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DNA. DNA Molecular Structure - Regular. http://www.britannica.com/EBchecked/media/18426/Animated-structure-of-a-DNA-molecule. "The Blueprint of Life". DNA Molecular Structure - Honors. http://www.dnatube.com/video/1017/Compare-DNA-and-RNA-in-structural-basis.
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DNA DNA Molecular Structure - Regular http://www.britannica.com/EBchecked/media/18426/Animated-structure-of-a-DNA-molecule "The Blueprint of Life" DNA Molecular Structure - Honors http://www.dnatube.com/video/1017/Compare-DNA-and-RNA-in-structural-basis
DNA FACTS • established by James Watson and Francis Crick • Shape of a double helix
codes for your genes (traits) • made of repeating subunits called nucleotides
What is a nucleotide? Has three parts: PHOSPHATE Group DEOXYRIBOSE (a 5-carbon sugar) NITROGENOUS BASE (A,T,G,C)
Base-Pair Rule Adenine <==> Thymine Guanine <==> Cytosine The sides of the DNA ladder are phosphate & sugar held together by hydrogen bonds
Base Pair Rule One side: A T A T C A T G C G G G Other side:
How the Code Works The combination of A,T,G,C determines what traits you might have, for ex. C A T C A T = purple hair T A C T A C = yellow hair
Think of the bases of DNA like letters.Letters form words....Words form sentences.... *endless combinations
Let's Review What We Know About DNA 1. DNA stands for: De _____ ribo ______ acid 2. What is the shape of DNA? _______________ 3. Who established the structure of DNA? ____________ 4. Adenine always pairs with _______________ 5. The sides of the DNA ladder are deoxyribose and _____ 6. Guanine always pairs with _____________ 7. What is the complimentary sequence: A A T G C A 8. The two sides of DNA are held together by _______ bonds. 9. DNA is composed of repeating subunits called ______________________ 10. What are the 4 bases that make up the rungs of the DNA ladder? _______________________________________
DNA REPLICATION the process by which DNA makes a copy of itself SEMI-CONSERVATIVE - half of the old strand is saved
STEPS OF DNA REPLICATION • Enzymes, Helicases, separate the DNA strands at various locations to speed up the process. The hydrogen bonds are broken. The Y-shaped region of separation is called the replication fork. • Enzymes, DNA polymerases, add complimentary nucleotides found floating freely in the nucleus. • DNA polymerases finish replicating the DNA and fall off.
DNA REPLICATION ERRORS • Rare occurrences. Only about one error occurs for every billion paired nucleotides added. • DNA polymerases have a repair enzyme that “proofread” DNA. The enzyme removes the incorrect nucleotide and replaces it with the correct nucleotide. • Some errors escape repair. Chemicals and UV radiation can also damage DNA. This changes the DNA sequence and is called a mutation. • Mutations can have serious effects on the function of an important gene and disrupt cell function. However, some mutations can be beneficial and lead to adaptation and evolution
DNA Replication http://www.youtube.com/watch?v=5UoKYGKxxMI