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DNA Function genetic information –how to build/grow, operate, and repair cells –Specifically how and when to make proteins passed from one cell generation.

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Presentation on theme: "DNA Function genetic information –how to build/grow, operate, and repair cells –Specifically how and when to make proteins passed from one cell generation."— Presentation transcript:

1 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 (heritable); –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 “non-coding”: ~97% of DNA ~3% of DNA “chromosome” Genes on a chromosome

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

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

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

9 Importance of base-pairing, information is preserved ATTCGCGATATTCGCGAT ATTCGCGATATTCGCGAT TAAGCGCTATAAGCGCTA ATTCGCGATATTCGCGAT TAAGCGCTATAAGCGCTA

10 ATTCGCGATATTCGCGAT TAAGCGCTATAAGCGCTA TAAGCGCTATAAGCGCTA Importance of base-pairing continued ATTCGCGATATTCGCGAT TAAGCGCTATAAGCGCTA TAAGCGCTATAAGCGCTA ATTCGCGATATTCGCGAT

11 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

12 1 copy of all DNA 2 copy of All DNA Replication of DNA 1 copy 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

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14 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) Mutations can occur during this process

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16 Protein Synthesis: making proteins from DNA 1.Transcription= DNA  mRNA –(in nucleus) 2.Translation = mRNA  Protein –(in ribosome) DOES NOT INCLUDE REPLICATION

17 Nucleic Acids - RNA continued Single stranded chains of nucleotides Sugar = ribose Bases and Pairing –G, C, A, U replaces T –G-C 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) 2-59

18 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

19 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

20 Protein Synthesis: the genetic code dna sequence  mRNA sequence  amino acid sequence 3-43 DNA template strand

21 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

22 Transcription 3-36 Template strand Coding strand RNA Polymerase

23 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

24 Transcription

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

26 Translation, part 1

27 Translation, part 2

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29 DNA  mRNA  Proteins  function/structure

30 Genetic Expression: from DNA to cell function/structure DNA  mRNA  Proteins  cell function/structure structure transport contraction receptors cell ID hormones/signaling 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

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

32 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 codons Change amino acid sequence Change protein Change protein function or make non-functional

33 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

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

35 Basic Types of Mutations Point mutations –substitution –insertion –deletion frame-shift mutations

36 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

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

38 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……….

39 (histone)

40 Chromatin 3-31

41 Chromatin continued 3-33 and methylation

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


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