2. Molecular Genetics

3. DNA Structure  Nucleotides  Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base 12.1 DNA: The Genetic Material Chapter 12

4. Molecular Genetics Orientation  On the top rail, the strand is said to be oriented 5′ to 3′.  The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′. 12.1 DNA: The Genetic Material Chapter 12

5. A simplified diagram of DNA

6. 12.1 DNA: The Genetic Material Molecular Genetics Chromosome Structure  DNA coils around histones to form nucleosomes, which coil to form chromatin fibers.  The chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis. Chapter 12

7. 12.2 Replication of DNA Molecular Genetics Semiconservative Replication  Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA. Chapter 12

8. Molecular Genetics Base pairing  DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand. 12.2 Replication of DNA Chapter 12

9. 12.2 Replication of DNA Molecular Genetics Comparing DNA Replication in Eukaryotes and Prokaryotes  Eukaryotic DNA unwinds in multiple areas as DNA is replicated.  In prokaryotes, the circular DNA strand is opened at one origin of replication. Chapter 12

10. 12.3 DNA, RNA, and Protein Molecular Genetics Central Dogma  RNA  Contains the sugar ribose and the base uracil  Usually is single stranded Chapter 12

11. Comparing DNA and RNA

12. Molecular Genetics Messenger RNA (mRNA)  Long strands of RNA nucleotides that are formed complementary to one strand of DNA Ribosomal RNA (rRNA)  Associates with proteins to form ribosomes in the cytoplasm Transfer RNA (tRNA)  Smaller segments of RNA nucleotides that transport amino acids to the ribosome 12.3 DNA, RNA, and Protein Chapter 12

13. Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12

14.  DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an mRNA will be synthesized. Molecular Genetics Transcription  Through transcription, the DNA code is transferred to mRNA in the nucleus. 12.3 DNA, RNA, and Protein Chapter 12

15. Molecular Genetics RNA Processing  The code on the DNA is interrupted periodically by sequences that are not in the final mRNA.  Intervening sequences are called introns.  Remaining pieces of DNA that serve as the coding sequences are called exons. 12.3 DNA, RNA, and Protein Chapter 12 DNA and Genes

16. Molecular Genetics The Code  Experiments during the 1960s demonstrated that the DNA code was a three-base code.  The three-base code in DNA or mRNA is called a codon. 12.3 DNA, RNA, and Protein Chapter 12

17. Molecular Genetics Translation  In translation, tRNA molecules act as the interpreters of the mRNA codon sequence.  At the middle of the folded strand, there is a three- base coding sequence called the anticodon.  Each anticodon is complementary to a codon on the mRNA. 12.3 DNA, RNA, and Protein Chapter 12

18. Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12 Visualizing Transcription and Translation

19. A Summary of Protein Synthesis or the Central Dogma of Biology

20. Molecular Genetics Eukaryote Gene Regulation  Controlling transcription  Transcription factors ensure that a gene is used at the right time and that proteins are made in the right amounts  The complex structure of eukaryotic DNA also regulates transcription. 12.4 Gene Regulation and Mutation Chapter 12

21. Molecular Genetics Hox Genes  Hox genes are responsible for the general body pattern of most animals. 12.4 Gene Regulation and Mutation Chapter 12

22. Molecular Genetics Mutations  A permanent change that occurs in a cell’s DNA is called a mutation.  Types of mutations  Point mutation  Insertion  Deletion 12.4 Gene Regulation and Mutation Chapter 12

23. Molecular Genetics 12.4 Gene Regulation and Mutation Chapter 12

24. State the Type of Mutation!

25. Molecular Genetics Protein Folding and Stability  Substitutions also can lead to genetic disorders.  Can change both the folding and stability of the protein 12.4 Gene Regulation and Mutation Chapter 12

26. Molecular Genetics Causes of Mutation  Can occur spontaneously  Chemicals and radiation also can damage DNA.  High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic. 12.4 Gene Regulation and Mutation Chapter 12

27. Molecular Genetics Body-cell v. Sex-cell Mutation  Somatic cell mutations are not passed on to the next generation.  Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring. 12.4 Gene Regulation and Mutation Chapter 12