L11B BACTERIA & ARCHAEA Flashcards

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1
Q

What type of cells are bacteria & archaea?

A

Prokaryotes.

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2
Q

List the defining features of prokaryotes. (6)

A
  1. Most are unicellular and small 0.5-10um
  2. They lack a nucleus
  3. They have a simple genome and one circular chromosome
  4. Most have a cell wall
  5. They have a ribosome structure different than eukaryotes
  6. They reproduce asexually through binary fission.
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3
Q

TRUE OR FALSE: Prokaryotes are only found in moist environments.

A

FALSE: Prokaryotes are everywhere and are the most abundant organism on earth.

think of bacteria when you think of prokaryote!!

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4
Q

What are the two main variations in metabolic diversity of prokaryotes? What are the two sub-types of each?

A

Sources of energy (CHEMOtroph: energy from chemical bonds or PHOTOtroph: energy from sunlight.)

Sources of carbon (AUTOtroph: inorganic CO2 or HETEROtroph: organic compounds like sugar, fat, carb, AA, protein.)

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5
Q

Fill in the blanks.

A
  1. Photoautotroph
  2. Photoheterotroph
  3. Chemoautotroph
  4. Chemoheterotroph
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6
Q

Name the two types of -trophs that only prokaryotes use.

A

Photoheterotrophism and Chemoautotrophism.

Plants and some protists are photoautotrophic (photosynthesis), and all Animals & Fungi and many protists are chemoheterotrophic.

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7
Q

Describe the different types of anaerobes found in prokaryotes.

A
  1. Obligate aerobes: need O2 for cellular respiration
  2. Obligate anaerobes: poisoned by O2.
  3. Facultative anaerobes: can use O2 if present but is not necessary
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8
Q

What is binary fission?

A

Process whereby prokaryotic cells reproduce. The DNA replicates and the cell grows, then it divides and each daughter cell receives identical copy of parental DNA.

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9
Q

If bacteria reproduce asexually, how is there so much genetic diversity among them? (4)

A

4 different ways:
1. Mutation ie. horizontal gene transfer
2. Transduction ie. virus
3. Transformation ie. picking up DNA bits from environment
4. Conjugation ie. genetic material transfer thru sex pilus

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10
Q

How do archaea siffer from bacteria? (3)

A
  1. They lack peptidoglycan in their cell walls.
  2. Their cell membranes have unique membrane lipids
  3. Their DNA & RNA structures differ from bacteria.
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11
Q

Name the three groupings within Archaea.

A
  1. Methonogens live under anaerobic environments (ie herbivore gut) where they produce methane.
  2. Halophiles live under high salt concentrations (ie great salt lake)
  3. Thermoacidophiles live in hot acidic environments (ie hydrothermal vent)
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12
Q

What is an extremophile?

A

Archaebacteria that lives in extreme environments.

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13
Q

What is the relation between the circular DNA and the plasmid in prokaryotes?

A

The DNA in the nucleiod region holds the information necessary for the existence of the bacteria, and plasmids are smaller fragments of DNA that usually don’t carry genes essential for survival.

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14
Q

What is transduction?

A

Transduction is a virus aka phage injecting its DNA into recipient cell’s chromosome.

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15
Q

What is conjugation?

A

Transfer of genetic material (DNA and plasmids) between two bacteria via sex pilus.

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16
Q

What is transformation?

A

Bacteria cell picks up pieces of DNA from surroundings.

17
Q

What is horizontal gene transfer?

A

The movement of genetic material through mating barriers between two bacteria.

18
Q

What is the use for plasmids?

A

They carry special genes useful in certain situations. IE plasmid can hold gene for antibiotic resistance, and when exposed those individuals will survive.

19
Q

How do bacteria survive extreme conditions?

A

By producing endospores: dormant, tough, NON REPRODUCTIVE structures that encloses cells until it can rehydrate in better environment.

20
Q

What is an endospore?

A

Structure that helps bacteria survive. It is tough and dormant and can survive extreme heat, cold, dryness, frozen environments. Will rehydrate and revive in mor favourable contitions.

21
Q

List economic benefits of bacteria (4).

A
  1. Produces lactic acid that aids in curdling cheese & yogourt.
  2. Act as probiotic in human gut microbiome.
  3. Produce antibiotics
  4. Used in BIOREMEDIATION: bacterial decontamination of a site (toxin breakdown)
22
Q

List ecological benefits of bacteria(4 basic).

A
  1. Their major role is in decomposition
  2. Eubacteria are pathogenic (disease causing)
  3. Are mutualistic symbionts with many organisms.
  4. Cyanobacteria are important producers of useable oxygen.
23
Q

relating to ecological significance

Describe different mutualistic symbionts between bacteria & other organisms. (3!)

A
  1. Herbivores: they eat grass but dont have the enzyme needed to break down cellulose. bacteria break down the cellulose for them in exchange for shelter and food.
  2. Humans: gut symbionts produce vitamins, aid in digestion, prevent pathogen invasion.
  3. Plants: bacteria fixes unuseable N2 to useable NH3 or NO3 ions
24
Q

relating to ecological significance

What is commensalism?

A

An ecological relationship in which one species benefits and the other is not harmed or helped in any significant way.
We have commensal bacteria in our pores.

25
Q

Describe the 5 steps of nitrogen fixation.

A
  1. Nitrogen Fixation: bacteria take N2, fix to NH4+
  2. Ammonification: fungi decompose organic material to NH4+.
  3. Nitrification: bacteria convert the NH4+ produced in steps 1 & 2 to useable NO3+ for plant use.
  4. Assimilation: roots absorb useable NO3+ and NH4+.
  5. Denitrification: reduction of nitrates resulting in gaseous N2 release.
26
Q

Why are cyanobacteria now considered bacteria instead of algae?

A

They lack a membrane-bound nucleus and chloroplasts.