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Understanding DNA Structure and Genetics in Human Genetics

Explore the transformative principles of DNA and genes in human genetics, including the double helix structure, nitrogenous bases, chromosome composition, and DNA replication technologies. Learn about PCR and its applications in forensics, agriculture, and medicine.

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Understanding DNA Structure and Genetics in Human Genetics

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  1. DNA Structure(“transforming principle”) Human Genetics Chp. 9

  2. A gene is a long section of a DNA molecule whose sequence of building blocks specifies the sequence of amino acids in a particular protein. Genes combine to form amino acids as letters combine to form words. Amino acids make proteins DNA Structure

  3. DNA Structure • DNA shape is a double helix • View from the side • Partially unwound double helix so you can see components

  4. Views from the top Model X-Ray Photo-51

  5. DNA composed of nucleotides Sugar (deoxyribose) Phosphate group Nitrogenous bases Purines Guanine (G) Adenine (A) Pyrimidines Cytosine (C) Thymine (T) DNA Structure (Where are they?)

  6. A 5 C sugar and a phosphate group form the backbone DNA is directional Antiparallelism the head to tail arrangement of the 2 entwined chains of DNA double helix DNA Structure

  7. Nitrogenous bases A, T, C, & G make up the rungs on the ladder DNA Structure

  8. Bases held together with Hydrogen bonds Guanine pairs with Cytosine Triple bond Adenine pairs with Thymine Double bond Complementary Base Pairing

  9. Minor Groove Major Groove binding proteins interact with DNA in the major groove b/c backbone isn’t in the way DNA Structure

  10. DNA Structure • Chromosomes – not just DNA! • 1/3 DNA • Histone proteins • Other DNA binding proteins • also a small amount of RNA • All together the chromosome material is called Chromatin

  11. A single molecule of DNA can be 1 in. long How does it fit into a space that is 1 millionth that size? Histones proteins that DNA coils around DNA Structure 3D Video Clip (Click next 4 times)

  12. Nucleosome- A unit of the chromatic structure • 8 Histones • DNA • “linking” histone DNA Structure GREAT DIAGRAM (FIG. 9.11) ON PG 179 Clicker ?’s 7-13

  13. DNA Replication- • Preserves genetic information • S phase of Interphase • Gives each new cell a complete set of operating instructions • 5’ to 3’ direction only • 3 Hypothesized mechanisms for DNA Replication ?

  14. DNA Replication (cont.)

  15. Proved by Meselson and Stahl Marked DNA with 14N 2nd generation DNA had ½ 14N and ½ 15N

  16. Replication Technology • PCR- Polymerase Chain Reaction • Uses DNA Polymerase to rapidly produce millions of copies of a specific DNA sequence of interest. • Perhaps the most successful technology to ever emerge from LIFE SCIENCE!!! • Many Uses • Forensics- • blood, convict, exonerate false accusations • Agriculture, Vet., Medicine, Env. Sci., • Microorganisms, viruses, parasites…

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