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Questions and Answers
The Central Dogma states that DNA is used to make ______ is used to make Protein.
The Central Dogma states that DNA is used to make ______ is used to make Protein.
RNA
A ______ region acts as the template for the transcribed RNA, located downstream of the transcription start site.
A ______ region acts as the template for the transcribed RNA, located downstream of the transcription start site.
transcribed
The transcription start site is denoted as '+1' corresponding to the first ______ at the 5' end of the RNA product.
The transcription start site is denoted as '+1' corresponding to the first ______ at the 5' end of the RNA product.
nucleotide
Prokaryotes depend largely on ______ regulation, using repressor proteins to control gene expression.
Prokaryotes depend largely on ______ regulation, using repressor proteins to control gene expression.
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Eukaryotes depend on ______ regulation of gene expression, but also regulate gene expression with transcription factors.
Eukaryotes depend on ______ regulation of gene expression, but also regulate gene expression with transcription factors.
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Basal transcription factors bind to the ______ to recruit RNA polymerase.
Basal transcription factors bind to the ______ to recruit RNA polymerase.
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Regulatory transcription factors including both activators and ______ can bind to proximal control elements upstream of the promoter.
Regulatory transcription factors including both activators and ______ can bind to proximal control elements upstream of the promoter.
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Position-independent elements called ______ greatly increase transcription when bound by transcriptional activators.
Position-independent elements called ______ greatly increase transcription when bound by transcriptional activators.
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The ______ domain is located upstream of the transcription start site.
The ______ domain is located upstream of the transcription start site.
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The base positions denoted by negative numbers are located ______ of the transcription start site.
The base positions denoted by negative numbers are located ______ of the transcription start site.
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For transcription, one strand of DNA acts as a template for the production of an RNA strand by the enzyme ______ polymerase.
For transcription, one strand of DNA acts as a template for the production of an RNA strand by the enzyme ______ polymerase.
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The process of transcription occurs in stages: ______ - RNA polymerase interacts with the promoter at the TATA box to establish a transcription complex.
The process of transcription occurs in stages: ______ - RNA polymerase interacts with the promoter at the TATA box to establish a transcription complex.
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Transcription in eukaryotes makes ______-mRNA that must be processed to mature mRNA for translation.
Transcription in eukaryotes makes ______-mRNA that must be processed to mature mRNA for translation.
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A ______ cap and a 3' polyA tail both protect the mRNA, aid in export of mature mRNA to the cytoplasm, and improve translation efficiency by the ribosome.
A ______ cap and a 3' polyA tail both protect the mRNA, aid in export of mature mRNA to the cytoplasm, and improve translation efficiency by the ribosome.
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Splicing removes ______, which are extra nucleotides in the transcribed region of genes, and ligates together exons to make a mature mRNA with a correct protein coding sequence.
Splicing removes ______, which are extra nucleotides in the transcribed region of genes, and ligates together exons to make a mature mRNA with a correct protein coding sequence.
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MRNA has a protein coding sequence using ______ which are translated using tRNA.
MRNA has a protein coding sequence using ______ which are translated using tRNA.
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Translation occurs in the ______, a large multi-protein complex that interacts with mRNA and enzymatically assembles polypeptides.
Translation occurs in the ______, a large multi-protein complex that interacts with mRNA and enzymatically assembles polypeptides.
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During ______, a charged tRNA enters the A-site.
During ______, a charged tRNA enters the A-site.
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The ______ tRNA exits at the E site and the process repeats until a stop codon lines up with the A-site and binds to a release factor, halting translation.
The ______ tRNA exits at the E site and the process repeats until a stop codon lines up with the A-site and binds to a release factor, halting translation.
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Translate an mRNA using a ______ table, starting at the first 5' AUG.
Translate an mRNA using a ______ table, starting at the first 5' AUG.
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Study Notes
Transcription
- One strand of DNA acts as a template for the production of an RNA strand by the enzyme RNA polymerase.
- RNA polymerase unwinds DNA locally and assembles complementary RNA nucleotides along the DNA template strand, linking them with phosphodiester bonds into a polynucleotide.
- RNA polymerase can only add to the 3’-end of the growing polymer.
- Unlike DNA polymerases, RNA polymerases do not need a primer.
Stages of Transcription
- Initiation: RNA polymerase interacts with the promoter at the TATA box to establish a transcription complex.
- Elongation: the RNA polymerase extends the new RNA by adding to the 3' end.
- Termination: a sequence in the DNA (terminator) halts transcription.
Transcription in Eukaryotes
- Transcription in eukaryotes makes "pre-mRNA" that must be processed to mature mRNA for translation.
- A 5’ cap, a 3’ polyA tail, and splicing are all required for maturation.
- Once these processes are complete, the mRNA can be exported to the cytoplasm.
mRNA Processing
- The 5' cap and 3' polyA tail both protect the mRNA, aid in export of mature mRNA to the cytoplasm, and improve translation efficiency by the ribosome.
- Splicing removes introns, which are extra nucleotides in the transcribed region of genes, and ligates together exons to make a mature mRNA with a correct protein coding sequence.
Translation
- mRNA has a protein coding sequence using codons which are translated using tRNA.
- There is a different tRNA and associated enzyme for each of the 20 amino acids.
- A tRNA hydrogen bonds with the proper codon on mRNA through its anti-codon using strict base pairing.
- Codons represent a degenerate code, with more than one codon representing the same amino acid.
Stages of Translation
- Initiation: the small ribosomal subunit binds to mRNA near the 5'-end.
- Elongation: a charged tRNA enters the A-site, and ribosomal enzymes cut the growing polypeptide free from the P-site tRNA, and attach it to the new amino acid on the tRNA in the A-site with a peptide bond.
- Termination: a stop codon lines up with the A-site and binds to a release factor, halting translation.
Gene Structure
- The information encoding proteins is organized as genes on DNA, and all genes have the same basic structure.
- A transcription start site denoted as "+1" corresponding to the first nucleotide at the 5' end of the RNA product.
- A transcribed region that acts as the template for the transcribed RNA, located "downstream" of the transcription start site.
- A regulatory domain called a promoter located "upstream" of the transcription start site.
Regulation of Gene Expression
- Prokaryotes depend largely on negative regulation, using repressor proteins to control gene expression.
- Eukaryotes depend on positive regulation of gene expression, but also regulate gene expression with transcription factors acting as activators or repressors of RNA polymerase activity.
- Basal transcription factors bind to the promoter to recruit RNA polymerase, with their presence or absence acting as an on/off switch for transcription.
- Regulatory transcription factors including both activators and repressors can bind to proximal control elements upstream of the promoter, modifying transcription at different times, or in different cells.
- Position-independent elements called enhancers greatly increase transcription when bound by transcriptional activators.
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