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Microbiology > Lectures 6-7 > Flashcards

Lectures 6-7 Flashcards

(57 cards)

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1
Q

“Karyote”

A

“nucleus”

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2
Q

reason against using the term prokaryote

A

ancient divergence between bacteria and archaea. They are about the most different from each other as you could get… why should we lump them together?

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3
Q

reason for using term prokaryote

A

bacteria and archaea share many things in common due to their small size. It’s quickly useful to distinguish from eukarya and viruses

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4
Q

primary cell components

A

carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur - all else = micronutrients

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5
Q

micronutrients

A

equally as essential as macronutrients but not needed in as large quantities

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6
Q

cell membrane structure

A

hydrophilic (polar) head, hydrophobic tail (fatty acid)
(lipids and proteins)

(same concept as soap micelle)

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7
Q

cell membranes general function

A
  • info transfer from enviro
  • nutrient / waste exchange
  • chemiosmotic energy conservation (proton / sodium pumping)
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8
Q

mitochondria

A

powerhouse of eukaryotic cells

  • where energy is produced (spec. in membrane)
  • The mitochondria was initially bacteria (theory of endosymbiosis)
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9
Q

the theory of endosymbiosis

A

proposes that eukaryotic organelles like mitochondria and chloroplasts originated from free-living prokaryotes that were engulfed by an ancestral eukaryotic cell and formed a mutually beneficial relationship

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10
Q

where is energy produced in prokaryotic cells

A

cell membrane

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11
Q

the nucleoid

A

contains instructions to make cell:
- dna genome encodes for proteins that do everything in the cell
- generally very small in prokaryotes 1-10000
euks : 5000- a lot

humans 30,000

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12
Q

plasmids

A

“mini-genome” - encode dozens of genes

very important in antibiotic resistance

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13
Q

cytoplasm

A

gel-like liquid filling the cell… contains some organelles
where many chemical reactions occur (biosynthesis),
protein synthesis occurs in ribosomes,
DNA rep –> mRNA transcrip. –> protein transl.
“inclusions” storage (inorganic nutrients, food)

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14
Q

nucleoid functions

A

The nucleoid contains the primary, circular DNA of prokaryotes, controlling cell functions and reproduction

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15
Q

plasmid functions

A

plasmids are smaller, extra-chromosomal DNA molecules that often carry genes for traits like antibiotic resistance or toxin production, providing additional survival advantages

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16
Q

ribosome function

A

protein synthesis

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17
Q

Why stay small?

A

SA to volume ratio

  • less effort to move nutrients around
  • grow / reproduce faster and more easily
  • easier to perform essential functions
  • easier to fix internal problems
  • require less resources
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18
Q

diffusion change w size

A

as you get bigger, diffusion works less and less efficiently.

diffusion too slow for bigger eukaryotes - they have “plumbing” to solve this problem

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19
Q

“plumbing”

A

endoplasmic reticulum, cytoskeleton, etc.

not as fast as diffusion - this is big reason why eukaryotes grow slower

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20
Q

simple diffusion

A

extremely quick access to nutrients for prokaryotes, this is key to their explosive growth

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21
Q

what goes on in the cytoplasm?

A

In the cytoplasm, various cellular processes occur, including protein synthesis (by ribosomes), metabolic pathways, and the organisation of organelles and cellular components. It also provides a medium for the movement and interaction of these components.

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22
Q

microbes in very low-nutrient enviros

A

tiny algae that are highly adapted to area… high sa to v ratio makes them very competitive at competing for the nutrients

