Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 19: Viruses & Chapter 27: Archaea and Bacteria - Coggle…
Chapter 19: Viruses
&
Chapter 27: Archaea and Bacteria
19.1: Virus Composition
Severe Acute Respiratory Syndrome-CoronaVirus-2 virus
causes COVID-19
COronaVIrus Disease 2019
disease
caused by SARS-CoV-2
identified in 2019
became pandemic in 2020
caused millions of deaths globally
capsid
protein shell
encloses a viral genome
complex in shape
rod-shaped
polyhedral
viral envelopes
membrane
derived from membranes of host cell
cloaks capsid
encloses a viral genome
viruses
discovered by researchers
in late 1800s
studied plant disease -> tobacco mosaic disease
small nucleic acid genome
enclosed in protein capsid
sometimes membranous viral envelope
genome
single-stranded DNA
single-stranded RNA
double-stranded DNA
double-stranded RNA
19.3: Viruses and Prions
epidemic
widespread disease outbreak
vaccine
harmless variant/derivative of pathogen
stimulates host’s immune system to mount defenses against pathogen
prions
infectious agent
misfolded version of normal cellular protein
appear to increase in # by converting folded versions of protein to more prions
slow-acting
virtually indestructible
infectious proteins
cause brain diseases
in mammals
pandemic
global epidemic
bacteria
defend themselves against phage infections
CRISPR-Cas system
19.2: Replicate
host range
limited number of species
cells can be infected by virus
lytic cycle
type of phage
replicative cycle
results in release of new phages by lysis of host cell
virulent phage
phage
replicates by lytic cycle
lysogenic cycle
type of phage
replicative cycle
viral genome
incorporated into bacterial host chromosome as prophage
replicated along with chromosome
does not kill host
temperate phages
phage
capable of replicating
either lytic or lysogenic cycle
prophage
phage genome
inserted into specific site
on bacterial chromosome
restriction enzymes
endonuclease
recognizes and cuts DNA molecules foreign to bacterium
enzyme cuts at specific nucleotide sequences
retroviruses
RNA virus
replicates by transcribing RNA into DNA
inserts DNA into cellular chromosome
class of cancer-causing viruses
reverse transcriptase
enzyme
encoded by retroviruses
uses RNA as a template for DNA synthesis
human immunodeficiency virus
infectious
agent causes AIDS
HIV is a retrovirus
acquired immunodeficiency syndrome
symptoms/signs present during late stages of HIV infection
defined by a specified reduction in # of T cells
appearance of characteristic secondary infections
provirus
viral genome that is permanently inserted into a host genome
viruses
use
ribosomes
synthesize progeny viruses
during replication
small molecules of host cells
enzymes
enter plants as well
horizontal transmission
damaged cells
vertical transmission
inherited
H1N1 2009 flu virus
combination
human
bird viral genes
pig
outbreaks
usually not new
caused by existing diseases
expand host's territory
27.1: Structure & Function
capsule
prokaryotes
dense layer of polysaccharide or protein
surrounds cell wall
sticky
protects cell
enables it to adhere to substrates or other cells
sporangium of a bryophyte (moss, liverwort, or hornwort)
endospores
thick-coated
resistant cell
produced by bacterial cells
when exposed to harsh conditions
gram-negative
group of bacteria with cell wall
structurally more complex
less peptidoglycan than gram-positive bacteria cell wall
more toxic than gram-positive bacteria
fimbriae
short
hairlike appendage of a prokaryotic cell
helps adhere to substrate or other cells
Gram-positive
describes group of bacteria
have cell wall
structurally less complex
more peptidoglycan than gram-negative bacteria cell wall
less toxic than gram-negative bacteria
pili
in bacteria
structure
links 1 cell to another at start of conjugation
AKA sex pilus or conjugation pilus
Gram stain
staining method
distinguishes between 2 kinds of bacterial cell walls
used to determine medical response to infection
taxis
oriented movement
toward or away from stimulus
peptidoglycan
type of polymer
bacterial cell walls
consist of modified sugars cross-linked by short polypeptides
prokaryotic species
reproduce quickly by binary fission
leads to large populations
27.6: Benefits and Disadvantages
Exotoxins
toxic protein
secreted by prokaryote or pathogen
produces specific symptoms
even if pathogen is no longer present
Endotoxins
toxic component
of outer membrane of gram-negative bacteria
released when bacteria die
bioremediation
organisms detoxify
restore polluted and degraded ecosystems
people
depend on mutualistic prokaryotes (species in intestines that digest food)
Pathogenic bacteria
cause disease
release exotoxins or endotoxins
Horizontal gene transfer
spreads genes
