W2-lecture 1: Structure and function of procaryotes

Question 1

What are the different shapes of bacteria and archaea

Answer 1

Question 2

What dictate the shape

Answer 2

The cell wall

Question 3

What is the function of the cell wall in bacteria

Answer 3

to withstand intracellular osmotic pressure and responsible for the shape and rigidity of the bacteria.

Question 4

State the steps of the gram’s stain?

Answer 4

Question 5

Why does bacteria stain differently?

Answer 5

Because they have different cell walls.

Question 6

T or F : the petidoglycan layer is present in the cell wall of archaea

Answer 6

false it is not present

Question 7

What is the type of linkage that is insensitive to lysosyme?

Answer 7

ß(1-3)

Question 8

What are the two sugars of the peptidoglycan subunit in bacteria?

Answer 8

NAM and NAG

Question 9

What are the two sugars of the peptidoglycan subunit in archea?

Answer 9

NAG : N-acetylglucosamine
NAT : N-actetylalosaminuronic acid

Question 10

Why is lysosyme secreted by tears and saliva?

Answer 10

Because it distruct the linkage betweent the NAG and NAM.

Question 11

What are the 4 amino acids attached to the carbon 3 of the NAM molecule in bacteria’s peptoglycan layer?

Answer 11

1. L-Alanine
2. D-glutamic acid
3. Diaminopimelic acid
4. D-alanine

Question 12

What are the two molecules that have never been found in eukarya and archaea?

Answer 12

1. NAM
2. DAP

Question 13

What is the structure of the glycan tetrapeptide

Answer 13

Question 14

What are the differences in the cross-linking between gram postive bacteria and gram negative bacteria?

Answer 14

Gram positive : indirect cross linking (crossing between the interbridge and the L-lysin)
Gram negative : direct cross linking (crossing between the DAP and D-alanine).

Question 15

T or F : in gram positive, there is some indirect cross-linking. Meaning that there is a link between the interbridge and the L-Lysin.

Answer 15

T

Question 16

What is the other name of the cross-linking?

Answer 16

Transpeptidation

Question 17

What is the composition of the outer membrane in gram negative bacteria?

Answer 17

phospholipids and polysaccharides

Question 18

What is the composition of the outer membrane in gram positive bacteria?

Answer 18

Peptidoglycan

Question 19

What is the periplasm ?

Answer 19

Question 20

Name one function of the outermembrane in the gram negative bacteria?

Answer 20

A major function of the outer membrane is to prevent cellular proteins whose activities must occur outside the cytoplasm from diffusing away from the cell. These extracellular proteins reside in the periplasm.
Also, The LPS layer helps protect the bacteria against a variety of substances, including antibiotics, and against the host defense system.

Question 21

Name the part of the LPS that is responsible for the symptoms of gram negative pathogenic bacteria.

Answer 21

The lipid A. it is an endotoxin.

Question 22

Why does the archaea are resistant to pennicilin (antibiotic) while bacterias are not?

Answer 22

Because archaea have a ß1-3 linkage in their pseudopeptidoglycan layer.

Question 23

Describe the structure of the LPS membrane

Answer 23

O-specific polysaccharide or o antigen : repeted units of 2-4 monosaccharides.
Core polysaccharide : repeted units of
KDO : Links the lipid A to the polysaccharide chain
Lipid A : it is a NAG attached to 6 tails embedded in the cytoplasmic membrane.

Question 24

T or F : lipid A is an exotoxin

Answer 24

False because the toxin stays within the cell wall of the bacteria so it is an exotoxin.

Question 25

T or F : Peptidoglycan is absent in the cell wall of Archaea and there is usually no outer‐membrane.

Answer 25

True, the layer is a pseudopeptidoglycan layer

Question 26

How does pseudomurein resemble peptidoglycan?

Answer 26

2 sugars with amino acids attached to the carbon 3 of one of the sugar.

Question 27

How does the pseudomurein and the peptidoglycan differ?

Answer 27

1. the amino acids attached to one of the sugar are in the L configuration 2. The linkage between the 2 sugars is a ß1-3 instead of a ß1-4. 3. It contains N-acetyltalosaminuronic (NAT) acid instead of N-acetylmuramic acid

Question 28

What is the structure of the S-layer

Answer 28

interlocking molecules of proteins and glycoproteins.

Question 29

T or F : the outermembrane is always the outermost layer in bacteria

Answer 29

False, the S-layer is always the outermost membrane in archaea and bacteria when there is one.

Question 30

T or F : capsule and slime layers are synonyms

Answer 30

False, the capsule is organized in a thigh matrix and is thigly attached while the slime layer is not

Question 31

What is the other name of the S-layer?

Answer 31

The paracrystalline surface layer

Question 32

What is the function of the capsule?

