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Microbio lecture > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

cytoplasm

A

gel-like network made of proteins and other macromolecules

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2
Q

cell membrane

A

encloses the cytoplasm. The structure that defines the existence of the cell.

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3
Q

cell wall

A

covers the cell membrane, b/w inner and outer membrane.

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4
Q

nucleoid

A

non-membrane bound area of cytoplasm w/ chromosome in the form of looped coils

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5
Q

cell membrane made up of

A 
•Double layer of phospholipids
• Proteins embedded in membrane
-Anchor membranes to envelope
-Sense the outside world
-Transport materials into cell
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6
Q

cell membrane functions

A 
• Mechanical boundary
• transport nutrients/waste
• Site for electron transport chain
-Respiration
-Photosynthesis
• Contain (“sensing”) receptor proteins
• Most membrane proteins (~80%) are integral, the rest
are peripheral
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7
Q

most membrane lipids are

A

phospholipids. Phospholipids are amphipathic = have a polar and non-polar end.

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8
Q

proteins float in

A

2-dimensional “sea” of phospholipids. membrane fluidity is required.

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9
Q

increase membrane fluidity

A

• Use lipid molecules with shorter chain lengths and that have more double bonds (unsaturation)– adds “kinks”

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10
Q

• Decrease membrane fluidity (increase rigidity)

A 
• Use longer chain lengths (Van der Waals)
• Use fewer double bonds
• Use molecules that hinder movement of phospholipids
-Stiff planar rings
-Reinforcing agents
-Sterols (e.g.) cholesterol
     -Eukaryotes
-Hopanoids
     -Structurally similar to steroids
      -Prokaryotes
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11
Q

Bacteria would adapt to increasing

temperature by?

A

Increase # of long chain lipids, decrease # of double bonds.

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12
Q

proteins form about

A

half the mass of the membrane

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13
Q

Transport across the cell membrane

A
  • The cell membrane acts as a semipermeable barrier
  • Selective transport is needed for survival
  • weak acids/bases can cross membrane
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14
Q

diffusion

A

Small uncharged molecules, like O2 and CO2, permeate the membrane

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15
Q

transporters

A

pass material into and out of cell

• Polar/charged molecules need transport

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16
Q

concentration gradient

A

always going from high to low.

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17
Q

passive transport

A

molecules move along their concentration gradient

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18
Q

active transport

A

molecules move against their concentration gradient

• Requires energy

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19
Q

How do prokaryotes protect their cell membrane?

A

cell envelope includes structural support (cell wall.)
-some have S-layer
• prokaryotes like mycoplasmas have cell membrane w/ no outer layers

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20
Q

sacculus

A

bacterial cell wall w/ single interlinked molecule that covers cell.
• cage-like structure (flexible)
• has shape and withstands intracellular turgor pressure

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21
Q

Most bacterial cell walls are composed of

A

peptidoglycan (murein)

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22
Q

glycan chains

Long polymers of two disaccharides:

A

• N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

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23
Q

Peptidoglycan

A

polymer of peptide-linked chains of amino sugars. unique to bacteria. good for antibiotics.

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24
Q

Gram-positive-
gram negative-
Mycobacteria-

A

– thick cell wall (e.g. firmicutes)
– thin cell wall (e.g. proteobacteria)
– multilayered envelope w/ defensive structures like mycolic acids (e.g. Mycobacterium tuberculosis)

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25
Q

gram positive cell envelope

A 
• S-layer
-Made of protein (contains large pores)
• Thick cell wall (3-20 layers of peptidoglycan)
• teichoic acids for strength
• Cell membrane
26
Q

gram negative cell envelope

A

• Outer membrane (OM)
-Covers peptidoglycan layer
-has defensive abilities and toxigenic properties
• Thin peptidoglycan layer (1-2 sheets)
• Periplasm – area b/w membranes(cell wall)

27
Q

• Inward facing leaflet of OM (gram neg.)

