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B202 > Ch.27 - Bacteria and Archaea > Flashcards

Ch.27 - Bacteria and Archaea Flashcards

1
Q

Goals of Ch.27

  • Identify components of prok cells and diff fr euk cells
  • Know classifications based on cell shape/wall
  • Explain, in detail, the three ways genetic recombination occurs in proks
A

Goals of Ch.27

  • Identify components of prok cells and diff fr euk cells
  • Know classifications based on cell shape/wall
  • Explain, in detail, the three ways genetic recombination occurs in proks
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2
Q

Lifes earliest division involved what?

A

Proks diverged v early into two lineages:

  • Archaea: some bac traits/ some euk traits/ many unique traits
  • Bacteria: extremely diverse, every mode of nutrition and metabolism
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3
Q

Collective mass of proks is _____ (more or less) than ten times mass of all euks

A

Collective mass of proks is MORE than ten times mass of all euks, i.e. proks are “dominant” orgs.

of proks in handful of soil is greater than # of people who have ever lived

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4
Q

Describe the general struc, size, and shape of proks

A

Most unicellular; some form colonies

Most 0.5 μm - 5 μm (1μm=1/1000 of a mm)

Shapes:

  • Cocci (spheres)
  • Bacilli (rods)
  • Spirals

Arrangement:

  • Di- = two cocci side-by-side
  • Strepto- = string of cocci
  • Staphylo- = bowling pins
  • Sarcina = cube
  • Tetrad = square
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5
Q

Effect of hyper- vs hypotonic environ on cell

A
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6
Q

Bac cell walls contain ____________, a network of modified sugar polymers crosslinked by other short polymers

A

Bac cell walls contain peptidoglycan, a network of modified sugar polymers crosslinked by other short polymers

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7
Q

T/F: like bac, archael cell walls also contain peptidoglycans

A

FALSE

Archaeal cell walls contain a variety of polysacchs and proteins but lack peptidoglycan

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8
Q

Identify gram-positive vs -negative bac in attached imaged, and describe characteristics of assoc cell wall

A

Gram positive = dark blue/purple

  • Simple walls
  • Relativey high amnt of peptidoglycan

Gram negative = pink/red

  • Complex walls
  • Less peptidoglycan
  • Outer layer contains lipopolysacchs
  • Lipid layer
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9
Q

Gram-pos/neg and infection/treatment

A

Gram positive:

  • Some antibiotics (ex. penicillin) inhibit crosslinking of peptidoglycans
  • Can also evolve antibiotic resistance

Gram negative:

  • Complex outer layer is often resistant to body’s defenses and entry of antibiotics
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10
Q

What is a capsule?

A

Capsule: sticky layer of polysacchs or proteins that forms a covering over a cell wall

  • Enables bac to adhere to colony or substrate
  • May also protect against dehydration or attacks by host’s immune system
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11
Q

Compare fimbriae and sex pili

A

Fimbriae (singular: fimbria): hairlike protein appendages; allow proks to stick to substrate or one/an

  • Aka attachment pili

Sex pili: longer than fimbrae, allow proks to exchange DNA

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12
Q

~___% of proks are capable of directional movement

A

~50% of proks are capable of directional movement

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13
Q

Taxis vs flagella

A

Taxis: movement toward/away fr stimulus

Flagella (singular flagellum):

  • 1/10 as wide as euk flagella
  • not covered by pmem
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14
Q

Proks lack mem-bound organelles like mito. How is metabolism performed?

A

Specialized mems

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15
Q

Describe genome of proks

A

Typ genome: circular chromo, less DNA, and fewer proteins

  • Plasmids: smaller rings of separately replicating DNA
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16
Q

Where are prok chromos located w/i cell?

A

Nucleoid region

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17
Q

What are plasmids?

A

Plasmids are smaller rings of separately replicating DNA

18
Q

Proks have characteristically adapted to some extreme environs. Describe possible adaptations

A

Endospore forms when nutrients are limited

Tough wall around chromo copy

Metabolism halts when water lost

Cell disintegrates

Endospore survives in soil for years

19
Q

Halophiles and thermophiles are two types of ________

A

Halophiles and thermophiles are two types of archaea (extremophiles)

Halophiles: high-salt environments

Thermophiles: extreme heat, adaptations keep DNA from denaturing

20
Q

How do proks reproduce?

A

Binary fission: single prok cell divides into two cells

  • Under ideal conditions will divide once every 1-3 hours
  • Limits on reprod: exhaust nutrition supply, buildup of waste, competition, predation
21
Q

Why are proks so genetically variable?

