3-1: Microbial Genome Flashcards
First step in cell division
DNA replication
What part of mRNA is converted into proteins
Open reading frames
Nucleotides are comprised of…
Nucleobase (nitrogenous base), deoxyribose, phosphate at 5’
Difference btw nucleoside and nucleotide
Nucleosides lack P
How are nucleotides connected
Phosphodiester bonds btw 5’ P and 3’ OH
What are the four nucleobases of DNA
Adenine, cytosine, guanine, thymine
What are the pyrimidines
Cytosine and thymine
C/G base pair stronger because…
3 hydrogen bonds
Differences between RNA and DNA?
RNA = 2’ OH group on ribose sugar (less chemically stable), thymine replaced by uracil, single stranded
How are prokaryotic chromosomes structured
Circular with extensive supercoiling
What is the nucleoid
Region of cell containing chromosome (not membrane bound like nucleus)
What is an example of a bacterium with two chromosomes
Vibrio cholerae
Structure of eukaryotic chromosomes?
Multiple linear chromosomes, larger, less compact genomes (euk microbes most compact)
What are genes
Genetic material that encodes functional protein or RNA product
Microbial genome makeup?
85-90% protein-coding genes
How are genes organized
Functionally related clusters
What is an endosymbiont
Can only exist within another cell
Who has the smallest genome size?
Endosymbionts, parasites
How are genome size and number of genes related
Genome size increase, so does number of genes
What is the core genome
Genes present in all members (conserved genes)
What is the pan genome
All genes present in any member (includes rare genes)
What is synteny
Homologous genes arranged in same order in genomes of closely-related lineages
What is a genomic island vs islet
When unique genes of genome found in blocks
Island = large block
Islet = small block
What is a prophage
When a bacteriophage integrates into the bacterial genomes, become a part of it
What is a cargo gene
Carried by prophage, provide the bacterial host with new genes
What is a plasmid
Circular DNA molecules replicated in the cytoplasm that encode “non-essential” genes (only required under certain conditions; e.g. antibiotic resistance genes)
