SlideShare a Scribd company logo
1 of 25
Download to read offline
Lesson Overview   Fermentation




                                 Lesson Overview
                                     13.1 RNA
Lesson Overview         Fermentation


  THINK ABOUT IT
       DNA is the genetic material of cells. The sequence of nucleotide bases
       in the strands of DNA carries some sort of code. In order for that code to
       work, the cell must be able to understand it.

       What, exactly, do those bases code for? Where is the cell’s decoding
       system?
Lesson Overview       Fermentation


  The Role of RNA
     How does RNA differ from DNA?
Lesson Overview          Fermentation


  The Role of RNA
     How does RNA differ from DNA?

     There are three important differences between RNA and DNA: (1) the
     sugar in RNA is ribose instead of deoxyribose, (2) RNA is generally single-
     stranded and not double-stranded, and (3) RNA contains uracil in place of
     thymine.
Lesson Overview           Fermentation


  The Role of RNA
     Genes contain coded DNA instructions that tell cells how to build proteins.

     The first step in decoding these genetic instructions is to copy part of the
     base sequence from DNA into RNA.

     RNA, like DNA, is a nucleic acid that consists of a long chain of
     nucleotides.

     RNA then uses the base sequence copied from DNA to direct the
     production of proteins.
Lesson Overview         Fermentation


  Comparing RNA and DNA
       Each nucleotide in both DNA and RNA is made up of a 5-carbon sugar,
       a phosphate group, and a nitrogenous base.

       There are three important differences between RNA and DNA:

       (1) The sugar in RNA is ribose instead of deoxyribose.

       (2) RNA is generally single-stranded and not double-stranded.

       (3) RNA contains uracil in place of thymine.

       These chemical differences make it easy for the enzymes in the cell to
       tell DNA and RNA apart.
Lesson Overview        Fermentation


  Comparing RNA and DNA
       The roles played by DNA and RNA are similar to the master plans and
       blueprints used by builders.
Lesson Overview          Fermentation


  Comparing RNA and DNA
       A master plan has all the information needed to construct a building.
       Builders never bring a valuable master plan to the building site, where it
       might be damaged or lost. Instead, they prepare inexpensive,
       disposable copies of the master plan called blueprints.
Lesson Overview         Fermentation


  Comparing RNA and DNA
       Similarly, the cell uses DNA “master plan” to prepare RNA “blueprints.”

       The DNA molecule stays safely in the cell’s nucleus, while RNA
       molecules go to the protein-building sites in the cytoplasm—the
       ribosomes.
Lesson Overview         Fermentation


  Functions of RNA
       You can think of an RNA molecule, as a disposable copy of a segment
       of DNA, a working copy of a single gene.

       RNA has many functions, but most RNA molecules are involved in
       protein synthesis only.

       RNA controls the assembly of amino acids into proteins. Each type of
       RNA molecule specializes in a different aspect of this job.
Lesson Overview       Fermentation


  Functions of RNA
       The three main types of RNA are messenger RNA, ribosomal RNA, and
       transfer RNA.
Lesson Overview          Fermentation


  Messenger RNA
       Most genes contain instructions for
       assembling amino acids into
       proteins.

       The RNA molecules that carry
       copies of these instructions are
       known as messenger RNA
       (mRNA): They carry information
       from DNA to other parts of the cell.
Lesson Overview        Fermentation


  Ribosomal RNA
       Proteins are assembled on ribosomes,
       small organelles composed of two
       subunits.

       These ribosome subunits are made up
       of several ribosomal RNA (rRNA)
       molecules and as many as 80 different
       proteins.
Lesson Overview        Fermentation


  Transfer RNA
       When a protein is built, a transfer
       RNA (tRNA) molecule transfers each
       amino acid to the ribosome as it is
       specified by the coded messages in
       mRNA.
Lesson Overview       Fermentation


  RNA Synthesis
     How does the cell make RNA?
Lesson Overview          Fermentation


  RNA Synthesis
     How does the cell make RNA?

