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Microbial Genetics - Coggle Diagram
Microbial Genetics
History
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Pre-1940s: Scientists knew were hereditary factors, but not sure from where. Proteins seemed likelier than DNA
Avery, MacLeod & McCarty (1944): Discovered purified DNA could tranform harmless strains to virulent
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Watson & Crick (1953): Used Franklins data and Chargaff's ratios, proposed right‑handed antiparallel double helix (sugar phosphate backbone, complementary base pairs). Received 1962 Nobel Prize
DNA Replication
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4) lagging strand synthesized discontinuously, primase synthesizes short RNA primer, extended by DNA polymerase, forms Okazaki fragment
5) RNA primer replaced by DNA, DNA ligase joins okazaki fragment onto growing strand
Mutation
Spontaneous: absense of mutation causing agent, errors in DNA replication. Mutagens: Agents that cause mutation. Chemical, radiation, UV light
Base substitution/point mutation: Missense (substitutoin of different a.a, Sickle Cell Anemia). Nonsense (base substitution, stop codon in middle of mRNA)
Framsshift: 1+ nucleotide pairs deletered/inserted in DNA, results in shift of translationional reading frame and inactive protein production, Huntington's disease
Silent: base code changes, but a.a is the same, CUU mutates to CUG = no change in protein. Can be harmful and removed when cell dies, can be beneficial and introduce new trail to enhance survival.
Origin of Replication
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Specific DNA sequence where DNA replication is initiated, marking the starting point for DNA duplication
P: single origin of replication per chromosome. E: multiple origins to facilitate replication of larger genomes
Genes/Genetic Info
Genes: Units of hereditary, determine traits, DNA sequences carry info for proteins
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Genetic info flows within cell, produces protein to grow and survive (gene expression). Central dogma universal to ALL living cells
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DNA vs. RNA
DNA
Carries genetic info, made of sequences of nucleotides, organized into chromosomes
Chromosomes: Structures within cells that contain DNA (humans = 23 pairs, bacteria = 1 pair)
Chargaff's Rule: A=T, C=G
RNA
Several forms (mRNA, tRNA, rRNA). Regulatory purposes
Single-stranded, uracil instead of thymine
Genes
Units of hereditary, determine traits, DNA sequences carry info for proteins
Bacteria more gene dense, more areas code for genes
Nucleotides
A sugar (DNA = deoxyribose, RNA = ribose)
Nitrogenous base (DNA = adenine, thymine, cytosine, RNA = guanine, uracil)
Gene transfer
Horizontal: Bacteria increase diversity. Transformation (Acquisition of DNA from environment). Transduction (Involves a virus). Conjugation (2 different strains of bacteria, donor and recipient)
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