Chapter Sixteen: Bacterial Genes Flashcards
an adult human carries ___ bacteria, which is about the same as the number of human cells
30-50 trillion
most bacteria are in the ___, but they are also found in the ___, ___, and ___
intestines
skin, mouth, and respiratory tracts
___ are common for people with intestinal bacteria issues
fecal transplants
bacteria are ___ to ___ in length
200nm to 500micrometers
bacteria lack a ___ and ___
nucleus and membrane bound organelles
bacteria store their DNA in a single ___ folded into a ___
chromosome
nucleoid body
most bacteria have a ___, and some antibiotics inhibit ___ because human cells don’t have this characteristic
cell wall
cell wall synthesis
bacteria have adapted to a ___ of habitats
range
four possible habitats for bacteria
- on land
- in aquatic environments
- parasites
- symbionts inside another life form
bacterial ___ must be adapted to its environment
metabolism
some bacteria obtain energy from ___, others from ___
ammonia
sunlight
three natural processes that bacteria play a role in
- decomposition of materials for nutrient cycling
- important in nitrogen cycling
- some eat oil
bacteria that eat oil
bioremediation bacteria
a ___ fraction of bacteria is pathogenic
small
pathogenic bacteria invade ___ and produce ___
tissues
toxins
proteins that interfere with cell function or destroy cells
toxins
toxin that results in paralysis by interfering with communication between nerves and muscles
tetanus toxin
pretty much any bacteria that gets ___ will kill you
into your blood (septic)
the typical bacterial genome is composed of ___
one circular chromosome
there are ___ of DNA in most common studied bacteria
4-5Mb
the DNA molecule condenses by ___ and ___
supercoiling and looping
each bacterium replicates its chromosome and then divides by ___ into two daughter cells
binary fission
bacterial genomes are ___ with genes
tightly packed
___ of E. coli DNA encodes proteins; ___ of human DNA encodes proteins
90%
5%
E. coli have no ___ in their genome
introns
E. coli K12 genome has ___ genes
4288
genomes of ___ of E. coli strains have been sequences
100s
genes that are found in all strains of a species
core genome
there are about ___ core genes for E. coli
1000
functions of core genes
characteristics of life: nutrient assimilation, metabolism, waste removal, responding to environment, transcription and translation, replication, etc.
core genome plus all genes that are found in some strains of a species but not others
pangenome
the E. coli pangenome consists of about ___ genes
15,000
do bacterial genes contain transposons
yes
small bacterial transposons that do not contain selectable markers
insertion sequences (IS)
like the ends of DNA transposons in eukaryotic cells, the ends of IS elements are ___
inverted repeats of each other
each insertion sequence includes a gene that encodes ___
transposase
insertion sequences can disrupt ___
gene function
IS can rearrange bacterial genomes by causing ___ or ___
deletions or inversions
a bacterial transposon carrying transposase and drug resistance genes flanked by ISs
Tn elements
___ carry additional DNA
plasmids
plasmids are small circles of ___
double stranded DNA
plasmids are used as ___
cloning vectors
plasmids may contain genes that ___ or ___
benefit host bacterium or contribute to bacterial pathogenicity
plasmids that provide resistance to antibiotics
resistance plasmids
antibiotic resistance is often due to the presence of ___ on a plasmid
composite IS/Tn transposons
resistance plasmids can be transferred from ___ to ___ in nature easily
one bacteria to another
resistance plasmids are ___ for humans taking antibiotics
not good
the collective analysis of genomic DNA from an entire community of microbes
metagenomics
the initiative to identify all species of microorganisms that are symbionts with humans, and to correlate differences in microorganism populations with phenotypic differences and disease states
human microbiome project
there have been ___ species of bacteria identified in the human microbiome project
10,000
individuals vary in ___ of bacteria they carry
species
proteins that work under unusual conditions
extremophiles
a type of extremophile DNA polymerase
Taq DNA polymerase
extremophile bacteria that grow well in high pH have enzymes that are used in ___
laundry detergents
bacteria must be grown and studied in ___
cultures
bacteria are grown as ___ in liquid media
cell suspension
bacteria are grown as ___ on solid nutrient agar plates
colonies
the most studied and best understood bacterial species
E. coli
E. coli normally inhabits ___
intestines of warm-blooded animals
E. coli can grow in the complete absence of ___ or in ___
oxygen
air
lab strains of E. coli are not ___, but other strains can cause ___
pathogenic
intestinal diseases
E. coli are ___, meaning they can grow in minimal media
phototrophic
E. coli cells divide every ___
20 minutes