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chapter 27 Flashcards

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1
Q

What are prokaryotes?

A

Single-celled organisms that lack a nucleus and other membrane-bound organelles

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2
Q

Where can prokaryotes thrive?

A

Almost everywhere, including places that are too acidic, salty, cold, or hot

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3
Q

What is the size range of most prokaryotic cells?

A

0.5–5 μm

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4
Q

Into how many domains are prokaryotes divided?

A

Two domains: Bacteria and Archaea

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5
Q

Where are bacteria commonly found?

A

In nearly every habitat on earth, including soil, water, and inside other organisms

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6
Q

What are some roles of bacteria?

A
  • Beneficial (e.g., gut bacteria)
  • Can cause diseases
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7
Q

In what type of environments are Archaea often found?

A

Extreme environments (e.g., hot springs, deep-sea)

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8
Q

What is a significant characteristic of prokaryotic organisms in terms of their structure?

A

Not all prokaryotes are unicellular; some form colonies

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9
Q

What were likely the Earth’s first organisms?

A

Prokaryotes

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10
Q

How do the sizes of prokaryotic cells compare to eukaryotic cells?

A

Prokaryotic cells are much smaller than eukaryotic cells (0.5–5 μm vs 10–100 μm)

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11
Q

What are the three most common shapes of prokaryotic cells?

A
  • Spheres (cocci)
  • Rods (bacilli)
  • Spirals
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12
Q

What is the primary function of the cell wall in prokaryotic cells?

A
  • Maintains cell shape
  • Protects the cell
  • Prevents it from bursting
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13
Q

What are eukaryotic cell walls primarily made of?

A
  • Cellulose
  • Chitin
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14
Q

What is the main structural component of bacterial cell walls?

A

Peptidoglycan

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15
Q

What do archaeal cell walls contain?

A

Polysaccharides and proteins but lacks peptidoglycan

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16
Q

What is the purpose of the Gram stain?

A

To classify bacteria by cell wall composition

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17
Q

What type of bacteria appear purple/violet after Gram staining?

A

Gram-positive bacteria

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18
Q

What type of bacteria appear pink/red after Gram staining?

A

Gram-negative bacteria

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19
Q

What is the composition of Gram-positive bacteria’s cell wall?

A

Simpler walls with a large amount of peptidoglycan

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20
Q

What is the composition of Gram-negative bacteria’s cell wall?

A

Less peptidoglycan and an outer membrane

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21
Q

Who developed the Gram stain and in what year?

A

Hans Christian Gram in 1884

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22
Q

What are endospores?

A

Metabolically inactive survival forms that remain viable in harsh conditions for centuries

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23
Q

What are fimbriae and their function?

A

Hair-like structures that allow prokaryotes to stick to substrates or other individuals

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24
Q

How do pili differ from fimbriae?

A

Pili (or sex pili) are longer than fimbriae and allow prokaryotes to exchange DNA

