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Introduction to DNA. By Devin Murray. What is the function of DNA? . . DNA is the code stored in individual genes. Recall that g enes are specific sections of chromosomes . Function: DNA’s code determines how all organisms look and act . So where are chromosomes again?.
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Introduction to DNA By Devin Murray
What is the function of DNA? . • DNA is the code stored in individual genes. Recall that genes are specific sections of chromosomes. • Function: DNA’s code determines how all organisms look and act.
So where are chromosomes again? Chromosomes are located in the nucleus and are stored just outside of the nucleolus.
DNA structure • When you unravel tightly coiled DNA from the chromosome its overall shape of DNA is a double helix.
DNA structure • The most basic subunit of DNA’s double helix is called a nucleotide. • A DNA nucleotide has 3 parts: base, sugar, phosphate
DNA structure • Bases of the DNA nucleotide: • There are 4 nitrogenous bases: Adenine, Thymine, Cytosine, and Guanine • Nitrogenous means composed of nitrogen • Bases are typically abbreviated by their first initial capitalized (i.e. A = Adenine, G = guanine, etc.)
DNA structure • Bases of the DNA nucleotide: • Bases pair together using these rules: • A pairs with T (or you could say T pairs with A) • C pairs with G (or you could say G pairs with C)
DNA structure • Sugar in the DNA nucleotide: • The type of sugar in DNA is deoxyribose. • Deoxyribose is a 5 carbon sugar • This is the “D” in DNA. • Phosphate in the DNA nucleotide: • Compound with the chemical formula PO4
From Nucleotides to DNA • Sugar and Phosphate are in DNA typically referred to as the “The Sugar-Phosphate Backbone” because the pattern is like a chain repeating throughout the molecule.
From Nucleotides to DNA • The sugar of one nucleotide is linked to a phosphate of the next nucleotide by a covalent bond. • Nitrogenous bases are held together by hydrogen bonds.
DNA’s code • Complementary base pairing(i.e. G-C and A-T) makes a long zipper like molecule of DNA. • The sequence of nucleotides bases forms the unique genetic code for an organism.
Pop Quiz – 10 Questions 1. In the cell, where are chromosomes are located? 2. What are the three parts of a DNA nucleotide? 3. What forms the unique genetic code for all organisms? 4. According to complementary base pairing rules, A pairs with __ and C pairs with __. 5. What type of bond secures the sugar-phosphate backbone of a DNA molecule?
Pop Quiz – 10 Questions 6. Describe the shape of a DNA molecule. 7. What does the “D” in DNA stand for. 8. What are the names of the bases represented: A, G, C, T 9. What are specific sections of chromosomes called? 10. Explain the meaning of nitrogenous.
Works Cited • Bray, L. Germline genetic engineering: an ethical analysis. Retrieved February 27 , 2010 from http://lukebray.files.wordpress.com/2009/04/dna-double-helix.jpg • Claydon, S (Publisher). (2009) Dna structure and replication. [Image] Science Aid. Retrieved from http://scienceaid.co.uk/biology/genetics/images/nucleotide.jpg • Crisp, E. (2010). Four nucleotides. [Image]. Retrieved from http://www.wvup.edu/ecrisp/fournucleotides.jpg • Martin. (2010). Understanding genes and dna. [Image]. Retrieved from http://myweb.tiscali.co.uk/ataxia.pages/ • The Cell Nucleus [Image]. (2007) Retrieved February 27, 2010 from http://www.cartage.org.lb/en/themes/Sciences/Zoology/AnimalPhysiology/Anatomy/AnimalCellStructure/Nucleus/Nucleus.htm • United States Department of Health and Human Services. (2006, October). How genes work. Retrieved from http://publications.nigms.nih.gov/thenewgenetics/thenewgenetics.pdf • [Untitled drawing showing a chromosome is made of genes and genes are made of dna]. Retrieved March 9, 2010 from http://www.eurogentest.org/content/images/unit6/patientLeaflets/english/genesChromosomesDna.jpg