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Questions and Answers
What is the expected length of the mRNA product after transcription of the 10 kb DNA segment?
What is the expected length of the mRNA product after transcription of the 10 kb DNA segment?
Which of the following statements about the bacterial chromosome is true?
Which of the following statements about the bacterial chromosome is true?
What would you expect to see on the DNA gel after transcription?
What would you expect to see on the DNA gel after transcription?
Which of the following best describes the relationship between the DNA and mRNA in this experiment?
Which of the following best describes the relationship between the DNA and mRNA in this experiment?
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Which gel would likely show a band at 1.5 kb?
Which gel would likely show a band at 1.5 kb?
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If the transcription efficiency were to decrease, what would it likely affect?
If the transcription efficiency were to decrease, what would it likely affect?
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What does a band appearing at 1.5 kb on the mRNA gel indicate?
What does a band appearing at 1.5 kb on the mRNA gel indicate?
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Which of the following provides insight into the gene's coding potential?
Which of the following provides insight into the gene's coding potential?
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In which direction does RNA polymerase read the DNA template strand during transcription?
In which direction does RNA polymerase read the DNA template strand during transcription?
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What is the role of the promoter in gene transcription?
What is the role of the promoter in gene transcription?
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Which statement best captures the nature of the strands in the DNA double helix?
Which statement best captures the nature of the strands in the DNA double helix?
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For Gene A, which strand will be used as the template for transcription?
For Gene A, which strand will be used as the template for transcription?
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What is the significance of the polyA signal in the gene representation?
What is the significance of the polyA signal in the gene representation?
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What is the primary function of exons in a gene?
What is the primary function of exons in a gene?
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Which of the following describes the function of introns during transcription?
Which of the following describes the function of introns during transcription?
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Which of the following is true about the transcribed regions of Gene A and Gene B?
Which of the following is true about the transcribed regions of Gene A and Gene B?
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What is the primary function of a promoter in the transcription process?
What is the primary function of a promoter in the transcription process?
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Which statement accurately describes the role of terminators in transcription?
Which statement accurately describes the role of terminators in transcription?
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In eukaryotic cells, what modifications occur to mRNA after transcription?
In eukaryotic cells, what modifications occur to mRNA after transcription?
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How do prokaryotic and eukaryotic transcription differ?
How do prokaryotic and eukaryotic transcription differ?
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What is the role of the spliceosome in eukaryotic transcription?
What is the role of the spliceosome in eukaryotic transcription?
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What is typically found at the +1 position in a eukaryotic gene?
What is typically found at the +1 position in a eukaryotic gene?
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What impact do transcription factors have on gene expression?
What impact do transcription factors have on gene expression?
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When comparing genetic information organization in prokaryotes and eukaryotes, which of the following is true?
When comparing genetic information organization in prokaryotes and eukaryotes, which of the following is true?
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What does hnRNA represent in the context of RNA processing?
What does hnRNA represent in the context of RNA processing?
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Which of the following statements accurately describes mRNA?
Which of the following statements accurately describes mRNA?
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What might be indicated if a scientist observes a high frequency of shorter RNA sizes in a sample?
What might be indicated if a scientist observes a high frequency of shorter RNA sizes in a sample?
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What is the significance of the size distribution of RNA molecules in the study of mRNA processing?
What is the significance of the size distribution of RNA molecules in the study of mRNA processing?
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How are mRNAs that are attached to ribosomes identified in a sample?
How are mRNAs that are attached to ribosomes identified in a sample?
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What could explain the presence of various RNA sizes in a sample from a population of cells?
What could explain the presence of various RNA sizes in a sample from a population of cells?
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Which of the following conclusions can be drawn from analyzing the size distribution of RNA molecules?
Which of the following conclusions can be drawn from analyzing the size distribution of RNA molecules?
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Why is it important to study both hnRNA and mRNA in RNA processing?
Why is it important to study both hnRNA and mRNA in RNA processing?
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What is the main goal of changing each nucleotide in the promoter region?
What is the main goal of changing each nucleotide in the promoter region?
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In the car analogy, what does changing one component at a time demonstrate?
In the car analogy, what does changing one component at a time demonstrate?
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What is indicated by measuring transcription levels after nucleotide changes?
What is indicated by measuring transcription levels after nucleotide changes?
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Which nucleotide change could most likely lead to a significant decrease in gene transcription?
Which nucleotide change could most likely lead to a significant decrease in gene transcription?
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What effect does changing multiple components in the car analogy likely illustrate?
What effect does changing multiple components in the car analogy likely illustrate?
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Why is it necessary to change one nucleotide at a time in the experiment?
Why is it necessary to change one nucleotide at a time in the experiment?
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What characteristic of the transcribing process is being tested by modifying the nucleotide sequence?
What characteristic of the transcribing process is being tested by modifying the nucleotide sequence?
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What is the purpose of the various car components in relation to the transcription experiment?
What is the purpose of the various car components in relation to the transcription experiment?
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What is the primary difference between hnRNA and mRNA?