     In transcription, segments of DNA serve as templates to produce
     complementary RNA molecules.
Lesson Overview        Fermentation


  Transcription
       Most of the work of making RNA takes place during transcription.
       During transcription, segments of DNA serve as templates to produce
       complementary RNA molecules.

       The base sequences of the transcribed RNA complement the base
       sequences of the template DNA.
Lesson Overview          Fermentation


  Transcription
       In prokaryotes, RNA synthesis and protein synthesis take place in the
       cytoplasm.

       In eukaryotes, RNA is produced in the cell’s nucleus and then moves to
       the cytoplasm to play a role in the production of proteins. Our focus will
       be on transcription in eukaryotic cells.
Lesson Overview        Fermentation


  Transcription
       Transcription requires an enzyme, known as RNA polymerase, that is
       similar to DNA polymerase.
Lesson Overview        Fermentation


  Transcription
       RNA polymerase binds to DNA during transcription and separates the
       DNA strands.
Lesson Overview        Fermentation


  Transcription
       RNA polymerase then uses one strand of DNA as a template from
       which to assemble nucleotides into a complementary strand of RNA.
Lesson Overview        Fermentation


  Promoters
       RNA polymerase binds only to promoters, regions of DNA that have
       specific base sequences.

       Promoters are signals in the DNA molecule that show RNA polymerase
       exactly where to begin making RNA.

       Similar signals in DNA cause transcription to stop when a new RNA
       molecule is completed.
Lesson Overview          Fermentation


  RNA Editing
       RNA molecules sometimes
       require bits and pieces to be cut
       out of them before they can go
       into action.

       The portions that are cut out and
       discarded are called introns.

       In eukaryotes, introns are taken
       out of pre-mRNA molecules while
       they are still in the nucleus.

       The remaining pieces, known as
       exons, are then spliced back
       together to form the final mRNA.
Lesson Overview         Fermentation


  RNA Editing
       Biologists don’t have a complete
       answer as to why cells use
       energy to make a large RNA
       molecule and then throw parts of
       that molecule away.

       Some pre-mRNA molecules may
       be cut and spliced in different
       ways in different tissues, making
       it possible for a single gene to
       produce several different forms of
       RNA.
Lesson Overview        Fermentation


  RNA Editing
       Introns and exons may also play
       a role in evolution, making it
       possible for very small changes
       in DNA sequences to have
       dramatic effects on how genes
       affect cellular function.

More Related Content

What's hot (20)

DNA Double Helix Structure
DNA Double Helix StructureDNA Double Helix Structure
DNA Double Helix Structure
 
Molecular genetics 2014
Molecular genetics 2014Molecular genetics 2014
Molecular genetics 2014
 
Central dogma
Central dogmaCentral dogma
Central dogma
 
Dna repair systems
Dna repair systemsDna repair systems
Dna repair systems
 
Central Dogma of Molecular Biology
Central Dogma of Molecular BiologyCentral Dogma of Molecular Biology
Central Dogma of Molecular Biology
 
Gene Expression & regulation
Gene Expression & regulationGene Expression & regulation
Gene Expression & regulation
 
The nucleic acids
The nucleic acidsThe nucleic acids
The nucleic acids
 
Translation (protein formation)
Translation (protein formation)Translation (protein formation)
Translation (protein formation)
 
Transcription factors and machinery
Transcription factors and machineryTranscription factors and machinery
Transcription factors and machinery
 
Central dogma
Central dogmaCentral dogma
Central dogma
 
Lesson 14.1
Lesson 14.1Lesson 14.1
Lesson 14.1
 
Nucleic acid..biochem
Nucleic acid..biochemNucleic acid..biochem
Nucleic acid..biochem
 