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25
How do most motile bacteria propel themselves?
By flagella scattered about the surface or concentrated at one or both ends
26
What are the flagella of bacteria, archaea, and eukaryotes composed of?
Different proteins
27
What is a significant characteristic of the prokaryotic genome compared to the eukaryotic genome?
It has less DNA
28
What is the structure of most prokaryotic genomes?
A circular chromosome
29
Where is the prokaryotic chromosome located?
In the nucleoid region
30
What are plasmids?
Smaller rings of DNA found in some species of bacteria
31
What are the three processes that have differences between prokaryotes and eukaryotes?
DNA replication, transcription, and translation
32
Why can some antibiotics inhibit bacterial growth without harming human cells?
Because human cells don't have cell walls
33
What is the composition of the cell wall in many types of bacteria?
Peptidoglycan
34
Do prokaryotes have a nucleus?
No
35
Do eukaryotes have membrane-bound organelles?
Yes
36
What is the size range of prokaryotic cells?
0.1–5 μm
37
What is the size range of eukaryotic cells?
10–100 μm
38
What type of DNA do prokaryotes have?
Circular (plasmid)
39
What type of DNA do eukaryotes have?
Linear (chromosomes)
40
Give an example of a prokaryotic organism.
E. coli or Streptococcus
41
Give examples of eukaryotic organisms.
Animals, plants, fungi
42
What is binary fission?
A type of asexual reproduction where an organism splits into two identical organisms. ## Footnote Binary fission is common in prokaryotes.
43
What are the three factors that contribute to genetic diversity in prokaryotes?
* Rapid reproduction * Mutation * Genetic recombination ## Footnote Each factor plays a significant role in the evolution of prokaryotic populations.
44
How do prokaryotes reproduce?
By binary fission. ## Footnote This process results in offspring cells that are generally identical to the parent.
45
What is the mutation rate during binary fission?
Low. ## Footnote Despite the low mutation rate, rapid reproduction allows mutations to accumulate quickly.
46
What is genetic recombination?
The process where organisms exchange or combine genetic material. ## Footnote This process increases genetic variation among prokaryotes.
47
What are the methods of genetic recombination in prokaryotes?
* Transformation * Transduction * Conjugation ## Footnote These methods allow for the exchange of genetic material between different individuals.
48
What is horizontal gene transfer?
The movement of genes among individuals from different species or different domains of life. ## Footnote This process contributes significantly to genetic diversity and evolution.
49
What are the three types of Genetic Recombination?
* Transformation * Transduction * Conjugation ## Footnote These processes are essential for genetic variation in prokaryotic organisms.
50
What is transformation in prokaryotic cells?
A process where a prokaryotic cell takes up and incorporates foreign DNA from the surrounding environment into its own genome. ## Footnote This process allows for genetic diversity and adaptation.
51
Define transduction
The transfer of bacterial DNA from one bacterium to another via a virus (bacteriophage). ## Footnote This method can introduce new genetic material into bacterial populations.
52
What is conjugation in prokaryotic cells?
The process where genetic material is transferred between prokaryotic cells via direct cell-to-cell contact. ## Footnote This method is crucial for horizontal gene transfer among bacteria.
53
How does DNA transfer occur during conjugation?
It is one way, from the donor bacterial cell to the recipient. ## Footnote This unidirectional transfer allows for the spread of advantageous traits.
54
What role does the pilus play in conjugation?
A donor cell attaches to a recipient by a pilus, pulls it closer, and transfers DNA. ## Footnote The pilus is essential for establishing the connection between cells.
55
What is the F factor in bacterial conjugation?
A piece of DNA required for the production of pili. ## Footnote The F factor is crucial for the ability of bacteria to engage in conjugation.
56
What is the function of cells containing the F plasmid during conjugation?
They function as DNA donors. ## Footnote This allows for the transfer of genetic material to recipient cells.
57
What role do cells without the F factor play in conjugation?
They function as DNA recipients. ## Footnote These cells receive genetic material from donor cells during the process.
58
Is the F factor transferable during conjugation?
Yes, the F factor is transferable during conjugation. ## Footnote This allows for the propagation of the F plasmid among bacterial populations.
59
What adaptations have evolved in prokaryotes?
Diverse nutritional and metabolic adaptations ## Footnote These adaptations allow prokaryotes to survive in various environments.
60
How can prokaryotes be categorized?
By how they obtain energy and carbon ## Footnote This categorization helps in understanding their metabolic processes.
61
What do phototrophs obtain energy from?
Light ## Footnote Phototrophs are crucial in ecosystems as they convert light energy into chemical energy.
62
What do chemotrophs obtain energy from?
Chemicals ## Footnote Chemotrophs include organisms that oxidize inorganic or organic substances.
63
What is the carbon source requirement for autotrophs?
CO2 ## Footnote Autotrophs can synthesize their own organic compounds from carbon dioxide.
64
What do heterotrophs require to make organic compounds?
An organic nutrient ## Footnote Heterotrophs obtain their energy by consuming other organisms.
65
What type of oxygen requirement do Mycobacterium and Pseudomonas have?
Obligate aerobes – they require O₂
66
Which bacteria can survive with or without oxygen?
facultative anaerobes – examples: E. coli, Staphylococcus.
67
What type of bacteria is poisoned by oxygen?
Obligate anaerobes – example: Clostridium botulinum.
68
Why is nitrogen essential for organisms?
It is needed to make amino acids and nucleic acids
69
What is nitrogen fixation?
The process by which certain prokaryotes convert atmospheric nitrogen (N₂) into ammonia (NH₃), a usable form.
70
Why is nitrogen fixation important?
Most organisms, including plants, cannot use atmospheric nitrogen directly.
71
What is a biofilm?
A community of microorganisms that attach to surfaces coating colonies, forming protective layer
72
What are the benefits of biofilms to microorganisms?
They offer protection from antibiotics and environmental threats and help in long-term survival.
73
What are the two domains of prokaryotes?
bacteria and archaea
74
Name the major groups in the domain Archaea
AOTES Korarchaeotes, Euryarchaeotes, Crenarchaeotes, Nanoarchaeotes
75
Name major groups in the domain Bacteria
Proteobacteria, Chlamydias, Spirochetes, Cyanobacteria, Gram-positive bacteria.
76
What types of metabolism are found in Proteobacteria?
Photoautotrophs, Chemoautotrophs, and Heterotrophs. Some are anaerobic, and others aerobic
77
gram negative bacteria. Some are anaerobic, and others aerobic
proteobacteria
78
alpha protoebacteria ex:
ancestors of mitochondria, rhizobium, agrobacterium
79
beta proteobacteria
nitrosomonas, neiserria
80
gamma proteobacteria
vibrio, salmonella, eccoli, legionella
81
delta proteobacteria
mycobacteria, bdellovibrios
82
epsilon proteobacteria
helicobacteria,campylobacter
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