Chapter 27 Bacteria And Archaea

Front 1

Describe the structure, composition, and functions of prokaryotic cell walls.

Back 1

Cell wall maintains cell shape, provides physical protection and prevents the cell from bursting in a hypotonic enviroment. wall made up of peptidoglycan, a network of modified-sugar polymers crosslinked by short polypeptides.

Front 2

Distinguish between the structure and staining properties of gram-positive and gram-negative bacteria.

Back 2

Gramp positive has thick cell wall and is purple
Gram negative has thin cell wall and is pink. outer membrane.

Front 3

Describe how prokaryotes carry out photosynthesis and cellular respiration when theylack compartmentalized organelles such as chloroplasts and mitochondria.

Back 3

As well as specialized infoldings of the Prokaryotes plasma membrane ( aerobic prokaryotes's infoldings function as mitochondria in cellular respiration and thylakoid membranes are found in cyanobacteria which function like chloroplasts to conduct photosynthesis).

Front 4

Describe serial endosymbiosis.

Back 4

Eukaryotic cells are derived from prokaryotic cells. Eukaryotic organelles such as mitochondria and chloroplasts derived from endosymbionts ( an organism that lives in the body of another organism) of prokaryotes; smaller prokaryotes living within larger, host prokaryotes gave rise to organelles such as mitochondria and chloroplasts in eukaryotes.

Front 5

Explain why prokaryotes are unable to grow in very salty or sugary foods, such as cured meats or jam.

Back 5

In response to these harsh conditions endospores are formed. In essence, endospores are a tough, multi-layerd wall surrounding a duplicated set of the Prokaryotes' chromosomes. Eventually as water is removed from the cell its metabolism halts, the cell lyses and releases the endospore. In this manner prokaryotes die out in harsh conditions like sugary or salty foods because it puts the prokayotes in a hypertonic enviroments which dehydrates the cell

Front 6

6.State the function(s) of each of the following prokaryotic features:
a.capsule
b.fimbriae
c.sex pilus
d.nucleoid
e.plasmid
f.endospore

Back 6

Capsule- a sticky layer of polysaccharide or proteins. protects against dehydration.
Fimbriae- hair like proteins that help stick to their substrate or to one another.
Sex pili-
appendages that pull two daughter cells together prior to DNA transfer from one cell to another. Longer and less numerous than fimbriae.
Nucleoid- a region of cytoplasm that appears lighter than the surrounding cytoplasm in electron micrographs. Nucleoid region contains rings of prokaryotic genomes (genome: in prokaryotes, a single ring of DNA with few associated proteins.)
Plasmids- smaller rings of DNA found in some prokarytoes, containing only a few genes.
Endospore- a multilayerd, metabolically inactive resistant cell formed from Bacteria when essential nutrients for Bacteria are lacking in environment. Endospores are made when a bacteria duplicates it's chromosomes and surrounds one chromosome with a durable, multi-layered wall. The original cell lyses to leave only the endospore with the original cell's genetic material. Water is removed from Endospore, which halts it's metabolism. Water removal thus halted metabolism is what allows endospore to live for centuries in unfavorable conditions.

Front 7

Three factors that give rise to genetic diversity in Prokaryotes?

Back 7

Rapid reproduction, mutation and genetic recombination.

Front 8

Describe three processes that produce recombinant DNA in prokaryotes.

Back 8

Transformation- Uptake of "naked" DNA from surrounding environment. Many bacteria have specialized surface proteins that recognize and transport closely related bacterial species' DNA into the bacterial cell.
Transduction- Type of horizontal gene transfer when a phage carries bacterial genes from one host cell to another, replacing the some of the homogolous(same) DNA with transfered DNA, giving rise to a recombinant cell.
Conjugation- transfer of genetic material between two bacterial cells that are temporarily joined by a sex pilus, which forms a temporary mating bridge. Conjugation is one-way: one bacterial cell "donates" DNA and another bacterial cell "recieves" donated DNA. The ability to form a sex pilus and donate DNA during conjugation resutls from the presence of an F factor.

Front 9

Explain how R plasmids confer antibiotic resistance on bacteria

Back 9

R plasmids are "resistant genetic fragments" that code for enzymes to alter the surface proteins of pathogens, or bacterial cells, so that the altered surface proteins no longer transport the antibiotic into the cell, thus inhibiting the antibiotics effect or actually destroying the antibiotic.

Front 10

How R plasmids are contributing to the increasing spread of difficult-treating bacterial infections.

Back 10

R plasmids also have genes like F plasmids which encode for the formation of sex pilus, thus intiating conjugation (transfer of genetic material between two temporarily joined bacterial cells). This spreads the R plasmids to daughter cells and multiple bacteria generations.

Front 11

Distinguish among photoautotrophs, chemoautotrophs, photoheterotrophs, and chemoheterotrophs.

