Prokaryotes Flashcards
Almost present everywhere as they are many, despite lacking in size (microscopic)
They thrive almost everywhere, including places with extreme conditions
Prokaryotes
Structure of prokaryotes
Simple unlike complex eukaryotes
shape of prokaryotes’ flagellum
Rod-shaped
Parts of a Prokaryotic Cell
Comprised of a cell wall, plasma membrane, cytoplasm, capsule, nucleoid, ribosomes, pili, and flagellum, cytoplasm, circular DNA
Outermost layer of prokaryotes
Contains pili or fimbriae;
Capsule
the sticky layer present in capsule is made out of
Sticky layer of polysaccharide or
protein
Maintains shape, provides physical
protection, and prevents the cell from
bursting in a hypotonic environment
Cell Wall
Cell Wall Comprised of two layers
outer membrane and the peptidoglycan layer
Leading component of the cell
May include specialized membranes that perform metabolic functions
Plasma Membrane
specialized membranes that perform metabolic functions in prokaryotes
Respiratory membrane
Thylakoid membrane
naked DNA inside the plasma
membrane; in the nucleoid region
Circular DNA
Smaller rings of DNA in prokaryotes
Plasmids
compact structures that only contain RNA and proteins.
in the cytoplasm of a prokaryotic cell are widely distributed.
Cytoplasmic Ribosomes
“Cytosolic ribosomes”
May contain proteins, lipids, or carbohydrates, depending on the organism
storage granules
Used for locomotory services
Flagellum
Allows prokaryotes to stick to their substrates or other individuals in a colony;
short, hair-like structures on the cell surface of prokaryotic cells. They can have a role in movement, but are more often involved in adherence to surfaces, which facilitates infection
Pili (Pilus)
long version of a Pili, help the cell stick to a surface
Fimbriae
Part of the cell used for Gram stain
Cell Wall
test used For the classification of bacterial species into groups
Based on the cell wall composition
Gram stain
is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria.
Gram stain
thick peptidoglycan layer;
not resistant to antibiotics
Gram-positive
narrow peptidoglycan layer;
sandwiched by two other layers;
coated by lipopolysaccharide
resistant to antibiotics (requires high
potency antibiotics because of the
additional layers)
Gram-negative
coat that hinders the staining of the Gram-negative bacteria;
lipopolysaccharide
gram-positive stain
Dark purple stain
gram-negative stain
Light purple or pink
medication that prevents cell wall formation
Antibiotics
Motility of prokaryote
Through the use of flagella
Depending on the species, the flagella may be one to many. It may also surround the entire cell, apical or basal.
true
in what enviroment may bacteria exhibit taxis
heterogenous environment
the ability to move toward or away from certain stimuli.
taxis
movement toward or away from
a source of light
Phototaxis
response to chemical presence, movement toward or away
Chemotaxis
Located in the cytoplasm; hence, the flagellum cannot easily be detached from the cell body as it is deeply attached.
Basal Apparatus
Endosymbiotic explanation states that the flagellum may be
another bacterium (it is another spirochete that is attached to the developing proto-eukaryote.
It may be another bacterium attached to a body
Living component of the cell
Cytoplasm
lack complex compartmentalization
Prokaryotes
Presence of respiratory membrane
in the plasma membrane
Aerobic prokaryotes
Presence of thylakoid membrane in
the plasma membrane
Photosynthetic prokaryote
Located in the nucleoid region
Plasmids
Smaller rings of DNA found in bacteria; separate from the major ring of DNA
Circular DNA (naked DNA)
Quick reproduction
Division is every 1-3 hours
binary fission
Many prokaryotes form __________
o Spores resistant to harsh conditions
endospores
Bacteria reproduce asexually but exhange
genetic information in three ways:
conjugation, transduction, and transformation
Direct transfer of genetic material between two bacterial cells that are temporarily join
Conjugation
conjugation of two bacteria is Joined by the
conjugation pilus
“male”: DNA donor -
F factor, sex pili
“Female”: DNA recipient
true
Transfer of bacterial genes carried by phages from one host cell to another; how viruses
(phages) reproduce
Transduction
The alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from the surrounding environment
DNA that is scattered is being absorbed by a living bacterium, which causes a mutation
Transformation
Produce their own food
Autotrophs
Produce their own food
Among photosynthetic organisms
Absorption of light and carbon dioxide
Photoautotroph
Produce their own food
Gets energy from the inorganic chemicals
inside their bodies (ex. Hydrogen sulfide gas)
Chemoautotroph
Highly dependent on other available food
sources
Heterotrophs
Heterotrophs
Degrades organic compounds to get carbon
Photoheterotroph
Heterotrophs
Decomposers; most prokaryotes
Gets both energy and carbon from organic
compounds
Chemoheterotroph
require O2; they die without it
Obligate Anaerobes
Can survive with or without O2
Facultative Aerobes
poisoned by O2 Most primitive
Obligate Anaerobes
Plausible cases of evolution
Obligate Anaerobes → Obligate Aerobes → Facultative Aerobes
Obligate Anaerobes → Facultative Aerobes → Obligate Aerobes
presence of heterocyst
Nitrogen Fixation
surface-coating colonies where metabolic
cooperation occurs in
colonies of bacteria
Biofilms
ex of Biofilms
Tartar
First classified as a separate group of
prokaryotes in 1977.
