Biology 100 Unit 16 Flashcards
single celled organisms (few exceptions) which lack a nucleus and membrane bound organelles
Prokaryotes
Prokaryotes are considered to be the most
ancient and simplest life-forms
Prokaryotes are still the most
numerous and most widespread organisms on Earth today.
Prokaryotes are two domains, ______________________.
Archae and Bacteria
Prokaryotes are
1–5 μm in diameter
Prokaryotes (numberous)
– are found wherever there is life.
– outnumber all eukaryotes
combined.
Prokaryotes:
– can cause ________.
– can be __________.
– have no __________.
disease
beneficial
organelles
Prokaryotes typically take the form of
1 of 3 different shapes
Nearly all prokaryotes have
a cell wall
A prokaryote’s cell walls
– provide physical protection and
– prevent the cell from bursting in a hypotonic environment.
When Gram stained, cell walls of bacteria are either
gram positive or gram negative
with more layers of peptidoglycan, or
gram positive
with less peptidoglycan, however a more complex cytoplasmic membrane & more likely to cause disease.
gram negative
The cell wall of many prokaryotes is covered by a
capsule, a sticky layer of polysaccharides or protein.
_____________: enables prokaryotes to adhere to their substrate or to other individuals in a colony and
capsule
A capsule shields _____________________ from attacks by a host’s immune system.
pathogenic prokaryotes
Some prokaryotes have external structures that extend
beyond the cell wall
help prokaryotes move in their environment.
flagella
Hairlike projections called ______________ enable prokaryotes to stick to their substrate or each other
fimbriae
exhibit much more nutritional diversity than eukaryotes.
Prokaryotic
obtain energy from sunlight and use carbon dioxide for carbon.
Photoautotrophs
obtain energy from sunlight but get their carbon atoms from organic molecules.
Photoheterotrophs
harvest energy from inorganic chemicals and use carbon dioxide for carbon.
Chemoautotrophs
acquire energy and carbon from organic molecules.
Chemoheterotrophs
____________: are complex associations of one or several species of prokaryotes
biofilms
Prokaryotes attach to surfaces and form biofilm communi
are difficult to eradicate
are large complex “cities” of microbes that
– communicate by chemical signals, coordinate a division of labor & defense, and use channels to distribute nutrients and collect wastes.
biofilms
example of a biofilms
plaque on teeth and drains in pipes
Prokaryotes are useful for cleaning up contaminants in the environment because prokaryotes
– have great nutritional diversity,
– are quickly adaptable, and can form biofilms.
______________is the use of organisms to remove
pollutants from soil, air, or water.
bioremediation
are the mainstays of sewage treatements facilities
prokaryotic decomposers
The domain Bacteria is currently divided into
five groups, based on comparisons of genetic sequences.
all gram negative bacteria, diverse, some are symbiotic with legumes (N2 fixers)
Proteobacteria
as diverse as proteobacteria
Gram-positive bacteria
the only group of prokaryotes with plantlike,
oxygen-generating photosynthesis. Some are N2 fixers.
Cyanobacteria
intracellular bacteria that live inside eukaryotic host cells.
Chlamydias
are helical bacteria and notorious pathogens, causing syphilis and Lyme disease.
Spirochetes
All organisms are almost constantly exposed to
pathogenic bacteria.
Most bacteria that cause illness
produce a poison
___________are proteins that bacterial cells secrete
into their environment.
exotoxins
are components of the outer membrane of gram-negative bacteria.
endotoxins
are unicellular microbes that are capable to inhabiting extreme environments. They have unusual proteins and other molecular adaptations that enable them to metabolize and reproduce effectively.
archae
Extreme _____________thrive in very salty places.
halophiles
– Extreme _____________thrive in
– very hot water, such as geysers, and
– acid pools.
thermophiles
_________________: live in anaerobic environments, and give off methane as a waste product from
ex: the digestive tracts of cattle, deer, and in decomposing materials of landfills.
Methanogens
are a diverse collection of mostly unicellular eukaryotes. Protists refer to eukaryotes that are not plants, animals or fungus, however they often share some similarities to these eukaryotes.
Protists
– This makes classification of Protists
difficult, and classification is not universal among all Biologists.difficult, and classification is not universal among all Biologists.
Protists are found in many habitats including
– anywhere there is moisture and
– the bodies of host organisms.
Protists mode of
diverse nutricion
autotrophs which produce their food
by photosynthesis,
algae
heterotrophs which eat bacteria and other protists.
protozoans
heterotrophs which derive their nutrition from a living host
parasites
use photosynthesis and heterotrophs
mixotrophs
explains the origin of mitochondria and chloroplasts.
The endosymbiont theory
eukaryotic cells evolved when
when prokaryotes established residence within other, larger prokaryotes.
This theory is supported by present-day __
mitochondria and chlorplasts
Support for Endosymbiosis includes
– structural and molecular similarities to prokaryotic
cells
– replication and use their own DNA, separate from the nuclear DNA of the cell.
the process in which an autotrophic eukaryotic protist became endosymbiotic in a heterotrophic eukaryotic protist.
Secondary endosymbiosis:
This is thought to be a key of protist diversity.
Secondary endosymbiosis:
are a large supergroup including autotrophs, heterotrophs, and mixotrophs.
Chromalveolates
Representatives of Chromalveolates
– diatoms,
– dinoflagellates – brown algae, – water molds, – ciliates,
– Plasmodium
____________, unicellular algae with a glass cell
wall containing silica,
diatoms
____________, unicellular autotrophs, heterotrophs, and mixotrophs that are common components of marine plankton,
dinoflagellates
_____________, large, multicellular autotrophs,
brown algae
unicellular heterotrophs,
water molds
_____________, unicellular heterotrophs and mixotrophs that use cilia to move and feed,
ciliates
a group including parasites, such as ____________, which causes malaria.
plasmodian
are a claude (group) grouped together by DNA similarities.
Rhizarians
include Foraminiferans & Radiolarians which are often referred to as amoebas
Rhizarians
____________: are found in the oceans and in fresh
formaminaferenas
are mostly marine
– produce a mineralized internal skeleton made of
silica.
Radiolarians:
is a new clade on the basis of molecular and morphological similarities.
excavata
have modified mitochondria that lack functional electron transport chains and
use anaerobic pathways such as glycolysis to extract energy.
excavates
