Ch 24: Bacteria and Archaea

Question 1

Plasmid

Answer 1

In bacteria, a small circular molecule of DNA carrying a small number of genes that replicate independently of the DNA in the bacterium’s circular chromosome.

Question 2

Peptidoglycan

Answer 2

A complex polymer of sugars and amino acids that makes up the cell wall in bacteria.

Question 3

Bacteria

Answer 3

One of the three domains of life, consisting of single-celled organisms with a single circular chromosome but no nucleus that divide by binary fission and differ from archaeons in many aspects of their cell and molecular biology.

Question 4

Archaea

Answer 4

One of the three domains of life, consisting of single-celled organisms with a single circular chromosome but no nucleus that divide by binary fission and differ from archaeons in many aspects of their cell and molecular biology.

Question 5

Carbon Cycle

Answer 5

The intricately linked network of biological and physical processes that shuttles carbon among rocks, soil, oceans, air, and organisms.

Question 6

Horizontal Gene Transfer

Answer 6

The transfer of genetic material between organisms that are not parent and offspring.

Question 7

Conjugation

Answer 7

The direct cell-to-cell transfer of DNA, usually in the form of a plasmid.

Question 8

Transformation

Answer 8

The conversion of cells from one state to another, as from nonvirulent to virulent, when DNA released to the environment by cell breakdown is taken up by recipient cells. In recombinant DNA technology, the introduction of recombinant DNA into a recipient cell.

Question 9

Transduction

Answer 9

Horizontal gene transfer by means of viruses.

Question 10

Oxygenic

Answer 10

Producing oxygen

Question 11

Aerobic

Answer 11

Utilizing oxygen.

Question 12

Anoxygenic

Answer 12

Not producing oxygen; anoxygenic photosynthetic bacteria do not use water as an electron donor and so do not generate oxygen gas.

Question 13

Bacteriochlorophyll

Answer 13

A light-harvesting pigment found in photosynthetic bacteria; closely related to the chlorophyll found in plants, algae, and cyanobacteria.

Question 14

Fermentation

Answer 14

A variety of metabolic pathways that produce ATP from the partial oxidation of organic molecules without oxidative phosphorylation or an electron acceptor, such as oxygen.

Question 15

Photoheterotrophs

Answer 15

An organism that uses the energy from sunlight to make ATP and relies on organic molecules obtained from the environment as the source of carbon for growth and other vital functions.

Question 16

Chemoautotrophs

Answer 16

A microorganism that obtains its carbon by the fixation of carbon dioxide, using energy derived from chemical reactions, not from sunlight.

Question 17

Primary Producers

Answer 17

An organism that takes up inorganic carbon, nitrogen, phosphorus, and other compounds from the environment and converts them into organic compounds; a source of food for heterotrophic organisms in the local environment.

Question 18

Assimilation

Answer 18

The process by which organisms incorporate nutrients obtained from the environment into more complex molecules.

Question 19

Nitrogen Fixation

Answer 19

The process by which some Bacteria and Archaea convert nitrogen gas (N2) into ammonia (NH3), a form biologically useful to primary producers.

Question 20

Nitrification

Answer 20

The process by which chemoautotrophic bacteria oxidize ammonia (NH3) to nitrite (NO2–) and then nitrate (NO3–).

Question 21

Denitrification

Answer 21

The process in which some bacteria use nitrate as an electron acceptor in respiration, releasing N2 to the environment.

Question 22

Anammox

Answer 22

Anaerobic ammonia oxidation; energy metabolism found in some bacteria in which ammonium ions are oxidized by nitrite, yielding nitrogen gas as a by-product.

Question 23

Periodic Selection

Answer 23

The episodic loss of diversity as a successful variant outcompetes others.

Question 24

Proteobacteria

Answer 24

The most diverse bacterial group, defined largely by similarities in rRNA gene sequences; it includes many of the organisms that populate the expanded carbon cycle and other biogeochemical cycles.

Question 25

Gram Positive Bacteria

Answer 25

Bacteria that retain, in their thick peptidoglycan walls, the diagnostic dye developed by Hans Christian Gram. (Bacteria with thin walls, which do not retain the dye, are said to be gram negative.)

