DNA, RNA and Protein How the Information in DNA Is Used to Build a Protein

DNA RNA Protein Information Flow From DNA transcription translation Replication (prior to nuclear division) (maintain cell metabolism and support growth) Gene: sequence of DNA that codes for a protein

DNA and RNA Structure DNA DNA RNA RNA Primary Structure Chain of nucleotides Secondary Structure Double helix Single folded chain Nucleotide = phosphate + sugar + nitrogen-containing base

DNA and RNA Structure DNA RNA RNA Purine bases Adenine (A) Guanine (G) Adenine (A) Guanine (G) Pyrimidine bases Cytosine (C) Thymine (T) Cytosine (C) Uracil (U) 5-carbon sugar deoxyriboseribose Phosphate PO 4 PO 4 OHOH OHH

Nucleotide Chain Nucleotides are joined together by dehydration synthesis Nucleotides are joined together by dehydration synthesis The phosphate of one nucleotide is joined to sugar of next nucleotide, forming a “sugar-phosphate backbone” The phosphate of one nucleotide is joined to sugar of next nucleotide, forming a “sugar-phosphate backbone”

DNA Structure Two nucleotide chainsTwo nucleotide chains In opposite orientationsIn opposite orientations Held together by hydrogen bondsHeld together by hydrogen bonds Twisted into a helixTwisted into a helix G A C A C T G T A T T A 5’ end has free phosphate 3’ end has free sugar 3’ end 5’ end A pairs with T G pairs with C

Applying Your Knowledge In the DNA double helix, which base is paired with adenine? 1.Adenine 2.Cytosine 3.Guanine 4.Thymine 5.Uracil

DNA Replication DNA chains separateDNA chains separate Each chain is used as a pattern to produce a new chainEach chain is used as a pattern to produce a new chain Each new DNA helix contains one “old” and one “new” chainEach new DNA helix contains one “old” and one “new” chain

DNA Replication DNA replication requires 1. Enzymes, including DNA polymerase that adds nucleotides in a 5’  3’ direction. 1. Enzymes, including DNA polymerase that adds nucleotides in a 5’  3’ direction. 2. nucleotides 2. nucleotides 3. energy 3. energy 5’—A G C T — 3’ 3’—T C G A — 5’ A — 5’G C G 3’— T CT— 3’5’— A

Applying Your Knowledge After DNA replication, what is the composition of the new double-helical molecules? 1.Two new chains 2.Two old chains 3.One old and one new chain 4.One helix has two new chains and one has two old chains 5.None of these is correct.

5’ 3’ 5’ 3’ Your completed model will have two DNA chains, each with 9 nucleotides. Building Your DNA Model Join the phosphate of one nucleotide to the sugar of the next one One chain can have bases in any order, the other chain must be complementary

Transcription = Production of RNA Using DNA as a Template DNA chains separateDNA chains separate ONE DNA chain is used as a pattern to produce an RNA chainONE DNA chain is used as a pattern to produce an RNA chain RNA chain is released and the DNA chains reform the double-helixRNA chain is released and the DNA chains reform the double-helix In DNA In RNA A U T A G C C G

Transcription Transcription requires 1. Enzymes, including RNA polymerase that adds nucleotides in a 5’  3’ direction. 1. Enzymes, including RNA polymerase that adds nucleotides in a 5’  3’ direction. 2. nucleotides 2. nucleotides 3. energy 3. energy 3’---TACAAAGAGACT---5’ 5’---ATG TTTCTC TGA---3’ 3’---TACAAA GAGACT---5’ DNA template 5’---ATG TTTCTC TGA---3’ 5’---AUGUUUCUCUGA---3’ mRNA

Applying Your Knowledge What is the sequence of an RNA molecule transcribed from a DNA template strand that reads 3’-ATG-5’? 1. 5’-TAC-3’ 2. 5’-CAU-3’ 3. 5’-AUG-3’ 4. 5’-UAC-3’ 5. 3’-TAC-5’

Products of Transcription Messenger RNAMessenger RNA Contains the code words for the sequence of amino acids in a specific protein CODON = group of three nucleotides acting as a code word for an amino acid CODON = group of three nucleotides acting as a code word for an amino acid