Back 11

Photoautotrophs- Photosynthetic organisms that use light as their source of energy to convert inorganic (non-living, non-carbon like the exception CO^2) materials into their necessary carbon source. Ex: Cyanobacteria.
Chemoautotrophs- Oxidize inorganic(non-living, no carbon) substances into their energy form and need only an inorganic molecule like CO^2 to synthesize their carbon. Ex: Sulfolobus
Photoheterotrophs- Harness their energy needs from sun lights but cannot create their carbon needs from inorganic substances thus NEED organic substances(carbon containing) for their carbon needs. Ex: Rhodobacter
Chemoheterotrophs- Must consume organic molecules to obtain their necessary energy and carbon needs. Ex: clostridium

Front 12

Distinguish among obligate aerobes, facultative anaerobes, and obligate anaerobes.

Back 12

Obligate aerobes- An organism that requires O2 to perform cellular respiration.
Obligate anaerobes- An organism that is poisoned by O2 and performs cellular respiration either by fermentation or anaerobic cellular respiration(where inorganic molecules, other than O2, are broken down and accept electrons from electron transfer chains).
Facultative anaerobes- Can use either O2, when available, or fermentation or anaerobic respiration for cellular metabolism.

Front 13

Explain the importance of nitrogen fixation to life on Earth.

Back 13

Nitrogen is essential to all living organisms as it is an essential component of proteins and nucleic acid( where the genetic information of a cell is). Nitrogen fixation is a process where nitrogen fixating prokaryotes convert N2(atmospheric nitrogen that is relatively not very reactive) into ammonia (NH3) , making atmospheric nitrogen available to themselves(the prokaryotes) and eventually all other organisms.

Front 14

Describe the specializations for nitrogen fixation in a filamentous colony of the cyanobacteria Anabaena.

Back 14

Nitrogen fixation takes place in heterocytes, which convert atmospheric nitrogen, N2 into ammonia NH3 which can be used by all organisms, as nitrogen is essential to synthesize proteins and nucleic acid. The specializations within cyanobacteria are unique as cyanobacteria are photosynthetic prokaryotes, meaning they produce O2 from sunlight but O2 inactivates the enzymes used in nitrogen fixation, so within the cyanobacteria Anabaena, there are specialized cells called heterocysts which have thickened walls that prevent the entrance of O2, thus allowing nitrogen fixation to take place.

Front 15

Explain why some archaea are known as extremophiles. Describe the distinguishing features of extreme halophiles and extreme thermophiles.

Back 15

Archaea live in enviroments so extreme that few other organisms can survive there(extremeophiles).
Extreme halpophiles- live in highly saline enviroments
Extreme thermophiles- Thrive in very hot enviornments.

Front 16

Discuss the metabolism and environmental significance of methanogens.

Back 16

Methanogens are Archaea(in the clade Eubacteria) that release methane as byproduct of their unique ways of obtaining energy; many methanogens use CO2 to oxidize H2 which produces both energy and methane waste.
Methanogens are the strictest of Anaerobes, being poisoned by O2.
Methanogens live in either extreme environments, such as under km of ice or in marshes.
They are important factors in sewage treatment as they act as decomposers.

Front 17

Distinguish among mutualism, commensalism, and parasitism. Provide an example of a prokaryote partner in each type of symbiosis.

Back 17

Mutualism- where both symbiotic organisms benefit from their relationship. Within the human intestines, many species of bacteria live and digest food that our own intestines could not do alone, such like the E-coli bacteria.
Commensalism- one symbiotic organism benefits where the other is either unharmed or benefits. An example of a prokaryote commensalism relationship is the bacteria that live on our body surface where we provide them with food like the oils that exude from our pores and in return they do not harm us.
Parasitism -prokaryotes that have an ecological relationship in which a parasite eats the cell contents, tissues or bodily fluids of it's host. One example is the mycobacterium tuberculosis.

Front 18

Distinguish between exotoxins and endotoxins and give an example of each.

Back 18

Exotoxin- proteins secreted by bacteria that cause illness.(Example is botox)
Endotoxins- Lipopolysaccharide attach to the outermembrane of a gram- bacteria.(Example typhoid fever)

Front 19

Describe the evidence that suggests that the dangerous E. coli strain O157:H7 arose through horizontal gene transfer.

Back 19

Scientists sequenced the genome O157:H7 and compared it with the denome of harmless strain of E.coli called K-12. They discovered that 1000 out of 5000 genes in O157:H7 have no counterpart in K-12.

Front 20

Define bioremediation. Describe two examples of bioremediation involving prokaryotes.

Back 20

Bioremediation is the use of organisms to remove pollutants from the soil, air or water. An example of bioremediation with prokaryotes is the decomposing of human sewage into usable fertilizer: Anaerobic bacteria decompose the organic matter into a material that can be used as a fertilizer. Also, as a biodegradable plastic by extracting the polymer PHA which stores energy and converting it into pellets used to make durable, biodegradable plastics.