Podcast
Questions and Answers
What is the role of transcription factors in the initiation of transcription?
What is the role of transcription factors in the initiation of transcription?
In which direction does RNA polymerase synthesize RNA during elongation?
In which direction does RNA polymerase synthesize RNA during elongation?
What triggers the termination of transcription in eukaryotes?
What triggers the termination of transcription in eukaryotes?
What is the function of the TATA box in eukaryotic transcription?
What is the function of the TATA box in eukaryotic transcription?
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During elongation, which strand of DNA does RNA polymerase walk along?
During elongation, which strand of DNA does RNA polymerase walk along?
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Which statement accurately reflects the Central Dogma of Molecular Biology?
Which statement accurately reflects the Central Dogma of Molecular Biology?
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What is the primary role of mRNA in gene expression?
What is the primary role of mRNA in gene expression?
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In eukaryotic cells, which process occurs after transcription but before translation?
In eukaryotic cells, which process occurs after transcription but before translation?
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Which molecule serves as the primary component of the ribosome during translation?
Which molecule serves as the primary component of the ribosome during translation?
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What distinguishes prokaryotic gene regulation from eukaryotic gene regulation?
What distinguishes prokaryotic gene regulation from eukaryotic gene regulation?
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What is the primary function of transfer RNA (tRNA) in protein synthesis?
What is the primary function of transfer RNA (tRNA) in protein synthesis?
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Which structure is responsible for coupling tRNA anticodons to mRNA codons during translation?
Which structure is responsible for coupling tRNA anticodons to mRNA codons during translation?
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In the process of translation, which end of the tRNA molecule is where the amino acid is attached?
In the process of translation, which end of the tRNA molecule is where the amino acid is attached?
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During transcription, which process converts the DNA sequence into an mRNA sequence?
During transcription, which process converts the DNA sequence into an mRNA sequence?
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What is the sequence of the tRNA anticodon corresponding to the mRNA codon UAC?
What is the sequence of the tRNA anticodon corresponding to the mRNA codon UAC?
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What is the role of introns in eukaryotic DNA?
What is the role of introns in eukaryotic DNA?
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In the process of translation, which molecule is primarily responsible for synthesizing proteins?
In the process of translation, which molecule is primarily responsible for synthesizing proteins?
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How does the redundancy of the genetic code benefit protein synthesis?
How does the redundancy of the genetic code benefit protein synthesis?
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What is the key feature of codons in the mRNA sequence?
What is the key feature of codons in the mRNA sequence?
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During translation, what role does the 'wobble' in codons play?
During translation, what role does the 'wobble' in codons play?
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Which of the following statements accurately describes the transcription process?
Which of the following statements accurately describes the transcription process?
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What is an example of a stop codon in the genetic code?
What is an example of a stop codon in the genetic code?
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How can the genetic code encode for 20 different amino acids using only four nucleotide bases?
How can the genetic code encode for 20 different amino acids using only four nucleotide bases?
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What is the main purpose of adding a 5' cap to pre-mRNA?
What is the main purpose of adding a 5' cap to pre-mRNA?
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Which of the following accurately describes splicing?
Which of the following accurately describes splicing?
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What is the role of the polyA tail in mRNA processing?
What is the role of the polyA tail in mRNA processing?
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Which statement is true about introns?
Which statement is true about introns?
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What is the approximate length of a typical primary mRNA transcript?
What is the approximate length of a typical primary mRNA transcript?
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Which component is NOT involved in splicing?
Which component is NOT involved in splicing?
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In which cellular location does mRNA processing primarily occur?
In which cellular location does mRNA processing primarily occur?
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How many A nucleotides are typically found in a polyA tail?
How many A nucleotides are typically found in a polyA tail?
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Which of the following best defines exons?
Which of the following best defines exons?
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What process follows post-transcriptional modifications of mRNA?
What process follows post-transcriptional modifications of mRNA?
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What role does the A site in a ribosome play during polypeptide synthesis?
What role does the A site in a ribosome play during polypeptide synthesis?
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During which phase of protein synthesis does the mRNA and ribosome subunits come together?
During which phase of protein synthesis does the mRNA and ribosome subunits come together?
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What occurs in the E site of the ribosome?
What occurs in the E site of the ribosome?
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How does elongation in protein synthesis primarily occur?
How does elongation in protein synthesis primarily occur?
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Which of the following describes the termination process in protein synthesis?
Which of the following describes the termination process in protein synthesis?
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What is the function of ribosomal RNA (rRNA) in ribosomes?
What is the function of ribosomal RNA (rRNA) in ribosomes?
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What is the function of the initiator tRNA during the initiation stage?
What is the function of the initiator tRNA during the initiation stage?
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Which sequence correctly represents the order of amino acids added during elongation?
Which sequence correctly represents the order of amino acids added during elongation?
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Study Notes
Course Information
- Course Title: The Human Body PJ1311
- Lecturer: Dr Lamia Kandil
- Lecturer Credentials: Lecturer of Pharmacy Practice, PhD, FHEA, MB138
- Contact Email: [email protected]
Kandil Lectures
- Three lectures on Genomics, Central Dogma of Life (Transcription, Translation), and Cell cycle and control mechanism will be covered.
Learning Outcomes
- Understand the Central Dogma of Molecular Biology
- Differentiate Between Key Processes: Transcription and Translation
- Identify the Role of mRNA, tRNA, and rRNA
- Post-transcription and Post-Translational modifications
- Gene regulation in Prokaryotes and Eukaryotes and its importance
- Application of knowledge through four different activities
The "Central Dogma"
- Flow of genetic information in a cell
- Movement of information from DNA to proteins.
