Chapter 12 Flashcards
What is a genome
The entire complement of genetic information. Includes genes, regulatory sequences, and noncoding DNA
What is genomics
Discipline of mapping, sequencing, analyzing, and comparing genomes
What is shotgun sequencing
A technique used by virtually all genomic sequencing projects. Random fragments of entire genome are cloned or amplified and sequenced to produce millions of sequence “reads”
How can you sequence with shotgun sequencing
The organisms genome is broken up into random fragments, there will be so many fragments that every part of the genome will be sequenced. Computer algorithms assemble the overlapping reads into contiguous regions in order to produce the entire genome
What are some difficulties with shotgun sequencing
Assembly of complete circular chromosome
When sequencing a circular chromosome how are gaps between contigs filled
They can be filled using PCR or cloning techniques or by sequencing methods that will produce very long reads
What is a closed genome
A genome that is complete
What is a draft genome
A fast and cheap method of sequencing but will contain gaps
What is annotation
Converting raw sequence data into a list of genes present in the genome. The majority of genes encode proteins
What is a functional ORF
An open reading frame that encodes a protein. The ORFs are bounded by start/stop codons, Shine-Dalgarno sequences upstream of ATG start site.
How are ORFs used in genomics
You can compare new ORFs that have been identified by a computer to those previously found in other genomes, finding homologs suggests the gene is real
What is bioinformatics
Science that applies computational tools to DNA and protein sequences. Analyze, annotate, and compare homologs. And identify genes for metabolic pathways by comparison to those well-studied model organisms
What is comparative analysis and what is it used for
Identifying genes by comparing similarities between sequences with previously identified genes in other organisms. Allows for predictions of metabolic pathways and transport systems. Can be used to determine how to grown an organism in a lab
What are homologous genes
Genes that may have a common evolutionary ancestor
What are hypothetical genes and proteins
Only about 70% or less of total ORFs are detected and these are the uncharacterized ORFs. They encode for proteins that likely exist but whose function is unknown (nonessential genes). All essential genes have been identified
Describe a metagenome
The total gene content of all organisms present in an environment. Allow a variety of bioinformatic analyses to identify organisms, types of metabolisms, etc. Can be obtained by shotgun sequencing of total DNA from an environmental sample. Goal is to determine DNA sequences of organisms in a population and identify all of them. Sequencing the rRNA is primarily used.
Describe a transcriptome
Provides data on expressed genes by measuring RNA. The entire complement of RNA produced under a given set of growth conditions (temperature, nutrients, other organisms)
What are microarrays
Hybridization technique based on genomic sequence data for target organism. Thousands of gene probes are arrayed in a known pattern on solid-state chips or glass slides