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MIC 102 > Bacterial and Archaeal cell Structures > Flashcards

Bacterial and Archaeal cell Structures Flashcards

1
Q

What kind of shapes can the cells take on?

A
  • many, such as spheres, commas, spirals
  • they can cluster, form rods, and fruiting bodies
  • overall very diverse
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2
Q

what is the cell membrane?

A
  • the fluid mosaic model for plasma membrane applies to bacteria too
  • bacteria use same ester linkage as eukaryotes
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3
Q

permeability of membrane

A
  • is amphiphathatic with hydrophobic & hydrophilic domains
  • small uncahrged, polar molecules can cross (h20,urea,glycerol)
  • hydrophobic molecules can
  • large uncharged polar molecules and ions cannot diffuse across
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4
Q

Isotonic solution

A
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4
Q

Isotonic solution

A

equal concentration of solutes in cell and out of the cell, optimal for cell growth

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5
Q

Hypertonic solution

A
  • solute concentration is increased out the cell, the cell loses water, plasmolysis
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6
Q

Hypotonic solution

A
  • solute concentration is lower outside the cell, water then goes into the cell
  • high osmotic pressure, potential lysis
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7
Q

External features of a prokaryotic cell ?

A
  • flagella, fimbriae, slime layer, etc.
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8
Q

Features of the envelope on a prokaryotic cell?

A
  • outermemebrane with LPS
  • lipoprotein
  • cell wall
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9
Q

Internal features of a prokaryotic cell?

A
  • the cytoplasm, cytoskeleton, nucleoid/chromosome, ribosomes, inclusions
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10
Q

Gram positive bacteria

A
  • bacterial envelope has a thick outer cell wall
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11
Q

Gram-negative bacteria

A
  • bacteria envelope does not have thick outer membrane

- cell wall anchored to the inside of the outer membrane

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12
Q

What is peptidoglycan (murein)?

A
  • what builds the cell wall as muramic acid and (NAG) polymerize into a chain
  • peptide side chain on (NAM) can the link together with neighboring chains
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13
Q

What links together the peptide groups in a gram-positive bacterium?

A
  • peptides are linked together with (Gly)x5

- tight link, with low mobility

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14
Q

How does a gram-negative cell wall differ from that of a gram-positive?

A
  • the link between the peptides is more flexible

link is between a Diaminoacid (DAP) and D-Ala

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15
Q

How is the cell wall of a gram-negative cell more complex that of a Gram-positive?

A
  • the outer surface of the membrane has Lipopolysaccharides (LPS), which vary in shape and size and can function as another barrier, slowing down diffusion
  • transport into the cell is harder: use porins: generalized receptor
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16
Q

Lipopolysaccharides have four main sections, what are they?

A

lipid A, inner core, outer core, and O- anitgen

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17
Q

What is the lipid A section of an LPS ?

A
  • lipid A is the most conserved section of the LPS, as it’s in the bacterial envelope (unexposed)
  • conserved in all species
  • can have fatal immune responses to lipid A (endotoxin)
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18
Q

What is the inner core section of the LPS?

A
  • section after lipid A

- also highly conserved among all species

19
Q

What is the outer core section of the LPS?

A
  • the section after the inner core

- less conserved among species

20
Q

What is the O-antigen of the LPS?

A
  • the outer part of the LPS
  • varies between species
  • recognized by the immune system
  • can be used to ID by “O-antigen” type
21
Q

What are porins?

A
  • make pores in the outer membrane
  • specific family of channel proteins
  • gram-negative exclusive
22
Q

What are Acid-fast bacteria ?

A
  • bacteria with a waxy layer that makes cells resistant to acid, soaps (no lipid bilayer)
  • waxy layer slows down nutrient uptake and growth
  • does not react with much, but do have proins
    ex) Mycobacterium tuberculosis
23
Q

What are mycoplasmas?

