Lecture 4

Question 1

A few bacterial cell types, notable Mycobacteria tuberculosis, contains large amounts of ____ which are complex long chain hydrocarbons with sugars and other modifying groups.

Answer 1

Waxes

Question 2

The dye carbolfucin is used in _____ stains. Which bacterial group (genus) is identified by this method?

Answer 2

acid fast; Mycobacteria

Question 3

What layers are found in gram positive bacteria?

Answer 3

It has multiple layers of peptidoglycan in the cell wall.

• teichoic acid
• lipoteichoic acid
• murein (thick cell wall)

Question 4

What layers are found in gram negative bacteria?

Answer 4

• lipopolysaccharide
• phospholipid
• lipoprotein
• murein (thin layer)
• membrane proteins

Question 5

What is a peptidoglycan?

Answer 5

• a crystal lattice structure formed from linear chains of two alternating amino sugars
• polysaccharide chains with peptide crosslinks

Question 6

What does a peptidoglycan do for bacteria cell walls?

Answer 6

It is responsible for the rigidity of the cell, morphology of bacteria, and resistance to the internal osmotic pressure.

Question 7

What is NAG?

Answer 7

• a type of peptidoglycan
• N-acetylglucosamine
• also called GlcNAc

Question 8

What is NAM?

Answer 8

• a type of peptidoglycan
• N-acetylmuramic acid
• also called MurNAc

Question 9

How are NAM and NAG connected?

Answer 9

Beta 1-4 linkages

Question 10

What shape are bacilli bacteria?

Answer 10

rod shaped

Question 11

What shape are cocci bacteria?

Answer 11

sphere shaped

Question 12

What shape are spirilla bacteria?

Answer 12

helix shaped

Question 13

In gram negative bacteria, what does the lipid bilayer do?

Answer 13

• anchors LPS

* anchors various transport proteins

Question 14

What is below the outer membrane of gram negative bacteria? What happens there?

Answer 14

• periplasmic space is below the outer membrane

* it is the site of hydrolytic enzymes, transpeptidases, or drug binding proteins

Question 15

In E. coli, what is between the outer membrane and inner membrane?

Answer 15

A single layer of peptidoglycan embedded inside of the periplasic space.

Question 16

What is found in the outer membrane of a gram negative bacteria?

Answer 16

• LPS (lipopolysaccharide)

* special channels called porins

Question 17

Describe the 3 parts of a LPS.

Answer 17

• above core (repetitive polysaccharide unit called the “O antigen”)
• central (core polysaccharide)
• below core (Lipid A)

Question 18

What is the O antigen of a LPS and what does it do?

Answer 18

It protrudes outside the gram negative envelope and excludes hydrophobic toxic molecules from entering.

Question 19

What is Lipid A of a LPS and what does it do?

Answer 19

It is a phosphorylated disaccharide with attached branched chain fatty acids. It makes up the toxic moiety of gram negative bacteria (endotoxin).

Question 20

What is the outer membrane of a gram negative bacteria impervious too?

Answer 20

It is impervious to hydrophilic molecules.

Question 21

What do porins do in the outer membrane of gram negative bacteria?

Answer 21

They are channels that permit passive diffusion of small hydrophilic compounds like sugars and amino acids.

Question 22

What would happen to bacteria if the cell wall is removed by treatment with lysozyme or treatment with penicillin during active growth?

Answer 22

The bacteria are lysed and die.

Question 23

What is a protoplast?

Answer 23

• originates from gram positive

* it is the osmotically sensitive sphere formed upon treatment with lysozyme

Question 24

What is a spheroplast?

Answer 24

• originates from gram negative bacteria (does not completely shed peptidoglycan due to the outer membrane)
• it is the osmotically sensitive sphere formed upon treatment with lysozyme

Question 25

How is acid fast stained?

Answer 25

1. Basic dye (carbolfuchsin) 2. Wash with acid alcohol (1 or 2%) 3. Background stain with methylene blue (it stains everything but the bacteria)

Question 26

What is the 1st stain chemical used in gram staining and acid fast staining?

Answer 26

* gram staining: crystal violet | * acid fast staining: carbolfuchsin

Question 27

Describe what happens to bacteria during acid fast staining with an acid alcohol solution.

Answer 27

The organisms resist decolorization.

Question 28

What are some examples of what can be stained by acid fast?

Answer 28

* Mycobacteria tuberculosis | * Cryptosporidium

Question 29

The waxy coat of acid fast contains what?

Answer 29

It is interlaced with murrain, polysaccharides, and lipids.

Question 30

What is the purpose of the waxy coat of acid fast?

Answer 30

It provides protection for mycobacteria from being killed by white blood cells.

Question 31

Why do acid fast grow slowly? What is the time frame of division?

Answer 31

Because of the rate of uptake of nutrients is limited by the waxy covering. They divide once every 24 hours, which is slow.

Question 32

What is wax very rich in?

Answer 32

Unusual lipids (mycelia acid)

Question 33

What does the wax form in acid fast?

Answer 33

It forms a hydrophobic barrier, impervious to acids, and is responsible for the "acid fast" characteristic of Mycobacteria

Question 34

Describe how tuberculosis spreads and how the body reacts to it.

Answer 34

* spreads by cough of small drops of saliva that may contain the TB micro bacteria which are breathed in by another person and can travel into their respiratory tract and lungs to cause infection * the body detects the invasion and sends out macrophages which eats the bacteria and sends it to the lymph nodes where the bacteria is neutralized

Question 35

What is latent tuberculosis?

Answer 35

When a person has neutralized tuberculosis bacteria. They have the bacterium, but they are not sick.

Question 36

What percentage of the world is infected with tuberculosis?

Answer 36

33%--however, only a small percentage become sick

Question 37

What percentage of TB cases become sick? What age range is affected?

Answer 37

5%--normally children because their immune systems are not fully developed

Question 38

What is active TB?

Answer 38

When latent TB wakes up, possibly months or years later. It can happen in adults with weakened immune systems (HIV +, chemo patients, organ transplant patients)

Question 39

How does TB spread?

Answer 39

Once it is in the lungs, it spreads through the blood stream or the lymphatic system to other parts of the body (lymph nodes, bones, joints, digestive system, central nervous system, liver, and heart).

Question 40

What happens when someone has active TB?

Answer 40

If the infection is in the lungs, the patient will cough, have difficulty breathing, and have chest pains. If the symptoms persist with fever, night sweats, and weightless, it is signs for TB. They'll see the doctor and receive treatment.

Question 41

What is the most common area for TB to infect in the human body?

Answer 41

In the lungs