“written in your book” (Ps 139:16): g 8/15 5-6; g 11/11 4-5; lf 13, 17; w07 6/15 22-23
genetic engineering: g89 7/22 10-13
antibiotics: g96 2/22 11
appreciation for Awake! articles on: g01 5/22 30; g89 10/22 30
blue roses: g 10/07 26
disease testing: g 1/07 6-7; g00 9/22 8-9; g89 7/22 11-12
drug production: g89 7/22 10-11
mouse altered: g88 7/22 30
mussel adhesive: g01 9/22 22-23
pigs: g86 9/22 29
plants: g01 9/22 6, 11; g01 12/22 6; g00 4/22 25-27; g99 2/22 22
predicted application to humans: g00 9/22 3-11; g98 10/22 28
spider-silk production: g89 2/8 30
tomato grows in salt water: g02 4/8 28
how sex is determined: g93 6/8 30; g92 7/8 6
identification of people: g03 8/8 28
Jacob’s lesson: it-1 1244
nucleotides and nucleic acids:
probability of chance formation: g87 1/22 6-7
origin of mankind: w89 2/15 8-9
controversy between geneticists and paleontologists over: w88 4/15 21
DNA studies indicate one male and one female ancestor of all mankind: ct 98
gap between man and apes or monkeys: g03 12/22 29
prolonging life through: g00 7/8 20-22
selecting sex of offspring: g97 4/8 28
telomeres: la 21; g00 7/8 21-22; g00 12/8 18; w99 10/15 5
tree breeding: g92 10/22 25-27
Your Cells—Living Libraries!
COVER SUBJECT
Your Cells—Living Libraries!
IN 1953, molecular biologists James Watson and Francis Crick published a discovery that was critical to our scientific understanding of life. They had discovered the double-helical structure of DNA.* This threadlike substance—mostly found in the nucleus of cells—contains encoded, or “written,” information, making cells living libraries, as it were. This amazing discovery opened up a new era in biology! But what purpose is served by the “writing” in cells? More intriguing, how did it get there?
WHY CELLS NEED INFORMATION
Have you ever wondered how a seed becomes a tree or how a fertilized egg becomes a human? Have you ever wondered how you inherited your traits? The answers involve the information found in DNA.
Nearly all cells have DNA, complex molecules that resemble long twisted ladders. In the human genome, or our complete set of DNA, the ladders have approximately three billion chemical “rungs.” Scientists call these rungs base pairs because each rung is made up of two chemical substances, of which there are four altogether. Using the first letter of each, these substances are abbreviated A, C, G, and T—a simple, four-letter alphabet, as it were.* In 1957, Crick proposed that it is the linear sequence of the chemical rungs that forms coded instructions. In the 1960’s, that code began to be understood.
Information, whether in the form of pictures, sounds, or words, can be stored and processed in many ways. Computers, for example, do this all digitally. Living cells store and process information chemically, DNA being the key compound. DNA is passed on when cells divide and organisms reproduce—abilities that are considered defining characteristics of life.