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microbiology > morphology 9/21 > Flashcards

morphology 9/21 Flashcards

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Biology 101 flashcards
1
Q

what is the cytoplasm and what is it made of

A
  • material bounded by the plasmid membrane
  • Cytoplasm - ~ 90 – 92 % water; dissolved solutes (ions, sugars, amino acids, etc); somewhat viscous; cytoskeleton ? (+/-); cyclosis ?; contains many enzymes and ribosomes
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2
Q

what is the cytoskeleton and how are bactera, archaea and eukaryotes similar

A
  • Network of fibrous proteins within cytoplasm
  • Homologs of all 3 eukaryotic cytoskeletal elements have been identified in bacteria and 2 in archaea
  • Functions are similar as in eukaryotes

–Role in cell division, protein localization, and determination of cell shape

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3
Q

what are intracytoplasmic membranes and where are they found

A

•1) Cell membrane infoldings

–observed in many photosynthetic bacteria

  • analogous to thylakoids of chloroplasts
  • reactions centers for ATP formation

–observed in many bacteria with high respiratory activity

•2) Anammoxosome in Planctomycetes

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4
Q

what are inclusions and what are they enclosed by

A
  • Inclusions – membrane bound storgage structures containing granules of organic or inorganic material that are stockpiled by the cell for future use
  • Some are enclosed by a single-layered membrane, but not a unit membrane

–membranes vary in composition

–some made of proteins; others contain lipids

–may be referred to as microcompartments

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5
Q

what do storage inclusions store

A

  • Storage of nutrients, metabolic end products, energy, building blocks
  • Glycogen storage
  • Carbon storage

–poly-β-hydroxybutyrate (PHB)

  • Phosphate - Polyphosphate (Volutin)
  • Amino acids - cyanophycin granules
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6
Q

what are microcompartments and what do they include

A
  • Not bound by membranes but compartmentalized for a specific function
  • Carboxysomes - CO2 fixing bacteria

–contain the enzyme ribulose-1,5,-bisphosphate carboxylase (Rubisco), enzyme used for CO2 fixation

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7
Q

what are gas vacuoles

A

–found in aquatic, photosynthetic bacteria and archaea

–provide buoyancy in gas vesicles

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8
Q

what are magnetosomes

A

-inclusion

–found in aquatic bacteria

–magnetite particles for orientation in Earth’s magnetic field

–cytoskeletal protein MamK

•helps form magnetosome chain

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9
Q

what are ribosomes

A

•Complex structures

–consisting of protein and ribosomal RNA

–sites of protein synthesis

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10
Q

how many units are in the entire ribosome of bacterial, archaea and eukaryotic

A

–bacterial and archaea ribosome = 70S

–eukaryotic (80S) S = Svedburg unit

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11
Q

how many units in bacterial and archaeal ribosomal RNA

A

–16S small subunit

–23S and 5S in large subunit

–archaea has additional 5.8S (also seen in eukaryotic large subunit)

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12
Q

how are ribosomes in bactera, archaea, and eukarya related

A

–archaea more similar to eukarya than to bacteria and proteins vary

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13
Q

nucleus and prokayotes

A

  • There is no nucleus “per se” in prokaryotic cells but there is ds DNA (and a few examples of surrounding membranes). The DNA is found in an irregularly shaped region of the cytoplasm called the nucleoid or nuclear area. It is typically about 10 -15 % of the volume of the cytoplasm.
  • Prokaryotic DNA is generally circular and supercoiled. Most prokaryotes have only1piece of double stranded, circular, supercoiled DNA making up there chromosomes.
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14
Q

what are plasmids

A
  • many prokaryotes have additional, smaller, circular but not supercoiled ds DNA in there cytoplasm. They contain “non essential” genes.
  • Extrachromosomal DNA

–found in bacteria, archaea, some fungi

–usually small, closed circular DNA molecules

•Exist and replicate independently of chromosome

–episomes – may integrate into chromosome

•Contain few genes that are non-essential

–confer selective advantage to host (e.g., drug resistance)

  • May exist in many copies in cell
  • Inherited stably during cell division
  • Curing is the loss of a plasmid
  • Classification of plasmids based on mode of existence, spread, and function
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15
Q

what is the bacterial endospore

A
  • Complex, dormant structure formed by some bacteria in various locations within the cell
  • Function is to survive extreme environments for the organism
  • Resistant to numerous environmental conditions

