Question

Incorrect Question 3 0/2 pts Cell membranes act as selective barriers. Which of the following is best at crossing a pure lipid bilayer? amino acid such as tyrosine a sodium ion a gas such as oxygen an antibody a glucose molecule

Answer 1

AS PER CHEGG GUIDELINES ONLY FIRST QUESTION ANSWERED Q. 3. Cell membranes act as a selective barrier. Which of the following is best at crossing a pure lipid bilayer? Amino acid such as tyrosine A sodium ion A gas such as oxygen An anti body A glucose molecule Ans. A gas such as oxygen. cell membrane consist of lipid bilayer which has phosphate

head and a lipid tail. The phosphate heads are charged and hydrophilic (water loving) and lipid tails are hydrophobic (water fearing) and unchanged. This unique structure of the cell membrane makes it unique as well as selectively permeable. So any kind of charged molecule or ion, such as Nat, kt, Catt, glucose (which is a sugar), amino acids, fatty acids can not pass through this membrane as they are repelled by the hydrophobic tails of the phospholipid bilayer. But by the means of passive transport which includes diffusion allows the gaseous molecule to cross the membrane easily without any energy loss. So, a gas such as oxygen pass through the membrane easily inspite of it's selective permiability but amino acid such as tyrosine, a sodium ion which is a changed ion, an antibody which is also formed with amino acids, and glucose molecule which water soluble can not pass it easily.