Gene and Genome organisation of bacteria and viruses Flashcards
What is the definition of a genome?
The entire genetic content of an organism
What differences can a genome of an organism have?
- Can be double stranded or single stranded
- Can be DNA or RNA
- Can be linear or circular
- Can be contained in single or multiple units
What is the definition of a chromosome?
The physical location of a gene
Where can genomes be found?
Nucleus
Mitochondria
Chloroplasts
Why are genes arranged in chromosomes?
- Grouping together genes provides easy duplication of DNA and can be partitioned into daughter cells easily
- Chromosomes contain at least one origin of replication to allow them to be replicated
What is the molecular material of a chromosome?
- Pure nucleic acid in Viruses
- DNA/Protein complex in bacteria
- Many different levels of protein at several levels to from chromatin in Eukaryotes
How are genes organised in bacteria?
Tightly packed genes, efficient genome usage
-roughly 1000bp per gene
What are polycistonic operons? Where are they found?
Two or more genes transcribed from the same promoter
-overlap of start/stop codons
UA(A)UG
Adenine shared
found in bacteria
What is the lac operon of E. Coli?
Permits coordinated expression of genes encoding functionally-related products
lac=lactose metabolism
How much of the human genome encodes proteins?
2%
What are overlapping genes within bacteriophages?
Some genes are encoded by the same segment of DNA but in different reading frames or in opposite orientations (from different 3’/5’ ends and on opposite double strands)
