<span>Gene
expression is taking place when chromatin is less condensed. Highly compacted
chromatin is not accessible to the enzymes involved in DNA transcription,
replication and repair because transcription is being inhibited or inactive. Therefore,
looser configuration permits transcription or gene expression to take place. </span>
There is a valve at the meeting point between each ureter and the bladder prevents the back flow of urine from the urinary bladder to the kidney
<span> RNA was thought of as little more than a messenger between DNA and proteins, carrying instructions as messenger RNA (mRNA) to build proteins. However, RNA can do far more. It can drive chemical reactions, like proteins, and carries genetic information, like DNA. And because RNA can do both these jobs, most scientists think life as we know it began in an RNA world, without DNA and proteins.</span>
