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Prokaryotes Flashcards

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1
Q

What are the two main methods by which organisms are classified?

A

Taxonomy and phylogeny.

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2
Q

Describe taxonomy.

A

Taxonomy is the classification of life according to specific rules, based on shared characteristics.

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3
Q

From broad to specific, what are the 8 levels of classification within taxonomy?

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Dreaded King Phillip Came Over For Great Spaghetti.

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4
Q

Phylogeny is based on what and is often represented by what?

A

Phylogeny is the classification of life based on the evolutionary history of a group of organisms. It is often depicted in a phylogenetic tree, wherein any two “nodes” root back to a common ancestor.

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5
Q

What do all bacteria and archaebacteria have in common? (3)

A

These are all prokaryotic and unicellular organisms. Their genomes are simple; consisting of a single chromosome located in the nucleoid region. They reproduce asexually through binary fission.

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6
Q

What is unique to only a fraction of all bacteria and archaebacteria? (3)

A

Only a small percentage are pathogenic (disease causing), the majority are essential for life on earth, some have flagella for motion and only some bacteria can form endospores.

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7
Q

What is an endospore?

A

A resistant cell in a dormant state, capable of withstanding harsh conditions and surviving for centuries.

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8
Q

The first bacteria and archaebacteria arose _____ years ago.

A

The first bacteria and archaebacteria arose 3.5 billion years ago.

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9
Q

Are there more prokaryotes or more eukaryotes in the biosphere?

A

Prokaryotes dominate the biosphere, there are more prokaryotes than eukaryotes.

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10
Q

Describe the cell wall of bacteria.

A

Bacteria cells are surrounded by cell walls made of peptidoglycan, which are sugar polymers, cross-linked by short peptides. Some bacteria are surrounded by a gelatinous capsule which protects bacteria against host defenses. This gelatinous capsule covers the molecules that would be recognized by antibodies.

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11
Q

What are the 3 functions of a bacterium’s cell wall?

A

To maintain cell shape (rod, sphere, spiral), to protect the cell and to prevent the cell from bursting in a hypotonic environment.

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12
Q

Do archaea have peptidoglycan in their cell walls?

A

No, archaea cells walls do not contain peptidoglycan.

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13
Q

What are the common bacteria cell shapes?

A

Bacilli (singular bacillus) are rod-shaped. Cocci (singular coccus) are sphere shaped. Spirilla (singular spirillum) are spiral shaped.

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14
Q

What are the characteristics of gram positive bacteria?

A

Gram positive bacteria have a large amount of peptidoglycan and appear purple after stain.

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15
Q

What are the characteristics of gram negative bacteria?

A

Gram negative bacteria have a small amount of peptidoglycan and appear pink after stain. These have an outer membrane containing lipopolysaccharide (endotoxin) and are more pathogenic (disease causing).

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16
Q

What are autotrophs?

A

Autotrophs acquire carbon from inorganic sources.

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17
Q

What are heterotrophs?

A

Heterotrophs acquire carbon from organic sources.

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18
Q

What are phototrophs?

A

Phototrophs obtain energy from light.

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19
Q

What are chemotrophs?

A

Chemotrophs obtain energy from chemical sources (either organic or inorganic molecules).

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20
Q

What is a photoautotroph?

A

Photoautotrophs acquire energy from light and their carbon from either CO2, HCO3-, etc. These consist of photosynthetic prokaryotes, plants & certain protists.

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21
Q

What is a chemoheterotroph?

A

Chemoheterotrophs acquire energy and carbon from organic compounds. These consist of many prokaryotes and protists, fungi, animals and some plants.

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22
Q

What are saprotrophs?

A

Saprotrophs are a type of chemoheterotroph that absorb nutrients from dead organisms (decomposers).

23
Q

Why is cyanobacteria significant?

A

Cyanobacteria (blue-green algae) are photoautotrophs that increased the concentration of O2 in the atmosphere around 2.3 billion years ago, making complex life possible.

24
Q

What are obligate aerobes?

A

Obligate aerobes are prokaryotes that require O2 for cellular respiration (aerobic respiration).

25
Q

What are facultative anaerobes?

A

Facultative anaerobes can grow in both the presence and absence of O2.

26
Q

What are obligate anaerobes?

A

Obligate anaerobes are unable to grow in the presence of O2. They use fermentation of anaerobic respiration in the absence of oxygen to produce ATP.

27
Q

How are vegetables pickled by bacteria?

A

Obligate aerobes convert sugars in vegetables into lactic acid by fermentation.

