exam 2 prokaryotes

capsule

polysaccharide or protein layer found outside the cell wall of certain bacteria, outermost layer

endospore

dormant, tough, and non-reproductive structure

dormant alternate life form formed internally during unfavorable conditions—such as nutrient starvation or high temperature—to protect the bacterial genome

fimbriae

thin, hair-like protein appendages on the surface of bacteria used for adhesion to surfaces and other cells in a colony

nucleoid

region where prokaryotic genome (ring of DNA) is located

sits directly in cytoplasm

holds bulk of genetic material (circular dna)

plasmids

smaller rings of DNA located in cytoplasm

replicate independently of the host chromosome. They typically carry non-essential, advantageous genes

used in horizontal gene transfer

sex pilus

long appendage used to facilitate genetic transfer through bacterial conjugation, transfers plasmids

• A pilus of the donor cell attaches to the recipient

• The pilus retracts, pulling the two cells together

• DNA is transferred through a temporary structure called the “mating bridge”

Conjugation

bacillus

elongated, pill like

coccus

balls, round

spirillum

spiral shaped

transformation

prokaryotic cells incorporate foreign DNA from surroundings

transduction

phages (from “bacteriophages,” viruses that infect bacteria) carry prokaryotic genes from one host cell to another

• generally an unintended result of the phage replicative cycle

conjugation

the process through which DNA is transferred between two prokaryotic cells

• the DNA transfer is always one way: One cell donates the DNA and the other receives it; through sex pilus

• A pilus of the donor cell attaches to the recipient

• The pilus retracts, pulling the two cells together

• DNA is transferred through a temporary structure called the “mating bridge”

genetic recombination

he process of exchanging genetic material (DNA) between organisms, resulting in new allele combinations that differ from parents

one factor that contributes to genetic diversity

done through transformation, transduction, conjugation

horizontal gene transfer

movement of genetic material between unicellular and/or multicellular organisms other than from parent to offspring

organisms rapidly acquire new traits, such as antibiotic resistance, from other individuals, including distantly related species\

examples) transformation, transduction, and conjugation

factors that increase genetic diversity

1. Rapid reproduction

2. Mutation

3. Genetic recombination

(Their short generation time allows prokaryotes to evolve quickly)

gram pos

purple stain

Thick peptidoglycan layer holds stain

gram neg

pink

thin peptidoglycan layer between 2 membranes

cant hold dye well

peptidoglycan

a polymer forming a cell wall around most bacteria. It provides structural integrity, maintains cell shape, and prevents osmotic lysis

found just outside the cytoplasmic membrane

photoheterotroph

1. Energy Source (what molecule is being used for ATP): Light

2. Carbon Source: Organic compounds

produces atp using light as an e- donor and absorbs organic carbon from enviroment

photoautotroph

1. Energy Source (what molecule is being used for ATP): light

2. Carbon Source: CO2 (inorganic compounds)

produces atp using light as an e- donor and absorbs inorganic carbon from enviroment

chemoorganoautotroph

1. Energy Source (what molecule is being used for ATP): organic compounds

2. Carbon Source: CO2 (inorganic compounds)

produces atp using organic compounds as an e- donor and absorbs inorganic carbon from enviroment

chemoheterotroph

1. Energy Source (what molecule is being used for ATP): organic compounds

2. Carbon Source: organic compounds

produces atp using organic compounds as an e- donor and absorbs organic carbon from enviroment

chemoautotroph

1. Energy Source (what molecule is being used for ATP): Hs2, Nh3 (inorganic compounds)

2. Carbon Source: CO2 (inorganic compounds)

Produces ATP using H₂S as an electron donor and absorbs inorganic carbon from the environment.

lithoheterotroph

1. Energy Source (what molecule is being used for ATP): Hs2, Nh3 (inorganic compounds)

2. Carbon Source: organic compounds

Produces ATP using H₂S as an electron donor and absorbs organic carbon from the environment.

obligate aerobe

require oxygen for cellular respiration and cannot grow without it.

obligate anaerobe

 poisoned by oxygen. They may live by fermentation or anaerobic respiration, using substances like nitrate or sulfate ions instead of oxygen as electron acceptors.

Facultative Anaerobe

 can use oxygen if it is present but can also perform fermentation or anaerobic respiration when oxygen is absent.

nitrogen fixation

chemical process of converting inert atmospheric nitrogen () into reactive, usable compounds like ammonia () or nitrates, which are essential for living organisms, prokaryotes metabolize nitrogen

heterocysts

specialized, thick-walled cells that differentiate in certain filamentous cyanobacteria (e.g., Anabaena, Nostoc) to fix atmospheric nitrogen into ammonia

biofilm

surface-coating colonies

Metabolic Cooperation

extremophile

 organisms that thrive in environments so extreme that few other organisms can survive there

thermophile

thrive in very hot environments, such as geothermally heated marine sediments, hot springs,  hydrothermal vents

psychrophile

organisms that are capable of growth and reproduction in low temperatures

acidophile

 generally live in acidic environments, such as sulfuric pools or acidic mine drainages, where the pH is very low

xerophile

organism that can grow and reproduce in conditions with a low availability of water

methanogens

anaerobic archaea that produce methane as a byproduct of their energy metabolism

the major nutritional modes

Photoautotrophs, Chemoautotrophs, Photoheterotrophs, Chemoheterotrophs, chemolithotroph, chemoorganotroph

Autotroph

Organisms that produce their own food using inorganic substances. They are the producers of the biosphere.

Heterotroph

Organisms that cannot produce their own food and rely on consuming other organisms or organic substances.

They are the consumers of the biosphere. 

phototroph

 Organisms that obtain energy from light

Chemotroph

Organisms that obtain energy from chemical/inorganic compounds

binary fission

 form of asexual reproduction primarily seen in prokaryotes like bacteria. The cell grows to double its size and divides into two identical cells.