Prokaryotes Flashcards by Miyaki Jan Lim

Almost present everywhere as they are many, despite lacking in size (microscopic)

They thrive almost everywhere, including places with extreme conditions

Prokaryotes

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Structure of prokaryotes

Simple unlike complex eukaryotes

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shape of prokaryotes’ flagellum

Rod-shaped

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Parts of a Prokaryotic Cell

Comprised of a cell wall, plasma membrane, cytoplasm, capsule, nucleoid, ribosomes, pili, and flagellum, cytoplasm, circular DNA

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Outermost layer of prokaryotes

Contains pili or fimbriae;

Capsule

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the sticky layer present in capsule is made out of

Sticky layer of polysaccharide or
protein

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Maintains shape, provides physical
protection, and prevents the cell from
bursting in a hypotonic environment

Cell Wall

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Cell Wall Comprised of two layers

outer membrane and the peptidoglycan layer

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Leading component of the cell

May include specialized membranes that perform metabolic functions

Plasma Membrane

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specialized membranes that perform metabolic functions in prokaryotes

Respiratory membrane

Thylakoid membrane

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naked DNA inside the plasma
membrane; in the nucleoid region

Circular DNA

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Smaller rings of DNA in prokaryotes

Plasmids

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compact structures that only contain RNA and proteins.
in the cytoplasm of a prokaryotic cell are widely distributed.

Cytoplasmic Ribosomes
“Cytosolic ribosomes”

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May contain proteins, lipids, or carbohydrates, depending on the organism

storage granules

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Used for locomotory services

Flagellum

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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)

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long version of a Pili, help the cell stick to a surface

Fimbriae

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Part of the cell used for Gram stain

Cell Wall

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test used For the classification of bacterial species into groups
Based on the cell wall composition

Gram stain

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is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria.

Gram stain

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thick peptidoglycan layer;
not resistant to antibiotics

Gram-positive

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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

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coat that hinders the staining of the Gram-negative bacteria;

lipopolysaccharide

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gram-positive stain

Dark purple stain

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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