What On Earth?

Click to follow
The Independent Online

If an organ is transplanted into someone, does that organ still retain the DNA from the previous owner, even if the organ grows larger?

If an organ is transplanted into someone, does that organ still retain the DNA from the previous owner, even if the organ grows larger?

A transplanted organ always retains the DNA of its previous owner. When an organ grows, it either "enlarges" already existing cells or its cells divide. In the case of enlarging, the cellular structures are extended using molecular compounds present in the body. The nucleus, which contains the DNA, is not affected by any of these processes. When cells divide, they do this in a process called mitosis, in which the genetic information – DNA – is duplicated with the rest of the cell. "Parental" and "daughter" cell are identical. Here, too, no alteration of the DNA is observed. In both cases the cells of the organ keep their original genetic information.

Why when I pour a fizzy drink does a stream of bubbles appear to come from one bubble that remains fixed to the glass?

The bubbles in fizzy drinks are undissolved carbon dioxide, which is also present in drinks as a dissolved gas. The gas bubbles form more easily on slightly rough, slightly porous places, so it may be that the points from which the bubbles rise are where the surface of your glass is less smooth. This is a trick known by the makers of beer glasses – sometimes you get glasses with pictures etched on the bottom, so the bubbles form there, and the "head" of the beer lasts longer. In Germany, they put rice grains in the bottom of the glass so more bubbles form and the drink doesn't go flat.

Why is the outer skin of cacti so fat?

The cactus is basically a big fat stem covered by a thick waxy cuticle. Because the cactus is naturally found in a dry habitat, conservation of water is vital. It has no leaves because they lose water too easily. The fact they are thin and have a large surface area means evaporation takes place rapidly. The cactus uses its stem to perform the function of the leaves; that is to absorb sunlight and photosynthesise making the plant's food. The thickness of the stem reduces water loss. The waxy cuticle that gives the plant its shiny appearance also prevents water loss.

Why do men have an Adam's apple and women don't?

The Adam's apple is a structure made of cartilage in the front of the neck. It is part of the voice box (larynx) and is usually larger in men than in women, so both men and women have an Adam's apple. They are larger in men because during puberty the male sex hormone testosterone causes it to grow larger. Because of this, men have longer vocal cords and a deeper voice.

For further information contact: www.sciencenet.org.uk; or ask your own questions on Science Line Freephone: 0808 800 4000

Comments