Unit 6.2 Gene Expression & Regulation 2
Page 1: Introduction to Gene Expression
AP Biology Unit 6.2: Covers Gene Expression and Regulation.
Page 2: Topics Overview
Key Sections:
Protein Synthesis: Transcription & Translation
Gene Regulation Overview
Gene Regulation in Bacteria
Gene Regulation in Eukaryotes
Self-Assessment Questions
Page 3: Protein Synthesis Overview
Focus: Understanding transcription and translation processes.
Page 4: Learning Objectives
Goals:
Describe the process of DNA transcription.
Transcribe specific DNA sequences.
Page 5: Flow of Genetic Information
Genes: Sequences of nucleotides in DNA that encode functional products (protein or RNA).
Central Dogma: Directional flow of genetic information from DNA to RNA to Protein (DNA → RNA → Protein).
Page 6: Proteins and Gene Expression
Proteins: Polypeptides composed of amino acids linked by peptide bonds.
Gene Expression: DNA directs protein synthesis through transcription and translation.
Page 7: Details of Transcription and Translation
Transcription: RNA synthesis using DNA information occurs in the nucleus.
Translation: Polypeptide synthesis using mRNA information occurs at ribosomes.
Page 8: Steps in Transcription
Stages:
Initiation
Elongation
Termination
Page 9: Initiation in Transcription
Process Start:
RNA polymerase attaches to the promoter region.
Promoter Location: Upstream of the gene to be transcribed.
Page 10: Eukaryotic vs Prokaryotic Initiation
Eukaryotes:
Promoter includes the TATA box.
Transcription factors assist in binding.
Prokaryotes:
RNA polymerase binds directly to the promoter.
Page 11: Elongation in Transcription
RNA Polymerase: Reads DNA template from 3’ to 5’, synthesizes mRNA from 5’ to 3’.
Small Sections Opened: DNA re-forms double helix after mRNA synthesis.
Page 12: Simultaneous Transcription
Multiple RNA Polymerase Molecules: Can transcribe a single gene simultaneously, increasing mRNA and protein production.
Page 13: Termination in Prokaryotes
Termination Sequence: Signals for RNA polymerase to detach and release mRNA.
mRNA: No modifications needed in prokaryotes.
Page 14: Termination in Eukaryotes
Polyadenylation Signal Sequence: Triggers release of pre-mRNA during transcription; modifications needed afterwards.
Page 15: Pre-mRNA Modifications
Modifications Required:
5’ cap
Poly-A tail
RNA splicing
Page 16: 5’ Cap and Poly-A Tail
5’ Cap: Modified guanine nucleotide added.
Poly-A Tail: 50-250 adenines added at the 3’ end.
Function: Assist mRNA exit from nucleus and protect from degradation.
Page 17: RNA Splicing
Process: Introns are removed and exons joined.
Introns: Non-coding segments.
Exons: Coding segments.
Page 18: Importance of Splicing
Alternative Splicing: One gene can code for multiple polypeptides.
Page 19: Mature mRNA
Post-Modification: Mature mRNA leaves nucleus for translation.
Page 20: Big Picture of Transcription
Overview: Transcription transfers DNA information to mRNA, facilitating protein translation.
Page 21: RNA Polymerase Function
Transcription Process: Catalyzes synthesis of mRNA from DNA.
Page 22: Promoter Domains
Promoter Regions: RNA polymerase binding stalls characterized by the TATA box in eukaryotic organisms.
Page 23: Template Strand Reading
RNA polymerase unwinds DNA and reads the template strand in the 3’ → 5' direction.
Page 24: Termination of Transcription
End Signal: Transcription halts upon reaching a termination sequence.
Page 25: Template and Non-Template Strands
Strands Identified:
Coding Strand: Sense strand matching RNA transcript (T → U).
Noncoding Strand: Template strand for mRNA transcription.
Page 26: mRNA Modification (Eukaryotes)
Primary Transcript: Pre-mRNA modified before translation.
5’ GTP Cap and 3’ Poly-A Tail are important modifications.
Page 27: RNA Splicing in Eukaryotes
Intron Removal: Only exons form the mature mRNA; bacterial mRNA lacks splicing.
