BIOL2010 Week 5 Microbial Genetics PDF

www.udst.edu.qa BIOL2010 Week 5 – Microbial Genetics Microbial Genetics The basis of heredity DNA – Biological molecule made up of nucleotides as monomers. Each nucleotide is made up of three pieces: 1 – Sugar (deoxyribose), 2 – Phosphate, & 3 – Nitrogenous base. There are 4 nitroge...

www.udst.edu.qa BIOL2010 Week 5 – Microbial Genetics Microbial Genetics The basis of heredity DNA – Biological molecule made up of nucleotides as monomers. Each nucleotide is made up of three pieces: 1 – Sugar (deoxyribose), 2 – Phosphate, & 3 – Nitrogenous base. There are 4 nitrogenous bases: Adenine, Thymine, Guanine & Cytosine. Microbial Genetics Nucleic Acids - Information storage and transfer. Storage: Hold all instructions for all proteins and metabolic reactions, this makes an individual organism or cell. Transfer: This information can be passed down to offspring, nucleic acids can be reproduced, and information can be passed from DNA to RNA to form proteins. Microbial Genetics Chromosomes are made up of DNA, circular in Prokaryotes and linear in eukaryotes. A gene is a sequence of nucleotides located at some point on the chromosome – a locus. There can be different versions of a gene, these versions are called alleles. Microbial Genetics Genotype: The full collection of genes a cell or organism can have. Phenotype: The physical characteristics of an individual as a result of the interaction of the genes and the environment. Protein Synthesis Transcription: Reading a specific section of the genome to map production of proteins Map = DNA -> messenger RNA (mRNA) Translation: Interpreting the mRNA to produce a specific protein mRNA -> Protein Protein synthesis Remember the codon table. These are mRNA bases. Every three bases, code for an amino acid. Mutations A heritable change in the DNA sequence of an organism. The ‘mutant’ could have a change in phenotype from the ‘wild type’ (most common in nature) Types of mutations Point mutation: a single base is substituted or replaced by another. Insertion: The addition of one or more bases. Deletion The removal of one or more bases. Types of mutations Effects on Proteins: Silent mutation: No effect Missense mutation: A different amino acid is incorporated into the protein. Nonsense mutation: converts a codon into a stop codon, typically a non functional protein. Adaptation and Mutation A ‘mutant’ can be: Successful – It can be considered adaptive (mutant has more success than non-mutants), Neutral – (no difference between mutant vs non- mutant) Deleterious – (mutant is less successful than non-mutant). Adaptation is when, in a population, a successful mutation appears and eventually becomes the main state (successful mutants take over). DNA / Chromosome Replication Occurs in three phases: Initiation Elongation Termination DNA / Chromosome Replication Initiation: Locate the origin of replication site – oriC A specific sequence of bases that mark the start point for DNA replication DNA strand is unwound at the oriC start point, creating two strands Helicase unwinds Two replication forks DNA / Chromosome Replication Elongation: Polymerase is used to replicate the two strands Cannot initiate synthesis, only extend an existing strand Primase used to prime the strands for replication A primer is added to both strands that is recognized by the polymerase Replication begins in both directions: leading and lagging Okazaki fragments are created and a ligase binds to make contiguous strand Topoisomerases (gyrase) deal with winding issues. DNA /Chromosome Replication Termination: Termination (Tus-Ter) sequence is located by the polymerase Replication stops at Tus-Ter sequence Two new loops are formed and migrate to either end of the bacterium Septum begins to form to create two new cells Gene Transfer Binary Fission: Simple asexual cell division No genetic diversity. Bacterial Conjugation: A donor cell transfers new genetic information to a recipient Genetic diversity Bacterial Transformation: Can pick up genetic information from the environment New characteristics imbued. Genetic diversity. Bacterial Transduction: Bacterial cell infected by bacteriophage Viral DNA inserted in Bacterial DNA and Virus replicated. Picks up strands of bacterial + viral DNA Re-infects other bacteria Biotechnology The science of using living systems to benefit humankind. Genetic engineering is when we alter an organisms genetics to achieve desirable traits. We use recombinant DNA technology and procedures to produce a recombinant DNA molecule in vitro. That recombinant DNA is then placed into a host organism. That organism is then called transgenic.