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Molecular Genetics

Molecular Genetics. Remember, -DNA is a nucleic acid -DNA is found in the nucleus. 2 functions of DNA. To store and use info to direct cell activities To copy itself exactly during cell division. Remember…. DNA is made up of monomers called nucleotides. 3 parts of a nucleotide in DNA.

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Molecular Genetics

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  1. Molecular Genetics Remember, -DNA is a nucleic acid -DNA is found in the nucleus

  2. 2 functions of DNA • To store and use info to direct cell activities • To copy itself exactly during cell division

  3. Remember… • DNA is made up of monomers called nucleotides.

  4. 3 parts of a nucleotide in DNA • A phosphate group • A 5-carbon sugar (deoxyribose) • 4 different nitrogen bases

  5. 4 nitrogen bases • Adenine A • Thymine T • Cytosine C • Guanine G

  6. The base pairing rule • When nitrogen bases pair and form bonds, Adenine always pairs with Thymine and Cytosine always pairs with Guanine.

  7. The structure of DNA • DNA is a double helix. Think of this as a twisted ladder. • This structure was discovered by James Watson and Francis Crick in 1953. • DNA is double stranded. The two strands are complimentary. When they unwind they serve as templates or guides for replication.

  8. DNA replication • The enzyme DNA helicase “unzips” the 2 strands. • The now unpaired bases combine with free bases in the nucleus. • The enzyme DNA polymerase connects the nucleotides. • DNA is repaired by more than 20 “proof-reading” enzymes.

  9. Practice DNA replication • T A G C A T G A T T A C C C G A T C G T A C T A A T G G G C

  10. Remember… • The sequence of nitrogen bases in DNA contains all the information that determines a cell’s structure and its function.

  11. DNA… …and the story of how to make a protein.

  12. 5-carbon sugar is deoxyribose DNA is a double stranded helix 4th nitrogen base is thymine 5-carbon sugar is ribose RNA is a single strand 4th nitrogen base is uracil DNA vs RNA

  13. Practice… • A U C G G A C U A G U A C G G U A C • U A G C C U G A U C A U G C C A U G

  14. Three types of RNA • Messenger (mRNA) • Transfer (tRNA) • Ribosomal (rRNA)

  15. Transcription • the process by which RNA is produced from DNA • this takes place in the nucleus

  16. Practice… DNA • T A G C A T C T A G A G • A U C G U A G A U C U C RNA

  17. Translation • the process of assembling amino acids from information encoded in RNA • this takes place in the cytoplasm

  18. Practice… • A U C G U A G A U C U C • Use the table in your textbook to translate the amino acid chain coded in this mRNA.

  19. Protein Synthesis • the assembling of amino acids into a specific protein • occurs in the ribosomes

  20. Vocab. • Codon-3 sequential bases in mRNA that “code” for a particular amino acid

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