A
  • cells that lack a cell wall completely
    (many antibiotics target cell walls)
  • many mycoplasmas use sterol extensively in their membranes from some structure
  • live in or on host cells
  • no need for a cell wall because of host homeostasis
24
Q

What is an S-layer in bacteria?

A
  • surface layer of protien,
25
Q

What is an S-layer in bacteria?

A
  • a surface layer of protein, primarily single monomers
  • can provide shape or protein
  • does impair diffusion
  • Archea can also make S-layers
26
Q

What are Capsules/ Slime layers ?

A
  • when contents of the cell are spewed out
  • usually polysaccharides, a few are amino acid polymers
  • limit diffusion of harmful compounds, limit drying out
  • avoid phagocytosis, can hide O-antigen from immune cells
27
Q

What is the glycocalyx function?

A
  • allows cells to adhere to surfaces and each other Biofilms
28
Q

What are some the flagellar arrangements?

A
  • Monotrichous
  • Lophotrichopus (multiple)
  • Peritrichous ( a lot)
  • Axial filament (flagella inside of cell)
29
Q

How does the flagella differ in gram-negative vs gram positive?

A

Falgella in gram-negative are more complex and have a basal body
in gram-positive, flagella are simpler as cell wall keeps it in place

30
Q

What is a basal body in a flagellum?

A
  • multi protein complex
  • rings anchor it into the envelope of the cell
  • basal body is built first, hollow flagella*
31
Q

How would you explain the assembly of a flagella?

A
  • basal body is built first –> hook –> Filament
  • built from the bottom-up
  • filaments self-assemble
32
Q

What are flagellin?

A
  • a subunit structures that self-assemble as they grow through the base
  • these bits break off frequently and are antigenic
33
Q

What is a bacterial pilus?

A
  • kind of like a grappling hook, single monomer
  • can be rapidly assembled and disassembled to change length
  • functions include conjugation, attachment, twitching motility
34
Q

What is a bacterial pilus?

A
  • kind of like a grappling hook, single monomer
  • can be rapidly assembled and disassembled to change length
  • functions include conjugation, attachment, twitching motility
35
Q

What structure in a bacterial cell organizes the DNA?

A
  • the nucleoid
  • DNA is not strictly separated from the rest of the cell
  • transcription and translation occur together
  • DNA just sits in the cell, the nucleoid
36
Q

What structure within a cell organizes the rest of the cell?

A
  • the cytoplasm
37
Q

What do the specialized structures gas vesicles?

A
  • made from protein
  • common among aquatic photosynthetic microbes like cyanobacteria
  • can tune buoyancy for optimum light
38
Q

What are Thylakoids?

A
  • extension of the cell membrane

- enhance light-gathering abilities by increasing membrane surface area

39
Q

What are carboxysomes?

A
  • structure that houses Rubisco
  • gases naturally diffuse, has proteins to get needed material
  • seems to enhance the function of Rubisco
40
Q

What are storage Granules?

A
  • hold uniform chunks of useful material when in abundance for later use
  • good long-term storage for carbon
41
Q

What are magnetosomes?

A
  • membrane-bound, iron-containing structures
  • several chained together act as a compass needle
  • help with up down movement in water column
42
Q

What are the main differences between archaeal and bacterial envelopes?

A
  • bacterial enveloped are bilayer
  • archaea typically have monolayers, which provide more rigidity and structure at higher temperatures
  • archaea membrane structure increases steric hindrance
43
Q

True of false Archaea mainly have one form of envelope structure?

A
  • false, many variety
44
Q

How does the (1-3) linkage between the amino acids in archaea walls affect them?

A

-gives them the 1-3 linkage which, our lysozyme enzyme can only cut through 1,4

45
Q

What are three ways in which archaea differ from bacteria?

A
  • archaeal ribosomes are an intermediate between bacterial and ribosomes
  • archaea use histones-like proteins in chromosomes management:
  • archaeal flagella are superficially similar but powered by ATP hydrolysis
46
Q

How do Enterosomes differ from carboxysomes?

A
  • enterosomes don’t have RuBisCO

MIC 102 (5 decks)

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