Products of Transcription Transfer RNATransfer RNA “Translates” the message by bringing a specific amino acid into the correct position on the growing protein chain Has ANTICODON = a group of three nucleotides on a tRNA that recognizes a mRNA codon Has amino acid attachment site mRNA In mRNA In tRNA A U U A U A G C G C C G C G

Genetic Code Chart is written as a CODON dictionary, reading 5’  3’

Products of Transcription Ribosomal RNARibosomal RNA One of the structural components of the ribosome One of the structural components of the ribosome Ribosome = organelle where protein synthesis occurs Has sites to bind both mRNA and tRNA small ribosomal subunit for tRNA mRNA binding site

Applying Your Knowledge Which molecule contains the information for assembling the amino acids in the correct order in the protein? 1. rRNA 2. tRNA 3. mRNA 4. All of these 5. None of these

5’ 3’ 5’ 3’ Your completed messenger RNA will have 9 nucleotides. Building Your DNA Model Choose one DNA chain as the template for RNA Read the template from 3’  5’ to produce the mRNA from 5’  3’

Translation At the ribosome, codons in mRNA are recognized by tRNA anticodons to place amino acids in the specific sequence specified by the DNA. Three Stages of Translation: Initiation- assemble components to start process Initiation- assemble components to start process Elongation- add amino acids in repeated cycles Elongation- add amino acids in repeated cycles Termination- release protein product Termination- release protein product

Translation Initiation mRNA binds to ribosome mRNA binds to ribosome First tRNA binds to mRNA First tRNA binds to mRNA 5’---AUGUUUCUCUGA---3’ mRNA UAC met

Translation Elongation Next tRNA binds to mRNA Next tRNA binds to mRNA 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA

Translation Elongation Amino acids are joined Amino acids are joined First tRNA is released First tRNA is released 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA

Translation Elongation Ribosome moves by one codon Ribosome moves by one codon 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA

Translation Elongation (second cycle) Next tRNA binds to mRNA Next tRNA binds to mRNA 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAAGAG leu

Translation Elongation (second cycle) Amino acids are joined Amino acids are joined Second tRNA is released Second tRNA is released 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA GAG leu

Translation Elongation (second cycle) Ribosome moves by one codon Ribosome moves by one codon 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA GAG leu

Translation Termination Termination factor binds to stop codon Termination factor binds to stop codon 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA GAG leu T

Translation Termination Protein chain is released Protein chain is released Other components separate Other components separate 5’---AUGUUUCUCUGA---3’ mRNA UAC metphe AAA GAG leu T

Applying Your Knowledge If the mRNA sequence for codons 5, 6, and 7 of a protein is 5’-AAG-AUU-GGA-3’, what is the amino acid sequence in the protein? 1.Gly-ile-lys 2.Arg-leu-glu 3.Glu-leu-arg 4.Asn-met-gly 5.Lys-ile-gly

Your completed model will have 3 tRNAs, one for each codon in mRNA. Show the name of the amino acid carried by each tRNA. Serine Building Your DNA Model Attach 3 bases to the tRNA to form the anticodon Read the CODON from 5’  3’ to find the name of the amino acid CODON

Summary of Completed DNA Model One DNA double helix, two chains of 9 nucleotides eachOne DNA double helix, two chains of 9 nucleotides each –one chain can have any sequence –second chain must be complementary One chain of mRNA, 9 nucleotides longOne chain of mRNA, 9 nucleotides long –must be complementary to one of the two DNA chains (DNA template is 3’  5’, mRNA is 5’  3’) Three tRNAs with appropriate amino acids attachedThree tRNAs with appropriate amino acids attached –tRNA anticodons must match mRNA codons

Functions of Nucleic Acids DNA is the genetic materialDNA is the genetic material RNA is an intermediary in protein synthesisRNA is an intermediary in protein synthesis The nucleotide ATP is an energy carrier for cell activitiesThe nucleotide ATP is an energy carrier for cell activities

A PP~ ADP )( A PP~~P Breakdown of ATP: Releasing Energy for Work ATP ( ) Energetic P ~

PiPiPiPi A PP~~P Synthesis of ATP: Storing Energy (Inorganic Phosphate) + ATP ( ) + energy A PP~ ADP )(