Archaea
Basis of systematists in prokaryotic
taxonomy
Based on form
phenotypic criteria
Most common bacterial shapes
▪ Spherical (cocci)
▪ Rod-shaped (bacilli)
▪ Spiral
Three Domains
Bacteria: Most primitive
Archaea
Eukarya: Most derived/advanced
Most primitive
Domain Bacteria
Most primitive clades
Gram-negative bacteria
Subgroup:
Alpha Proteobacteria
Beta Proteobacteria
Gamma Proteobacteria
Delta Proteobacteria
Epsilon Proteobacteria
Proteobacteria
Subgroup of Domain Bacteria
Alpha Proteobacteria
Beta Proteobacteria
Gamma Proteobacteria
Delta Proteobacteria
Epsilon Proteobacteria
Living between the root nodules of legumes
plants/organisms and other
Infecting bacterium in the nodule
Symbiotic relationships with
plants as they can fix nitrogen
Rhizobium (arrows)
Involved in nitrogen metabolism (nitrates to nitrite)
Nitrosomonas
Subgroup: Gamma Proteobacteria
Chromatium
Subgroup: Delta Proteobacteria
Chrondromyces crocatus
Bdellovibrio bacteriophorus
Helical structure
Housed in the pylorus in mammals
Causes ulcers
Subgroup: Epsilon Proteobacteria
Helicobacter pylori
Found in the urine of rats
Cause of Leptospirosis
Leptospira
No cell wall
are more advanced than
the gram-negative bacteria
Gram-Positive Bacteria
Cyanobacteria genus
Gloeocapsa, Oscillatoria, Spirulina,
Anabaena, Nostoc, Rivularia,
Has heterocyst in between its vegetative cells (intercalary heterocyst);
thicker mucilaginous sheath
Group: secretes mucilaginous sheath
Nostoc
Tapered body organization;
Basal: heterocyst
Has mucilaginous sheath
Rivularia
Also has heterocyst in between its vegetative
cells (intercalary heterocyst)
Anabaena
Spiral bodies; homocystous; forms hormogonia (small fragments used to reproduce asexually);
highly nutritious cyanobacteria; used for supplements
Spirulina (Arthrospira platensis)
homocystous; forms hormogonia (small fragments used to reproduce asexually);
highly nutritious cyanobacteria; used for supplements
Oscillatoria
Their colonies are composed of very small organisms; causes red tides
Microcystis
The cells secrete individual gelatinous sheaths which can often be seen as sheaths around recently divided cells within outer sheaths. Recently divided cell pairs often appear to be only one cell since the new cells cohere temporarily.
Gloeocapsa
ram-negative bacteria that can obtain biological energy via oxygenic photosynthesis.
Cyanobacteria
boulder structures
Most ancient biological rocks on earth
Layered accretionary structures formed in shallow water by trapping, binding, and cementation of sedimentary grains by biofilms of cyanobacteria
stromatolites
Similar to domain bacteria -
Prokaryotes living in extreme environments
o “Extremophiles”
has no peptidoglycan in walls
has Histones or porteins associated with DNA
Domain Archaea
Archaea that live in Very hot environments
Extreme Thermophiles
Archaea that live in Highly saline environments
Extreme Halophiles
Archaea that live in Highly acidic environments
Acidophiles
Archaea that live in Swamps and marshes;
Produce methane as a waste product
Methanogens
Ponds containing water that is 5-6x saltier than seawater
o The colors reflect the ability of the species to withstand varying saline levels
Salt Bed
Roles of Prokaryotes in the Biosphere
Chemical Recycling
Decomposers
Nitrogen-fixing
Pneumonia
streptococcus pneumoniae
Klebsiella pneumoniae
Cholera
Vibrio cholerae
Stomach ulcers
Helicobacter pylori
Botulism
Clostridium botulinum
Gonorrhea
Neiserria gonorrhoeae
Salmonellosis
Salmonella enterica
Causes diseases by releasing exotoxins or
endotoxins
Potential weapons of bioterrorism
Pathogenic Prokaryotes
Causes diseases even when the producers are not physically present
Toxins that have been previously released to the environment
Exotoxins
Only released when the cell wall is broken after the death of a bacteria
Bacteria is present
Endotoxins
Letters traced with anthrax were
distributed
Bacillus anthracis scare
Koch’s Postulates process
o Find the candidate bacterium in every case of the disease
o Isolate and grow in pure culture
o Show that the cultured bacterium causes the disease when transferred to a healthy subject
o If the injected animal acquires the disease, then it can be concluded that the bacterium is the cause of the disease.
o Isolate from experiment subject and compare with the original bacterium
Disease Prevention for prokaryotes
Disinfectants
Alcohol, iodine, bleach
Cold temperatures (refrigeration)
Heating/cooking
Antibiotics
Beneficial Impacts of Prokaryotes
DNA technological advances
Synthesis of vitamins
Production of antibiotics, hormones, and other products
Prokaryotes are the principal agents in
bioremediation