Dna structure
Dna structureDna structure
Dna structure
 
Translation
TranslationTranslation
Translation
 
Genetic code
Genetic codeGenetic code
Genetic code
 
Central dogma
Central dogmaCentral dogma
Central dogma
 
Dna and rna
Dna and rnaDna and rna
Dna and rna
 
Transcription and Translation PowerPoint
Transcription and Translation PowerPointTranscription and Translation PowerPoint
Transcription and Translation PowerPoint
 
Dna structure and analysis
Dna structure and analysisDna structure and analysis
Dna structure and analysis
 
RNA
RNARNA
RNA
 

Viewers also liked

Biodiversity
BiodiversityBiodiversity
BiodiversityElisa
 
Biology 120 lectures for 2nd exam 2012 2012
Biology 120 lectures for 2nd exam 2012 2012Biology 120 lectures for 2nd exam 2012 2012
Biology 120 lectures for 2nd exam 2012 2012Marilen Parungao
 
Biodiversity and Human Population Growth
Biodiversity and Human Population GrowthBiodiversity and Human Population Growth
Biodiversity and Human Population Growthmashapiro
 
Traditional versus Modern Biotechnology (Exam 2 coverage)
Traditional versus Modern Biotechnology (Exam 2 coverage)Traditional versus Modern Biotechnology (Exam 2 coverage)
Traditional versus Modern Biotechnology (Exam 2 coverage)Marilen Parungao
 
Biodiversity: Living and Non-Living Resources
Biodiversity: Living and Non-Living ResourcesBiodiversity: Living and Non-Living Resources
Biodiversity: Living and Non-Living ResourcesMarilen Parungao
 
Chapter 14- Human Genetics
Chapter 14- Human GeneticsChapter 14- Human Genetics
Chapter 14- Human GeneticsMary Beth Smith
 
Population 2012
Population  2012Population  2012
Population 2012mashapiro
 
IB ESS Topic 4: Conservation and biodiversity
IB ESS Topic 4: Conservation and biodiversityIB ESS Topic 4: Conservation and biodiversity
IB ESS Topic 4: Conservation and biodiversityGURU CHARAN KUMAR
 
Chapter 14 Assessment & Review
Chapter 14 Assessment & ReviewChapter 14 Assessment & Review
Chapter 14 Assessment & ReviewJavier Aguirre
 
Biodiversity in Ecosystems
Biodiversity in EcosystemsBiodiversity in Ecosystems
Biodiversity in EcosystemsNigel Gardner
 
Biology in Focus - Chapter 9
Biology in Focus - Chapter 9Biology in Focus - Chapter 9
Biology in Focus - Chapter 9mpattani
 
Forest & Bio-diversity management
Forest & Bio-diversity managementForest & Bio-diversity management
Forest & Bio-diversity managementKaushik Deb
 
Biology in Focus - Chapter 7
Biology in Focus - Chapter 7Biology in Focus - Chapter 7
Biology in Focus - Chapter 7mpattani
 
Threats to Biodiversity
Threats to BiodiversityThreats to Biodiversity
Threats to BiodiversityVivek Kumar
 
BIODIVERSITY: definition, levels and threats
BIODIVERSITY: definition, levels and threatsBIODIVERSITY: definition, levels and threats
BIODIVERSITY: definition, levels and threatsMarilen Parungao
 
15277 biodiversity updated
15277 biodiversity updated15277 biodiversity updated
15277 biodiversity updatedEajaz Khan
 

Viewers also liked (18)

Biodiversity
BiodiversityBiodiversity
Biodiversity
 
Biology 120 lectures for 2nd exam 2012 2012
Biology 120 lectures for 2nd exam 2012 2012Biology 120 lectures for 2nd exam 2012 2012
Biology 120 lectures for 2nd exam 2012 2012
 
Biodiversity and Human Population Growth
Biodiversity and Human Population GrowthBiodiversity and Human Population Growth
Biodiversity and Human Population Growth
 
Traditional versus Modern Biotechnology (Exam 2 coverage)
Traditional versus Modern Biotechnology (Exam 2 coverage)Traditional versus Modern Biotechnology (Exam 2 coverage)
Traditional versus Modern Biotechnology (Exam 2 coverage)
 