Answer 32

The capsule function is to make the bacteria more efficient in attacking host cells since they are not recognized by the host.

Question 33

T or F : The capsule may be covalently bound to the outer membrane or to the peptidoglycan layer.

Answer 33

T

Question 34

What are composed the capsule and slime layer

Answer 34

Heteropolysaccharides (Majority of bacteria) Homopolysaccharides (Some Gram‐negative)

Question 35

What is the difference between cilia and fimbriae

Answer 35

Cilias are found in eukaryotes and fimbria are found in procaryotes

Question 36

T or F : Only Eukaryotes have the ability to move around using Cilia

Answer 36

T, because procaryotic cells don't have cilia.

Question 37

What are the different type of flagella?

Answer 37

Monotrichous, Peritrichous and Lophotrichous

Question 38

What are the two types of polar flagellation?

Answer 38

Monotrichous and lophotrichous.

Question 39

What is the structure of the flagellum?

Answer 39

Question 40

Name the different rings in gram (-) of the flagella and in what layer are emebbed the rings?

Answer 40

L – LPS P – Peptidoglycan MS – Membrane Superficial C ‐ Cytoplasm

Question 41

What sets the rotational speeds of the flagella?

Answer 41

The proton motor flow rate through the mot proteins.

Question 42

What is the ring missing in flagella of the gram (+) bacteria

Answer 42

The L ring.

Question 43

What is the name of the protein that compose the flagella?

Answer 43

Flagellin

Question 44

Explain movment in peritrichous bacteria.

Answer 44

Peritrichous: Forward motion is imparted by all flagella forming into a bundle and rotating counterclockwise (CCW). Clockwise (CW) rotation causes the bundle to break apart and the cell to tumble. A return to counterclockwise rotation leads the cell off in a new direction

Question 45

Explain movment in polar bacteria

Answer 45

Cells change direction by reversing flagellar rotation (thus pulling instead of pushing the cell)

Question 46

Explain movment in unidirectional flagela

Answer 46

stopping periodically to reorient and then moving forward by clockwise rotation of its flagella.

Question 47

What is twiching

Answer 47

Question 48

What is slime extrusion?

Answer 48

Glides by secreting a polysaccharide slime from pores onto the outer surface of the cell.The slime contacts both the cell surface. As the excreted slime adheres to the surface, the cell slides along.

Question 49

What is taxis?

Answer 49

• Directed movement toward or away from a gradient of chemical or physical agents.

Question 50

What is the role of the fimbria?

Answer 50

involved primarly in the attachment of the microorgainsm to structure. They are found primarly on gram negative bacteria

Question 51

Fimbriae are found primarly on gram ___ bacteria

Answer 51

negative

Question 52

What are the proteins required for the assembly of the fimbriae in gram negative bacteria

Answer 52

The chaperone and the ushers.

Question 53

What is the method of assembly of the fimbriae in the gram-positive bacteria

Answer 53

the enzyme sortase attach the peptidoglycan layer and the fimbriae.

Question 54

What are the two modes of adhesions in gram positive bacteria?

Answer 54

By the surface adhesins or by the pili (also called fimbriae).

Question 55

Highlight the differences between the fimbriae for gram positive vs gram negative bacteria.

Answer 55

Question 56

What is an endospore?

Answer 56

highly differentiated cells that are extremely resistant to harsh environmental conditions: heat, chemicals, radiation, nutrient depletion, desiccation, etc.

Question 57

What is the composition of the endospore?

Answer 57

Question 58

Of what is made up the spore coat of the endospores?

Answer 58

Keratin-like proteins

Question 59

Of what is made the core of the endospore?

Answer 59

Ca2+ dipicolinic acid (DPA) SASPs (small, acid soluble spore proteins).

Question 60

Name a substance unique to endospors and why it is important in the endospores?

Answer 60

Dipicolinic acid (DPA) it is important because it gives resistance to heat by to the endospore because it binds calcium and bind water (dehydration of the core)

Question 61

What is the role of the SASP in the endospores?

Answer 61

Binds the DNA and help in the protection against the UV light dammage.

Question 62

What is the composition of the exosporium of the endospore?

Answer 62

proteins

Question 63

Complete : in the endospores the _____ (full name) binds the DNA while the _____ (full name) binds the Ca+ and water

Answer 63

SASPs : small acid soluble spore proteins) DPA : dipicolinic acid

Question 64

What are the two things necessary in order to have germination?

Answer 64

Heat and water

Question 65

# Define the term : 1. Germination 2. Sporulation

Answer 65

Sporulation : the process of forming endospores is called endosporulation (or sporulation) Germination : Forming a vegetative cell from an endospore

Question 66

What are the sporulation stages?

Answer 66

Question 67

What are the three steps by which an endospore convert back to a vegetative cell?

Answer 67

Activation, germination and outgrowth.