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Ch. 10 NotesDNA: Transcription and
Translation
Ch. 10 NotesDNA: Transcription and
Translation
GOALSGOALS
Compare the structure of RNA with that of DNA Summarize the process of transcription Relate the role of codons to the sequence of
amino acids that results after translation Outline the major steps of translation Discuss the evolutionary significance of the
genetic code Describe how the lac operon is turned on or off Summarize the role of transcription factors in
regulating eukaryotic gene expression Describe how eukaryotic genes are organized Evaluate three ways that point mutations can
alter genetic material
Compare the structure of RNA with that of DNA Summarize the process of transcription Relate the role of codons to the sequence of
amino acids that results after translation Outline the major steps of translation Discuss the evolutionary significance of the
genetic code Describe how the lac operon is turned on or off Summarize the role of transcription factors in
regulating eukaryotic gene expression Describe how eukaryotic genes are organized Evaluate three ways that point mutations can
alter genetic material
Decoding the Information in DNA
Decoding the Information in DNA
RNARNA 1. Nucleic acid made of nucleotides linked together
2. Single stranded
1. Nucleic acid made of nucleotides linked together
2. Single stranded
Decoding the Information in DNA
Decoding the Information in DNA
RNARNA 3. Contains 5C ribose sugar (one more oxygen than DNA)
3. Contains 5C ribose sugar (one more oxygen than DNA)
Decoding the Information in DNA
• RNA • 4. Has A, G and C bases, but no T
• 5. Thymine replaced by uracils (which pairs with adenine)
Decoding the Information in DNA
Decoding the Information in DNA
Transcription
Transcription
Instructions for making protein are transferred from a gene to an RNA molecule
Instructions for making protein are transferred from a gene to an RNA molecule
Decoding the Information in DNA
Decoding the Information in DNA
Translation
Translation
Two types of RNA are used to read instructions on RNA molecule and put amino acids together to make the protein
Two types of RNA are used to read instructions on RNA molecule and put amino acids together to make the protein
Decoding the Information in DNA
Decoding the Information in DNA
Gene Expression
Gene Expression
Protein synthesisProtein making process
based on information encoded in DNA
Protein synthesisProtein making process
based on information encoded in DNA
TRANSCRIPTIONTRANSCRIPTION
Transcription
Transcription
Transfers info from a gene on DNA to RNA
In prokaryotes- occurs in cytoplasm
In eukaryotes- occurs in nucleus
Transfers info from a gene on DNA to RNA
In prokaryotes- occurs in cytoplasm
In eukaryotes- occurs in nucleus
TRANSCRIPTIONTRANSCRIPTION
Transcription(STEPS)
Transcription(STEPS)
1. RNA polymerase binds to start signal “promoter” on DNA
2. RNA polymerase unwinds and opens DNA double helix
1. RNA polymerase binds to start signal “promoter” on DNA
2. RNA polymerase unwinds and opens DNA double helix
TRANSCRIPTIONTRANSCRIPTION
Transcription(STEPS)
Transcription(STEPS)
3. RNA polymerase reads genes- adds and links matching nucleotides by base pairing (A-U and G-C)
3. RNA polymerase reads genes- adds and links matching nucleotides by base pairing (A-U and G-C)
TRANSCRIPTIONTRANSCRIPTION
Transcription(STEPS)
Transcription(STEPS)
4. RNA polymerase reaches stop signal at end of gene
5. As RNA polymerase works, a single strand of RNA grows
4. RNA polymerase reaches stop signal at end of gene
5. As RNA polymerase works, a single strand of RNA grows
TRANSCRIPTIONTRANSCRIPTION
Transcription(STEPS)
Transcription(STEPS)
6. DNA helix zips itself back up as RNA polymerase passes by
6. DNA helix zips itself back up as RNA polymerase passes by
TRANSCRIPTIONTRANSCRIPTION
Transcription(STEPS)
Transcription(STEPS)
7. Many identical RNA molecules are made simultaneouslyFeather like appearance in
photos
7. Many identical RNA molecules are made simultaneouslyFeather like appearance in
photos
The GENETIC CODEThe GENETIC CODE
Messenger RNA
Messenger RNA
mRNA Made when cells need a
protein madeDelivers protein making
instructions from gene to translation site
Instructions written in codons
mRNA Made when cells need a
protein madeDelivers protein making
instructions from gene to translation site
Instructions written in codons
The GENETIC CODEThe GENETIC CODE
CodonsCodons Three nucleotide sequences along mRNA
64 possible codonsEach corresponds to:
An amino acid ORA stop signal ORA start signal
Three nucleotide sequences along mRNA
64 possible codonsEach corresponds to:
An amino acid ORA stop signal ORA start signal
Can You Tell Me?Can You Tell Me?
