Presentation on theme: "Central Dogma Big Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes."— Presentation transcript:
1 Central DogmaBig Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes.
2 Essential Knowledge3A1: DNA, and in some cases RNA, is the primary source of heritable information.
3 Central Dogma! Protein Synthesis Genetic info flows from nucleotide sequence in a gene to amino acid sequence in a protein
4 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM FigDNA1Synthesis ofmRNA in thenucleusmRNANUCLEUSCYTOPLASMFigure 5.26 DNA → RNA → protein
5 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 FigDNA1Synthesis ofmRNA in thenucleusmRNANUCLEUSCYTOPLASMmRNA2Movement ofmRNA into cytoplasmvia nuclear poreFigure 5.26 DNA → RNA → protein
6 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 FigDNA1Synthesis ofmRNA in thenucleusmRNANUCLEUSCYTOPLASMmRNA2Movement ofmRNA into cytoplasmvia nuclear poreRibosomeFigure 5.26 DNA → RNA → protein3Synthesisof proteinAminoacidsPolypeptide
7 mRNA: Carries info from DNA to ribosome Types of RNA InvolvedmRNA: Carries info from DNA to ribosome
8 Types of RNA InvolvedtRNA: Bind specific amino acids and allow info in the mRNA to be translated into a linear peptide sequence.
9 rRNA: functional building blocks of ribosomes (site of translation) Types of RNA InvolvedrRNA: functional building blocks of ribosomes (site of translation)
10 Types of RNA InvolvedRNAi: RNA interference molecules that inhibit gene expression; sometimes destroy mRNA.2 molecules involved: microRNA and siRNA (small interfering RNA) that regulate gene expression.
12 Transcription DNA mRNA, made by RNA polymerase II RNA polymerase binds on promoter (nucleotide), reads DNA from 3’ to 5’3 stages: Initiation,Elongation, Termination
13 A on DNA complements U on RNA RULE!A on DNA complements U on RNARNA has no T base!
14 InitiationPromoters: start RNA synthesis, TATA box is one in eukaryotesTranscription factors: help binding of RNA polymeraseCompleted assembly called a transcription initiation complex
15 Several transcription factors must bind to the DNA before RNA Fig. 17-81A eukaryotic promoterincludes a TATA boxPromoterTemplate5335TATA boxStart pointTemplateDNA strand2Several transcription factors mustbind to the DNA before RNApolymerase II can do so.Transcriptionfactors53353Additional transcription factors bind tothe DNA along with RNA polymerase II,forming the transcription initiation complex.Figure 17.8 The initiation of transcription at a eukaryotic promoterRNA polymerase IITranscription factors53355RNA transcriptTranscription initiation complex
16 ElongationTranscription progresses at a rate of 40 nucleotides per second in eukaryotes
17 TerminationIn bacteria: polymerase stops transcription at end of terminator (nucleotide sequence)In eukaryotes: polymerase continues transcription after pre-mRNA is cut polymerase eventually falls off DNA
18 RNA Processing Enzymes modify mRNA Ex: Addition of poly-A tail on 3’ end and a GTP 5’ CapHelps export mRNA and protect from degrading hydrolytic enzymes
20 TranslationmRNA message gets translated into a protein w/ help of transfer RNA (tRNA)
21 Occurs at Ribosomes2 ribosomal subunits (large and small) are made of proteins and ribosomal RNA (rRNA)
22 Either free floating in cytoplasm RibosomesEither free floating in cytoplasm
23 Or Attached to Rough Endoplasmic Reticulum RibosomesOr Attached to Rough Endoplasmic Reticulum
24 P Site: holds tRNA that carries growing polypeptide chain A Site: holds next tRNA that will add a. acid to chainE Site: holds exit tRNA that doesn’t have an a. acidRibosomes
25 Initiation of Translation mRNA interacts w/ rRNA of ribosome at start codon AUGmRNA is read in triplets called codons, which encodes a specific amino acid.tRNA carries the amino acid to the mRNA and ribosome
26 Termination of Translation Amino acids join to make a peptide chainStop codon stops process, release of new peptide chain.