What is the central dogma of molecular biology?

It explains the flow of information in biological systems, especially in eukaryotes. It can be simplified to "DNA makes RNA makes protein". This explains how DNA, which is passed down the generations can lead to expression of a phenotype. DNA is first transcribed to messenger RNA (mRNA), via a DNA-dependent-RNA-polymerase. The mRNA is able to leave the nucleus, whereas the very large and complex DNA molecule cannot. This also allows control of expression of different genes via controlling mRNA production. mRNA is then translated into a polypeptide in a ribosome using transfer RNAs, which bring amino acids together to form a chain. The polypeptide chain may need to undergo further folding and modification before it is functional.