1. During DNA replication, what molecule “reads” the strand of DNA to make the matching strand?
2. During transcription, what molecule “reads” the DNA?
3. What material does the transcription process create?
1. During DNA replication, what molecule “reads” the strand of DNA to make the matching strand?
2. During transcription, what molecule “reads” the DNA?
3. What material does the transcription process create?
The GENETIC CODE
• RNA’s role in translation
• Takes place in cytoplasm• Transfer RNA (tRNA) and
ribosomes help in protein synthesis
The GENETIC CODEThe GENETIC CODE
Transfer RNA
Transfer RNA
tRNA Single strand, carries
amino acidFolded shapeContains anticodon
tRNA Single strand, carries
amino acidFolded shapeContains anticodon
The GENETIC CODEThe GENETIC CODE
AnticodonAnticodon 3 nucleotides on tRNA that are complementary to a mRNA codon
3 nucleotides on tRNA that are complementary to a mRNA codon
The GENETIC CODEThe GENETIC CODE
Ribosomal RNA
Ribosomal RNA
rRNA makes up part of ribosomes
rRNA makes up part of ribosomes
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
1. mRNA leaves nucleus, enters cytoplasm
2. Ribosome hooks onto mRNA at start codon
1. mRNA leaves nucleus, enters cytoplasm
2. Ribosome hooks onto mRNA at start codon
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
3. tRNA attaches to ribosome subunit and binds to mRNAAnticodon of tRNA binds to
codon of mRNA
3. tRNA attaches to ribosome subunit and binds to mRNAAnticodon of tRNA binds to
codon of mRNA
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
4. tRNA drops off amino acid its carrying
5. Another tRNA comes and drops an amino acid off
4. tRNA drops off amino acid its carrying
5. Another tRNA comes and drops an amino acid off
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
6. Another tRNA enters, first tRNA leaves
6. Another tRNA enters, first tRNA leaves
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
7. Each amino acid bonded to previous one to form a chain
8. tRNA detaches leaving
amino acid attached to
remaining tRNA
7. Each amino acid bonded to previous one to form a chain
8. tRNA detaches leaving
amino acid attached to
remaining tRNA
The GENETIC CODEThe GENETIC CODE
Translation process
Translation process
9. Repeats until ribosomal subunit reaches stop codon
10. Newly made protein is released
9. Repeats until ribosomal subunit reaches stop codon
10. Newly made protein is released
TRANSLATIONTRANSLATION
TRANSLATION
TRANSLATION
TRANSLATIONTRANSLATION
TRANSLATIONTRANSLATION
TRANSLATIONTRANSLATION
Assessment OneAssessment One
Distinguish two differences between RNA structure and DNA structure
Explain how RNA is made during transcription
Interpret the genetic code to determine the amino acid coded for by the codon CCU
Compare the roles of the three different types of RNA during translation
What is the maximum number of amino acids that could be coded for by a section of mRNA with the sequence GUUCAGAACUGU?
Distinguish two differences between RNA structure and DNA structure
Explain how RNA is made during transcription
Interpret the genetic code to determine the amino acid coded for by the codon CCU
Compare the roles of the three different types of RNA during translation
What is the maximum number of amino acids that could be coded for by a section of mRNA with the sequence GUUCAGAACUGU?
