Lecture 7

Question 1

The outer layer of the outer membrane of gram - bacteria

Answer 1

lipopolysaccharide (LPS)

Question 2

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

Answer 2

lipoprotein

Question 3

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

Answer 3

membrane; fewer

Question 4

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.

Answer 4

outer membrane/ LPS; ribitol phosphate

Question 5

The gram stain is considered a _________ stain

Answer 5

differential

Question 6

What are the three components of LPS?

Answer 6

lipid A, core polysaccharide, O polysaccharide/ O antigen

Question 7

Toxic part of LPS; comparable in structure to
a phospholipid

Answer 7

Lipid A

Question 8

What makes LPS soluble in water?

Answer 8

core and O polysaccharide

Question 9

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

Answer 9

glucosamine phosphates

Question 10

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

Answer 10

glycosidic linkage

Question 11

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

Answer 11

acetyl; phosphate

Question 12

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

Answer 12

ester

Question 13

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.

Answer 13

amino; carboxyl; carbon; carboxyl

Question 14

Why isn’t lipid A soluble in water?

Answer 14

because of the large fatty acid component

Question 15

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.)

Answer 15

OH; hydroxyl

Question 16

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

Answer 16

species; genus

Question 17

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

Answer 17

different

Question 18

What is a polysaccharide?

Answer 18

10+ sugars

Question 19

What kind of bond connects the sugars in a
polysaccharide?

Answer 19

beta 1-4 glycosidic linkage

Question 20

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

Answer 20

genus

Question 21

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

Answer 21

same

Question 22

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

Answer 22

no, because Bacillus is gram +

Question 23

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.

Answer 23

glucosamine phosphate; ester; peptide

Question 24

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

Answer 24

endotoxin; exotoxin

Question 25

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

Answer 25

endotoxin

Question 26

What does endotoxin do to the body? Why?

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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

Answer 28

soluble; glucosamine phosphate

Question 29

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

Answer 29

lipooligosaccharide (LOS)

Question 30

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

Answer 30

Neisseria

Question 31

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?

Answer 31

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

Question 32

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?

Answer 32

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