with virulence
to species or strains
Prokaryotes
in bioremediation and production
vitamins
antibiotics
plastics
27.3: Nutritional & Metabolic Adaptations
Obligate aerobes
organism
requires oxygen for cellular respiration
cannot live without it
anaerobic respiration
catabolic pathway
inorganic molecules other than oxygen
accept electrons at end of electron transport chains
nitrogen fixation
conversion of atmospheric nitrogen to ammonia
biological nitrogen fixation is carried out by prokaryotes
some have mutualistic relationships with plants
biofilms
surface-coating colony
1 or more species of unicellular organisms
engage in metabolic cooperation
most biofilms are formed by prokaryotes
heterocysts
specialized cell
engages in nitrogen fixation
in some filamentous cyanobacteria AKA heterocyte
nutritional diversity
much greater in prokaryotes than in eukaryotes
includes all 4 modes of nutrition
chemoautotrophy
photoheterotrophy
photoautotrophy
chemoheterotrophy
among prokaryotes
obligate aerobes require O2
obligate anaerobes are poisoned by O2
facultative anaerobes can survive with or without O2
unlike eukaryotes
prokaryotes metabolize nitrogen in many forms
convert atmospheric nitrogen -> ammonia
process called nitrogen fixation
prokaryotic cells & species cooperate metabolically
in surface-coating biofilms too
27.5: Biosphere
decomposers
organism
absorbs nutrients from nonliving organic material (corpses, fallen plant material, and living organism wastes)
converts them to inorganic forms
detritivore
symbiosis
ecological relationship
between organisms of 2 different species
live together in direct and intimate contact
host
larger participant
in symbiotic relationship
provides home & food source for smaller symbiont
symbiont
smaller participant in symbiotic relationship
living in or on host
mutualism
positive-positive ecological interaction
benefits individuals of both interacting species
commensalism
positive-neutral ecological interaction
benefits individuals of 1 species but neither harms nor helps individuals of other species
parasitism
positive-negative ecological interaction
1 organism (parasite) benefits
feeds upon another organism (host) which is harmed
some parasites live within host (feeding on its tissues)
others feed on the host’s external surface
parasite
organism
feeds on cell contents, tissues, or body fluids of host
while in or on host organism
harm but usually do not kill host
pathogens
organism or virus
causes disease
Decomposition
by heterotrophic prokaryotes
synthetic activities of autotrophic
nitrogen-fixing prokaryotes
contribute to element recycling
Many prokaryotes
have symbiotic relationship with host
ranging relationships for prokaryotes and hosts
commensalism
parasitism
mutualism
27.4: Lineages
extremophiles
organism
live in extreme environments
few species can survive
halophiles & thermophiles
Extreme halophiles
organism
lives in saline environment (Great Salt Lake or Dead Sea)
Extreme thermophiles
organism
thrive in hot environments (60-80 degrees C or higher)
methanogens
organism
produces methane as waste product from way it gets energy
in domain Archaea
Molecular systematics
helps biologists classify prokaryotes
Diverse nutritional types
among major groups of bacteria
2 largest groups
proteobacteria
gram-positive bacteria
archaea (thermophiles and halophiles)
live in extreme environments
Other archaea
live in moderate environments (soils and lakes)
27.2: Reproduction, Mutation, Recombination
transduction
process
phages (viruses) carry bacterial DNA from 1 bacterial cell to another
2 cells are members of different species
results in horizontal gene transfer
series of steps
link mechanical, chemical, or electrical stimulus to cellular response
conjugation
prokaryotes
direct transfer of DNA between 2 cells
temporarily joined
2 cells, members of different species
conjugation results in horizontal gene transfer
ciliates
sexual process
2 cells exchange haploid micronuclei
do not reproduce
F factor
bacteria
DNA segment confers ability to form pili for conjugation and functions
required for transfer of DNA from donor to recipient
F factor may exist as plasmid or integrated into bacterial chromosome
F plasmid
plasmid form of the F factor
R plasmids
bacterial plasmid
carries genes
confer resistance to certain antibiotics
prokaryotes proliferate rapidly
mutations increase population’s genetic variation
prokaryotic populations often evolve in short time periods
response to changing conditions
genetic diversity
prokaryotes
arise by DNA recombination from 2 cells (via transformation, transduction, or conjugation)
transferring advantageous alleles (for antibiotic resistance)
recombination promotes adaptive evolution in prokaryotic populations