Question

**Physiology

6. What features are necessary for the cell to engage in facilitated diffusion rather than simple diffusion? Secondary active transport rather than primary active transport (is this different for symport and antiport? What advantages do we derive by putting these modifications in place?

2. Make a concept map of the cell membrane. Include each of the functions of the cell membrane listed below. Make sure each function is correctly linked to the components of the cell membrane responsible for each function

1. separates intracellular fluid (ICF) from extracellular fluid (ECF)
2. provides permeability barrier
3. contains surface proteins acting as antigens - important for recognition of “self”
4. provides cell communication: receptors and signal transduction pathways for hormones and neurotransmitters
5. contains a variety of adhesion molecules allows anchoring, tissue organization
6. acts as a highly selective filter

7. In mythology, the cosmic man appears grossly swollen and may be seen pictures as a human rain cloud. Propose a mechanism whereby this mythological creature could swell up and fill with water. (It is not going to be true, so you can’t look this up – it’s just for fun to see if you understand how it could work.)

Answer 1

6.

Facilitated diffusion means that cell membrane allow the certain molecules to pass through it selectively by utilizing the energy.

Secondary active transport means that molecular transportation occurs by utilizing energy source from other than ATP.

The following features are necessary for the cell for facilitated diffusion:-

• Cell membrane should consist phospholipid bilayer, that to phosphate molecules are arranged in such a way that hydrophilic head to the outside and hydrophobic head to the inside.
• Between the phospholipid molecules there should be membrane proteins which allows specified molecules
• Should consist the specific receptors on the membrane protein.

If the cell have above features it allows facilitated diffusion and secondary active transport.

Advantages :-

1. It allows only the selected molecules to pass through the membrane.
2. Prevents the entry of free radicals which are harmful
3. Regulates the concentration of ions in and outside of cell