(L8) DNA Transcription to Translation (4)
Page 1: Introduction to Biological Sciences
University of Central Lancashire (UCLan) Course FZC021
Instructor: Wesley Ward (email: wward4@uclan.ac.uk)
Theme: Where opportunity creates success
Page 2: Learning Outcomes
Fundamental knowledge of cellular organelles involved in protein synthesis.
Comprehensive understanding of genes and genetic coding.
Thorough understanding of transcription and translation processes.
Basic understanding of genetic regulatory mechanisms.
Foundational knowledge of genetic mutations.
Page 3: Associated Organelles Overview
Highlights eukaryotic cell structure, focusing on organelles involved in DNA transcription and translation.
Page 4: Figure 7.8 - Eukaryotic Cells
Depicts a cutaway view of a generalized animal cell.
Reference: Campbell, Neil, et al. Biology: a Global Approach, Global Edition.
Page 5: Associated Organelles - Nucleus
Constituents:
Nuclear Envelope: Protection and compartmentalization; selective transport.
Nucleolus: Dense fibers and granules near chromatin; synthesizes ribosomal components.
Chromatin: DNA packaging, repair, and gene control.
Histones: Basic proteins that assist DNA coiling and form nucleosomes.
Functions: Stores genetic information in chromosomes.
Page 6: Structure of the Nucleus
Diameter: ~5µm.
Nuclear Envelope: Lipid bilayer with pores, maintains shape via nuclear lamina.
Staining: Uses H & E stain to visualize nucleic acids and proteins.
Page 7: Associated Organelles - Ribosomes
Structure: Small subunit (40S) & Large subunit (60S).
Sites:
A site: Binds incoming tRNA.
P site: Holds tRNA with growing polypeptide chain.
E site: Holds tRNA about to exit.
Ribosomes are located on the rough endoplasmic reticulum, with a complete size of 80S (Svedberg units).
Page 8: Associated Organelles - Golgi Apparatus
Composed of stacked, membrane-bound cisternae.
Functions:
Processes and sorts proteins from the ER for transport.
Synthesizes glycolipids and sphingomyelin.
Polarity: Distinct entry (cis) and exit (trans) faces.
Page 9: Genetic Code Introduction
Focus on the significance of the genetic code in protein synthesis.
Page 10: Genetic Code Constituents
Roles of RNA:
tRNA: Carries amino acids.
rRNA: Forms ribosomes.
mRNA: Transmits genetic information from nucleus to ribosomes.
Page 11: Genetic Code Composition
Bases: Purines (A, G) and Pyrimidines (T, C).
Base pairing rules: A-T (U) and C-G.
Percentage calculations based on base pairing for understanding ratios in DNA.
Page 12: Genetic Code - Codons
Use of triplet codons allows specification of 64 amino acids despite there being only 20.
Redundancy and universality of the genetic code across organisms.
Page 13: Summary of Amino Acids
Lists amino acids with abbreviations, properties, and chemical formulas.
Page 14: Codon Table
Provides a codon table demonstrating first, second, and third bases with corresponding amino acids.
Discusses stop codons and the reason for their number.
Page 15: Reading Frames
Emphasizes importance of correct codon grouping.
Example of reading frames illustrated through a sentence analogy.
Page 16: Genetic Code - Genes
Genes consist of nucleotide sequences transcribed to functional RNA or coding for proteins.
Introns vs. Exons: Non-coding regions are removed post-transcription.
Page 17: Transition to Transcription
Overview of the transcription process.
Page 18: Transcription Process
Involves RNA polymerase, which separates DNA strands to form RNA.
Stages: Initiation, elongation, termination.
Page 19: Transcription - Initiation
RNA polymerase binds to the promoter region and unwinds the DNA.
Page 20: Transcription - Elongation
Moves to elongate the RNA strand by unwinding DNA and adding nucleotides according to base pairing rules.
Page 21: Transcription - Termination
Terminated when RNA polymerase reaches a stop codon, releasing mRNA.
Page 22: RNA Processing Introduction
Newly formed mRNA undergoes processing before leaving the nucleus.
Page 23: RNA Processing Steps
Involves splicing of introns, adding a 5' cap, and a poly-A tail to the 3' end for stability.
Page 24: Transition to Translation
Introduction to the translation process.
Page 25: Translation - Initiation
Begins with start codon AUG, aligning ribosomal subunits.
Page 26: Translation - Elongation
Describes peptide bond formation between amino acids via tRNA binding to ribosomes.
Page 27: Translation Continuation
Cycle of translocation and tRNA recycling in protein synthesis.
Page 28: Visual Diagram
Diagram illustrating codon recognition and translation processes.
Page 29: Translation - Termination
Occurs when a stop codon is reached; involves release of the completed polypeptide.
Page 30: General Overview of Translation
Recaps translation process and significance in protein synthesis.
Page 31: Polyribosomes
Explains simultaneous translation by multiple ribosomes on a single mRNA.
Page 32: Transition to Post-Translation
Overview of post-translation processes.
Page 33: Post-Translation Modifications
Describes protein folding and modifications such as cleavage, glycosylation, etc.
Page 34: Transition to Genetic Control
Introduction to gene function regulation.
Page 35: Mechanisms of Genetic Control
Role of promoters, repressors, and activators in transcription regulation.
Page 36: Codons in Genetic Control
Details on start and stop codons and their functions in translation.
Page 37: Promoters in Genetic Control
Function as binding sites for RNA polymerase, acting as "on-switches" for genes.
Page 38: Repressor Functionality
Binding of repressor proteins to operators inhibits transcription.
Page 39: Activators in Transcription
Activator proteins enhance transcription by recruiting the transcription machinery.
Page 40: Summary of Activators
Visual representation of how activators interact with DNA and transcription machinery.
Page 41: Epigenetics Overview
Discusses heritable changes in gene function independent of DNA sequence alterations.
Page 42: Transition to Mutations
Introduction to mutations in genetics.
Page 43: Overview of Mutations
Describes types of mutations and their potential effects on organisms.
Page 44: Point Mutations
Different types: substitution (silent, neutral, missense, nonsense) and their impacts on proteins.
Page 45: Mechanism of Point Mutations
Describes how point mutations are introduced during DNA replication.
Page 46: Silent Mutations
Changes in the DNA sequence that do not affect the amino acid sequence due to redundancy.
Page 47: Neutral Mutations
Alters mRNA sequences but results in similar amino acids, maintaining functionality.
Page 48: Missense Mutations
Affects protein function by coding for a different amino acid.
Page 49: Nonsense Mutations
Introduces stop codons resulting in truncated proteins.
Page 50: Frameshift Mutations
Caused by insertions or deletions, disrupting reading frames and protein function.
Page 51: Effects of Insertion & Deletion
Changes mRNA reading frame and may lead to shorter or longer non-functional proteins.
Page 52: Chromosome Mutations Overview
Discusses large-scale mutations: deletion, inversion, translocation, duplication.
Page 53: Chromosome Mutation Examples
Specific syndromes caused by chromosomal mutations, e.g., cri-du-chat syndrome.
Page 54: Causes of Mutations
Spontaneous errors vs. mutagens such as chemicals and radiation.
Page 55: Summary of Key Concepts
Organelles, genetic code characteristics, transcription stages, and translation significance.
Page 56: Suggested Further Reading
Essential Cell Biology, Biochemistry, and Principles of Biochemistry for in-depth understanding.