What is the primary difference between hnRNA and mRNA?
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Based on the experiment, which of the following conclusions is correct regarding the lengths of hnRNA and mRNA?
Based on the experiment, which of the following conclusions is correct regarding the lengths of hnRNA and mRNA?
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What role does mRNA play in the cell?
What role does mRNA play in the cell?
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What is often true about heterogeneous nuclear RNA (hnRNA)?
What is often true about heterogeneous nuclear RNA (hnRNA)?
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In the context of RNA processing, which of the following statements is accurate?
In the context of RNA processing, which of the following statements is accurate?
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Why is it important to analyze the size distribution of RNA molecules in samples?
Why is it important to analyze the size distribution of RNA molecules in samples?
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What does a higher proportion of larger RNA molecules in a sample indicate about hnRNA?
What does a higher proportion of larger RNA molecules in a sample indicate about hnRNA?
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Which statement accurately reflects the relationship between hnRNA and mRNA in terms of genetic information?
Which statement accurately reflects the relationship between hnRNA and mRNA in terms of genetic information?
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Study Notes
Nucleic Acid Structure
- Nucleic acids carry genetic information
- DNA (deoxyribonucleic acid) carries instructions for protein creation
- DNA is a polymer of nucleotides
- Nucleotides consist of a sugar, phosphate, and base
- Bases:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
- DNA strands are held together by hydrogen bonds between bases
Central Dogma of Molecular Biology
- DNA → RNA → Protein
- DNA is the cookbook library
- RNA is a copy of a recipe
- Protein is the cooked dish
- Transcription: DNA to RNA
- Translation: RNA to protein
The Cell
- Cells need mechanisms to regulate their internal environment (homeostasis)
- Cells need mechanisms to acquire, transform, and use energy
- Cells need information storage and transfer
Gel Electrophoresis
- Separates nucleic acid fragments by size
- DNA moves to the positive end of the gel
- Longer molecules move slower, shorter molecules faster
Denaturation/Renaturation of DNA
- Heating separates DNA strands
- Hydrogen bonds break first
- Cooling re-anneals DNA strands
- Special conditions required
- Complementary bases rejoin
DNA Melting Temperature
- Tm (melting temperature) is related to the G+C content
- Higher G+C content = higher Tm
- Sequences with more G-C bonds have higher melting temperature
Hybridization of Nucleic Acids
- Nucleic acids hybridize if they are complementary and antiparallel
- A 5' end of a sequence with the 3' end of a complimentary sequence can hybridize
- 5' - ATCG - 3' and 3' - TAGC - 5' are complementary and can hybridize
Three DNA Samples
- Gel electrophoresis separates DNA samples by size.
- 8 kb, 5 kb, 250 bp, 750 bp, 3 kb, 4 kb are sample sizes
- Samples are loaded in one lane which creates a mixture.
Transcription in Prokaryotes and Eukaryotes
- Transcription is the process of creating mRNA from a DNA template
- Prokaryotes have different structures than eukaryotes.
- Eukaryotic mRNA is processed in stages in the nucleus.
- Prokaryotes do not have a nucleus, and do not have a poly-A tail
- Eukaryotes do have a nucleus and have a poly-A tail
- Prokaryotes have a single mRNA and different enzymes. Eukaryotes have multiple enzymes and a polyA tail
- In prokaryotes, transcription and translation occur simultaneously.
Transcriptional Units
- Eukaryotic transcriptional units are called genes
- Genes can be coded on either strand of DNA
- Promoter region is essential for transcription in eukaryotic cells
RNA Polymerase
- The enzyme that catalyzes the synthesis of RNA from a DNA template
- Reads the DNA template strand in the 3' to 5' direction
- Adds nucleotides in the 5' to 3' direction on the growing RNA transcript
Transcription Termination
- Different in prokaryotes and eukaryotes
- Prokaryotes have Rho-dependent and Rho-independent mechanisms.
- Polyadenylation signal is where the eukaryotic RNA polymerase will stop.
mRNA Processing
- The process where primary mRNA is converted into mature mRNA
- Intron removal (splicing)
- mRNA modifications are added (5' cap and 3' poly(A) tail).
- This modification allows mRNA to exit the nucleus
Splicing
- Introns are removed from the pre-mRNA to form mature mRNA
- The spliceosome is the structure that aids in this process
Gene Mutations
- Mutations in splice sites can cause abnormal splicing, leading to incorrect mRNA being formed
- The resulting mRNA might have a different size from the template, and will not have an expected product.
Eukaryotic Gene Structure
- Eukaryotic genes contain introns and exons.
- Introns are non-coding regions that are removed during splicing.
- Exons are coding regions that are joined together to form the mature mRNA.
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Description
Explore the fundamental concepts of nucleic acids, including DNA and RNA, their role in genetic information, and the processes of transcription and translation. Understand the methods like gel electrophoresis used to analyze nucleic acids and comprehend cellular mechanisms for maintaining homeostasis and energy use.