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23
Q

oligotroph

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A

organism adapted to low nutrient conditions

24
Q

prokaryotic cell shapes

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A

coccus - sphere
bacillus - rods
curved rods - corkscrew
pleomorphic - crazy

25
advantages of prokaryotic cell shapes
coccus (SA to V ratio) bacillus (symmetry for cell division) curved rods (burrowing into muccus)
26
What is diffusion? At what length scale is it effective?
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration, and it is most effective over short distances or small length scales.
27
Why does it get harder to supply nutrients and exchange waste for larger cells?
Smaller SA to V ratio. Diffusion harder/ not possible.
28
What are the smallest cells and the largest cells known? What is special about them?
tiny prochlorococcus and large diatoms
29
all cells composed...
of the same elements and macromolecules, but the arrangement is simpler in prokaryotic cells
30
solutions to loss of diffusion
plumbing, gills, lungs
31
cell membrane site of
energy generation - where chemicals are transported in and out of cytoplasm
32
microbial cells mostly live in
hypotonic enviros - pressure inside cells comparable to car tires
33
bacterial cell walls made up of
peptidoglycan
34
peptidoglycan
pepti = peptide glycan = sugar (glucose)
35
What happens if you break peptidoglycan down?
lysis comes out -- "LYSOZYME" part of our innate immune system (first isolated from tears)
36
The way peptidoglycan is distributed defines
the two main types of bacterial cells gram - and gram +
37
gram + vs gram -
gram staining identifies which pathogen is present in sample Important because gram positive and gram negative bacteria will respond to different drugs A lot of drugs have something against gram positive or negative (work better with one than the other) PINK (safarin) is gram -
38
penicillin
targets peptidoglycan synthesis - which is essential for bacterial cell wall construction selective toxicity - doesnt harm humans weakens bacterial cell walls causing them to burst due to osmotic pressure
39
lipopolysaccharide LPS
(gram - cell structure) ex. e. coli have this outer membrane : potent "endotoxin" which causes big immune response when recognized by body
40
endotoxin
compounds such as lps in cell wall of gram - bacteria cause large immune response
41
exotoxin
active excretion of a toxin e.g. shiga toxin
42
horseshoe crab blood
used to test for endotoxins
43
endotoxins and healthcare
cause severe fever symptoms by immune response so critical healthcare items are endotoxin free
44
gram - cell structure : the periplasm
space btw inner (cytoplasmic) membrane and outer membrane in gram - bacteria. has gel-like matrix filled w proteins involved in nutrient transport, enzyme activity and defence mechanisms (antibiotic resistance)
45
ecological relevance of the periplasm
selfish uptake - relevant for gut bacteria
46
What two macromolecules is peptidoglycan composed of? What is its function? What can happen if it is disrupted?
peptides and sugars Its function is to provide structural support and rigidity to bacterial cell walls, and if disrupted, the cell may lyse due to osmotic pressure.
47
What is the main difference between gram negative and positive cells? What is the clinical significance of this distinction?
Gram-positive cells have a thick peptidoglycan layer, while Gram-negative cells have a thin layer and an outer membrane. This affects antibiotic resistance and infection severity. gram + more susceptible to antibiotics
48
What is the outer membrane of gram negative bacteria also known as? Why is it dangerous? What is the periplasm?
Lipopolysaccharide (LPS) layer contains endotoxins that can trigger strong immune responses, leading to inflammation and potentially septic shock. periplasm : space btw inner cytoplasmic membrane and outer membrane. contains proteins and enzymes involved in nutrient transport and defence mechanisms
49
Mycobacteria
not gram + nor - cause severe diseases ... leprosy and tuberculosis waxy coat : resistant to chemical treatments (antibiotics)
50
advantages of no cell wall?
- flexibility & shape : adapt - antibiotic resistance : no wall to attack - osmotic tolerance - better at invading immune system mycoplasma (tenericutes) have no cell wall
51
mycoplasma
pleomorphic morphology ... weird structures for attachment no cell wall aka tenericutes
52
endospores
special type of resistant cell structure very very resistant ... dangerous in healthcare setting not killed by boiling ! can remain dormant for very long time
53
Why were autoclaves invented?
because endospores arent killed by boiling pressure-steam sterilizer
54
tetanus
Clostridium tetani endospore forming bacteria spasms can break bones
55
What is the outer cell wall of mycobacteria made out of? Why does this allow them to be resistant to stress?
mycolic acids waxy, thick impermeable and hydrophobic
56
What are examples of cell wall-less bacteria?
mycoplasma
57
What compounds do cell wall-less bacteria use to keep their cell membrane rigid?
stolen sterols

Microbiology (21 decks)

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