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.
Today I found what causes birthmarks. There are several different types of birthmarks. What causes them is an excess of pigment cells (Melanoctyes), or an excess of blood vessels confined to one area of the skin. Birthmarks caused by an excess of pigment in certain areas of the skin are known as pigmented birthmarks. The color of your skin is a result of the amount of melanin in the bottom layer of your epidermis.