Question 26

Cyanobacteria

Answer 26

A monophyletic group of bacteria capable of oxygenic photosynthesis.

Question 27

Hyperthermophiles

Answer 27

An organism that requires an environment with high temperature.

Question 28

Methanogens

Answer 28

Archaea that generate natural gas (methane, CH4) as a by-product of anaerobic energy metabolism.

Question 29

Stramatolites

Answer 29

A layered structure that records sediment accumulation by microbial communities.

Question 30

Coevolution

Answer 30

The process in which species evolve together, each responding to selective pressures from the other.

Question 31

Phylo-phenetic Species Concept

Answer 31

“A monophyletic and genomically coherent cluster of individual organisms that show a high degree of overall similarity in many independent characteristics, and is diagnosable by a discriminative phenotypic property.”

Question 32

Oxygen is generated during a reaction if the process is:

Answer 32

oxygenic

Question 33

What is the equation for anammox?

Answer 33

NH4+ + NO2− → N2 + 2H2O

Question 34

When plants reduce SO4 to form H2S during _____, SO4 _____ electrons.

Answer 34

assimilation; gains

Question 35

T/F: If photosynthesis was mapped on a prokaryotic phylogenetic tree, all photosynthetic groups would have a single common ancestor.

Answer 35

False

Question 36

Because thaumarchaeote archaeons reduce CO2 in their environments to produce organic compounds and also oxidize inorganic substances to gain energy, they are:

Answer 36

chemoautotrophs.

Question 37

A student notices two bacteria cells of the same species in close association with one another, with a thin projection running between them. He assumes that these two cells are fusing, forming a new individual. His instructor informs him that this is not the case. Why?

Answer 37

Cell fusion does not occur with bacterial cells, and these cells are likely undergoing conjugation.

Question 38

T/F: Fermentation can be performed only by bacteria and not by archaeons.

Answer 38

False

Question 39

T/F: H2S is absorbed from the environment by bacteria, algae, and plants; however, this molecule is quickly reduced by organisms to form SO4-.

Answer 39

False

Question 40

A researcher is culturing several different strains of bacteria in the same petri dish. One day, he finds that all of the strains have died off except one. He continues to grow his bacteria for several weeks, and new strains develop. However, after a month he again notices that all but one of his bacterial strains have died off. This is an example of:

Answer 40

Periodic Selection

Question 41

You may know that scientists are able to synthesize new strands of DNA through a process known as PCR, which utilizes a DNA polymerase derived from bacteria. By repeatedly heating the reaction products to 70˚C, researchers can create new DNA from a template DNA strand. What does this tell you about bacteria compared to archaeons?

Answer 41

Some bacteria can survive at high temperatures, although archaeons can survive in much hotter environments.

Question 42

The fossil record shows life originated on Earth at least 3.5 billion years ago and consisted entirely of microorganisms. Paleontologists provide the strongest evidence of this conclusion through the discovery of:

Answer 42

stromatolites

Question 43

T/F: Chemoautotrophy is unique to prokaryotes because eukaryotes cannot use inorganic compounds as a chemical energy source.

Answer 43

True

Question 44

A biologist draws a tree of life having only three branches. Which groups did the biologist most likely choose for her diagram?

Answer 44

Archaea, Bacteria, and Eukarya

Question 45

A researcher is comparing the sequences of genes encoding cell wall proteins in archaeons with those coding cell wall proteins in bacteria. How similar do you expect these sequences will be?

Answer 45

These sequences will be dissimilar, as archaeon cell walls are not composed of peptidoglycan.

Question 46

_____ is an element that is abundant in Earth’s atmosphere; however, usable forms of this element, such as ammonia, are comparatively rare in certain soils. Symbiotic relationships between plants like soybeans and bacteria have formed to circumvent this problem.

Answer 46

Nitrogen

Question 47

_____ results in the oxidation of NH3 to form NO3-, and _____ results in the reduction of NO3- to form N2.

Answer 47

Nitrification; denitrification