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LSCI230 > W2-lecture 1: Structure and function of procaryotes > Flashcards

W2-lecture 1: Structure and function of procaryotes Flashcards

1
Q

What are the different shapes of bacteria and archaea

A
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2
Q

What dictate the shape

A

The cell wall

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3
Q

What is the function of the cell wall in bacteria

A

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

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4
Q

State the steps of the gram’s stain?

A
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5
Q

Why does bacteria stain differently?

A

Because they have different cell walls.

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6
Q

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

A

false it is not present

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7
Q

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

A

ß(1-3)

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8
Q

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

A

NAM and NAG

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9
Q

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

A

NAG : N-acetylglucosamine
NAT : N-actetylalosaminuronic acid

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10
Q

Why is lysosyme secreted by tears and saliva?

A

Because it distruct the linkage betweent the NAG and NAM.

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11
Q

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

A
  1. L-Alanine
  2. D-glutamic acid
  3. Diaminopimelic acid
  4. D-alanine
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12
Q

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

A
  1. NAM
  2. DAP
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13
Q

What is the structure of the glycan tetrapeptide

A
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14
Q

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

A

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).

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15
Q

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.

A

T

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16
Q

What is the other name of the cross-linking?

A

Transpeptidation

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17
Q

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

A

phospholipids and polysaccharides

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18
Q

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

A

Peptidoglycan

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19
Q

What is the periplasm ?

A
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20
Q

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

A

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.

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21
Q

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

A

The lipid A. it is an endotoxin.

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22
Q

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

A

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

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23
Q

Describe the structure of the LPS membrane

A

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.

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24
Q

T or F : lipid A is an exotoxin

A

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

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25
Q

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

A

True, the layer is a pseudopeptidoglycan layer

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26
Q

How does pseudomurein resemble peptidoglycan?

A

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

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27
Q

How does the pseudomurein and the peptidoglycan differ?

A
  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
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28
Q

What is the structure of the S-layer

A

interlocking molecules of proteins and glycoproteins.

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29
Q

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

A

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

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30
Q

T or F : capsule and slime layers are synonyms

A

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

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31
Q

What is the other name of the S-layer?

A

The paracrystalline surface layer

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32
Q

What is the function of the capsule?

A

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

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33
Q

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

A

T

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34
Q

What are composed the capsule and slime layer

A

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

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35
Q

What is the difference between cilia and fimbriae

A

Cilias are found in eukaryotes and fimbria are found in procaryotes

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36
Q

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

A

T, because procaryotic cells don’t have cilia.

37
Q

What are the different type of flagella?

A

Monotrichous, Peritrichous and Lophotrichous

38
Q

What are the two types of polar flagellation?

A

Monotrichous and lophotrichous.

39
Q

What is the structure of the flagellum?

A
40
Q

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

A

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

41
Q

What sets the rotational speeds of the flagella?

A

The proton motor flow rate through the mot proteins.

42
Q

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

A

The L ring.

43
Q

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

A

Flagellin

44
Q

Explain movment in peritrichous bacteria.

A

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

45
Q

Explain movment in polar bacteria

A

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

46
Q

Explain movment in unidirectional flagela

A

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

47
Q

What is twiching

A
48
Q

What is slime extrusion?

A

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.

49
Q

What is taxis?

A

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

50
Q

What is the role of the fimbria?

A

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

51
Q

Fimbriae are found primarly on gram ___ bacteria

A

negative

52
Q

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

A

The chaperone and the ushers.

53
Q

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

A

the enzyme sortase attach the peptidoglycan layer and the fimbriae.

54
Q

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

A

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

55
Q

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

A
56
Q

What is an endospore?

A

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

57
Q

What is the composition of the endospore?

A
58
Q

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

A

Keratin-like proteins

59
Q

Of what is made the core of the endospore?

A

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

60
Q

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

A

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)

61
Q

What is the role of the SASP in the endospores?

A

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

62
Q

What is the composition of the exosporium of the endospore?

A

proteins

63
Q

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

A

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

64
Q

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

A

Heat and water

65
Q

Define the term :

  1. Germination
  2. Sporulation
A

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

66
Q

What are the sporulation stages?

A
67
Q

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

A

Activation, germination and outgrowth.

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LSCI230 (20 decks)

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