Cell Transport Mechanisms and Permeability
Exercise 1: Cell Transport
Mechanisms and Permeability:
Activity 1: Simulating Dialysis (Simple Diffusion) Lab Report Pre-lab Quiz Results You scored 75% by answering 3 out of 4 questions correctly.
1. The driving force for diffusion is Your answer : c. the membrane transport protein.
Correct answer: b. the kinetic energy of the molecules in motion.
2. In diffusion, molecules move
You correctly answered: a. from high concentration to low concentration.
3. Which of the following dialysis membranes has the largest pore size? You correctly answered: d. 200 MWCO
4. Avogadro’s number is a constant for the number of
You correctly answered: b. molecules.
Experiment Results Predict Question: Predict
Question 1: The molecular weight of urea is 60.
7. Do you think urea will diffuse through the 20 MWCO membrane? Your answer : a. Yes, but very slowly. Predict
Question 2: Recall that glucose is a monosaccharide, albumin is a protein with 607 amino acids, and the average molecular weight of a single amino acid is 135 g/mole. Which of the following will be able to diffuse through the 200 MWCO membrane? Your answer : b. oth glucose and albumin
Stop & Think
Questions: The reason sodium chloride didn’t diffuse left to right is that
You correctly answered: c. the membrane pore size was too small. Glucose is a six-carbon sugar. Albumin is a protein with 607 amino acids. The average molecular weight of a single amino acid is 135 g/mole. There is no reason to run these solutes at the 20 MWCO because
Your answer : b. glucose is a protein and therefore too large to pass. Correct answer: d. glucose and albumin are both too large to pass.
The rate of diffusion for urea
Your answer : c. s faster than that for sodium because urea is a smaller molecule.
Correct answer: b. is slower than that for sodium because urea is a larger molecule.
Post-lab Quiz Results
You have not completed the Post-lab Quiz.
Review Sheet Results
- Describe two variables that affect the rate of diffusion. Your answer: the solute and the MWCO
- Why do you think the urea was not able to diffuse through the 20 MWCO membrane? How well did the results compare with your prediction? Your answer: I was wrong. The urea was too large to diffuse through the 20 MWCO
- Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane. How well did the results compare with your prediction? Your answer: I was wrong here as well. Only the glucose was able to diffuse.
- Put the following in order from smallest to largest molecular weight: glucose, sodium chloride, albumin, and urea. Your answer: sodium chloride, urea, glucose and albumin.