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Flashcards in Lecture 2 Deck (93):
1

Prokaryotic flagella

How does it move compared to Eukaryotes?

Stiff, coiled screw-like. Rotate instead of moving in an undulating pattern like  in Eukaryotes

2

Instead of a nucleus, DNA chromosome is floating in cytosol in a compact ____

nucleoid

3

In prokaryotes, translation and transcription ___

occur in the same area/ are not seperated

4

Bacteria are diploid or haploid? Shape of bacterial DNA? 

haploid. They only have one version of their chromosome(s)

bacterial DNA can be circular or linear

5

What are plasmids?

What do they carry?

when do they replicate?

 

double stranded DNA molecules, usually circular that are independent of the bacterial chromosome.

They carry genes that may be useful but are not necessary for basic living.

Replicate the same time as chromosome

6

What happens when a daughter cell does not inherit a plasmid? 

What has to happen to a plasmid to ensure a 100% rate of passing it down to every daughter cell?

it will replicate at a faster rate bc it wont have copy plasmid DNA. 

problem for people who are trying to copy useful genes with plasmids. 

Plasmids can integrate with bacterial genome, in which case, daughter cells will recieve plasmid DNA

7

Most bacteria lack steroles T/F

exception:

T

mycoplasma because they do not have a cell wall and will steal eukaryotic sterols in order to survive better in harsher environments

 

8

Bacterial membrane contains:

It functions like ____ in eukaryotes

transport proteins for uptake/release of materials

ion pumps to create membrane potential

various enzymes

 

It functions like inner membrane of mitochondiria in eukaryotes (Undergoes oxidative phosphoylation)

9

Quorum Sensing:

bacteria secrete small signalling molecules to communicate. Detection of these molecules leads to a reponse from the cell iin the form of increased/decreased expression of various genes

10

Bacterial Ribosome:

70S

made of 30S and 50S subunits

30S unit has important 16S rRNA

11

Locations of biochemical pathways in Prokaryotes:

Glycolysis, pentose phosphate, Entner Doudoroff, TCA, ETC, 

Glycolysis, pentose phosphate, Entner Doudoroff, TCA -cytoplasmic matrix

ETC and oxidative phosphorylation: Cell membrane

12

Flagella shape?

Flagella composition?

Powered by?

ropelike propellers (hollow rigid helix)

made of helically arranged proteins called flagellin

powered by [H+] transmembrane gradient

13

spirochetes have what kind of flagella? What does this enable the bacteria to do?

are gram positive or gram negative

endoflagella rotate and cause spirochetes to have flexing and spinning movements

gram negative

14

Pili and fimbriae 

 

thinner than flagella

also extend beyond cell wall

slender tubes of helically arranged protein subunits (pilin)

pilin- bacterial sex, allows transfer of DNA (1-10 per cell)

Fimbrae- thin, used for adhesion of cell to surfaces (up to 1000 per cell)

15

How do prokaryotes secrete proteins and large molecules?

*Not vesicle based unlike Eukaryotes

transmembrane channels for large molecules

general secretory pathway

16

General secretory pathway

Why is this not enough in gram negative bacteria

transport unfolded proteins across cell membrane 

similar to the trans ER membrane movement of proteins during translation by ER membrane ribosomes in Eukaryotes

In gram negative bacteria: protein leaves inner membrane and is folded using chaperone proteins in the periplasmic space. Another mechanism must be used to cross outer membrane

17

What is Eukaryotic exoskeleton made of? Do bacteria have this?

Eukaryotic exoskeleton made of tubulin and actin. Bacteria do not have this but recently tubulin and actin homologs were discovered

18

Tubulin homolog

ubiquitus in bacteria/Archaea

binds/hydrolyzes ATP

key player in bacterial division

19

actin homolog

forms dynamic, helical filaments inside cell

Can segregate low copy plasmids to cell poles

E.g. In Escherichia coli (rod shaped)

20

Bacterial cell walls contain 

peptidoglycan 

21

Archaea have peptidoglycan? 

Do they stain gram positive/negative?

No

Yes

22

Some bacteria have inclusion bodies, such as ____.

what do these form?

volutin granuoles (storage form of polyphosphate). These form a metachromatic material

23

metachromatic material

stains a different color than that of the original dye

24

Glycocalyx is made of what?

Is is necessary for cell metabolism?

What is its function

it aids in the formation of ___

 made of capsules and slime layers outside of the cell wall.

