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Cell bio > Chapter 27 Prokaryotes > Flashcards

Chapter 27 Prokaryotes Flashcards

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1
Q

What are prokaryotes?

A

Prokaryotes are unicellular organisms that lack a nucleus and include bacteria and archaea.

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2
Q

When did prokaryotes first appear on Earth?

A

Prokaryotes first appeared approximately 3.5 billion years ago.

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3
Q

What is the size range of prokaryotic cells?

A

Prokaryotic cells typically range from 0.5 to 5 µm in diameter.

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4
Q

What is the function of the prokaryotic cell wall?

A

The cell wall maintains cell shape, protects the cell, and prevents it from bursting in hypotonic environments.

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5
Q

What is the composition of bacterial cell walls?

A

acterial cell walls are made of peptidoglycan, a sugar-polypeptide polymer.

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6
Q

How do archaeal cell walls differ from bacterial cell walls?

A

Archaeal cell walls lack peptidoglycan and are composed of polysaccharides and proteins.

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7
Q

What is the Gram staining technique used for?

A

Gram staining is used to categorize bacteria based on cell wall composition.

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8
Q

What are the characteristics of Gram-positive bacteria?

A

Gram-positive bacteria have a thick peptidoglycan layer and stain purple.

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9
Q

What are the characteristics of Gram-negative bacteria?

A

Gram-negative bacteria have a thin peptidoglycan layer with an outer membrane made of lipopolysaccharides and stain pink/red.

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10
Q

What are capsules and slime layers in prokaryotes?

A

Capsules are dense and well-defined outer layers, while slime layers are looser and less organized. Both enable adhesion and provide protection.

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11
Q

What are endospores?

A

Endospores are resistant, dormant structures formed by some bacteria to survive extreme conditions.

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12
Q

What are fimbriae and pili?

A

Fimbriae are hairlike appendages for attachment, while pili are longer appendages involved in DNA transfer.

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13
Q

What is the structure of bacterial flagella?

A

Bacterial flagella consist of a motor, hook, and filament, and are composed of 42 different proteins.

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14
Q

What is taxis in prokaryotes?

A

Taxis is the directed movement of prokaryotes in response to stimuli, such as chemotaxis towards nutrients or away from toxins.

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15
Q

How do prokaryotic genomes differ from eukaryotic genomes?

A

Prokaryotic genomes are typically single circular chromosomes located in the nucleoid, with additional DNA in plasmids.

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16
Q

What is binary fission?

A

Binary fission is the process by which prokaryotes reproduce, leading to exponential population growth under ideal conditions.

17
Q

What are the three mechanisms of genetic recombination in prokaryotes?

A

The three mechanisms are transformation, transduction, and conjugation.

18
Q

What is transformation in prokaryotes?

A

Transformation is the uptake of foreign DNA from the surroundings by a prokaryotic cell.

19
Q

What is transduction in prokaryotes?

A

Transduction is the transfer of DNA from one bacterial cell to another by bacteriophages.

20
Q

What is conjugation in prokaryotes?

A

Conjugation is the transfer of DNA between two bacterial cells that are temporarily connected.

21
Q

What is the F factor in prokaryotes?

A

The F factor (fertility factor) is a DNA segment that allows the formation of pili and DNA transfer during conjugation.

22
Q

What are R plasmids?

A

R plasmids are plasmids that carry antibiotic resistance genes.

23
Q

What are the oxygen requirements for prokaryotic metabolism?

A

Prokaryotes can be obligate aerobes, obligate anaerobes, or facultative anaerobes.

24
Q

What is nitrogen fixation?

A

Nitrogen fixation is the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by certain prokaryotes.

25
Q

What is metabolic cooperation in prokaryotes?

A

Metabolic cooperation involves prokaryotic cells working together to utilize environmental resources, such as in biofilms or filamentous cyanobacteria.

26
Q

What are biofilms?

A

Biofilms are surface-coating colonies of prokaryotic cells that produce polysaccharides and proteins to stick together and to surfaces.

27
Q

What is the significance of prokaryotic diversity and evolution?

A

Prokaryotes have diversified extensively over billions of years, adapting to nearly all life-sustaining environments and playing crucial roles in ecosystems.

28
Q

What are extremophiles?

A

Extremophiles are archaea that thrive in extreme conditions, such as high salinity or high temperatures.

29
Q

What are methanogens?

A

Methanogens are archaea that produce methane as a by-product of energy production and are strict anaerobes.

30
Q

What is the ecological importance of prokaryotes?

A

Prokaryotes are essential for nutrient cycling, decomposition, and maintaining ecosystem health.

Cell bio (18 decks)

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