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Medical Microbiology > Lecture 4 > Flashcards

Lecture 4 Flashcards

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Biology 101 flashcards USMLE® Step 1 flashcards
1
Q

What are the basic characteristics of prokaryotes?

A
  • no nucleus
  • no membrane-bound organelles
  • unicellular
  • reproduce by binary fission
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2
Q

What are the common shapes of bacteria?

A

bacillus: rod shaped
coccus: sphere
spirillum
star-shaped
rectangular

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3
Q

What are the different groupings of bacteria called?

A

pairs: diplo-
clusters: staphylo-
chains: strepto
groups of 4: tetrads
cubelike group of 8: sarcinae

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4
Q

What is glycocalyx? What is it made of?

A

cell coating on the cell wall
- viscous and gelatinous
- polysaccharide or polypeptide

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5
Q

What are the 2 types of glycocalyx?

A

capsule: organized and firmly attached
slime: unorganized

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6
Q

What is the function of glycocalyx?

A

prevents phagocytosis
- helps form biofilms

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7
Q

What is flagella and archaella?

A

help for movement of bacteria (external appendages)
- made of protein flagellin

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8
Q

What are the 3 parts of the flagella?

A

1) Filament
2) Hook
3) Basal body: anchors flagellum to cell wall

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9
Q

What are flagella proteins?

A

H antigens

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10
Q

What are axial filament? Where are they found? How does it move?

A
  • endoflagella
  • found in spirochetes
  • moves by rotation, like a corkscrew
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11
Q

What are fimbriae?

A

hairlike appendages that allow for attachment

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12
Q

What is pili?

A

used for movement (gliding and twitching)
- conjugation helps with DNA transfer from one cell to another

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13
Q

What is the bacterial cell wall made of?

A

peptidoglycan

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14
Q

What is the purpose of the cell wall?

A

prevents osmotic lysis and protects cell membrane

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15
Q

What is peptidoglycan?

A

polymer of repeating disaccharide in rows
- NAG
- NAM

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16
Q

How does gram staining work?

A

Gram-positive: alcohol dehydrates peptidoglycan and crystal violet-iodine crystals form inside cell
Gram-negative: alcohol dissolves outer membrane and leaves holes in peptidoglycan and cells are colorless; safranin added to stain cells

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17
Q

What are the characteristics of gram-negative cell walls?

A
  • thin peptidoglycan
  • periplasmic space (periplasm between outer membrane and plasma membrane with peptidoglycan)
  • outer membrane with polysaccharides, lipoproteins, and phospholipids
  • protects from phagocytes, complement, and antibiotic
  • made of lipopolysaccharides
  • porins form channels through membrane
  • 4 rings in basal body of flagella
  • produces endotoxins and exotoxins
  • low susceptibility to penicillin
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18
Q

What are the characteristics of gram-positive cell walls?

A
  • thick peptidoglycan
  • teichoic acids
  • polysaccharides and teichoic acids provide antigenic specificity
  • 2 rings in basal body of flagella
  • produce exotoxins
  • high susceptibility to penicillin
  • disrupted by lysozyme
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19
Q

What are teichoic acids? What charge? What is their function?

A
  • lipoteichoic acids link cell wall to plasma membrane
  • wall teichoic acid links peptidoglycan
  • carries negative charge
  • regulates movement of cations
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20
Q

What are 3 examples of atypical cell walls?

A
  • acid-fast cell walls
  • mycoplasmas
  • archaea
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21
Q

What are acid-fast cell walls?

A
  • similar to gram-positive cell walls
  • waxy lipid bound to peptidoglycan
  • mycobacterium
  • nocardia
  • stain with carbolfuchsin
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22
Q

What are mycoplasmas?

A
  • sterols in plasma membrane
  • lack cell walls
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23
Q

What are archaea?

A
  • no cell wall
    OR
  • walls of pseudomurein (no NAM or D-amino acids)
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24
Q

When are endospores produced? By what? What are they resistant to?

A
  • produced when nutrients are depleted by Bacillus and Clostridium
  • resistant to desiccation, heat, chemicals, radiation
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25
Q

What is sporulation?

A

endospore formation

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26
Q

What is germination?

A

endospore returning to vegetative state

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27
Q

What causes damage to cell walls?

A
  • lysozyme hydrolyzes bonds in peptidoglycan
  • penicillin inhibits peptide bridges in peptidoglycan
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28
Q

What are examples of wall-less gram cells?

A
  • protoplast: wall-less gram-positive cell
  • spheroplast: wall-less gram-negative cell
  • L forms: wall-less cells that swell into irregular shapes
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29
Q

What cells are susceptible to osmotic lysis?

A

protoplast and spheroplast

30
Q

What are the functions of the plasma membrane?

A
  • selective permeability
  • contains enzymes for ATP production
  • photosynthetic pigments on chromatophores
31
Q

What is in the plasma membrane?

A
  • peripheral proteins on the surface
  • integral and transmembrane proteins in the membrane
  • phospholipid bilayer that encloses cytoplasm
32
Q

What is passive transport?