- DNA → RNA→ Protein → Trait
- DNA gets all the glory; proteins do all the work!
From Gene to Protein
- Overview of the process.
- Transcription takes place in the nucleus.
- mRNA moves from nucleus to cytoplasm
- Translation occurs in the cytoplasm, involving ribosomes, tRNA, and amino acids
- Gene expression results from the process.
Gene Expression
- The process by which information encoded in genes is used to create functional products.
Transcription in Eukaryotes
- DNA cannot leave the nucleus
- Transcription steps
- RNA processing is required for mature mRNA production
The Process of Building mRNA
- Initiation: Assembly of initiation complex
- Elongation: Adding nucleotides
- Termination: Signals to stop transcription
Transcription in Eukaryotes
- Initiation complex binds to the promoter region, upstream of the gene.
- Proteins bind to DNA to turn on/off transcription.
- TATA box binding site is crucial
- Transcription factors trigger RNA polymerase binding to DNA .
Elongation
- RNA polymerase 2 "walks" along the template strand (3' to 5')
- RNA polymer is complementary to the template DNA and is synthesized in a 5' → 3' orientation.
- Matching RNA nucleotides are added to the 3' end of the RNA strand
Termination
- RNA polymerase continues until termination signals are received
- Polyadenylation is a process that includes adding a poly-A tail (AAUAAA) to the 3′ end of the pre-mRNA.
- Signals the termination of transcription.
Post-Transcriptional Processing
- Eukaryotic mRNA needs processing
- Protect mRNA from enzymes in cytoplasm by adding a 5' cap.
- mRNA splicing: Editing out introns
- Adding a poly-A tail
Post-Transcriptional modifications
- Primary RNA is modified to produce a mature messenger RNA or mRNA
Processes Involved
- Splicing: removal of introns from pre-mRNA
- Capping: addition of a cap molecule to the 5' end of mRNA
- Tailing: addition of a poly A tail to the 3′ end
- RNA transport: Transport of mature mRNA from the nucleus into the cytoplasm
- Protein Transport:
Splicing must be accurate
- Precise splicing procedures are crucial.
- A change in the reading frame (single base addition/loss) results in errors and wrong protein synthesis.
Activity: Comparing Transcription in Prokaryotes and Eukaryotes
- Objective: Identify the differences between transcription in prokaryotes and eukaryotes.
Prokaryote vs. Eukaryote genes
- Prokaryotes: circular chromosomes, DNA in cytoplasm, naked DNA, no introns
- Eukaryotes: linear chromosomes, DNA in nucleus, DNA wound on histone proteins, introns
Prokaryotes vs. Eukaryotes
- Prokaryotes: transcription and translation happen in cytoplasm, RNA polymerase directly binds to promoter, no mRNA processing
- Eukaryotes: transcription in nucleus, translation in cytoplasm, DNA in nucleus, mRNA travels, RNA polymerase uses transcription factors, pre-mRNA processed to mRNA, introns removed.
Translation
- Nucleic acid language converted to amino acid language
- Codons: Three nucleotides that code for amino acids
mRNA codes for proteins in triplets
- Three nucleotides form codons
- Codons are specific for amino acids
The code
- Code is redundant: several codons for each amino acid
- Third base "wobble" good reason
How are the codons matched to amino acids?
- tRNA matches mRNA codons to amino acids.
- tRNA has an anticodon that is complementary to the codon.
From gene to protein
- Transcription produces mRNA transcribed from DNA
- mRNA leaves nucleus, moves to cytoplasm
- Ribosomes translate mRNA into proteins, aided by tRNA
Transfer RNA structure
- Clover leaf structure
- Anticodon at one end
- Amino acid attachment site at the other end
Ribosomes
- Facilitate coupling of tRNA anticodon to mRNA codon.
- Organelle or enzyme?
- Structure: ribosomal RNA (rRNA) and proteins, large and small subunits, A site, P site, E site
Sites of Ribosome
- These sites aid in tRNA binding
- P site: peptidyl-tRNA site; holds tRNA with growing polypeptide chain
- A site: aminoacyl-tRNA site; holds tRNA carrying the next amino acid
- E site: exit site; empty tRNA leaves the ribosome
Building a polypeptide
- Initiation: Bringing together mRNA, ribosome subunits, initiator tRNA
- Elongation: Adding amino acids based on codon sequence
- Termination: end codon
Activity: Transcription vs Translation
- Objective: To identify the key protein differences between transcription and translation
Post-translational modifications (PTMs)
- Amino acid side-chain modifications
- Affects many aspects of protein functions.
- Affects enzyme function, assembly, protein lifespan, interactions, trafficking, receptor activation
Regulation of Gene Expression
- Control the timing, location and amount of gene expression
- Carried out by regulatory proteins and chemical modifications of DNA
- Crucial for organism responses.
Gene Regulation in Prokaryotes
- Proteins for a specific function are encoded in blocks (operons).
- Activators (increase expression), repressors (suppress expression), inducers (inactivate repressors) are regulatory proteins.
Eukaryotic Gene Regulation
- More complex and can happen at many levels, including : epigenetic, transcriptional, post-transcriptional, translational, and post-translational. Genes are not organized into operons.
Importance of regulation of Gene Expression
- Organisms adapt to environmental challenges through altering gene expression patterns.
- Gene regulation is affected by hormones, heavy metals, and chemicals
- Transcription control results in tissue-specific gene expression
- Dysregulation leads to diseases..
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Description
Test your knowledge on the processes of transcription and translation in molecular biology. This quiz covers transcription factors, RNA polymerase, mRNA functions, and the differences between prokaryotic and eukaryotic gene regulation. Challenge yourself and deepen your understanding of these essential biological processes.