-It is not used in cell growth but increases the fitness of a bacterium inside host

-can form a barrier to detergents

-can be used to adhere to surfaces or bacteria

-aids in the formation of biofilms 

 

25

Glycocalyx: capsules made of?

exception:

 

Capsules are loose and surround cell wall

They are made of polysaccharides

exception: Bacillus anthracis has capsule made of polypeptide 

26

Glycocalyx: Slime layers

 

loosly adherent and nonuniform in thickness/density

27

Biofilms

organized layers of microbial cells. Can form on parts of body or surgically implanted prosthetics/ medical devices that may express differnt gene products than sigular bacteria due to quorum sensing

28

Quorum sensing regulates gene expression in response to ____

cell population density flucuations

 

29

Autoinducers are

chemical signal molecules

30

autoinducers increase in concentration as 

cell density (population) increases

31

Gene expression in a dense population of bacteial cells may change if a ___ of autoinducers is detected 

minimum stimulatory threshold concentration

32

What kind of bacteria use quorum sensing? (gram pos or gram neg)

both

33

What is quorum sensing used to regulate?

virulence

DNA uptake competance

conjugation

antibiotic production

motility

sporulation

biofilm production

34

autoinducers are used in signalling between whom?

within and between species. Autoinducers can incite specific repsonses from host organisms 

35

Prokaryotic cell wall provides ____ and protects the cell from ____ forces.

It helps ___ to other cells and eluding ____

structure and shape

osmotic forces (20-30 ATM pressure inside cell, easily popped if not for cell wall)

Assists in attaching to other cells due to proteins on outer surface of cell wall and helps elude antimicrobial drugs (if drugs can't get past the wall they cant harm the bacteria)

36

Why is peptidoglycan important 

It is unique to bacteria so we can target it with antibiotics to kill bacteria without causing harm to other cells

37

The cell wall is __. It protects the cell from ___.

a porous corset (water can enter/exit with ease)

protects cell from osmotic lysis

38

NAG

 

N-acetylglucosamine

39

NAM

N-acetylmuraminic acid

40

NAG-NAM 

disaccharide that forms chains

41

NAG-NAM chains

form tetrapeptide bridges to conect together

may be covelently bonded (E.G. Eschericha coli)

may be held together by an additional connecting chain (peptide interbridge) (E.G Stphylococcus aureus)

42

Peptidoglycan forms a 

rigid prous meshwork

43

Escherichia coli

gram negative 

NAG-NAM chains form peptide linkage

44

Lysozyme

cleaves between NAG-NAM disaccharides

45

Precusor to peptidoglycan

pentapeptide attached to NAM 

Diamino acid such as L-Lysine must be in the 3rd position for a cross link to form

 

 

46

Transpeptidation reaction

bond between aa 4 and 5 broken in the pentapeptide

aa 3 binds with NH2 on a NAM on a parallel chain

47

Acid fast bacteria are gram ____ visually. 

They are resistant to gram stains T/F

gram positive cell wall structure. However, cell wall 60% mycolic acid, which helps the bacteria survive, but cause it to grow slowly. 

T. They are resistant to gram staining staining and we must use harsher staining methods to stain them. 

48

Identity of the first 2 aas on NAM can vary between organisms t/f

T

49

The pentapeptide has many moeties not found in proteins T or F

 

T

examples: 

D-glutamic acid, D-alanine, D-lactate, D-serine, and meso-diaminopimelic acid

50

D-amino acids protect against 

Proteases

51

Terminal dipeptide of pentapeptide is usually 

D-alanine-D-alanine 

but it can be D-alanine-D-lactate or D-alanine-D-serine

52

Synthesis of peptidoglycan best studied in 

Straphylococcus aureus

53

Straphylococcus aureus 

gram positive 

54

Gram positive Cell Wall

thickness/percent comp. of peptidoglycan?

thick layer (15-50 nm)

~50% cell weight pep[tidoglycan

55

teichoic acids

Unique polysaccharides in gram positive cell walls

Some covelently linked to lipids= lipoteichoic acids

56

lipoteichoic acids

in gram positive cell walls

anchor cell wall to cell membrane

 

57

C polysaccharides 

complex polysaccharides in gram positive bacterial cell walls that can be used to identify streptococci

 

58

Gram positve cell wals ___ crystal violet dye because  ___. Cells appear ___ when stained.

retain; the thick peptidoglycan layer prevents it from being washed out. Cells appear purple

59

M protein of streptococci is a ____ protein. These associate with the peptidoglyccan layer and form _____. 

virulence protein; attachment fimbrae

60

teichoic acid can covelently bind to

peptidoglycan 

61

teichoic acid and lipoteichoic acid are antigenic, which means

what can the bacteria use them for 

they can be used to distinguish bacterial serotypes (strains)

they are used to anchor the bacteria to other bacteria and to mammalian surfaces

62

Gram negative 

Cell wall peptidoglycan composition? Where is attched?

