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Microbial Genetics - Coggle Diagram
Microbial Genetics
Flow of Genetic Info.
DNA>RNA>Proteins
Replication
Origin: Prok (single) Euk (multi)
Copying DNA
Anabolic, 2ATP/nucleotide
Initiation
: Helicase unwinds, Single-strang binding proteins stabalize, Primase adds RNA primers
Elongation
: DNA polymerase adds compl nucleotides in the 5 > 3 direction, Leading strand continuous synthesis, Lagging strand is synthesized in short Okazaki fragments joined by DNA ligase
Termination
:Occurs when replication forks meet, results in 2 identical DNA molecules
Transcription
Termination
: RNA polym. reaches terminator sequence, releasing the mRNA
Synt. of RNA from a DNA template. DNA --> mRNA
Initiation
:RNA polymerase binds to promoter region
Elongation
: RNA polym. adds compl. nucleotides (A,U,C,G)
Result
: Single-stranded mRNA
Translation
(Protein Synth)
Initiation
: mRNA binds to small ribosomal subunit, AUG (start) recognizes so tRNA brings methionine, Large ribosomal subunit joins
Elongation
: tRNAs bring amino acids, AA join via peptide bonds
Termination: stop codon (UAA, UAG, UGA), polypeptide chain is released for fold. and modif.
mRNA --> protein
Overview
: ribosome decodes mRNA to form polypeptide (chain of amino acids)
In Eukary
: new proteins move into endoplas retic. for further processing
In Prokary
: Occurs directly in cytoplasm
Degeneracy
64 possible codons, 20 amino acids = multiple codons for 1 amino acid
Simultaneous Transcr & Transl
: in bacteria, due to no nucleus serparating DNA & ribosomes
DNA contains instruction, transcribed into mRNA
Genotype > Phenotype: the gene seq. determine protein structure, which gives traits
Mutations
Permanent change in DNA seq.
Silent: no protein change, change codon but dont alter AA seq.
Frameshift: insert/delet -> inactive protein
Spontaneous: occur naturally (DNA replication errors) 10^-6
Induced by mutagens (chem, radiation, UV) ^ 1000x
Beneficial: antibiotic resist.
Plasmids
Conjugation (F)
: Codes for sex pili & plasmid transfer
Dissimilation
: encodes enzymes ro catabolize unusual substances
Resistance (R) factors:
provide resist to antibiot, heavy metals, toxins, code for enzymes that inactivate drugs, carry mult resist genes
Virulence
: Enhance pathogenicity by coding for toxins
Transposons
: move from one loc to another(between chromo, plasmid, virus), natural mechanism for spreading genes
Small, self-replicating circular DNA molecules
Foundation of Genetics
Science of heredity. (Genes: fund. units of heredity
Genome: Total genetic information of a cell
1869 - Mischer (DNA Discovery)
1953 - Franklin --> Watson & Crick (determined the double-helix)
Humans: 23 pairs (linear). Bacteria: single, circular choromosome
DNA Structure
Nucleotides
: sugar (DNA or RNA), phosphate, nitrogeneous base (DNA: Aden, Thym, Cytos, Guan) (RNA: Aden, Urac, Cytos, Guan)
Double Helix: repeating nucleotides linked by phosphodiester bonds, antiparallel, complement base pairing
Chargaff's rules: the amount of A=T, C=G
Held together by hydrogen bonds between complem. bases
5' (phosphate group) 3' (hydroxyl group)
Horizontal Gene Transfer
Transformation
: uptake of DNA from enviro., Cells that take up DNA are competent, Incorporation -> recombinant cell
Conjugation
: One-way DNA transfer from donor (F+) to recip (F-), direct contact via sex pili, mediated by fertility plasmid
Transduction
: bacterpha. transfers DNA,
Generalized
(random bact genes packaged in phage during lytic cycle),
Specialized
(specific near prophage insert. are transfered)
Transfer of genetic material between organisms not offspring
Regulation of Gene Expression
Operon Model: promoter (binding site), operator (on/off switch), structural genes (encode related proteins, Regulatory gene (produces repressor protein that controls operon)
Repressible: turned ON until end product is abundant
Inducible: turned OFF until substrate is present