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Microbiology > Lectures 5-7 > Flashcards

Lectures 5-7 Flashcards

1
Q

A _____ _______ is needed to control effects of osmotic pressure when cells are placed in a _______ solution.

A

cell wall; hypotonic

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2
Q

movement across semipermeable membrane

A

osmosis

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3
Q

If the cell is placed in a ______ solution it will shrink. The cell wall does not protect from that.

A

hypertonic

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4
Q

The sugar found in chitin and bacterial cell walls

A

N-acetylglucosamine (NAG)

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5
Q

The sugar found in cellulose in plant cell walls

A

glucose

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6
Q

In the cellulose chains, OH groups are polar and will form _______ bonds w one another. The O is slightly ____ and the H is slightly ____.

A

Hydrogen; negative; positive

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7
Q

What are the two sugars that alternate in peptidoglycan?

A

N-acetylglucosamine and N-acetylmuramic acid

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8
Q

What bond connects the sugars to each other in peptidoglycan? in chitin and cellulose?

A

Beta 1-4 glycosidic linkage for both.

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9
Q

A glycosidic bond is a covalent bond that joins two sugars or joins a sugar to another molecule.
It resembles the _________________found in phospholipids in ________________. In that
case __________________was being joined to isoprene.

A

ether bond; Archaea; glycerol

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10
Q

Is there an acetyl group in the sugar in the cell walls of plants or fungi? What larger molecule was it a part of?

A

fungi; chitin

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11
Q

_______ can form a peptide bond with an amino acid
because it has a carboxyl group. Where as _____ does not.

A

NAM; NAG

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12
Q

When two amino acids form a peptide bond,
________is very important.

A

electronegativity

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13
Q

What kind of reaction is peptide bond formation? why?

A

condensation; water is produced as a by-product

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14
Q

When forming a peptide bond, the C in the carboxyl group is slightly ____ and the N in the amino group is slightly_____.

A

positive; negative

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15
Q

In E. coli _______ is connected to NAM by a peptide bond. (This amino acid is the first in the tetrapeptide of this org).

A

alanine

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16
Q

What does NAM have that allows alanine to bond to it?

A

carboxyl group

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17
Q

What bond links together the tetrapeptides hanging from the glycan chains to form a layer?

A

crosslinking peptide bond

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18
Q

All gram - bacteria contain a special
amino acid in its peptidoglycan called what?

A

diaminopimelic acid (DAP)

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19
Q

What does the special amino acid in gram - bacteria involved in?

A

Involved in forming the cross linking peptide bond between 2 tetrapeptides

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20
Q

Does gram + bacteria contain DAP?

A

Some but not all

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21
Q

DAP has two ______ groups and two _______ groups

A

amino; carboxyl

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22
Q

All 3 bonds in peptidoglycan are under what category of bonds?

A

covalent

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23
Q

The _______________________linkage connects the sugars in the glycan chains.

A

beta 1-4 glycosidic

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24
Q

The ________________bonds connects the amino acids in the tetrapeptide to one another and the
tetrapeptide to the sugar __________________.

A

peptide; N-acetylmuramic acid

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25
Q

The _____________________________connects two tetrapeptides present in two different glycan chains.

A

cross-linking peptide bond

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26
Q

What element in an amino acid has a slightly + charge? This element is critical to peptide bond formation.

A

carbon

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27
Q

_______ _________ peptidoglycan is different because it contains a glycine interbridge that connects the tetrapeptides.

A

Staphylococcus aureus

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28
Q

What bond does S. aureus have in its peptidoglycan instead of the crosslinking peptide bond?

A

interbridge peptide bond

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29
Q

What is the interbridge of S. aureus made of?

A

glycine

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30
Q

The interbridge peptide bond forms between what two amino acids?

A

lysine and glycine

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31
Q

What is the bond called that
connects the tetrapeptides in S.
aureus? In E. coli?

A

interridge peptide bond; crosslinking peptide bond

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32
Q

What amino acid is important in
E.coli crosslinking peptide bond
formation?

A

diaminopimelic acid (DAP)

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33
Q

What kind of bond forms between
NAG and NAM?

A

beta 1,4 glycosidic linkage

34
Q

an enzyme in the eyes and on the surfaces of
body organs that destroys existing peptidoglycan

A

lysozyme

35
Q

What specifically does lysozyme do? Do cells need to be actively dividing? why?

A

breaks the beta 1-4 glycosidic linkage; no, it breaks existing linkages does not prevent them.

36
Q

The cell will die if it is in a ______________solution because water rushes into the cell and the cell
wall cannot protect the cell from the ___________________ pressure.

A

hypotonic; osmotic

37
Q

the enzyme that makes the crosslinking peptide bond

A

transpeptidase

38
Q

What happens when penicillin binds to a transpeptidase?

A

it stops the crosslinking peptide bond from forming

39
Q

Penicillin works only on _____ ______ _______

A

actively dividing cells

40
Q

What are the “scissors” used to cut the peptidoglycan layers?

A

autolysins

41
Q

We produce __________________ to degrade the cell wall in bacteria whereas bacteria
produce _____________________ to do something similar.

A

lysozymes; autolysins

42
Q

When ________is added, cell death
occurs in all the bacterial cells
because the existing peptidoglycan is
destroyed when the b 1-4 glycosidic
linkages are broken.

A

lysozyme

43
Q

When ________is added the
crosslinking peptide bond formation is
stopped in cells that are dividing.

A

penicillin

44
Q

Penicillin would work best in the
___________________ phase or stage
of growth. In the
_________________phase, most cells
are not dividing so the affect of
penicillin would be less dramatic than
the affect of lysozyme during the same
stage.

