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DNA Location

DNA Location. DNA is contained inside the nucleus of a cell It is organized into 46 pieces referred to as chromosomes. DNA Function. genetic information how to build/grow, operate, and repair cells Specifically how and when to make proteins passed from one cell generation to the next;

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DNA Location

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  1. DNA Location • DNA is contained inside the nucleus of a cell • It is organized into 46 pieces referred to as chromosomes

  2. DNA Function • genetic information • how to build/grow, operate, and repair cells • 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

  3. 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 Genes on a chromosome

  4. 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) 1 OF 4 POSSIBLE BASES Strand/chain of nucleotides created by bonds between sugar and phosphate

  5. 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

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

  7. 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

  8. A T T C G C G A T A T T C G C G A T 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 T A A G C G C T A T A A G C G C T A A base sequence and its complementary pairs in a complete double strand of DNA A base sequence The two complete DNA molecules have the same base sequence as one another and the original DNA—the information has stayed the same If each strand separates and is bases re-pair with free nucleotides

  9. Nucleic Acids - RNA continued • Single stranded chains of nucleotides • Sugar = ribose • Bases and Pairing • G, C, A, U replaces T • G-C always pair with one another • If RNA is pairing with RNA then U-A always pair with one another • If RNA is pairing with DNA; a DNA A is paired with a RNA U • types of RNA (made from DNA): • Messenger RNA – mRNA: copy of DNA’s protein building instructions • Transfer RNA – tRNA: carries and delivers amino acids to mRNA/ribosomes • Ribosomal RNA – rRNA • others (siRNA, miRNA, RNA based enzymes, etc) • Beyond the scope of this course 2-59

  10. mRNA • A single stranded copy of a gene’s information • Bases organized into codons • 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

  11. Protein Synthesis continued • Ribosomes read 3 mRNA bases (= a triplet) at a time • Each triplet is a codon, which specifies an amino acid • Ribosomes translate codons into an amino acid sequence that becomes a polypeptide chainprotein 3-42

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

  13. Protein Synthesis: making proteins from DNA • Transcription= DNA  mRNA • (in nucleus) • Translation = mRNA  Protein • (in cytoplasm @ ribosome)

  14. Protein Synthesis: the genetic codedna sequence  mRNA sequence  amino acid sequence DNA template strand 3-43

  15. 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

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

  17. Transcription

  18. Translation:from mRNA  Protein • mRNA combines with a ribosome • tRNA with complimentary anticodon delivers amino acid to mRNA codon at ribosome • Another tRNA with complimentary anticodon delivers amino acid to mRNA at the next codon (at ribosome) • Adjacent amino acids bond together, first tRNA detaches and leaves ribosome • Next tRNA with complimentary anticodon delivers amino acid to mRNA at the next codon (at ribosome) Repeat until the stop codon is reached Protein has been built/assembled

  19. Translation, part 1

  20. Translation, part 2

  21. DNA  mRNA  Proteins  function/structure Order of bases Codons and codon order Amino acids and their order

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

  23. 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

  24. 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

  25. 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 GCCATC CGA TAT TTT CAC CCC ATA CGG TAT TTT TCG • ATT GCG ATC CGA TAT TTT CAC CCC ATA CGG TAA TTT TCG

  26. Mutations, DNA, and Proteins • Mutation = change in DNA base sequence • change in protien  change in structure and/or function

  27. Basic Types of Mutations • Point mutations • substitution • insertion • deletion frame-shift mutations

  28. Point Mutations • Substitution: • ATT GCG AGT TAT CCG • ATT GCG AGT TAG CCG • Insertion: • ATT GCG AGT TAT CCG • ATT GCG TAG TTA TCC G • Deletion • ATT GCG AGT TAT CCG • ATT GCG GTT ATC CG A frameshifts

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

  30. DNA Organization DNA is wrapped around histone (a protein) DNA + Histone = Chromatin Histone is important in making genes accessible or inaccesible (can be heritable) Histone can control which genes can be used=Epigenetics acetylation allows access/deacetylation shuts off methylation prevents access/shuts off phosphorylation and others……….

  31. DNA wrapped around histone proteins = chromatin chromatin ≈ chromosome Histone proteins

  32. Chromatin 3-31

  33. Chromatin continued and methylation 3-33

  34. DNA (genetics)  characteristics/physiology DNA + environment = phenotype (characteristics)

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