Motor proteins generally require ATP (or GTP) hydrolysis to ensure unidirectional movement. A. In the absence of ATP would you expect a motor protein to stop moving, to wander back and forth, to move in reverse, or to continue moving forward but more slowly? B. Assume that the concentrations of ATP, ADP, and phosphate were adjusted so that the free energy change for ATP hydrolysis by the motor protein was equal to zero (instead of very negative, as it is normally). Under these conditions would you expect a motor protein to stop moving, to wander back and forth, to move in reverse, or to continue moving forward but more slowly?
Motor proteins generally require ATP (or GTP) hydrolysis to ensure unidirectional movement. A. In the absence of ATP would you expect a motor protein to stop moving, to wander back and forth, to move in reverse, or to continue moving forward but more slowly? B. Assume that the concentrations of ATP, ADP, and phosphate were adjusted so that the free energy change for ATP hydrolysis by the motor protein was equal to zero (instead of very negative, as it is normally). Under these conditions would you expect a motor protein to stop moving, to wander back and forth, to move in reverse, or to continue moving forward but more slowly?
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2. Just like chemical reactions, protein conformational changes are bidirectional. Motor proteins are able to move in one direction by making coordinated conformational changes through the use of ATP. Why does this allow unidirectional movement instead of random walking?
A. ATP hydrolysis releases a charged phosphate which is used to push the motor protein. | |
B. The negatively charged phosphates of ATP electrostatically pull the motor proteins. | |
C. Coupling ATP hydrolysis to one conformational change means that the reverse conformational change would require a large energy input. | |
D. Coupling ATP hydrolysis to the +âG conformational changes allows the reaction to proceed. |
Value: 1
Anabolic pathways of metabolism are pathways that:
a. build complex molecules from simple ones.
b. release stored chemical energy.
c. take place primarily in skeletal muscle
d. make large quantities of ATP.
Value: 2
The sum of all chemical reactions in a cell is referred to as _______________.
Value: 3
Organisms that derive both their energy and carbon from organic compounds are:
a. photoautotrophs.
b. chemoautotrophs.
c. chemoheterotrophs.
d. photoheterotrophs
Value: 4
It is often stated that the phosphate bonds in ATP are "high energy," but in fact, they are not notably high in energy. Rather, they are easy to break, and the âG of hydrolysis is a "useful" quantity of energy. What makes the phosphate bonds easy to break?
a. They are close to the destabilizing nitrogenous base adenosine
b. Positive charges on amino groups repel each other.
c. Negative charges on phosphate groups repel each other
d. High acidity attacks bonds between amino acids.
Value: 5
Which of the following describes ATP hydrolysis? Select all that apply
[mark all correct answers]
a. exergonic
b. spontaneous
c. often coupled to a reaction that has a positive ÎG
Value: 6
Which of the following describes catabolic reactions?
a. They are endergonic and have a negative change in free energy
b. They are exergonic and have a negative change in free energy
c. They are exergonic and have a positive change in free energy.
d. They are endergonic and have a positive change in free energy.
Value: 7
Why are cells not infinitely big?
a. Because they wouldn't fit in an organism
b. Because they would have a small surface area:volume ratio and substances would diffuse in and out too slowly
c. Because they would have a large surface area to volume ratio and substances would diffuse in and out too quickly
Value: 9
How is organelle movement around cells controlled?
a. the nucleus directs the movement of organelles in a cell
b. the cytoskeleton is like a monorail that moves organelles in a cell via motor proteins
c. organelles do not move, they have a fixed position in the cell
d. organelles move by facilitated diffusion in the cell
Value: 10
1. Prokaryotic cells lack:
a. a. A nucleus
b. organelles
c. cell membrane
d. DNA
e. A and B
Value: 11
Rough endoplasmic reticulum (rER)
a. a. Makes cell membranes
b. has ribosomes attached
c. are a site of protein synthesis
d. all of the above
Value: 12
Match the items.
The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.
a. help to digest worn-out or damaged organelles. | |
b. Takes in molecules in transport vesicles, modifies them, and sends them back out in vesicles | |
c. makes sugar | |
d. makes ATP | |
e. assembles the ribosomes | |
f. gives the cell structure | |
g. move material around the cell | |
1. vesicles | a b c d e f g |
2. cytoskeleton | a b c d e f g |
3. the golgi apparatus | a b c d e f g |
4. lysosomes | a b c d e f g |
5. mitochondrion | a b c d e f g |
6. chloroplast | a b c d e f g |
7. nucleolus |