Bio diversity
Bio diversityBio diversity
Bio diversity
 
Material Cycling lecture
Material Cycling lectureMaterial Cycling lecture
Material Cycling lecture
 
Biodiversity: Living and Non-Living Resources
Biodiversity: Living and Non-Living ResourcesBiodiversity: Living and Non-Living Resources
Biodiversity: Living and Non-Living Resources
 
Chapter 14- Human Genetics
Chapter 14- Human GeneticsChapter 14- Human Genetics
Chapter 14- Human Genetics
 
Population 2012
Population  2012Population  2012
Population 2012
 
IB ESS Topic 4: Conservation and biodiversity
IB ESS Topic 4: Conservation and biodiversityIB ESS Topic 4: Conservation and biodiversity
IB ESS Topic 4: Conservation and biodiversity
 
Chapter 14 Assessment & Review
Chapter 14 Assessment & ReviewChapter 14 Assessment & Review
Chapter 14 Assessment & Review
 
Biodiversity in Ecosystems
Biodiversity in EcosystemsBiodiversity in Ecosystems
Biodiversity in Ecosystems
 
Biology in Focus - Chapter 9
Biology in Focus - Chapter 9Biology in Focus - Chapter 9
Biology in Focus - Chapter 9
 
Forest & Bio-diversity management
Forest & Bio-diversity managementForest & Bio-diversity management
Forest & Bio-diversity management
 
Biology in Focus - Chapter 7
Biology in Focus - Chapter 7Biology in Focus - Chapter 7
Biology in Focus - Chapter 7
 
Threats to Biodiversity
Threats to BiodiversityThreats to Biodiversity
Threats to Biodiversity
 
BIODIVERSITY: definition, levels and threats
BIODIVERSITY: definition, levels and threatsBIODIVERSITY: definition, levels and threats
BIODIVERSITY: definition, levels and threats
 
15277 biodiversity updated
15277 biodiversity updated15277 biodiversity updated
15277 biodiversity updated
 

Similar to Powerpoint 13.1

CVA Biology I - B10vrv4131
CVA Biology I - B10vrv4131CVA Biology I - B10vrv4131
CVA Biology I - B10vrv4131ClayVirtual
 
Chapter 13 packet
Chapter 13 packetChapter 13 packet
Chapter 13 packetjfg082
 
Chapter13 worksheets
Chapter13 worksheetsChapter13 worksheets
Chapter13 worksheetsCXG050
 
Physiology-brief about RNA and its types
Physiology-brief about RNA and its typesPhysiology-brief about RNA and its types
Physiology-brief about RNA and its typesDrHamza Nafees
 
Rna protein-synthesis
Rna protein-synthesisRna protein-synthesis
Rna protein-synthesislegoscience
 
DNA vs RNA and Comparison.pptx
DNA vs RNA  and Comparison.pptxDNA vs RNA  and Comparison.pptx
DNA vs RNA and Comparison.pptxYousefMElshrek
 
Structure of DNA and RNA and its functions
Structure of DNA and RNA and its functionsStructure of DNA and RNA and its functions
Structure of DNA and RNA and its functionsJeevan287994
 
Protein Synthesis in Prokaryotes and Eukaroytes
Protein Synthesis in Prokaryotes and EukaroytesProtein Synthesis in Prokaryotes and Eukaroytes
Protein Synthesis in Prokaryotes and EukaroytesBir Bahadur Thapa
 
Introduction to Transcription
Introduction to TranscriptionIntroduction to Transcription
Introduction to TranscriptionPrasanna R Kovath
 
RNA-Ribonucleic Acid PPT
RNA-Ribonucleic Acid PPTRNA-Ribonucleic Acid PPT
RNA-Ribonucleic Acid PPTKaran N
 
