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Biodiversity > Ch.24 > Flashcards

Ch.24 Flashcards

1
Q

Progressive Hypothesis

A

proposes that viruses evolved from mobile genetic elements, which acquired the ability to exit host cells and become infectious agents through the addition of structural proteins proposes that viruses evolved from more complex, possibly free-living organisms that gradually lost genetic information as they became obligate intracellular parasites proposes that viruses or virus-like entities existed before cellular life, potentially serving as precursors to the development of cells and playing a crucial role in the evolution of early life forms

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2
Q

Regressive Hypothesis

A

proposes that viruses evolved from more complex, possibly free-living organisms that gradually lost genetic information as they became obligate intracellular parasites

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3
Q

Virus-First Hypothesis

A

proposes that viruses or virus-like entities existed before cellular life, potentially serving as precursors to the development of cells and playing a crucial role in the evolution of early life forms

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4
Q

Viruses are not cellular, but they:

A

• Infect all cellular forms of life.
• Replicate, mutate, evolve, and interact with other organisms.
• Evolve independently of other organisms.
• Are derived from cells of other living organisms
* same forms of genetic information storage & transmission

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5
Q

There are far more metabolic pathways in the __________________ than the ____________________

A

archaea & bacteria / eukaryotes

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6
Q

Eukaryote energy metabolism is done

A

in mitochondria and chloroplasts that are descended from bacteria.

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7
Q

Anaerobes do not

A

use oxygen as an electron acceptor in respiration.

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8
Q

obligate anaerobes

A

oxygen is poisonous to them

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9
Q

facultative anaerobes

A

can shift metabolism between aerobic and anaerobic modes, such as fermentation

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10
Q

________________ cannot survive without oxygen

A

obligate aerobes ( NOT obligate Anaerobes )

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11
Q

what anaerobes are not damaged by oxygen but do not conduct cellular respiration

A

Aerotolerant anaerobes

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12
Q

photoautotrophs

A

perform photosynthesis

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13
Q

Bacteriochlorophyll absorbs longer wavelengths ( infrared light ) than chlorophyll which means…

A

they can live in water underneath dense layers of algae

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14
Q

Photoheterotrophs

A

use light as an energy source, but get carbon from compounds made by other organisms—carbohydrates, fatty acids, alcohols.

Sunlight provides ATP through photophosphorylation

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15
Q

Chemoautotrophs

A

get energy by oxidizing inorganic compounds and use the energy to fix CO2

Some oxidize ammonia or nitrite ions to form nitrate ions; others oxidize H2, H2S, S, and others

Many prokaryotic archaea are chemoautotrophs.

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16
Q

Chemoheterotrophs

A

obtain both energy and carbon from complex organic compounds that were synthesized by other organisms

Most bacteria and prokaryotic archaea are chemoheterotrophs, as are all animals, all fungi, and many protists

17
Q

lithotrophs

A

species that get energy from breakdown of inorganic molecules

18
Q

Many prokaryotes are decomposers

A

Organisms that metabolize dead organic compounds

The products, such as CO2, are returned to the environment, key steps in the cycling of elements

19
Q

Denitrifiers

A

use NO3– as an electron acceptor in anaerobic conditions, and release Nitrogen gas (N2 )

(e.g., species of Bacillus and Pseudomonas)

20
Q

Nitrogen fixers

A

convert atmospheric Nitrogen gas (N2) into ammonia (NH3)

This vital process is carried out by many archaea and bacteria, including cyanobacteria, but no other organisms.

21
Q

Nitrifiers are…

A

chemoautotrophic bacteria

Nitrosomonas and Nitrosococcus oxidize ammonia (NH3) to nitrite (NO2–) .
Nitrobacter oxidizes nitrite (NO2–) to nitrate (NO3–)

Electrons from the oxidation are passed through an electron transport chain

22
Q

Deep-sea hydrothermal vent ecosystems depend on

A

chemoautotrophic prokaryotes

These bacteria get energy by oxidizing H2S and other compounds released from the volcanic vents

23
Q

Why Virus phylogeny is still poorly known ?

A

• Viral genomes are tiny, which restricts analyses that can be done.
• Rapid mutation rate and evolution cloud evolutionary relationships.
• There are no known viral fossils.
• They are very diverse and probably evolved repeatedly.
* evolved rapidly among each of the major groups of life

24
Q

what are viruses classified on ?

A

genome structure

25
Q

Hadobacteria

A

are thermophiles (heat lovers)

26
Q

extremophiles

A

thrive under extreme conditions that Would kill most Other organisms

27
Q

Deinococcus

A

are resistant to radiation, can consume nuclear waste and other toxic materials, and survive extreme cold as well as heat

28
Q

Thermus aquaticus

A

originally isolated from a hot spring, was the source of thermally stable DNA polymerase, critical for development of PCR

29
Q

T. aquaticus

A

is found wherever hot water occurs (including hot water heaters)

30
Q

hyperthermophilic bacteria

A

Extreme thermophiles that live in hot springs, near volcanic vents, deep oil deposits, and other hot environments

31
Q

Firmicutes

A

mostly low GC gram-positive bacteria with genomes that have a low ratio of G-C to A-T
nucleotide base pairs

32
Q

endospores

A

heat-resistant resting structures with tough cell walls and spore coats that can survive harsh conditions because they are dormant

Closteridium and Bacillus form endospores. Some can be reactivated after 1,000 years of dormancy

Bacillus anthracis (anthrax) endospores activate when they sense the presence of macrophages in mammal blood

It has been used as a bioterrorism agent

33
Q

Staphylococcus ( staphylococci )

A

are abundant on skin and cause boils and other skin problems

34
Q

S. aureus

A

causes skin diseases and respiratory, wound, and intestinal infections

35
Q

S. aureus

A

causes skin diseases and respiratory, wound, and intestinal infections

36
Q

mycoplasmas

A

have no cell wall, are extremely small, and have very small genomes

They have less than half as much DNA as other prokaryotes, which may represent the minimum amount of DNA needed for a living cell

37
Q

Actinobacteria (high-GC Gram-positives)

A

High ratios of G-C/A-T base pairs
Form elaborately branching filaments

Some reproduce by forming chains of spores at the filament tips

Actinobacteria includes Mycobacterium tuberculosis

Most antibiotics are derived from the actinobacteria
Streptomyces produces streptomycin and hundreds of other antibiotics.

38
Q

Photosynthetic

A

uses chlorophyll alpha and release O2 gas

many species fix nitrogen

Biodiversity (3 decks)

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