A

substances moving from high to low concentration
- no energy needed

33
Q

What are examples of passive processes?

A
  • simple diffusion
  • facilitated diffusion
  • osmosis
34
Q

What is active transport?

A

substances needing energy to move from low to high concentration

35
Q

What are examples of active processes?

A
  • uniport
  • antiport
  • symport
36
Q

What is simple diffusion?

A

small molecules passing through the phospholipid bilayer

37
Q

What is facilitated diffusion?

A

solute combines with transporter protein
- transport ions and larger molecules with the concentration gradient

38
Q

What is osmosis?

A

movement of water across a selectively permeable membrane through:
- lipid layer
- aquaporins

39
Q

What is osmotic pressure?

A

pressure needed to stop the movement of water across the membrane

40
Q

What is an isotonic solution?

A

solute concentrations are equal inside and outside the cell

41
Q

What is hypotonic solution?

A

solute concentration is lower outside than inside
- water moves into the cell

42
Q

What is hypertonic solution?

A

solute concentration is higher outside of the cell than inside
- water moves out of the cell

43
Q

What does active transport require?

A

transporter protein and ATP

44
Q

Which direction is the flow for uniport? Antiport? Symport?

A

Uniport: one way
Antiport: opposite ways
Symport: coupled

45
Q

What is group translocation?

A

requires transporter protein and PEP
- substance changes as it crosses the membrane

46
Q

What is the cytoplasm and its function?

A

substance inside plasma membrane with the proteins, carbohydrates, lipids, and ions
- cytoskeleton

47
Q

What is the nucleoid and its function?

A

bacterial chromosome with circular thread of DNA
- contains cell’s genetic information

48
Q

What are plasmids?

A

extrachromosomal genetic elements that carry nonimportant genes

49
Q

What are ribosomes?

A

sites of protein synthesis
- made of protein and ribosomal RNA

50
Q

What are some examples of inclusions and their functions?

A
  • metachromatic granules: phosphate reserves
  • polysaccharide granules: energy reserves
  • lipid inclusions: energy reserves
  • sulfur granules: energy reserves
  • carboxysomes: Rubisco enzyme for CO2 fixation during photosynthesis
  • gas vacuoles: protein-covered cylinders to maintain buoyancy
  • magnetosomes: iron oxide inclusions, destroys H2O2
51
Q

How did eukaryotes come to be?

A

endosymbiotic theory
- larger bacterial cells engulfed smaller bacterial cells
- ingested photosynthetic bacteria became chloroplasts
- ingested aerobic bacteria became mitochondria

52
Q

What are cell walls made of in eukaryotes?

A

carbohydrates
- plants: cellulose
- fungi: chitin
- yeasts: glucan and mannan

53
Q

How are eukaryote and prokaryote plasma membranes similar?

A
  • phospholipid bilayer
  • integral and peripheral proteins
  • selective permeability
  • passive and active transport
54
Q

How are prokaryote and eukaryote plasma membranes different?

A

In eukaryotes:
- sterols: complex lipids
- carbohydrates: for attachment and cell-to-cell recognition
- phagocytosis: pseudopods extend and engulf particles
- pinocytosis: membrane folds inward to bring it fluid and dissolved substances

55
Q

What is cytoplasm?

A

anything inside the plasma and outside the nucleus

56
Q

What is cytosol?

A

fluid part of cytoplasm

57
Q

What is cytoskeleton and its function?

A

made of microfilaments and intermediate filaments
- gives shape and support

58
Q

What is cytoplasmic streaming?

A

movement of cytoplasm throughout a cell

59
Q

What are organelles and their function?

A

specialized structures within eukaryotic cells that perform distinct functions necessary for cellular operations
- compartmentalize various biochemical processes, better for organization and efficiency

60
Q

What is the difference between smooth and rough ER?

A

Smooth: no ribosomes, synthesizes cell membranes, fats, hormones
Rough: lots of ribosomes, synthesis of proteins

61
Q

What is the golgi complex and its function?

A

transports organelles and modifies proteins from ER
- transports modified proteins by secretory vesicles to the plasma membrane

62
Q

What are lysosomes and its function?

A

digestive enzymes
- trash disposal

63
Q

What are vacuoles and its function?

A

cavities formed from golgi complex
- brings food into cells and provides storage

64
Q

What is the mitochondria and its function?

A

contains inner folds (cristae) and fluid
- makes energy

65
Q

What is chloroplast and its function?

A

contains thylakoids with chlorophyll
- photosynthesis

66
Q

What are peroxisomes and their function?

A

free radical scavengers
- destroys H2O2 and oxidizes fatty acids

67
Q

What are centrosomes?

A

networks of protein fibers and centrioles
- forms mitotic spindle (good for cell division)

68
Q

What’s the main difference between flagella and cilia?

A

flagella: long tail, little amount
cilia: short, hair like, lots of them

69
Q

What’s the purpose of flagella and cilia?

A

for movement along cell surface

70
Q

How are microtubules organized?

A

9 pairs in a ring and 2 microtubules in the center

Medical Microbiology (22 decks)

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