellite glia
B
After an action potential, the opening of additional voltage-gated ________ channels and the inactivation of sodium channels, cause the membrane to return to its resting membrane potential.
a. sodium
b. potassium
c. calcium
d. chloride
B
What is the term for protein channels that connect two neurons at an electrical synapse?
a. Synaptic vesicles
b. voltage-gated ion channels
c. gap junction protein
d. sodium-potassium exchange pumps
C
Which of the following statements is false?
a. The soma is the cell body of a nerve cell.
b. Myelin sheath provides an insulating layer to the dendrites.
c. Axons carry the signal from the soma to the target.
d. Dendrites carry the signal to the soma
B
Which type of glial cell makes cerebral spinal fluid?
a. Microglia
b. Ependymal cells
c. Schwann cells
d. Oligodendrocytes
e. Astrocytes
B
Which cell types are found in the central nervous system? (Select all that apply.)
a. Ependymal cells
b. Microglia
c. Oligodendrocytes
d. Schwann cells
e. Astrocytes
A, B, C, E
Which two cell types are responsible for making the myelin sheath?
a. Astrocytes
b. Schwann cells
c. Microglia
d. Oligodendrocytes
e. Ependymal cells
B, D
Which cell type would respond following an injury to the central nervous system?
a. Ependymal cells
b. Microglia
c. Schwann cells
d. Astrocytes
e. oligodendrocytes
B
Which ion is more concentrated outside of the cell?
a. Sodium
b. Chloride
c. Potassium
A
In Condition B, two chambers are separated by an impermeable membrane with an ion channel permeable only to X-, an anion. The left side of the chamber has four double-charged cations, C++, and four single-charged anions, X-. The right side has four uncharged ions, Z0, and four single-charged anions, X-.
Which way will the X- ions move once the channel opens?
What gradient is driving the force behind ion movement?
a. To the right; concentration gradient
b. To the left; electrical gradient
c. To the left; electrical gradient
d. To the right; concentration gradient
A
In Condition A, two chambers are separated by an impermeable membrane with an ion channel permeable only to Y0, an uncharged ion. The left side of the chamber has six Y0 ions with no charge. The right side has three Y0 ions with no charge.
Which way will Y0 move once the channel opens?
What gradient is driving the force behind ion movement?
a. To the left; concentration gradient
b. To the left; electrical gradient
c. To the right; electrical gradient
d. To the right; concentration gradient
D
Which items are structural components of the cell that affect ion movement across the membrane (Select all that apply)
a. Electrical gradient
b. concentration gradient
c. Phospholipid bilayer
d. Ion channels
C, D
A cell is at rest at -65mV, and chloride channels open. In which direction does chloride flow and how does this affect the membrane potential?
a. No net movement; no change in membrane potential
b. Into the cell; makes the membrane potential more positive
c. Out of the cell; makes the membrane potential more negative
d. Out of the cell; makes the membrane potential more positive
e. Into the cell; makes the membrane potential more negative
E
A cell is at rest at -70mV, and potassium channels open. In which direction does potassium flow and how does this affect membrane potential?
a. No net movement; no change in membrane potential
b. Into the cell; makes the membrane potential more positive
c. Out of the cell; makes the membrane potential more negative
d. Out of the cell; makes the membrane potential more positive
e. Into the cell; makes the membrane potential more negative
C
What is the membrane potential?
a. The distribution of ion channels and pumps within the phospholipid bilayer
b. The difference in charge between the inside and outside of the neuron
c. The concentration of cations outside of the cell
d. The concentration of cations inside the cell
B
A cell is at rest at -70 mV, and chloride channels open. In which direction does chloride flow and how does this affect the membrane potential?
a. No net movement; no change in membrane potential
b. Into the cell; makes the membrane potential more positive
c. Out of the cell; makes the membrane potential more negative
d. Out of the cell; makes the membrane potential more positive
e. Into the cell; makes the membrane potential more negative
E
A cell is at rest at -70 mV, and sodium channels open.
In which direction does sodium flow? How does this ion flow affect the membrane potential?
a. No net movement; no change in membrane potential
b. Into the cell; makes the membrane potential more positive
c. Out of the cell; makes the membrane potential more negative
d. Out of the cell; makes the membrane potential more positive
e. Into the cell; makes the membrane potential more negative
B
Sodium channels open within the membrane, and sodium enters the cell. Assuming the cell was at rest at -65 mV, this ion flow would lead to which change in the membrane potential.
a. An increase in membrane potential
b. A decrease in membrane potential
c. No charge in membrane potential
A
Neurons contain ________, which can receive signals from other neurons
Dendrites
A(n) ________ neuron has one axon and one dendrite extending directly from the cell body.
Bipolar
When a ligand binds to a GPCR, which protein does the receptor activate first
G-protein
Glia that provides myelin for neurons in the brain are called ________.
Oligodendocytes
Which event occurs immediately after two RTKs bind to their respective ligands?
Dimerization
When activated microglia are _______
Bushy, less processes
At rest, where are sodium ions concentrated
Outside the cell
What structure is responsible for establishing and maintaining the presence of electrochemical gradients
Sodium-potassium pump
If a neuron’s membrane potential moves from -70 mV to -50 mV, is it undergoing depolarization or hyperpolarization
Depolarization
If a cell was treated with a drug that prevented the synthesis of ATP, how would the flow of sodium change
Decreases
