Painless Biology by Cynthia Pfirrmann

Author:Cynthia Pfirrmann
Language: eng
Format: epub
Publisher: Barrons Educational Services
Published: 2022-04-09T00:00:00+00:00

What Is DNA and How Does It Work?

Remember how we discussed DNA in Chapter 3? It never hurts to review, though, so let’s explore DNA and its relationship to genetics. DNA, also known as deoxyribonucleic acid, is the spiral ladder–shaped molecule in our bodies that carries the instructions to make each of us. It’s like the cookbook for you and me and every other living thing on Earth. The DNA “cookbook” is kept in a very specific order by the side rails of the DNA ladder. The side rails are identical in all living things. Throughout all strands of DNA, side rails are made up of the same sugar, deoxyribose, alternating with an identical phosphate group. The only variables in DNA are the following nitrogen bases: adenine, thymine, cytosine, and guanine. Since each molecule of DNA contains two sides of the twisted, or helical, ladder, it’s important to remember that the side rails are held together by paired nitrogen bases. Adenine (A) always pairs with thymine (T) and cytosine (C) always bonds with guanine (G) to form nitrogen base pairs. The sequence of nitrogen bases is the recipe for a protein. Proteins act as structural components, transporters, storage units, enzymes, antibodies, and messengers in our bodies. So, essentially, DNA is a biochemical cookbook with the instructions to make every living thing on Earth! Amazing, right?

BRAIN TICKLERSSet # 1

Select the best term to complete each sentence.

1.Prehistoric humans worked to develop animals and crops that were most useful to them. They did this by using (natural or selective) breeding.

2.A very specific characteristic of an organism is a (gene or trait).

3.The instructions to make all living things are held in molecules called (proteins or DNA).

(Answers are on page 152.)

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