A
  1. Rapid reprod
  2. Mutation
  3. Genetic recombination (transformation, transduction, conjugation)

For sexually reproducing species (i.e. NOT proks), most GV comes fr reshuffling allele combinations.

22
Q

For sexually reproducing species (i.e. NOT proks), most GV comes fr reshuffling allele combinations.

How, then, does genetic recomb contrib to prok GV?

A

Transformation - foreign DNA incorporated into genome.

Transduction - phage infiltrates → DNA recombines

Conjugation - GM xfrd b/w bac cells temporarily joined

23
Q

Describe genetic transformation in proks

A

Foreign DNA fr environ taken in (recog by cell surface proteins)

DNA incorporated into genome

Harmless strains can become harmful if alleles from pathogen strains brought in

24
Q

Describe genetic transduction in bac

A

Bacteriophages: viruses that infect bac; carry bac DNA b/w hosts.

  1. Phage infects bac
  2. Some new phages have bac DNA
  3. Recipient cell infected
  4. Host cell DNA recombines w recipient DNA

Results in a recombinant cell

25
Describe genetic conjugation in proks
GM xfrd b/w two bac cells that are temporarily joined **One-way xfr**: donor cell uses sex pili to attach to recipient cell **F factor (f=fertility):** piece of DNA w ~25 genes (most produce sex pili) * Can exist as plasmid or segment of chromo
26
An **F factor** is a piece of DNA w ~25 genes, most of wh prod sex pili. Describe F factor in *plasmids*
**F+ cells**: donors, have F factor as plasmid **F- cells**: receivers, DO NOT have F factor Sex pili forms mating bridge → F plasmid may be xfr'd; recipient cell becomes F+
27
An **F factor** is a piece of DNA w ~25 genes, most of wh prod sex pili. Describe F factor in *chromos*
**Hfr cell** (High Freq of Recomb) F factor in chromo – functions as *donor* Homologous DNA segments align w donor cell DNA → recipient cells *unlikely* to become F+
28
What are R plasmids, and how are they typ xfrd?
**R plasmids** (r=resistance): carry genes that **↓ antibiotics’ effectiveness** Typ xfrd cell-to-cell by **conjugation** Exposure to antibiotics provides selection for cells w resistance
29
T/F: All known pathogenic proks are bacteria
TRUE **All known pathogenic proks are bacteria**, i.e. no archaea * Bac orgs cause ~50% of all human disease * Illness typ caused by poisons produced
30
Exo vs endotoxins
**Exotoxins**: *proteins secreted* by bac * Signals body cells to carry out harmful actions, e.g. cholera → diarrhea **Endotoxins**: *lipopolysacchs* of outer *mem* of *gram-neg* bac. * Released only when bac die → cell walls break down, e.g. Salmonella
31
\_\_\_\_\_\_\_\_\_\_\_\_ is a form of antibiotic resistance in wh virulent genes are spread to normally harmless bac.
**Horizontal gene transfer** is a form of antibiotic resistance in wh virulent genes are spread to normally harmless bac. * E.g. pathogenic E. coli strains
32
Why do we place plants, fungi, and proks in diff taxa?
We place plants, fungi, and prokaryotes in difftaxa due to their **cell walls are composed of v diff biochemicals**
33
T/F: some, but not all, deuterostomes have a pseudo coelom
FALSE ALL deuterostomes have a pseudo coelom
34
T/F: Similar to most amoebozoans in the Unikonton group, some radiolarians have pseudopodia
TRUE Similar to most amoebozoans in the Unikonton group, some radiolarians have pseudopodia
35
T/F: Most cells retain full range of function in simple multicellularity
TRUE Most cells retain full range of function in simple multicellularity
36
T/F: Cell walls prevent cells from burning in hypotonic environment
FALSE Cell walls prevent cells from burning in **hypertonic** environment
37
T/F: Sponges have no true tissue
True Sponges have no true tissue
38
T/F: The animal kingdom in monophyletic
TRUE The animal kingdom in monophyletic
39
Peptidoglycan is a common compound found in gram-\_\_\_ (pos/neg) bacteria
Peptidoglycan is a common compound found in gram-**positive** bacteria
40
T/F: Sex pili are required for bacteria to carry genetic recombination through transformation
FALSE Sex pili ARE NOT req'd for bac to carry genetic recomb thru transformation * Sex pili are involved in *conjugation*

B202 (22 decks)

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