Microbial Genomics Flashcards
What is a “genome?”
What is genomics?
- Genome
- entire complement of genetic information
- Includes genes, regulatory sequences, and noncoding segments of the genome
- Genomics
- Discipline of mapping, sequencing, analyzing, and comparing genomes
What are the 3 steps to sequencing a genome?
- Sequence the DNA
- Assemble the sequences into chromosomes or large gragments called “contigs”
- Predict genes (annotation)
What was the first “major” way to sequence a genome?
- Sanger Sequencing
- Used a Dideoxy analog to the dNTP that was missing an OH on the 3’ Carbon
- This made whateversequence stop at that analog
- Used a Dideoxy analog to the dNTP that was missing an OH on the 3’ Carbon
What is “sequencing” in Genomics?
Determining the precise order of nucleotides in a DNA molecule
How many templates should a Sanger-esque sequencing technique have?
1, purified template
What are some of the New sequencing techniques?
- 454 - 1 million reads/run; 700 bp length (no longer supported)
- Illumina - 4 billion reads/run; 300 bp length
- PacBio - 125,000 reads/run; 2000 bp length
What is the “modern” standard for genome sequencing?
Illumina
What is the 4th generation sequencing Technology?
Basically, how does it work and what is its limitation?
- Nanopore sequencing
- Detects eletrical current as DNA is threaded through a protein pore
- Detects 3 bases at a time
- Uses a Helicase (maybe) to feed DNA through the pore.
- High error rate - 5-38.2%
How do you assemble a genome, after sequencing?
- Align all reads to generate longer sequences - contigs
- Gaps may still remain where no reads are found
- Orientation can be assumed if closely related genomes have been completed
- Must close the gap with PCR and sequencing of PCR amplicons by Sanger Seq
How do you fill gaps in your genome after you’ve sequenced it?
- You could try to orient it if closely related genomes have been completed
- Have to clsoe with PCR and sequencing of PCR amplicons by Sanger seq
What is the last step in sequencing a genoeme?
Annotating (Bioinformatics)
What is Annotation?
What do the majoirty of genes encode?
What are functional RNAs?
- Converting raw sequence data into a list of genes or elements present in the genome
- proteins - mRNAs
- Functional RNAs = rRNAs, tRNAs, ncRNAs
What is one way we could use organisms with a similar ORF for sequencing?
- Most genes code for proteins, and functional Rnas like rRNAs and tRNAs are very conserved
- So, if organisms have similar ORFs you can could assume function of the ORF or even assume sequence…
What is synteny?
arrangement of genes in a genome
What are things you can do with a genome?
- Compare gene sequences between bacteria
- Compare mutations between strains
- compare arrangement of genes in genome
- Design new therapeutics to treat