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Chapter 9 Notes Part 1

Chapter 9 Notes Part 1. Understanding DNA. What is DNA?. DNA stands for deoxyribonucleic acid. DNA is the molecules that carry the body’s genetic information. What is DNA?. The discovery of DNA was a turning point in our understanding of inheritance

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Chapter 9 Notes Part 1

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  1. Chapter 9 Notes Part 1 Understanding DNA

  2. What is DNA? • DNA stands for deoxyribonucleic acid. • DNA is the molecules that carry the body’s genetic information.

  3. What is DNA? • The discovery of DNA was a turning point in our understanding of inheritance • Inheritance= how traits are passed from parent to offspring.

  4. What is DNA? • DNA was first discovered in 1868 by a Swiss scientist named Johannes Miescher. • However, scientists were very slow to understand the importance of DNA to inheritance.

  5. What is DNA? • In the 1950’s, James Watson and Francis Crick determined the actual structure of DNA.

  6. What is DNA? • In 1985, it was discovered that portions of DNA are as unique to each individual as fingerprints. • This led to the establishment of a new field of forensic science, known as DNA typing or DNA profiling.

  7. What is DNA? • This meant that items like blood, semen, hair, and tissue could now be linked to a single individual.

  8. What is DNA? • Think of DNA as a blueprint for your body-it instructs your body on how to create proteins to make structures that are unique to you!

  9. What is DNA? • There are 60 trillion cells in the human body.

  10. What is DNA? • In the nucleus of each cell are chromosomes, which contain your DNA.

  11. What is DNA? • Along each chromosome are about 25,000 genes, which determine everything from hair color to susceptibility to disease.

  12. The Structure of DNA • DNA is a polymer, a very large molecule made by linking a series of repeating units (known as monomers).

  13. The Structure of DNA • The monomers that make up DNA are called nucleotides.

  14. The Structure of DNA • A nucleotide is composed of 3 parts: a sugar molecule, a phosphate molecule, and a nitrogen-containing molecule called a base.

  15. The Structure of DNA • The nucleotides make up the “rungs” of the DNA ladder.

  16. The Structure of DNA • There are only 4 bases present in the nucleotides of DNA: adenine (A), cytosine (C), guanine (G), and thymine (T).

  17. The Structure of DNA • The only arrangement of the bases that is possible in the double helix configuration of DNA is Adenine pairing with Thymine and Guanine pairing with Cytosine. • This is called complementary base pairing.

  18. The Structure of DNA • There is no specific order that they will be in, as long as A pairs with T and G pairs with C.

  19. The Structure of DNA • Try this: create the complementary strand for this single strand of DNA: T-A-T-T G-T-A-A G-T-C-A A-T-A-A C-A-T-T C-A-G-T

  20. The Structure of DNA • The average chromosome contains 100 million base pairs.

  21. The Structure of DNA • DNA is the blueprint for the production of proteins, which are used for all the various functions that your body performs.

  22. The Structure of DNA • Just as nucleotides are the building blocks of DNA, amino acids are the building blocks of proteins. • Proteins are all built from a combination of 20 different amino acids.

  23. The Structure of DNA • Each human has 23 chromosomes in the nuclei of their cells. • The order of bases on all 23 chromosomes is called the human genome. • The human genome has 2,300,000,000 base pairs.

  24. The Structure of DNA • We now have the technology to sequence the entire human genome of any person.

  25. Replication of DNA • Every time cells divide to form new cells, DNA must be copied and transferred to the new cell. • This process is called DNA replication.

  26. Replication of DNA • There are 3 basic steps in DNA replication.

  27. Replication of DNA • First, the DNA double helix is unwound to form two separate strands.

  28. Replication of DNA • Second, the two strands are exposed to a collection of free nucleotides.

  29. Replication of DNA • Finally, the double helix is recreated as the nucleotides are assembled in the proper order. • The result is two identical strands of DNA.

  30. REVIEW • A ____ is a structure in a cell nucleus composed of DNA, along which genes are located. • Polymer • Nucleotide • Chromosome • Protein

  31. REVIEW 2. In DNA, the base Adenine pairs with • Adenine • Guanine • Cytosine • Thymine

  32. REVIEW 3. Which of the following is not a base associated with DNA? • Threonine • Guanine • Cytosine • Adenine

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