1 Thursday 2/2/17 AIM: How can we transcribe the DNA code?DO NOW: 1- Explain the role of enzymes in DNA replication. 2- Describe DNA Replication 3- How does DNA Replication create a semi-conservative model?

2 Replicate the followingGATTACA GATTACA CTAATGT CTAATCT GATTACA CTAATGT

3 DNA and RNA are polymers of nucleotidesDNA is a nucleic acid, made of long chains of nucleotides Phosphate group Nitrogenous base Nitrogenous base (A, G, C, or T) Sugar Phosphate group Nucleotide Thymine (T) Sugar (deoxyribose) DNA nucleotide Polynucleotide Sugar-phosphate backbone Figure 10.2A

4 Partial chemical structureHydrogen bonds between bases hold the strands together: A and T, C and G Hydrogen bond Ribbon model Partial chemical structure Computer model Figure 10.3D

5 each strand is a template for a new strandUntwisting and replication of DNA each strand is a template for a new strand helicase DNA polymerase Figure 10.4B

6 DNA replication - Genes - the units of inheritance (6/10) - YouTube

7 Two daughter DNA moleculesDNA replication begins at many specific sites Parental strand Origin of replication Daughter strand Bubble 50 bases per sec in mammals, 500 bases per sec in bacteria. About a dozen enz needed for DNA replication.only about 1 mistake per billion. Proofreading and repairs are done by DNA polymerase, DNA ligase. Two daughter DNA molecules Figure 10.5A

8 Each strand of the double helix is oriented in the opposite direction5 end 3 end P P P P P P P P 3 end 5 end Figure 10.5B

9 Overall direction of replication3 DNA polymerase molecule DNA polymerase works in only one direction 5 end 5 Daughter strand synthesized continuously Parental DNA 5 3 Daughter strand synthesized in pieces 3 P 5 Telomere sequences are lost with each replication. Cancer, aging telomeres 5 P 3 DNA ligase Overall direction of replication Figure 10.5C

10 TRANSCRITION - YouTube

11 The information constituting an organism’s genotype is carried in its sequence of basesThe DNA is transcribed into RNA, which is translated into the polypeptide DNA TRANSCRIPTION RNA TRANSLATION Protein Figure 10.6A

12 DNA replicaation: both strands of the double helix act as templates to make new DNAIn transcription only one strand of DNA is the template (the gene)

13 Transcription produces genetic messages in the form of mRNARNA nucleotide RNA polymerase Direction of transcription Template strand of DNA Newly made RNA Figure 10.9A

14 Transcription The process that builds an RNA molecule from a DNA template Why does the cell want to build RNA? To get the genetic code out of the nucleus to the ribosome WHY? To build a protein and lead to a physical trait

15 Transcription cont. We want to transcribe the geneOnly one strand of the DNA double helix acts as a template and is transcribed Base Pair Rules A-U C-G Adenine on DNA attracts a Uracil of RNA

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17 Transcribe the followingDNA: AACGGTAGTACGTA RNA: UUGCCAUCAUGCAU

18 RNA: ribonucleic acid Large nucleic acid built from many nucleotides bonded together Remember a nucleotide consists of a phosphate group, 5 carbon sugar and nitrogen containing base

19 RNA nucleotide The 5-Carbon sugar is riboseThe 4 nitrogen containing bases: Adenine Uracil Cytosine Guanine

20 3 types of RNA mRNA: messenger RNA: carries the genetic code from the nucleus to the ribosome rRNA: ribosomal RNA: builds ribosomes tRNA: transfer RNA: carries amino acids to the synthesizing polypeptide

21 Assessment DNA: TTGCATGCAATCG transcribe

22 FRIDAY 2/3/17 AIM: How is RNA modified before it leaves the nucleus?DO NOW: Transcribe the following

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24 Modification of RNA The rough draft is called the primary transcriptBefore it leaves the nucleus it gets modified Addition of 5’cap and Poly-A tail The most important is RNA splicing

