Question

1. The figure below shows calcium concentration in a cell and its surrounding fluid.

Interstitial Fluid Ca2 0.4 Ca2 0.1%

(a)   Describe the general means of transport by which the illustrated cell could acquire more calcium to fuel muscle contractions.

(b)   (b) Discuss the properties of the cell and its cell membrane that allow this movement of ions across the membrane.

Answer 1

A) The cell shown has a hypertonicity to calcium as compared to the environment. In order to attain more calcium, the cell would use a calcium pump to attain more calcium ions. A calcium influx across the cells occur through the plasma membrane along with a calcium release from both sarcoplasm and the endoplasmic reticulum. The ATPase, that acts as the calcium pump. These ATPases are a member of the P type ion pumps and the transport of the calcium ions are an ATP dependent active transport process. Since these pumps include phosphorylation of the Aspartate present in the active site of the terminal ATP, thus, these are called as P type transporters.

B) The plasma membrane is a lipid bilayer that consists of phospholipid bilayer . This bilayer consists of the transporters embedded in between the bilayer along with scattered cholesterol molecules that are responsible in keeping the membrane fluidic. This model is called fluid mosaic. There are proteins and carbohydrates that are present in the membrane.