Amino acid entry into cells can occur via uniporters or symporters. If the rate of anamino acid entry into the cell increases when the pH decreases, this suggests that itis:O being transported by a uniporterbeing actively pumped across the membrane against its concentration gradientbeing transported by a H* symportercrossing the membrane via simple diffusionnone of the above Botulism, a type of food poisoning, can affect motor neurons to result in paralysisand death. This is due to the introduction of a protease which effectively cleavesVAMP, a V-SNARE protein. What effect would this have on the motor neuron?Uncontrolled vesicle fusion with plasma membranePrevention of vesicle docking with plasma membranePremature release of vesicles from actin cagePrevention of vesicle movement to plasma membraneIncreased secretion of neurotransmitter

Transport of molecules across a membrane can take place via various processes, in lifeforms. Uniport…

Answered: Botulism, a type of food poisoning, can…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Similar questions

Neurons have long thin processes called axons, structuresspecialized for conducting signals throughout the organism’s nervous system. Some axonal processes can be as long as 2 m—for example, the axons that originate in your spinal cord and terminate in the muscles of your toes. Small membrane-enclosed vesicles carrying materials essential to axonal function move along microtubules of the cytoskeleton, from the cell body to the tips of the axons. If the average velocity of a vesicle is 1 μm/s, how long does it take a vesicle to move from a cell body in the spinal cord to the axonal tip in the toes?
An analog of cGMP, 8-Br-cGMP, will permeate cellular membranes, is only slowly degraded by a rod cell’s PDE activity, and is as effective as cGMP in opening the gated channel in the cell’s outer segment. If you suspended rod cells in a buffer containing a relatively high [8-Br-cGMP], then illuminatedthe cells while measuring their membrane potential, what would you observe?
Botulinum toxin binds to receptors present at the terminal bouton in order to enter the neuron. What vesicular transport process do you think is involved in the toxin entering the neuron?
When nerve cells contact each other, they form adherens junctions (AJs) at the point of contact. The main transmembrane (TM) protein in the junctions is N-cadherin. N-cadherin is a single pass TM protein with a short intracellular domain and a large extracellular domain on the amino end. Proper formation of the AJs requires both actin (MF) and microtubules (MTs). Motor proteins for MTs are dynein (-) end and kinesin (+) end (and were discovered by Michael Sheetz). Maintenance of preformed AJs requires MFs . Adding drugs that disrupt MFs causes AJs to fall apart, and the N-cadherin is removed from the PM (by endocytosis). If the drugs are removed, MTs (& MFs) are required to restore the N-cadherin to the plasma membrane. choose answer for D1 and D2 D. Suppose cells contain a soluble kinase that modifies N-cadherin that has been removed from the PM. D-1. The kinase could catalyze modification(s) of the side chains of amino acids near (the N end) (the C end) (either end, but not…
The microtubules of an axon are thought to be nucleated at the centrosome, then severed from their nucleation site and moved into the axon. It was noted in the text that cytoplasmic dynein is responsible for the retrograde movement of organelles in axons, yet this same motor is thought to mediate the anterograde movement of microtubules in these same cellular processes. How is it possible that the same minus end–directed motor can be involved in both anterograde and retrograde movements?
Although purified actin can assemble reversibly in vitro, various actin-binding proteins regulate the assembly of actin filaments in the cell. Predict the effect on a cell’s actin cytoskeleton if function-blocking antibodies against each of the following were independently microinjected into cells: profilin, thymosin-β4, CapZ, and the Arp2/3 complex.
Actin filaments at the leading edge of a crawling cell are believed to undergo treadmilling. What is treadmilling, and what accounts for this assembly behavior?
You are studying a Drosophila protein called FROZN that you think is a vesicle snare that plays a role in exocytosis of synaptic vesicles containing acetylcholine at the neuro-muscular junction. Because this protein has been isolated from neuromuscular junctions, you hypothesize that this snare is a Ca+2 sensor that mediates the final merging of vesicles with the membrane. To test this hypothesis you perform 2 experiments: 1. You make a mutant Drosophila that lacks FROZN and find that synaptic vesicle release at the neuromuscular junction is blocked. 2. You block Ca+2 entry into the presynaptic neuron terminal in a normal (wild type) fly and find that synaptic vesicle release is blocked. Do these experiments support your hypothesis that FROZN is a vesicle snare and is the Ca+2 sensor? Is there another possible explanation for the function of FROZN? Explain your answer.
A synaptic vesicle has a diameter of 40 nm. The concentration of a neurotransmitter inside this vesicle is 250 mM. How many molecules of this neurotransmitter are in the vesicle?
Typically, there is an ion gradient between the cytoplasm and the interior of synaptic vesicles. The ion gradient has a functional role. Which of the following statements best describes the ion gradient across the synaptic vesicle membrane and its role? a.) There is a proton gradient across the synaptic vesicle membrane, and it provides the driving force for the transport of neurotransmitter into the vesicle. b.) There is a sodium gradient across the synaptic vesicle membrane, and it provides the driving force for the transport of neurotransmitter into the vesicle. c.) There is a proton gradient across the synaptic vesicle membrane, and it provides the driving force for the transport of neurotransmitter out of the vesicle. d.) There is a sodium gradient across the synaptic vesicle membrane, and it provides the driving force for the transport of neurotransmitter out of the vesicle.
Select the correct statement regarding the actin cytoskeleton. They are involved in the formation of the axoneme. Actin microfilaments are the most stable cytoskeleton network. Can undergo catastrophe due to GTP hydrolysis-mediated conformational changes. Synthesis and degradation of actin microfilaments is directional, with g-actin subunits added only to the + end of the microfilament while depolymerization occurs at the - end. From the list below, select the correct statements regarding the genetic code. Codons code for 30 distinct amino acids. The basis of the genetic code are codons. The genetic code has a possible 64 different codons. The genetic code has built-in degeneracy. Codons are formed by 5 consecutive nucleotides.
One of your classmates is planning to study endocytosis at neuronal synapses for their senior thesis. He is interested in what type of molecules neurons endocytose. They propose to use a cell line mutated in the microtubule motor kinesin to keep endocytic vesicles clustered at the synapse where they can be isolated into synaptosomes through differential centrifugation. The classmate shows you protocols for growing neurons in culture and one that demonstrates the feasibility of isolating synaptosomes. But you know there is something else wrong with this proposal that will keep it from succeeding. What is it?

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