YIJC [H2] CI2.11_Genetics of Bacteria (N)(Student)

2024 JC1 BIOLOGY LECTURE NOTES 1 CORE IDEA 2: GENETICS AND INHERITANCE TOPIC 2.11: GENETICS OF BACTERIA Learning Outcomes: Core Idea 1 [Recap – Lecture notes CI 1.1 Organelles and Cellular Structures] (d) describe the structure of a typical bacterial cell (small and unicellular, peptidoglycan cell wall, circular DNA, 70S ribosomes and lack of membrane-bound organelles) Core Idea 2: (d) [modified] describe the structure and organisation of prokaryotic genomes (including DNA/RNA, single-/double-stranded, number of nucleotides, packing of DNA, linearity/circularity and presence/absence of introns) (g) outline the mechanism of asexual reproduction by binary fission in a typical prokaryote and describe how transformation, transduction and conjugation (including the role of F plasmids but not Hfr) give rise to variation in prokaryotic genomes (i) explain how gene expression in prokaryotes can be regulated, through the concept of simple operons (including lac and trp operons), including the role of regulatory genes, and distinguish between inducible and repressible systems (knowledge of attenuation of the trp operon is not required) Use the knowledge gained in this section in new situations or to solve related problems. Textbooks and References Campbell, Urry, Cain, Wasserman, Minorsky, Reece (2018) Biology – A Global Approach (11 th Edition) (Global Edition) Chapter 27: Prokaryotes pg. 625 – 633, Chapter 18: Control of Gene Expression pg. 413 - 417 (Pearson Publication) ISBN-10 1-292-17043-3 Note: This textbook is available in our library. You may wish to borrow them to supplement your reading when necessary. H2

2 Contents 1. Bacterial Cell Structure 2. Bacteria Genome 2.1 Bacterial Chromosome 2.2 Bacterial Plasmid 3. Bacteria Reproduction via Binary Fission 3.1 Process of Binary Fission 4. Genetic Variation in Bacteria 4.1 Mutation 4.2 Genetic Transfer between Bacteria 5. Regulation of Gene Expression in prokaryotes 5.1 The Operon Model 5.2 Repressible operon (e.g. trp operon) 5.3 Inducible operon (e.g. lac operon) 5.4 Comparing Inducible and Repressible System

3 1. Bacteria Cell Structure Learning Outcome 1(d) Describe the typical structure of a bacterial cell (small and unicellular, peptidoglycan cell wall, circular DNA, 70S ribosomes and lack of membrane-bound organelles) • Bacteria (singular: bacterium) are small, unicellular prokaryotes. • They lack a true nucleus and membrane -bound organelles (e.g. rER , Golgi apparatus, mitochondrion, chloroplast). • They possess one circular double-stranded DNA in the nucleoid region and 70S ribosomes in the cytoplasm. Structure Function 1. Nucleoid Non-membrane bound. A region of cytoplasm where the bacterial chromosome is found. Appears lighter than the surrounding cytoplasm in electron micrographs. Contains one double -stranded, circular DNA molecule. Pr