In and surrounding a neuron, if sodium(Na) was absent, the diffusion of potassium(K) would result in a disturbed resting membrane potential of more negative value because there was no sodium which is pushed in the cell so potassium leaked outside. Therefore, there was more negative inside because potassium is positively(+ve) charged so they leaked outside and there is no sodium to come inside. This is the reason for more negative resting membrane potential.
During G1 phase, the cell grows in size and synthesizes mRNA and protein that are required for DNA synthesis. Once the required proteins and growth are complete, the cell enters the next phase of the cell cycle, S phase.