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C. 's. B. A. The of DNA. by: Kaytana Blades. TEKS. §112.23. Grade 7 Science
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C 's B A The of DNA by: Kaytana Blades
TEKS • §112.23. Grade 7 Science • (10) Science concepts. The student knows that species can change through generations and that the instructions for traits are contained in the genetic material of the organisms. The student is expected to: • (A) identify that sexual reproduction results in more diverse offspring and asexual reproduction results in more uniform offspring; • (B) compare traits of organisms of different species that enhance their survival and reproduction; and • (C) distinguish between dominant and recessive traits and recognize that inherited traits of an individual are contained in genetic material.
The alphabet contains 26 letters and DNA contains four of its very own letters. G uanine A denine C ytosine T hymine
Just as the 26 letters of the alphabet can be used to form millions of words for communication, DNA’s alphabet can be combined to form codes with more than five billion combinations of G’s, A’s, T’s, and C’s.
The differences in these combinations result in differences among human beings. The DNA molecule consists of two strands that form a double helix, a spiraling shape much like a twisted ladder.
How does DNA replicate ? Zipper Example
Look at the nucleotides on the two strands. A is on one strand, a T is on the other. Then C is on one strand, a G is on the other. Notice also, that C and T are smaller than G and A. C and G fit together and A and T fit together. Because of this they fit together only in these pairs, the free nucleotides float in and line up in the proper order all by themselves! This helps us make exact copies of the DNA. C G A T http://www.eurekascience.com/ICanDoThat/dna_rep.htm
Works Cited • Backgrounds and clip art courtesy of Microsoft Clip Art Gallery • DNA animation courtesy of http://www.eurekascience.com/ICanDoThat/dna_rep.htm