25 RNA modification 5’ cap and Poly A tail protect the RNA from being broken down by cellular enzymes They also help the ribosome recognize the RNA

26 RNA splicing Introns: junk DNA that does not code for proteinsExons: good DNA codes for protein Splicesome: enzymes that catalyze the removal of introns and the connection of exons Allows the human genome to produce a variety of polypeptides One gene codes for one polypeptide

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29 How do your cells know which amino acids it wants or needs?ANSWER: the genetic code determines the polypeptide (sequence of amino acids)

30 Now the mRNA is ready to leave the nucleus and enter the cytoplasm

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32 Quick Review What are the 3 major events that occur during transcription? Why is it important to modify the primary RNA before leaving the nucleus?

33 Monday 2/6/17 AIM: How is mRNA translated?DO NOW: 1-How does a cell know which proteins to synthesize? 2- Why do our cells make proteins? 3-Explain the importance of messenger RNA. HOMEWORK: Text read pages and page 341 EXAM THURSDAY

34 DO NOW ANSWER 1- The chromosomes which carry genes determine which proteins to make 2- Our cells make proteins so that they can express physical traits 3- mRNA: messenger RNA carries the genetic code out of the nucleus into the cytoplasm

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36 The Genetic code Codon: sequence of 3 nucleotides that specify an amino acid There are 20 amino acids that build ALL polypeptides It is the unique sequence of amino acids that build polypeptide chains It is the unique folding of polypeptides that build proteins Proteins then lead to physical traits

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39 Codons to know AUG: start codon. All mRNA start with this codon. It translates to Methionine (Met) UAA Stop codons UAG tells translation UGA to end

40 An initiation codon marks the start of an mRNA messageAUG = methionine Start of genetic message End Figure 10.13A

41 Translation There is a specific start AUG codonThere are 3 possible stop codons that terminate UAA,UAG or UGA

42 3 types of RNA mRNA: messenger RNA: carries the genetic code from the nucleus to the ribosome rRNA: ribosomal RNA: builds ribosomes tRNA: transfer RNA: carries amino acids to the synthesizing polypeptide

43 Translation: RNA to amino acid sequenceInvolves mRNA, tRNA, rRNA and ribosomes Before mRNA leaves the nucleus, proteins called splicesomes cut out and paste together coding regions of the primary mRNA transcript Plays a major role in polypeptide diversity Now it is ready for translation

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45 mRNA: carries codon message out of the nucleus

46 tRNA: Transfer RNA carries amino acids to the mRNA-ribosome complex

47 tRNA anticodon 3 base pair sequence complementary to the mRNA codonAnticodon-codon complex allows amino acids to bond in proper sequence

48 Tuesday 2/7/17 AIM: How are proteins synthesized? DO NOW:DNA: TACGGCCAAGCACGA cDNA mRNA aa tRNA HOMEWORK: review book read q 1-12 pgs

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50 Ribosomal RNA builds ribosomes

51 Translation- mRNA and tRNA interact at a ribosome

52 Translation continued

53 Remember The gene is part of the DNA that has the actual instructions for building the protein It is transcribed into mRNA which is what gets translated

54 Remember 20 amino acids 4 Nitrogen bases3 Nitrogen bases make up a codon 64 codons in total for 20 amino acids This means some codons code for the same amino acid

55 Reading frame Each codon specifies an amino acidThe reading frame is the sequence of codons in a gene If the reading frame is changed, the amino acid sequence may be changed Possibly resulting in a dis-functional protein

56 Sickle cell anemia

57 How many amino acids build all of the human proteins?20

58 How many nitrogen bases build RNA? 4How many nitrogen bases make up a codon? 3

59 How many codons are there?64

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61 Therefore more than one codon can specify an amino acid

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64 Lets build a protein DNA : TACCCTCAACTCTCAACT mRNA: AUGGGAGUUGAGAGUUGAtRNA: UACCCUCAACUCUCAACU aa: met - gly- val- glu- ser

