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DNA Function

DNA Function. genetic information how to build, operate, and repair cell Specifically how and when to make proteins passed from one cell generation to the next; From one cell to the next within an individual passed from parent to child. DNA Organization.

candice-delgado
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DNA Function

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  1. DNA Function • genetic information • how to build, operate, and repair cell • Specifically how and when to make proteins • passed from one cell generation to the next; • From one cell to the next within an individual • passed from parent to child

  2. DNA Organization • DNA molecule = genes + regulatory DNA + “other” • gene =protein instructions • 20-25k estimated genes (but >100,000 estimated proteins….problem…..) • regulatory= when to activate gene/make a protein “chromosome” ~3% of DNA non-coding: ~97% of DNA

  3. DNA Structure • long chains of nucleotides • Nucleotide = sugar + phosphate + nitrogenous base • Sugar = deoxyribose (5C) • 4 Different Bases: A, T, G, C • Bases = pyrimidines (1 ring) or purines (2 rings)

  4. DNA Structure Cont.:Double Helix double stranded sugar-phosphate backbone=covalent base-base=hydrogen Twisted=helix 5’ 5’ 3’ 3’ hydrogen bond covalent bond ‘f’-five; ‘f’ phosphate; 5’ end

  5. DNA Structure Cont.:Complementary Base Pairing • 4 different bases • Complementary pairing • C—G • A—T

  6. Functional Characteristics of DNA: IMPORTANT!! Information = order of the bases/base sequence ATTGCGCA means something different then: ATTGCGGA Complementary base pairing Allows DNA to be copied over and over and the information stays the same. Allows information to be transferred to mRNA and stay the same

  7. Importance of base-pairing, information is preserved A T T C G C G A T A T T C G C G A T T A A G C G C T A A T T C G C G A T T A A G C G C T A

  8. Importance of base-pairing continued A T T C G C G A T T A A G C G C T A T A A G C G C T A A T T C G C G A T T A A G C G C T A T A A G C G C T A A T T C G C G A T

  9. DNA Replication • Happens as part of cell cycle • NOT! NOT! NOT! PART OF PROTEIN SYNTHESIS!!!!!!! • In preparation for cell division • Duplicates all the DNA: 1 copy  2 copies • One copy for each cell • semiconservative

  10. 1 copy of DNA 1 copy of all DNA 2 copy of All DNA 1 copy of DNA Replication of DNA • Mitosis divides/separate the two copies of identical chromosomes • Cytokinesis divides up the cytoplasm contents Parent/mother cell daughter cells: each one identical copy of all the DNA: genetically identical to the mother cell

  11. DNA Replication • DNA helicase “unzips” the DNA • New, complementary nucleotides are added/paired with the existing strands • DNA polymerase binds the new nucleotides together creating the P-S backbone • Result is two identical DNA molecules (i.e., the base sequence is the same)

  12. Protein Synthesis: making proteins from DNA • Transcription= DNA  mRNA • (in nucleus) • Translation = mRNA  Protein • (in cytoplasm @ ribosome) DOES NOT INCLUDE REPLICATION

  13. mRNA • Single stranded chains of nucleotides • Sugar = ribose • Bases and Pairing • G, C, A, U replaces T • G-C • T-A or A-U • Codons = 3-base groups • One codon is a “start” codon • Three codons are “stop codons” • Each codon corresponds to a specific amino acid (except stops) 2-59

  14. Transcription:from DNA  mRNA • promoter = how much transcription • RNA Polymerase unzips gene and moves down DNA • Complimentary RNA nucleotides bind DNA • RNA nucleotides bind together (via RNA poly) • at end of gene mRNA detaches and RNA poly detaches • DNA zips up when transcription is done • mRNA is made and leaves nucleus and enters cytoplasm 3-35

  15. Transcription Template strand RNA Polymerase Coding strand 3-36

  16. Transcription

  17. tRNA Amino acids • Single stranded piece of RNA • Carried and delivers amino acids • Anticodon binds w/ mRNA codon 3-44

  18. Translation, part 1

  19. Translation, part 2

  20. DNA  mRNA  Proteins  cell function/structure Genetic Expression: from DNA to cell function/structure This is the big picture: The instructions on DNA make proteins when the cell receives a signal and then those proteins are synthesized and used as enzymes, transport proteins, receptors, hormones or as building materials for the cell so that the cell can carry out its functions • structure • transport • contraction • receptors • cell ID • hormones/signaling

  21. Protein Synthesis and the Genetic Code DNA template strand 3-43

  22. Mutations, DNA, and Protiens • Mutation = change in DNA base sequence • change in protien  change in structure and/or function Change DNA sequence Change mRNA sequence Change amino acid sequence Change protein function or make non-functional Change protein Change codons

  23. Base Sequences and Human Variation • SNP’s (single nucleotide polymorphisms) • single nucleotide differences in the DNA between different individuals • responsible for most differences in appearance and physiology • ATT GCG ATC CGA TAT TTT AAC CCC ATA CGG TAT TTT TCG • ATT GCG TTC CGA TAT TTT AAC CCC ATA CGG TAT TTT TCG • ATT GCG ATC CGA TAT TTG AAC CCC ATA CGG TAT TTT TCG • ATT GCC ATC CGA TAT TTT AAC CCC ATA CGG TAA TTT TCG • ATT GCC ATC CGA TAT TTT CAC CCC ATA CGG TAT TTT TCG • ATT GCG ATC CGA TAT TTT CAC CCC ATA CGG TAA TTT TCG

  24. DNA (genetics)  characteristics/physiology DNA + environment = phenotype (characteristics individuals actually have/display)

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