Relatively thin (5-10% compostion). Attached to outer membrane via lipoprotein

63

Composition of outer membrane. What does it enclose

inner leaflet: phospholipids

outer leaflet: channel proteins (porins), lipopolysaccharides (LPS)

Outermembrane encloses periplasmic space

64

what is in the periplasmic space?

hyrolytic enzymes for digestion of macromolecules, many lytic virulence molecules, and ezymes that synthesize peptidoglycan layer

65

What is lipopolysaccharide also called? What effect does it have on immune system

Endotoxin

Stimulates immune system and can cause fever and shock 

 

66

Outer membrane function

(what can it keep out/protect the bacteria from?)

maintains cell structure and acts as permeabiltiy to large molecules and hydrophobic molecues. Can impeded entrance of hydrophillic antibiotics

barrier to lytic enzymes such as lysozyme

67

spheroplasts

produced when outer membrane is disrupted and lysozyme gains access to peptidoglycan layer

osmotically sensitive 

68

Gram negative bacteria stain ____

pink. and it can be easily washed out 

69

What is the toxic part of Lipopolysaccharide? Does killing the bacteria with antibiotics help the host

Lipid A is the toxic part 

killing the bacteria will only release the toxin into the host organism. In humans this can lead to unfavorable immune response ( fever, vasodilation, inflammation, shock, blood clotting due to cytokines from immune cells)

70

Neisseria sp.

Gram negative 

Has lipooligosaccharide (LOS) that steadily releases as they grow. 
Lacks O antigen. 

71

Lipopolysaccharide is made of (3 parts). What parts can we use to identify bacteria?

O antigen + core + lipid A

O-antigen: distinguishes different serotypes (strains)

core: same for a species 

Lipid A: same for related bacteria 

72

Divalent cations

strengthen outer membrane by linking phosphates of lipid A with the core 

73

chaperone proteins help fold proteins/prevent protein folding where?

Prevent protein folding inside cell

aid proper protein folding after translocation across the membrane

74

75

What helps facilitate unfolded protein across membrane?

Protein complex that forms transmembrane channel

76

What happens to protein after it is folded outside the membrane in gram positive bacteria?

Gram negative bacteria?

Gram positive: Inserts into cell membrane or leaves the cell 

Gram negative: proteins are folded in the periplasmic space by chaperone proteins (e.g. pilin)

Proteins can leave the periplasmic space by travelling through flagella or a syringe like (type III) secretion system (looks like flagella)

77

What can a type III syringe like system be used for? 

 

Insert toxic proteins into eukaryotic cells

78

Basal body of flagella in gram negative bacteria can transport flagellin units through ___ which crosses ___ membranes

central pore

both 

79

flagellin make a ____ that is attached to a ___ with a sharp bend just ___ the outer membrane

Where is the flagellin attached to the cell?

20 nm thick helical hollow tube called the filament, which often ends with a capping protein

hook 

basal body (surrounded by proteins that serve as a motor)

80

Basal body recieves ___ from the motor proteins and transfers it to the _____.

torque

hook and filament

81

Where are the flagellum basal body rings of gram negative bacteria? 

gram positive?

Gram negative:

1.  lipopolysaccharides of outer membrane (top leaflet)

2. peptidoglycan layer (cell wall)

3. embedded in plasma membrane (inner membrane)

4. attached to plasma membrane (inner membrane)

Gram postive:

1. peptidoglycan layer 

2. plasma membrane

82

Flaggelum used for:

motility and protein transport (type III transport)

83

How is a flagellum made? How is it powered?

components of flagellum transported through basal body and travel through the hollow tube, then get added on at the end (the tip)

rotation powered by [H+] gradient formed by oxidative phosphorylation & cell metabolism

84

Types of flaggelar arrangement

monotrichous (one)

amphitrichous (bilateral arrangement)

lophotrichous (many on one side 

petrichous (everywhere on cell body)

85

clockwise rotation =

counter clockwise =

runs

tumbles 

86

Spirochetes move using

spiral movements of axial filaments

also called endoflagella or periplasmic flagella 

87

Bacillus and Clostridium genus

gram positive soil bacteria

can form highly resistant endospores

88

Endospore

defense mechanism for bacteria

89

Sporogenesis/Sporulation

Vegetative state —► Endospore

8 hours

depletion of key nutrient (such as L-arginine)

-forms single endospore per mother cell (which disintegrates)

-only DNA and essential proteins in endospore

90

Vegitative State

bacteria is growing

it has lower resistance to things that can kill it

91

Endospore state

no growth, resting state

highly resistant to environmental conditions (boiling, radiation, attack from most enzymes/ chemicals

high concentration of Ca2+ bound to dipicolinic acid 

convered by inner membrane, 2 peptidoglycan layers, tough outer spore coat

spores are hard to decontaminate. Posts a problem in food/medical industries

 

 

92

Germination

Endospore —► Vegitative state

1.5 hours

water + triggering nutrient (such as L-arginine)

once it starts, cell is no longer resistant

93

endospore positions aid 

morphologic identifications