<h2>Membrane potential </h2>
Explanation:
- Membrane potential represents charge difference across the membrane, all biological cells are negative inside (cytoplasm) and positive outside (due to difference in ionic distribution)
- In a typical neuron cell membrane potential of cytoplasm is negative at rest (when no stimulus is applied) hence called resting membrane potential
- Resting membrane potential of excitable cells is established by Na+ and K+pump
- Repolarization starts with the efflux of K+ by the opening of voltage gated K+ channels
- Voltage gated K+ channels starts to open when voltage gated Na+ channels becomes inactive
- Hyperpolarization occurs due to excessive efflux of K+ by voltage gated K+ channels
- Additional efflux of K+ occurs due to slow inactivation of voltage gated K+ channels
Answer:
Cancer is formed when there are mutations in a number of genes.
Explanation:
Malignant tumors are gene diseases which do not mean that cancer is necessarily an inherited disease (only in 5-10% of cases the cancer is inherited) because the vast majority of other tumors are the result of somatic, ie secondary, mutations that lead to malignant transformation.
Only 2% of human diseases are monogenic (caused by a change in one gene). The remaining 98% of the disease is either polygenic (caused by a change in several genes at the same time) or epigenetic (caused by non-genetic or post-genetic disorders of cellular molecules).
Answer:
mRNA: Carry genetic information from DNA to protein; serve as template for protein synthesis.
tRNA: Serves as adapter molecule and deliver specific amino acid from the cell pool to the mRNA-ribosome complex.
rRNA: Structural component of ribosomes.
Explanation:
There are three types of nongenetic RNAs: mRNA, tRNA, and rRNA.
1. The messenger RNA (mRNA) is formed by the process of transcription in the nucleus. Transcription uses template strand of DNA to specify the nucleotide sequence in mRNA. The mRNA enters cytoplasm to join ribosomes. The nucleotide sequence of mRNA serves as a template and specifies the amino acid sequence of proteins.
2. The transfer RNA (tRNA) serves as an adapter molecule during the process of protein synthesis and binds to the specific amino acids to deliver them to the protein-synthesizing machinery. The anticodon of tRNA binds to the complementary mRNA codons.
3. The ribosomal RNA (rRNA) serves as structural components for ribosomes. Each of the subunits of ribosomes is made up of rRNA and proteins.