A

has lipoproteins that connect OM to peptide bridges of cell wall

28
Q

• Outward facing leaflet of OM (gram neg)

A

has lipopolysaccharide (LPS) (endotoxin)

29
Q

Mycobacterial cell envelope

A

-has features of both gram-positive and gram negative

• Unusual sugars -arabinogalactans

30
Q

in e coli, the cell membrane is called the

A

inner membrane. contains phospholipids, transporter proteins, and more molecules.

31
Q

nucleoid is not

A

enclosed by membrane.

32
Q

essential ions

A

potassium, magnesium, chloride ions

33
Q

nucleic acid content of bacteria

A

8% for e coli

34
Q

leaflets

A

two layers of phospholipids in the bilayer

35
Q

cardiolipin

A

double phospholipid linked by glycerol

36
Q

hopanoids

A

cyclopentane

37
Q

membrane lipids of archaea differ from bacteria and eukaryotes bc

A

instead of ester link, there is ether link (C-O-C)

38
Q

The E. coli nucleoid

A

appears as clear regions that exclude the ribosome and has DNA strands

39
Q

domains

A

nucleoid forms about 50 loops

40
Q

within each domain

A

DNA is supercoiled and compacted by gyrases and DNA-binding proteins

41
Q

the ribosome is a target for

A

antibiotics

42
Q

Protein synthesis and secretion

A

• In prokaryotes, membrane/secreted proteins are synthesized together w/ cell membrane
-signal recognition particle (SRP), which binds to the growing peptide

43
Q

replisome includes

A

leading strand and lagging strand

44
Q

septum

A

-DNA termination site. divides envelope. seals off the two daughter cells

45
Q
  • If septation occurs in:
  • Parallel planes-
  • Random orientations-
  • Right angles to the previous division-
A
  • cells form chains (Streptococcus)
  • cells form compact hexagonal arrays (Staphylococcus)
  • cells form tetrads and cubical octads (sarcinae)
46
Q

Thylakoids

A

folded intracellular membrane
• has layers of folded sheets (lamellae) or tubes of
membranes packed w/ chlorophyls and electron carriers

47
Q

Carboxysomes

A

polyhedral bodies packed w/ enzyme Rubisco for CO2 fixation

48
Q

Gas vesicles

A

increase buoyancy

49
Q

Storage granules

A
  • Glycogen, PHB, and PHA for energy

* Sulfur, for oxidation

50
Q

Magnetosomes

A
  • Membrane-embedded crystals of magnetite, Fe3O4

* Orient the swimming of magnetotactic bacteria

51
Q

Pili or fimbriae

A

– straight filaments of pilin protein

• Used in attachment

52
Q

stalks

A

extensions of cytoplasm

• Tips secrete adhesion factors called holdfasts

53
Q

nanotubes

A

intercellular connections that pass material from one cell to the next

54
Q

Peritrichous cells

A

(ex E. coli, Salmonella) have flagella randomly distributed around the cell
• Flagella rotate together in a bundle behind swimming cell

55
Q

Lophotrichous cells

A

(ex Rhodospirillum rubrum) have flagella attached at

one or both ends

56
Q

Monotrichous cells

A

(ex Caulobacter swarmer) have a single flagellum on

one end

57
Q

Chemotaxis

A

movement of a bacterium in response to a chemical

gradient

58
Q

• Attractants cause CCW rotation

A
  • Flagella bundle together
  • Push cell forward
  • “Run”
59
Q

• Repellants cause CW rotation

A
  • Flagella bundle falls apart
  • “Tumble”
  • Bacterium pauses, then changes direction
60
Q

“random walk”

A

The alternating runs and tumbles causes this

61
Q

bacteria do not undergo

A

mitosis or meiosis

62
Q

origin of replication

A

at the midpoint on dna. Attached to the cell envelope at a point on the cell’s equator

Microbio lecture (12 decks)

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