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.
Stretch marks are narrow pink or purplish streak-like lines that can develop on the surface of the skin. If you get them, they usually appear on your tummy, or sometimes on your upper thighs and breasts, as your pregnancy progresses and your bump starts to grow. When this happens will be different from woman to woman.