Protein SynthesisProtein Synthesis
Protein Synthesis in Prokaryotes
Protein Synthesis in Prokaryotes
Requires too much energy and too many materials for cell to make every protein encoded for by the DNA at all times
Gene expression can be regulated according to cell needs
Ex: E. coli bacteria
Requires too much energy and too many materials for cell to make every protein encoded for by the DNA at all times
Gene expression can be regulated according to cell needs
Ex: E. coli bacteria
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
1. Lactose in dairy products enters your intestines
2. E. coli there can use lactose for nutrition (to make glucose and galactose)
1. Lactose in dairy products enters your intestines
2. E. coli there can use lactose for nutrition (to make glucose and galactose)
Regulating Protein Synthesis
• Lac Operon
• 3. Three genes for breaking down lactose located next to each other on DNA (can turn them on or off)– Genes on: they’re ready to be
transcribed and translated
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
4. These 3 genes turn on in presence of lactose and turn off in its absence
4. These 3 genes turn on in presence of lactose and turn off in its absence
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
5. Operator- area on DNA (touching start/promoter) that acts as on and off switchCan block RNA polymerase
from transcribing
5. Operator- area on DNA (touching start/promoter) that acts as on and off switchCan block RNA polymerase
from transcribing
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
6. Operon consists of Operator PromoterThree genesAll work together to
control lactose metabolism
6. Operon consists of Operator PromoterThree genesAll work together to
control lactose metabolism
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
7. No lactose presentLac operon is turned off when
repressor protein binds to DNARepressor blocks RNA
polymerase from binding
7. No lactose presentLac operon is turned off when
repressor protein binds to DNARepressor blocks RNA
polymerase from binding
Regulating Protein Synthesis
Regulating Protein Synthesis
Lac Operon
Lac Operon
8. In presence of lactoseLactose binds to repressor
changing its shapeCauses repressor to fall off
DNAAllows RNA polymerase to bind
and transcribe
8. In presence of lactoseLactose binds to repressor
changing its shapeCauses repressor to fall off
DNAAllows RNA polymerase to bind
and transcribe
Regulating Protein Synthesis
Regulating Protein Synthesis
Protein synthesis in eukaryotes
Protein synthesis in eukaryotes
Most gene regulation is to control the onset of transcription (binding of RNA polymerase)
Most gene regulation is to control the onset of transcription (binding of RNA polymerase)
Regulating Protein Synthesis
Regulating Protein Synthesis
Protein synthesis in eukaryotes
Protein synthesis in eukaryotes
Transcription Factors- regulatory proteins that help rearrange RNA polymerase into the correct position
Transcription Factors- regulatory proteins that help rearrange RNA polymerase into the correct position
Intervening DNAIntervening DNA
Intervening DNA in Eukaryotic Genes
Intervening DNA in Eukaryotic Genes
1. Introns- longs segments of nucleotides with no coding informationBreak up DNA/genes
1. Introns- longs segments of nucleotides with no coding informationBreak up DNA/genes
Intervening DNAIntervening DNA
Intervening DNA in Eukaryotic Genes
Intervening DNA in Eukaryotic Genes
2. Exons- actual genes that are translated into proteins
2. Exons- actual genes that are translated into proteins
Intervening DNAIntervening DNA
Intervening DNA in Eukaryotic Genes
Intervening DNA in Eukaryotic Genes
3. After transcription, introns in mRNA are cut out by spliceosomesExons are stitched back
together
3. After transcription, introns in mRNA are cut out by spliceosomesExons are stitched back
together
Intervening DNAIntervening DNA
Intervening DNA in Eukaryotic Genes
Intervening DNA in Eukaryotic Genes
4. Large numbers of exons and introns allows evolutionary flexibility because they can be shuffled about to make new genetic codes
4. Large numbers of exons and introns allows evolutionary flexibility because they can be shuffled about to make new genetic codes
MutationsMutations
MutationsMutations Changes in DNA of a gene are rare
When in body cells, only affect individual
When in gametes, offspring can be affected
Changes in DNA of a gene are rare
When in body cells, only affect individual
When in gametes, offspring can be affected
MutationsMutations
MutationsMutations A. Gene rearrangements- entire gene moved to a new location (disrupts its function)
A. Gene rearrangements- entire gene moved to a new location (disrupts its function)
MutationsMutations
MutationsMutations B. Gene alterations- changes a geneUsually results in wrong amino
acid being hooked into protein (disrupts protein function)
B. Gene alterations- changes a geneUsually results in wrong amino
acid being hooked into protein (disrupts protein function)
MutationsMutations
MutationsMutations C. Point Mutation- single nucleotide changes
C. Point Mutation- single nucleotide changes
MutationsMutations
MutationsMutations D. Insertion Mutation- extra piece of DNA is inserted
D. Insertion Mutation- extra piece of DNA is inserted
MutationsMutations
MutationsMutations E. Deletion Mutation- segments of gene are lost
E. Deletion Mutation- segments of gene are lost
MutationsMutations
MutationsMutations F. Frame shift Mutations- causes gene to be read in wrong 3 nucleotide sequenceEx THE CAT ATE Remove CTHE ATE TE (makes no sense)
F. Frame shift Mutations- causes gene to be read in wrong 3 nucleotide sequenceEx THE CAT ATE Remove CTHE ATE TE (makes no sense)
WEBSITESWEBSITES DNA Workshop Transcription Interactive Transcribing and Translating a Gene
Protein Synthesis Animation Transcription Animation Translation Movie Protein Translation Animation Animation of Translation Protein Synthesis Movie Transcription Game Protein Synthesis Tutorial
DNA Workshop Transcription Interactive Transcribing and Translating a Gene
Protein Synthesis Animation Transcription Animation Translation Movie Protein Translation Animation Animation of Translation Protein Synthesis Movie Transcription Game Protein Synthesis Tutorial