MOLECULAR ORGANIZATION OF EKARYOTIC RNA
 MOLECULAR ORGANIZATION OF EKARYOTIC RNA MOLECULAR ORGANIZATION OF EKARYOTIC RNA
MOLECULAR ORGANIZATION OF EKARYOTIC RNAgohil sanjay bhagvanji
 
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdf
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdfBrief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdf
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdfmckenziecast21211
 
Unit2 lesson3-proteinsysnthesis
Unit2 lesson3-proteinsysnthesisUnit2 lesson3-proteinsysnthesis
Unit2 lesson3-proteinsysnthesisReitmans
 

Similar to Powerpoint 13.1 (20)

B10vrv4131
B10vrv4131B10vrv4131
B10vrv4131
 
CVA Biology I - B10vrv4131
CVA Biology I - B10vrv4131CVA Biology I - B10vrv4131
CVA Biology I - B10vrv4131
 
Chapter 13 packet
Chapter 13 packetChapter 13 packet
Chapter 13 packet
 
Chapter13 worksheets
Chapter13 worksheetsChapter13 worksheets
Chapter13 worksheets
 
Physiology-brief about RNA and its types
Physiology-brief about RNA and its typesPhysiology-brief about RNA and its types
Physiology-brief about RNA and its types
 
Rna protein-synthesis
Rna protein-synthesisRna protein-synthesis
Rna protein-synthesis
 
DNA vs RNA and Comparison.pptx
DNA vs RNA  and Comparison.pptxDNA vs RNA  and Comparison.pptx
DNA vs RNA and Comparison.pptx
 
Structure of DNA and RNA and its functions
Structure of DNA and RNA and its functionsStructure of DNA and RNA and its functions
Structure of DNA and RNA and its functions
 
Protein Synthesis in Prokaryotes and Eukaroytes
Protein Synthesis in Prokaryotes and EukaroytesProtein Synthesis in Prokaryotes and Eukaroytes
Protein Synthesis in Prokaryotes and Eukaroytes
 
Notes ch13 website
Notes ch13 websiteNotes ch13 website
Notes ch13 website
 
Introduction to Transcription
Introduction to TranscriptionIntroduction to Transcription
Introduction to Transcription
 
Structure of dna and rna
Structure of dna and rnaStructure of dna and rna
Structure of dna and rna
 
Unit 2 genetics nucleic acid rna
Unit 2 genetics nucleic acid rnaUnit 2 genetics nucleic acid rna
Unit 2 genetics nucleic acid rna
 
RNA-Ribonucleic Acid PPT
RNA-Ribonucleic Acid PPTRNA-Ribonucleic Acid PPT
RNA-Ribonucleic Acid PPT
 
MOLECULAR ORGANIZATION OF EKARYOTIC RNA
 MOLECULAR ORGANIZATION OF EKARYOTIC RNA MOLECULAR ORGANIZATION OF EKARYOTIC RNA
MOLECULAR ORGANIZATION OF EKARYOTIC RNA
 
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdf
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdfBrief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdf
Brief Concepts and Questions EXAM 2 Chapter 8 DNA RNA Protein What i.pdf
 
Unit2 lesson3-proteinsysnthesis
Unit2 lesson3-proteinsysnthesisUnit2 lesson3-proteinsysnthesis
Unit2 lesson3-proteinsysnthesis
 
DNA-RNA-PPT 01.pptx
DNA-RNA-PPT 01.pptxDNA-RNA-PPT 01.pptx
DNA-RNA-PPT 01.pptx
 
Central dogma of molecular biology
Central dogma of molecular biologyCentral dogma of molecular biology
Central dogma of molecular biology
 
NUCLEIC ACIDS: THE RNA DOCUMENT
NUCLEIC ACIDS: THE RNA DOCUMENTNUCLEIC ACIDS: THE RNA DOCUMENT
NUCLEIC ACIDS: THE RNA DOCUMENT
 

More from Mneel1

Classification
ClassificationClassification
ClassificationMneel1
 
Bell ringers
Bell ringersBell ringers
Bell ringersMneel1
 
Classifying chemical reactions
Classifying chemical reactionsClassifying chemical reactions
Classifying chemical reactionsMneel1
 