28
Q

Why don’t prokaryotes have mitochondria or chloroplasts?

A

Prokaryotes do not have mitochondria or chloroplasts because they are the ancestors of these organelles.

29
Q

How do aerobic, heterotrophic prokaryotes perform cellular respiration?

A

Aerobic, heterotrophic prokaryotes have a respiratory membrane, allowing for cellular respiration (specialized membrane).

30
Q

How do photoautotrophic prokaryotes perform photosynthesis?

A

Photoautotrophs have thylakoid membranes that allow for photosynthesis (specialized membrane).

31
Q

What is endosymbiosis?

A

Endosymbiosis is the theory that the endomembrane system formed through the in-folding of the plasma membrane and that mitochondria and plastids (such as chloroplasts) formed through endosymbiosis. The prokaryotes were engulfed by ancestral eukaryotes.

32
Q

Why do prokaryotes have limited metabolic activities, compared to eukaryotes?

A

Prokaryotes have limited metabolic activities because they are smaller, less compartmentalized and have a smaller genome than eukaryotes.

33
Q

What evidence is there supporting the theory of endosymbiosis?

A

Mitochondria and chloroplasts (among other plastids) are similar in size to prokaryotes, have membranes that contain proteins also found in prokaryotes, are split by binary fission, contain circular DNA and contain tRNA, ribosomes and other components required for transcription/translation.

34
Q

Some prokaryotes live in _____ with a host.

A

Some prokaryotes live in symbiosis with a host.

35
Q

What are the three types of symbiosis?

A

Symbiosis is when a smaller symbiont lives in close contact with a larger host. The three types of symbiosis are mutualism, commensalism and parasitism.

36
Q

What is mutualism?

A

Mutualism is when both the symbiont and the host benefit from the relationship.

37
Q

What is commensalism?

A

Commensalism is when only the symbiont benefits from the relationship, however the host is left unharmed.

38
Q

What is parasitism?

A

Parasitism is when the symbiont benefits from the relationship but the host is harmed.

39
Q

Why are prokaryotes ecologically important?

A

The existence of all other life is dependent on prokaryotes, as they are necessary for the chemical recycling between the living and nonliving components of the ecosystem.

40
Q

What do saprophytic prokaryotes do?

A

Saprophytic prokaryotes function as decomposers to break down dead organisms and waste products. They consume dead organic matter and transform it into inorganic matter to be used by producers.

41
Q

What do nitrogen-fixing prokaryotes do?

A

Nitrogen-fixing prokaryotes convert atmospheric nitrogen into ammonia (NH4). Certain biomolecules (especially proteins) require nitrogen, but most organisms cannot grab nitrogen gas from the atmosphere, except for nitrogen-fixing prokaryotes. These transform nitrogen into a form that is usable by other organisms.

42
Q

Archaea look similar to bacteria but have features in common with both _____ and _____.

A

Archaea look similar to bacteria but have features in common with both bacteria and eukaryotes.

43
Q

Do archaea have a nuclear envelope?

A

Like bacteria, archaea do not have a nuclear envelope.

44
Q

Do archaea have membrane bound organelles?

A

Like bacteria, archaea do not have membrane bound organelles.

45
Q

Do archaea have peptidoglycan in their cell walls?

A

Like eukaryotes, archaea do not have peptidoglycan in their cell walls.

46
Q

Do archaea have several kinds of RNA polymerase?

A

Like eukaryotes, archaea do have several kinds of RNA polymerase (rather than just one kind).

47
Q

What is the initiator amino acid for protein synthesis in archaea?

A

Like eukaryotes, the initiator amino acid for protein synthesis is methionine.

48
Q

Do archaea have introns in their genes?

A

While introns are common in many eukaryotic genes and are very rare in a bacterium’s genes, they are present in some genes within archaea.

49
Q

What is an intron?

A

An intron is a segment of mRNA that is chopped out in the conversion from pre-mRNA to mRNA.

50
Q

How do archaea respond to antibiotics (streptomycin and chloramphenicol)?

A

Like eukaryotes, the growth of archaea in the presence of these antibiotics is not affected.

51
Q

Do archaea have histones associated with their DNA?

A

While histone proteins are present in all eukaryotic species and absent from all bacteria, they are present in some species of archaea.

52
Q

Do archaea have circular chromosomes?

A

Like bacteria, archaea have a circular chromosome.

53
Q

Some archaea are known to _____ and _____ in extreme conditions.

A

Some archaea are known to grow and thrive in extreme conditions.

Biology (12 decks)

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