need help in physiology.. did them but i just need to double check if i am right
ID: 8602 • Letter: N
Question
need help in physiology.. did them but i just need to double check if i am right!
all or some of the answers could be correct! (not just one answer)
Which of the following statements about diffusion through the plasma membrane of animal cells is correct?
1. The rate of diffusion of a given molecule is proportional to the permeability of the membrane for this molecule.
2. Membrane permeability equals molecular size divided by lipid solubility.
3. The maximum rate of facilitated diffusion for glucose through the plasma membrane can be increased by increasing the number of GLUT proteins in the cell membrane. In the human body this can be mediated by increasing the plasma insulin levels.
4. Imagine two cells at different distances to the nearest blood capillary. Cell one is at 0.1 mm distance, and cell 2 is at 0.3 mm distance. It will take 9 times longer for nutrients to reach cell 2 by simple diffusion as compared to reaching cell 1.
5. Glucose can diffuse against a concentration gradient (high intracellular and low extracellular Glu concentration) into cells if the number of uniport carriers in the cell membrane is drastically increased.
The magnitude of an intracellular response that is mediated by a Gs-protein coupled receptor
1. is increased by increased GTPase activity of the beta/gamma subunit of the G-protein.
2. is decreased by increased GTPase activity of the alpha subunit of the G-protein.
3. is decreased by increased phosphodiesterase activity.
4. may be decreased by increased phosphatase activity.
5. may be decreased by receptor de-sensitisation.
The cellular response to an extracellular lipophobic chemical signal
1. depends on the receptor type present in the plasma membrane of the target cell.
2. depends on whether this receptor is coupled to Gs, Gi, or Gq proteins.
3. maybe integrated with other chemical signals on the level of second messenger signaling.
4. depends always on the presence of receptor proteins located in the cytoplasm of the target cell.
5. can be amplified by modulating the activity of proteins that produce second and third messengers.
are lipophilic, and therefore, are never released into the blood stream.
Steroid hormones 1. usually cause longer lasting effects than G-protein coupled receptors. 2. are made from cholesterol and are lipophilic. 3. may bind to cytoplasmatic receptors which can enter the nucleus and bind to HRE sequences on DNA. 4.
are lipophilic, and therefore, are never released into the blood stream.
5. may initiate the transcription of multiple target genes.Explanation / Answer
Which of the following statements about diffusion through the plasma membrane of animal cells is correct - 1, 2, 3, 4. are true. 5 is false, as glucose transport is symport mechanism. The magnitude of an intracellular response that is mediated by a Gs-protein coupled receptor - 1, 3, 5 are true. 2, 4 are false because alpha sub unit is not important. The cellular response to an extracellular lipophobic chemical signal-1, 3, 4, 5 are true. Steroid hormones Steroid hormones -1, 2, 3, 5 are true. These require receptors and not transported through blood.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.