Evolution powerpoint!
Evolution powerpoint!Evolution powerpoint!
Evolution powerpoint!Mneel1
 
Covalent bonds
Covalent bondsCovalent bonds
Covalent bondsMneel1
 
13 and 14 powerpoint
13 and 14 powerpoint13 and 14 powerpoint
13 and 14 powerpointMneel1
 
Ionic compounds naming
Ionic compounds namingIonic compounds naming
Ionic compounds namingMneel1
 
Powerpoint12.2
Powerpoint12.2Powerpoint12.2
Powerpoint12.2Mneel1
 
Chapter 7 powerpoint
Chapter 7 powerpointChapter 7 powerpoint
Chapter 7 powerpointMneel1
 
Powerpoint chp 1.1 and 1.2
Powerpoint chp 1.1 and 1.2Powerpoint chp 1.1 and 1.2
Powerpoint chp 1.1 and 1.2Mneel1
 

More from Mneel1 (10)

Classification
ClassificationClassification
Classification
 
Bell ringers
Bell ringersBell ringers
Bell ringers
 
Classifying chemical reactions
Classifying chemical reactionsClassifying chemical reactions
Classifying chemical reactions
 
Evolution powerpoint!
Evolution powerpoint!Evolution powerpoint!
Evolution powerpoint!
 
Covalent bonds
Covalent bondsCovalent bonds
Covalent bonds
 
13 and 14 powerpoint
13 and 14 powerpoint13 and 14 powerpoint
13 and 14 powerpoint
 
Ionic compounds naming
Ionic compounds namingIonic compounds naming
Ionic compounds naming
 
Powerpoint12.2
Powerpoint12.2Powerpoint12.2
Powerpoint12.2
 
Chapter 7 powerpoint
Chapter 7 powerpointChapter 7 powerpoint
Chapter 7 powerpoint
 
Powerpoint chp 1.1 and 1.2
Powerpoint chp 1.1 and 1.2Powerpoint chp 1.1 and 1.2
Powerpoint chp 1.1 and 1.2
 

