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Textbook Section 2.2: Comparing Bacteria + Archaea (Reproduction (Binary…
Textbook Section 2.2: Comparing Bacteria + Archaea
SECTION STARTS HERE - READ COUNTERCLOCKWISE
General Similarities:
They are both prokaryotes (unicellular)
They are both commonly in the shapes of spheres (cocci), rods (bacilli), and spirals
Cells in both domains can form aggregations (when multiple cells groups together in chains)
Nutrition
Archaea:
archaea undergo methanogenesis
This is the process that produces methane, the simplest organic compound
It is a fuel and a greenhouse gas
It occurs in environments that lack oxygen
Methane producing archaea live in the digestive tracts of cows
Bacteria:
They undergo photosynthesis
The cyanobacteria are the best known bacteria that undergo it
Habitats
Similarities:
Bacteria and Archaea can both occupy environments with and without oxygen
Archaea:
They can live in extreme climates such as deep seas, hot springs, salt lakes, and volcanic crater lakes
For this reason, they are called extremophiles
Bacteria:
They occupy environments with moderate conditions
Called mesophiles
There are some extremeophilic bacteria
Reproduction
Binary Fission:
Both reproduce through binary fission since they are prokaryotes
Binary fission: the asexual form of reproduction used by most prokaryotes in which a cell divides into 2 genetically identical cells
Cell grows
Makes a copy of original single chromosome
Cell elongates which separates the original and copy DNA
A partition between them is built called a septum
Cell splits
Conjugation / Genetic Recombination:
A process that transfers genetic material between cells
It produces cells with new genetic combinations
This allows some cells to be adapted to changing conditions
The cells link to each other
It then transfers all or some of its chromosomes to another cell
Recieving cell undergoes binary fission to produce more cells with its new genetic makeup
Plasmids:
Plasmids: small loops of DNA that are separate from the main chromosome
They have different genes than the chromosome
They can split from the chromosome and rejoin it
They can be transferred between cells during conjugation
They are an important means of genetic recombination in prokaryotes
Endospores
They are hard-walled structures that protect and store the organism's genetic material
They are resistant to extreme conditions (such as cold, radiation, and toxic chemicals)
When there are suitable conditions again, the endospore germinates back into an active bacterium
They have only been found in bacteria (not archaea)
Classifying and Identifying Bacteria and Archaea:
Gram stain: a stain that separates bacteria into 2 major divisions (gram positive and gram negative) based on the cell wall's response to the stain
Gram +: have a thick protein layer on their cell wall and stain purple
Gram -: have thin protein layer on cell wall and stain pink
Other methods used to classify and identify prokaryotes: shape, nutrition, movements, genetic components
Bacteria
Bacteria + Human Heath:
Bacteria carrying out their normal functions is the cause of food spoilage and disease
Botulism is a type of food poisoning caused by anaerobic bacteria
This bacteria is found in the soil
It forms endospores tat are resistant to heat and that germinate in anaerobic conditions
They are dangerous if they are trapped with food over a period of time under anaerobic conditions
Other diseases caused by bacteria: strep throat, ear infections, and cavities in teeth
Bacteria + the Environment:
Cyanobacteria produces oxygen through photosynthesis
2 billion years ago, Earth's atmosphere had little or no oxygen
Bacteria was able to release oxygen they made and change the composition of the atmosphere
Cyanobacteria can convert atmospheric nitrogen into a form that can be used by most organisms
Archaea
Archaea + Biotechnology:
Enzymes in only archaea allow it to live in extreme conditions (heat, cold acidity, salinity)
Scientists can use the archaic enzymes when doing DNA analysis or diagnosing diseases because they will not break down when exposed to extreme conditions