A

log/exponential; stationary

45
Q

Both lysozyme and penicillin and its analogs weaken the cell
wall so that when cells are in a ______________ solution water rushes into the cell and causes cell lysis.

A

hypotonic

46
Q

gram + cells have _______ ______ and ________ ________ embedded in their peptidoglycan.

A

teichoic acid and lipoteichoic acid

47
Q

In gram + cells, __________ ________ goes all the way through the peptidoglycan to the cytoplasmic membrane and anchors the peptidoglycan
to this membrane.

A

lipoteichoic acid

48
Q

Teichoic and lipoteichoic acid have
______ ___________with negative
charges that can ionically bond to Ca2+
and Mg2+. Why bond to these ions?

A

phosphate groups; makes it easier to transport these ions into the cell.

49
Q

is repeated several times to form
teichoic acid and lipoteichoic acid

A

ribitol phosphate

50
Q

How are each ribitol phosphate linked to one another?

A

phosphodiester linkages

51
Q

The outer layer of the outer membrane of gram - bacteria

A

lipopolysaccharide (LPS)

52
Q

In gram - bacteria, what anchors the OM to the peptidoglycan?

A

lipoprotein

53
Q

Gram - bacteria have a _________as part of their cell wall and have _______layers of peptidoglycan.

A

membrane; fewer

54
Q

The gram- cell wall contains a _________________________ (structure) which is absent in the cell walls
of gram+ bacteria, but gram+ bacteria contain the compound ________________ in their cell walls and it
is absent in gram- cell walls.

A

outer membrane/ LPS; ribitol phosphate

55
Q

The gram stain is considered a _________ stain

A

differential

56
Q

What are the three components of LPS?

A

lipid A, core polysaccharide, O polysaccharide/ O antigen

57
Q

Toxic part of LPS; comparable in structure to
a phospholipid

A

Lipid A

58
Q

What makes LPS soluble in water?

A

core and O polysaccharide

59
Q

The __________ ___________are the backbone of the lipid A, like glycerol is the backbone of a phospholipid.

A

glucosamine phosphates

60
Q

Lipid A contains two glucosamine phosphates that are linked
to one another by a _______ ________

A

glycosidic linkage

61
Q

When comparing the two, the glucosamine phosphate does not have a(n)_______________ group on it like NAG has and NAG is missing a _______________group.

A

acetyl; phosphate

62
Q

In a phospholipid, fatty acids are linked to
glycerol by an __________ linkage.

A

ester

63
Q

A peptide bond forms between a _____________ group and
a ________________group. The partial positive charge
important in the formation of the bond is on the
___________in the ___________group.

A

amino; carboxyl; carbon; carboxyl

64
Q

Why isn’t lipid A soluble in water?

A

because of the large fatty acid component

65
Q

Sugars, because they have a lot of
____________________ or ______________groups, can form H bonds with water which keeps the sugar in solution (like is the case with core and O polysaccharide.)

A

OH; hydroxyl

66
Q

The sugar composition of the O polysaccharide differs among different ______of the same _________.

A

species; genus

67
Q

Vibrio cholerae and Vibrio vulnificus would have __________ sugars in their O polysaccharides.

A

different

68
Q

What is a polysaccharide?

A

10+ sugars

69
Q

What kind of bond connects the sugars in a
polysaccharide?

A

beta 1-4 glycosidic linkage

70
Q

The sugars in core polysaccharide are the
same within a _______.

A

genus

71
Q

Vibrio cholerae and Vibro vulnificus would have _______sugars in their CORE polysaccharide.

A

same

72
Q

Do Bacillus anthracis and Bacillus cereus would have the same core
polysaccharides? Why or why not?

A

no, because Bacillus is gram +

73
Q

Lipid A is the toxic part; core and O polysaccharide make LPS soluble in water. The ___________________________ in lipid A are bonded to fatty acids by ____________linkages
and ______________________linkages.

A

glucosamine phosphate; ester; peptide

74
Q

Considered an ________– Toxin that is a
structural part of the cell; not as potent as an
________.

A

endotoxin; exotoxin

75
Q

An ___________is part of the structure of the bacterium and is shed but
not secreted

A

endotoxin

76
Q

What does endotoxin do to the body? Why?

A

if present in high enough amounts, will cause shock and high fever. It stimulates temp regulation part of the brain.

77
Q

How does lipid A in LPS cause sepsis? What does it bind to and what happens after?

A

Lipid A binds to receptors on immune cells, this causes overly leaky blood vessels, low blood vol causes tissues to shut down.

78
Q

Core and O polysaccharide in LPS allow lipid A to be _________________in the blood. Lipid A
contains the sugar _____________________.

A

soluble; glucosamine phosphate

79
Q

A molecule structured differently than LPS. It has fewer sugars in each chain (3 to 10) and is found in some gram- bacteria such as
Haemophilus and Neisseria

A

lipooligosaccharide (LOS)

80
Q

_______________does not have O
polysaccharide but its core polysaccharide is
branched.

A

Neisseria

81
Q

Some Neisseria species have sugars in their LOS that are similar to those on
various human cells. What is this called? How do bacteria use it to their advantage?

A

molecular mimicry; allows organism that has these sugars to hide from the immune system long enough to establish infection.

82
Q

Some Neisseria species also can change
the composition of the sugars on the LOS (switch sugars repeatedly) What is this called? How is it used to their advantage?

A

Antigenic variation; the immune sys has trouble creating a strong response before the organism has changed its outer “coat”

Microbiology (16 decks)

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