Powerpoint 13.1

  • 1. Lesson Overview Fermentation Lesson Overview 13.1 RNA
  • 2. Lesson Overview Fermentation THINK ABOUT IT DNA is the genetic material of cells. The sequence of nucleotide bases in the strands of DNA carries some sort of code. In order for that code to work, the cell must be able to understand it. What, exactly, do those bases code for? Where is the cell’s decoding system?
  • 3. Lesson Overview Fermentation The Role of RNA How does RNA differ from DNA?
  • 4. Lesson Overview Fermentation The Role of RNA How does RNA differ from DNA? There are three important differences between RNA and DNA: (1) the sugar in RNA is ribose instead of deoxyribose, (2) RNA is generally single- stranded and not double-stranded, and (3) RNA contains uracil in place of thymine.
  • 5. Lesson Overview Fermentation The Role of RNA Genes contain coded DNA instructions that tell cells how to build proteins. The first step in decoding these genetic instructions is to copy part of the base sequence from DNA into RNA. RNA, like DNA, is a nucleic acid that consists of a long chain of nucleotides. RNA then uses the base sequence copied from DNA to direct the production of proteins.
  • 6. Lesson Overview Fermentation Comparing RNA and DNA Each nucleotide in both DNA and RNA is made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base. There are three important differences between RNA and DNA: (1) The sugar in RNA is ribose instead of deoxyribose. (2) RNA is generally single-stranded and not double-stranded. (3) RNA contains uracil in place of thymine. These chemical differences make it easy for the enzymes in the cell to tell DNA and RNA apart.
  • 7. Lesson Overview Fermentation Comparing RNA and DNA The roles played by DNA and RNA are similar to the master plans and blueprints used by builders.
  • 8. Lesson Overview Fermentation Comparing RNA and DNA A master plan has all the information needed to construct a building. Builders never bring a valuable master plan to the building site, where it might be damaged or lost. Instead, they prepare inexpensive, disposable copies of the master plan called blueprints.
  • 9. Lesson Overview Fermentation Comparing RNA and DNA Similarly, the cell uses DNA “master plan” to prepare RNA “blueprints.” The DNA molecule stays safely in the cell’s nucleus, while RNA molecules go to the protein-building sites in the cytoplasm—the ribosomes.
  • 10. Lesson Overview Fermentation Functions of RNA You can think of an RNA molecule, as a disposable copy of a segment of DNA, a working copy of a single gene. RNA has many functions, but most RNA molecules are involved in protein synthesis only. RNA controls the assembly of amino acids into proteins. Each type of RNA molecule specializes in a different aspect of this job.
  • 11. Lesson Overview Fermentation Functions of RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA.
  • 12. Lesson Overview Fermentation Messenger RNA Most genes contain instructions for assembling amino acids into proteins. The RNA molecules that carry copies of these instructions are known as messenger RNA (mRNA): They carry information from DNA to other parts of the cell.
  • 13. Lesson Overview Fermentation Ribosomal RNA Proteins are assembled on ribosomes, small organelles composed of two subunits. These ribosome subunits are made up of several ribosomal RNA (rRNA) molecules and as many as 80 different proteins.
  • 14. Lesson Overview Fermentation Transfer RNA When a protein is built, a transfer RNA (tRNA) molecule transfers each amino acid to the ribosome as it is specified by the coded messages in mRNA.
  • 15. Lesson Overview Fermentation RNA Synthesis How does the cell make RNA?
  • 16. Lesson Overview Fermentation RNA Synthesis How does the cell make RNA? In transcription, segments of DNA serve as templates to produce complementary RNA molecules.
  • 17. Lesson Overview Fermentation Transcription Most of the work of making RNA takes place during transcription. During transcription, segments of DNA serve as templates to produce complementary RNA molecules. The base sequences of the transcribed RNA complement the base sequences of the template DNA.
  • 18. Lesson Overview Fermentation Transcription In prokaryotes, RNA synthesis and protein synthesis take place in the cytoplasm. In eukaryotes, RNA is produced in the cell’s nucleus and then moves to the cytoplasm to play a role in the production of proteins. Our focus will be on transcription in eukaryotic cells.
  • 19. Lesson Overview Fermentation Transcription Transcription requires an enzyme, known as RNA polymerase, that is similar to DNA polymerase.
  • 20. Lesson Overview Fermentation Transcription RNA polymerase binds to DNA during transcription and separates the DNA strands.
  • 21. Lesson Overview Fermentation Transcription RNA polymerase then uses one strand of DNA as a template from which to assemble nucleotides into a complementary strand of RNA.
  • 22. Lesson Overview Fermentation Promoters RNA polymerase binds only to promoters, regions of DNA that have specific base sequences. Promoters are signals in the DNA molecule that show RNA polymerase exactly where to begin making RNA. Similar signals in DNA cause transcription to stop when a new RNA molecule is completed.
  • 23. Lesson Overview Fermentation RNA Editing RNA molecules sometimes require bits and pieces to be cut out of them before they can go into action. The portions that are cut out and discarded are called introns. In eukaryotes, introns are taken out of pre-mRNA molecules while they are still in the nucleus. The remaining pieces, known as exons, are then spliced back together to form the final mRNA.
  • 24. Lesson Overview Fermentation RNA Editing Biologists don’t have a complete answer as to why cells use energy to make a large RNA molecule and then throw parts of that molecule away. Some pre-mRNA molecules may be cut and spliced in different ways in different tissues, making it possible for a single gene to produce several different forms of RNA.
  • 25. Lesson Overview Fermentation RNA Editing Introns and exons may also play a role in evolution, making it possible for very small changes in DNA sequences to have dramatic effects on how genes affect cellular function.