–heat

–radiation

–chemicals

–desiccation

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16
Q

what is the endospore structure

A
  • Spore surrounded by thin covering called exosporium
  • Thick layers of protein form the spore coat
  • Cortex, beneath the coat, thick peptidoglycan
  • Core has nucleoid and ribosomes
17
Q

what makes an endospore resistant

A
  • Calcium (complexed with dipicolinic acid)
  • Small, acid-soluble, DNA-binding proteins (SASPs)
  • Dehydrated core
  • Spore coat and exosporium protect
18
Q

what is sporulation

A
  • Process of endospore formation
  • Occurs in a few hours (up to 10 hours)
  • Normally commences when growth ceases because of lack of nutrients, or presence of toxic substances
  • Complex multistage process
19
Q

what is germination

A

•Transformation of endospore into vegetative cell complex, multistage process

20
Q

steps in formation of vegetative cell

A

•Activation

–prepares spores for germination

–often results from treatments like heating

•Germination

–environmental nutrients are detected

–spore swelling and rupture of absorption of spore coat

–loss of resistance

–increased metabolic activity

•outgrowth - emergence of vegetative cell

21
Q

what features are common between archaea and eukarya, bacteria, and unique elements to archaea

A

•Many features in common with Eukarya

–genes encoding protein: replication, transcription, translation

•Features in common with Bacteria

–genes for metabolism

•Other elements are unique to Archaea

–unique rRNA gene structure

–capable of methanogenesis

22
Q

general archaea

A
  • Highly diverse with respect to morphology, physiology, reproduction, and ecology
  • Best known for growth in anaerobic, hypersaline, pH extremes, and high-temperature habitats
  • Also found in marine arctic temperature and tropical waters
23
Q

archaeal size, shape, and arrangement

A
  • Much like bacteria, cocci and rods are common shapes
  • Other shapes can also exist

–no spirochetes or mycelial forms yet

–branched/flat shapes

  • Sizes vary (typically 1-2 x 1-5 μm for rods, 1-5 μm in diameter for cocci)
  • Smallest observed is 0.2 μm in diameter
  • Largest is a multicellular form that can reach 30 mm in length!
24
Q

cell envelopes in domain archaea

A

•Differ from domain Bacteria envelopes in the molecular makeup and organization

–S layer may be only component outside plasma membrane

–some lack cell wall

–capsules and slime layers are rare

25
Q

archaeal cell membranes

A
  • General structure - a phospholipid bilayer and proteins
  • Composed of unique phospholipids which:

–Lack fatty acids and ester bonds

–Instead, have isoprene (hydrocarbon) units (five carbon, branched) in place of fatty acids

–Since no carboxyl of fatty acids, instead have ether linkages rather than ester linkages to glycerol attached to fatty acids

•Some have a phospholipid monolayer structure instead of a bilayer structure as an adaptation to living in higher temp

26
Q

archaeal cell envelopes

A

–varied S layers attached to plasma membrane

–pseudomurein (peptidoglycan-like polymer)

–complex polysaccharides, proteins, or glycoproteins found in some other species

–only Ignicoccus has outer membrane

27
Q

how do archaeal cell walls differ from bacterial cell walls

A
  • Lacks peptidoglycan
  • Most common cell wall is S layer
  • May have protein sheath external to

S layer

-s layer more diverse than bacteria

  • S layer may be outside membrane and separated by pseudomurein
  • Pseudomurein (like peptidoglycan) may be outermost layer – similar to gram-positive microorganisms
28
Q

difference in archael cytoplasm compared to bacteria

A
  • Very similar – lack of membrane-enclosed organelles
  • May contain inclusion bodies (e.g. gas vesicles for buoyancy control)
  • All the usual components

–ribosomes

–nucleoid region

–inclusion bodies

29
Q

what is the nucleoid

A
  • Irregularly shaped region in bacteria and archaea
  • Usually not membrane bound (few exceptions)
  • Location of chromosome and associated proteins
  • Usually 1 chromosome
  • Supercoiling and nucleoid proteins (histones, Alba, condensins) aid in folding
30
Q

what are pili

A

–not well characterized as of yet

–some composed of pilin protein and homologous to bacterial type IV pili proteins

–pili formed have a central lumen similar to bacterial flagella, but not bacterial pili

–may be involved in archaeal adhesion mechanisms

-archael external structure

31
Q

how is the archaeal flagella different

A
  • Flagella thinner
  • More than one type of flagellin protein
  • Flagellum are not hollow
  • Hook and basal body difficult to distinguish
  • More related to Type IV secretions systems
  • Growth occurs at the base, not the end

microbiology (11 decks)

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