cell physiology exam 2

What percent of the ATP in a typical animal cell is consumed by the Na+-K+ pump? 1% 10% 25% 66%

25%

Which of the following has the fastest rate of transport? Channel-mediated diffusion Facilitated diffusion Active transport All of the above are equally fast.

Channel-mediated diffusion

Which statement about the glucose transporter is false? It transports glucose across the plasma membrane via a mechanism called facilitated diffusion. A conformational change in the transporter is involved in the transport process. It has 12 α-helical transmembrane segments. Flow through it is unidirectional.

Flow through it is unidirectional. Correct! Flow of glucose is usually from the outside to the inside of the cell, but in some cases, such as in liver cells (where glycogen breakdown can result in high intracellular concentrations of glucose), it can be transported outward.

Glucose from your breakfast traveled in blood to different tissues. It entered the neurons in the brain through: GLUT 4 GLUT 3 Glucose pump Passive diffusion

GLUT 3

If you had to run to school for 8am exam you would need more glucose to feed your muscle. This glucose will have entered the muscle through SGLT1 GLUT4 Glucose is not required for muscle function when I run to class GLUT1

GLUT1

Which statement about collagen is false? It contains an amino acid called hydroxyproline. It forms a double helix, with two collagen molecules wrapped around each other in a ropelike structure. It is a secreted protein.

It forms a double helix, with two collagen molecules wrapped around each other in a ropelike structure. Correct! This is false. Collagen forms a triple helix, not a double helix.

What is the effect of a β barrel on the permeability of a membrane? It decreases permeability. It increases permeability. Correct! A β barrel is a protein structural feature that spans a membrane, creating a pore-like opening. The presence of this feature therefore increases the permeability of a membrane. It has no effect. β barrels are peripheral membrane proteins

It increases permeability. Correct! A β barrel is a protein structural feature that spans a membrane, creating a pore-like opening. The presence of this feature therefore increases the permeability of a membrane.

The flow of which ion makes the largest contribution to the resting potential? K+ Na+ H+ Ca2+

K+

The resting plasma membrane potential as described by the Nernst equation is the sum of the movement of many ions. However, in practice, the movement of _______, a single ion, is the major component determining membrane potential. Ca2+ Cl- K+ Na+

K+ Correct! The resting membrane potential, -60 mV, is close to the equilibrium potential determined by intracellular and extracellular K+ concentrations, -75 mV.

In a typical mammalian cell, the concentration of _______ is higher on the inside, and the concentration of _______ is higher on the outside. Na+ and Cl-; K+ Na+; K+ and Cl- K+; Na+ and Cl-

K+; Na+ and Cl-

Voltage-sensitive K+ channels are 1,000 times more permeable to K+ than to Na+ because K+ ions are smaller than Na+ ions. K+ ions have a lower charge density than Na+ ions. a selectivity filter removes the water molecules from K+ ions but not from Na+ ions. K+ ions are more concentrated inside the cell than outside the cell

a selectivity filter removes the water molecules from K+ ions but not from Na+ ions.

Which of the following is true: alkaloids are nitrogen containing compounds Alkaloids are derived from acetate units Polyketides are derived from isoprene An example of a shikimic acid derivative is Ginkolide

alkaloids are nitrogen containing compounds

Plasma membrane phospholipids are located mostly in the outer leaflet of the bilayer. located mostly in the inner leaflet of the bilayer. symmetrically distributed between the two membrane halves. asymmetrically distributed between the two membrane halves.

asymmetrically distributed between the two membrane halves.

Cystic fibrosis is a genetic disease in which thick mucus accumulates over several types of epithelial cells, eventually blocking the pulmonary airways. The molecular basis of this disease is the production of a defective mucin. chloride channel. Na+-K+ pump. Na+-Ca2+ transporter

chloride channel

The major protein of the extracellular matrix of animal cells is fibronectin. chondroitin sulfate. collagen. keratin.

collagen

In the fluid mosaic model of biological membrane structure, transmembrane proteins are embedded nearly randomly in the lipid bilayer. Correct! Typically, only small, α-helical portions of the protein are embedded in the membrane, and individual proteins are distributed fairly randomly within the membrane bilayer. almost completely surrounded by membrane lipid. segregated into large protein clusters or rafts. weakly held in place on the surface of the lipid bilayer.

embedded nearly randomly in the lipid bilayer. Correct! Typically, only small, α-helical portions of the protein are embedded in the membrane, and individual proteins are distributed fairly randomly within the membrane bilayer.

Animal cells are embedded in a(n) pectin-rich basal lamina. extracellular matrix. cell wall. hemicellulose-rich hyaluronan layer.

extracellular matrix. Correct! Animal cells (e.g., fibroblasts) are embedded in an extracellular matrix.

If you ate really healthy breakfast (low glycemic index foods), the glucose from your breakfast will be available to your brain cells No answer text provided. For shorter time It does not matter what I eat, I am a genius anyway For longer time

for longer time

The glucose facilitated diffusion transporter can transport glucose into or out of the cell. into the cell only. out of the cell only. only in the presence of ATP.

into or out of the cell

Channels that open in response to neurotransmitters or other signal molecules are called _______ channels. voltage-gated ligand-gated signal-gated ion

ligand-gated

Which of the following is an example of a terpene? tetracycline limonene All of the above.

limonene

Although Na+ is smaller than K+, its passage through the K+ channel is blocked by the _______ filter. CO2 negativity positivity selectivity

selectivity Correct! The channel pore contains a narrow selectivity filter. The carbonyl oxygen atoms that line the selectivity filter are positioned to displace the water molecules to which K+ is bound, but are too distant from the smaller Na+ cation to do this.

Phospholipid bilayers are permeable only to molecules that are _______ and _______. large; uncharged large; charged small; uncharged small; charged

small uncharged

The fundamental building block of cellular membranes is the glycolipid. the phospholipid. cholesterol.

the phospholipid

Passive transport across a membrane refers to transport into the interior of a cell. transport out of a cell. transport in the energetically favorable direction. simple diffusion across membranes, without the help of proteins such as channels or carriers.

transport in energetically favorable position Correct! Passive transport refers to the transport of a molecule in the energetically favorable direction, taking into consideration concentration and electrochemical gradients via membrane channels or carrier proteins.

The major ATPase maintaining the plasma membrane potential is the Na+-K+ pump. True false

true

The mode of action of mitochondrial ATP synthase involves mechanical coupling between protein subunits and hence can be considered an example of a rotary motor. True False

true