(S2)C4 - transport across cell membrane

Question 1

DNP prevents Oxidative phosphorylation. when treated with DNP the sodium potassium pump no longer works. Why is this

Answer 1

• lack of ATP produced from oxidative phosphorylation
• pump = is active transport so requires energy from ATP
• if there is a lack of it then sodium ions cannot be transported out and the concentration gradient remains the same

Question 2

Why is it that sodium ions and amino acids are not absorbed from the lumen of the small intestine in the presence of DNP

Answer 2

• concentration of Na ions inside the cell aren’t transported so there is no concentration gradient
• as a result no facilitated diffusion of sodium ions from the lumen
• amino acid absorption requires diffusion of sodium ions so therefore cannot enter via co-transport

Question 3

By what mechanism would amino acids leave the epithelial cell

Answer 3

• facilitated diffusion