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DNA, Replication, Mutations, RNA, & Protein Synthesis

Molecular Genetics. DNA, Replication, Mutations, RNA, & Protein Synthesis . DNA. DNA Notes. Structure Watson and Crick (Rosalind Franklin) Discovered the shape of DNA (p.293) Double Helix – two strands wound around each other. Unravel DNA. Chromosome. Nucleosome. DNA double helix.

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DNA, Replication, Mutations, RNA, & Protein Synthesis

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  1. Molecular Genetics DNA, Replication, Mutations, RNA, & Protein Synthesis

  2. DNA

  3. DNANotes • Structure • Watson and Crick (Rosalind Franklin) • Discovered the shape of DNA (p.293) • Double Helix – two strands wound around each other.

  4. Unravel DNA Chromosome Nucleosome DNA double helix Coils Supercoils Histones Red= what you need to know.

  5. DNANotes • Structure • Start with a chromosome • Break it down into supercoils • Supercoils are coils piles of nucleosomes. • Nucleosomes are DNA wrapped around histones. • Histones are proteins used to tightly pack DNA. • Unravel a nucleosome, you are left with the histones and the double helix.

  6. DNA Structure • DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix. • A molecule of DNA is made up of millions of tiny subunits called Nucleotides. • Each nucleotide consists of: • Phosphate group • Pentose sugar (Deoxyribose) • Nitrogenous base

  7. Nucleotides Phosphate Nitrogenous Base Pentose Sugar

  8. Nucleotides • The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”. • There are four types of nitrogenous bases.

  9. Nucleotides A T C Adenine Thymine G Guanine Cytosine

  10. DoubleHelix Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Figure 12-7, page 294

  11. Nucleotides • Each base will only bond with one other specific base. • Adenine (A) • Thymine (T) • Cytosine (C) • Guanine (G) Form a base pair. Form a base pair.

  12. NitrogenousBases Purines Pyrimidines Adenine Guanine Thymine Cytosine Base Backbone Phosphate group Deoxyribose

  13. DNA Structure • Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand. • Chargaff’s rules • A pairs (bonds) with T and G bonds with C • So there are the same amount of A’s as there are T’s. • There is also the same amount of G’s as there are C’s.

  14. A T A A A T T T C C C G G G

  15. DNA Structure • A gene is a section of DNA that codes for a protein. • Each unique gene has a unique sequence of bases. • This unique sequence of bases will code for the production of a unique protein. • It is these proteins and combination of proteins that give us a unique phenotype.

  16. Then what is a gene? GENE

  17. DNA Gene Protein Trait Phenotype: Observable Physical Appearance

  18. Dnareplication

  19. DNAReplication • Before a cell divides, it duplicates its DNA – this is called replication (Interphase-S phase)

  20. DNAReplication 1. DNA Helicase unzips the original strand at the hydrogen bonds 2. DNA Polymerase brings new nucleotides to bind with the template. 3. DNA Polymerase “proofreads” the bases and repairs any mistakes. 4. Result – twoidenticalstrands from one original. 1 2 3 4

  21. What is the function of DNA? *DNA carries the instructions for making the proteins that determine traits. *Proteins function as: -antibodies -contractile proteins -transport proteins -storage proteins -enzymes -hormones

  22. DNA…RNA? RNA works with the DNA to make the protein building instructions...Proteins are made of chains of Amino Acids!!! Just like DNA is made of strands of nucleotides/base pairs.

  23. More on RNA next time

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