RNAs are the direct products of genes, and these small RNAs can bind to other specific messenger RNA (mRNA) molecules and either increase or decrease their activity, for example by preventing an mRNA from producing a protein.
What causes stretch marks? Stretch marks are caused when the skin rapidly stretches as a result of sudden growth or weight gain. The stretching causes the middle layer of skin (dermis) to tear, allowing the deeper skin layers to show through, forming stretch marks. The dermis contains strong, inter-connected fibres that allow your skin to stretch as your body grows.
They got even worse after my second pregnancy. Anatomy of a Stretch Mark. Stretch marks happen when your body grows faster than your skin can keep up with. This causes the elastic fibers just under the surface of the skin to break, resulting in stretch marks. You gain about 30 pounds during the 9 months you are pregnant, says Heidi Waldorf, MD.