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66 Amino acid sequence MET-GLY-VAL-GLU-SERWe got a polypeptide but is this a functional protein? NO! Remember it is the unique shape of a protein that gives it a specific function

67 What I want you to know about translationGene expression, protein synthesis Process that builds a polypeptide chain from a mRNA molecule The original message comes from the DNA template tRNA anticodon bonds to mRNA codon bringing an amino acid into its proper place Translation occurs in the ribosome

68 Translation Stage of Protein SynthesisRectangles = amino acids Crooked Cross = transfer RNA with an amino acid on top and anticodon at bottom X = messenger RNA molecule with codons Double oval = ribosome

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71 AIM: How are codons translated into polypeptides?DO NOW: Handout. Label 1-10 Homework: Handout

72 RNA:ribonucleic acid Polymer made up of small subunits called nucleotides Each nucleotide has a 5 C sugar, nitrogenous base and phosphate group The 5 carbon sugar in RNA is ribose The four possible nitrogenous bases are Adenine, uracil, cytosine and guanine

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74 Instead of thymine, adenine attracts a uracil nitrogenous base

75 mRNA: messenger RNA

76 mRNA: messenger RNA

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78 Assessment Handout 1-5 and A-E

79 AIM: How is the reading frame effected if the base pair sequence changed?DO NOW: Transcribe and translate the following: DNA: TACCCTCAACTCTCAACT Homework: Read Reading Check pages 267 and 269

80 How would mRNA and amino acid sequence change if the following DNA template changed?Original DNA: TACCCTCAACTCTCAACT Changed DNA: TACCCTCATTCTCAAC

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82 DO NOW ANSWER If the gene sequence is changed and causes a change in the amino acid sequence (polypeptide), the physical characteristic changes

83 Are all genes in each cell expressed in every cell?NO! All of the 30,000 genes are in each body cell but only specific genes are expressed in specific cells

84 Differentiation AKA Protein synthesis AKA gene expressionThe regulation of gene expression Different genes are expressed in different cells Different cells build different proteins

85 1- How many base pairs make up a single codon?2- How many amino acids build all human proteins?

86 3 nitrogen bases=codon 64 codons in total 20 amino acids build all proteins More than one codon for a single amino acid This is why some mutations have NO effect on the polypeptide chain

87 How do you make a polypeptide?Gene-mRNA-ribosome-codon/anticodon bonding which makes a long chain of amino acids

88 How are polypeptides related to physical characteristics?Polypeptides build proteins which lead to chemical reactions that cause physical traits

89 Functional protein Polypeptide: Long chain of amino acidsCombine with other polypeptides Folds into a unique shape This makes a functional protein The shape of a protein is unique to its function If you change the shape, you change the function

90 Denaturing a protein Changes the shape of the proteinIf the shape of the protein changes the function changes or it does not function at all. How would a protein get denatured? Gene mutation Mistake in mRNA modification Mistake in translation Mistake in polypeptide folding

91 If my DNA makes a mistake, how will the protein behave?The protein will have a different shape, and without its shape, it cannot function properly Proteins are shape specific Denature: changes the shape of a protein

92 GENE Mutations Change in nucleotide sequence of bases in a DNA molecule (gene) May or may not change the amino acid sequence Nonsense mutation: gene sequence changes but amino acid does not EX: normal DNA CTT mutated DNA: CTC

93 Gene Mutations Nucleotide substitutions: single base pair is replaced with a different incorrect pair Insertion: addition of 1 or more base pairs Deletion: removal of one or more base pairs

94 Sources of mutations Mutagen: any chemical that causes a change is nucleotide sequence of a gene Chemicals Medication Vaccine Radiation carcinogens

95 How are mutations inherited?If a mutation is in a gamete (sperm or egg), it will be inherited by the zygote

96 Mutations How is the polypeptide changed if the reading frame of an mRNA molecule is changes from GGC to AGC? amino acid in the polypeptide chain is changed from SER to GLY Mutation in reading frame of a gene could result in protein dysfunction