Page 28: Genetic Code
Codons: Series of three-nucleotide sequences on mRNA encoding amino acids.
Codon Redundancy: 64 codons specify 20 amino acids.
Universality: Commonality across species indicates life’s shared ancestry.
Page 29: Genetic Code Characteristics
Genetic Code: Nearly universal, highlighting shared biochemical processes.
Genetic Engineering Basis: Understanding codon relationships critical to genetic manipulation.
Page 30: Codon Chart
Illustrative Chart: Shows codon relationships to respective amino acids.
Page 31: Translation Overview
Transition from mRNA to polypeptide synthesis.
Page 32: Translation Mechanics
Key Player: tRNA carries amino acids, linking mRNA codons to protein synthesis.
Page 33: tRNA Functions
tRNA Structure: Anticodon region matches mRNA codons.
Charged tRNA: Amino acids attached by aminoacyl-tRNA synthetase.
Page 34: Ribosome Structure
Ribosomes: Comprise two subunits (prokaryotic vs. eukaryotic) facilitating protein synthesis.
Page 35: Ribosome Sites
Functional Sites: A (amino acid), P (peptide), and E (exit) sites in ribosome.
Page 36: tRNA Interaction Summary
Questions Concerning tRNA and Ribosomes: Address interaction dynamics and roles.
Page 37: Translation Steps Overview
Three stages of translation: Initiation, Elongation, and Termination.
Page 38: Initiation in Translation
Process starts with small ribosomal subunit binding to mRNA start codon (AUG).
Page 39: Elongation Phase
mRNA codons read by ribosome; tRNA brings amino acids sequentially.
Page 40: Elongation Steps Detailed
Three steps during elongation: Codon recognition, peptide bond formation, translocation.
Page 41: Termination of Translation
Completion occurs when a stop codon reaches the ribosome, triggering release of polypeptide.
Page 42: Translation Review Activity
Discussion prompt for peer review of translation stages.
Page 43: Quick Review of Protein Structures
Protein Structures:
Primary: Amino acid chain.
Secondary: Coils and folds.
Tertiary: 3D shape due to side chain interactions.
Quaternary: Assembly of multiple polypeptides.
Page 44: Protein Folding Insights
Folding process influenced by chaperone proteins and gene sequences.
Page 45: Integrated Overview of Processes
Visualization of DNA transcription leading to translation for protein synthesis insights.
Page 46: Retroviruses Information Flow
Unique Flow: RNA to DNA via reverse transcriptase in retroviruses (e.g., HIV).
Page 47: Overview of Translation Key Points
Translation overview including processes occurring in prokaryotic/eukaryotic cells.
Page 48: Translation Initiation Review
Initiation specifics including mRNA and ribosome interactions.
Page 49: Specificity of tRNA Binding
Each tRNA matches specific codons, contributing to amino acid chain formation.
Page 50: Termination in Translation
Process concludes upon reaching stop codon; polypeptide production finalizes.
Page 51: Prokaryotes vs. Eukaryotes Synthesis
Prokaryotes can couple transcription and translation; eukaryotes involve post-transcription modifications.
Page 52: Functional Overview of Synthesis Stages
Synthesis Steps: DNA replication, transcription, RNA processing, and translation.
Page 53: Uncharged tRNA
Uncharged state of tRNA reflects the absence of amino acid attachment.
Page 54: Gene Expression Process Requirement
Requires transcription followed by translation for gene expression.
Page 55: Promoter Deletion Impact Hypothetical
Discussion prompt contemplating implications of mutations on promoter sequences.
Page 56: Transcription in Laboratory Conditions
Classroom scenario regarding transcription initiation requirements in vitro.
Page 57: Sequencing Exercise for Transcription
Illustration of transcription directionality using specified DNA sequences.
Page 58: Pre-mRNA Modifications Exercise
Visualization task regarding final mRNA appearances after modifications.
Page 59: Involvement Identification Exercise
Activity examining involvement of components in transcription or translation.
Page 60 onwards: Self-Assessment Questions
Series of questions designed for self-testing comprehension of gene expression and regulation topics.