Lecture 1 - Morphology and Ultrastructure Flashcards Preview

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Flashcards in Lecture 1 - Morphology and Ultrastructure Deck (50):
1

What constitutes a species (5 things)

  1. Mating constraints (classical)
  2. Visible characteristics (Gram, shape, spores)
  3. Metabolism
  4. Surface structures
  5. Molecular Relatedness

2

Biochemical tests can assess relatedness only if...

the cell is metabolically active

3

Five tools for assessing relatedness

  1. Biochemical tests
  2. Numerical taxonomy
  3. DNA optical mapping (restriction digest)
  4. Serotyping
  5. Direct gene sequence comparisons

4

Optical map assembly involves _____ DNA molecules on a glass chip

linearized

5

Serotyping (strain typing) involves what 4 characteristics?

  1. Antigens
  2. Antobiotic/phage sensitivity profiles
  3. Toxin production
  4. surface molecules

6

6 important bacterial phyla

  1. Proteobacteria (a, ß, g, Σ)
  2. Chlamydiae
  3. Bacteroidetes
  4. Actinobacteriae (Myco, coryne, Actinomyces)
  5. Spirochaetae (Trep, Lepto, Borrelia)
  6. Firmicutes
     

7

Mycoplasma cell shape

pleiomorphic (and small)

8

Mycoplasma energetics/metabolism?

What does its membrane require

Obligate intracellular parasites

Cholesterol

9

Mycoplasma does not contain a _____, only a ________.

No cell wall

only a membrane

10

Various archaea shapes

cocci, rod, spiral, others

11

Two types of energetics found in archaea

Lithotrophs, heterotrophs

12

Three energetic properties of archaea

  1. many extremophiles
  2. some produce methane
  3. protein synthesis resembles eukaryotes

13

Archaea envelope -- it does not have ______ but has a ________

No peptoglycan *

Has a cell wall

 

**pseudo-pg, polysacch, protein

14

Major difference in archaea lipids

Ethers  (Other life has esters)

 

The lipids also have Branched Isoprene chains

(instead of unbranched fatty acids)

15

Prokaryotes reproduce via ____. They have a _______ chromosome usually.

binary fission

Single circular chromosome

16

Cytoplasm of prokaryotes contains....

membrane invaginations

17

Specific membrane structures of prokaryotes

Mesosomes

  Phycobilisomes, chromatophores

18

Cytoplasm of prokaryotes contains what?

Inclusion bodies (insoluble polymers, poly beta-OH butyrate, starch, glycogen, sulfur, polyphosphate granules)

Somal bodies (protein-bound vesicles, gas vesicles, magnetosomes (membrane-bound), carboxysomes)

19

Bacterial chromosome is.... (three properties

- anchored to membrane

  - highly folded (not histones)

  - few thousand genes 

20

Important functional sites in bacterial cytoplasm

Enzymatic reaction centers

(reaction centers depend on DNA, mRNA and protein localization)

21

Plasma membrane can be made more fluid by...

Lowering temp 

Shorter or more unsaturated fatty acids

22

Phosopholipid bilayer does not contain

sterols

 

(except mycolic acid)

23

Bacteria do not perform

Endocytosis

 

*Need transporter molecules

24

What is the Rocker-Switch mechanism?

external and internal binding sites for transported solute

 

and a “bottleneck” that is sometimes a selectivity filter

25

Bacteria require _____ to export proteins such as ____ and ______

Secretory systems

 

hydrolases, toxins

26

Four steps to gram stain

Crystal Violet

Iodine

Alcohol

Safranin

27

PG backbone made of 

GlcNAc - MurNAc linked beta 1-4

28

C6 O-acetyl MurNAc is resistant to 

lysozyme

29

PG side chain made of

tetrapeptide

 

*can vary 

30

Differences in PG side chain among types of bacteria

G- usu. have DAP at #3

 

G+ usu. have lysine

31

PG pentapeptide cross bridge is only in...

G+

32

Two molecules in glycan chains of PG

NAG and MURNAc (N acetylmuramic acid)

33

Tetrapeptide uses what weird molecules?

D amino acids

34

6 steps in PG synth

  1. Pentapeptide side chain is added to UDP-NAM
  2. UDP-MurNAc-5aa is then transferred to bactoprenol, NAG is added
  3. Bactoprenol is phosphorylated and flips sides
  4. New monomer is removed from BP and added to a space in wall by transglycosylation
  5. Transpeptidation (5th Ala is lost)
  6. BP is Dephosphorylated and flips again

35

LPS is in what cell type?

Gram -

36

LPS constituents

  1. O antigen
  2. Core polysaccharide
  3. Disaccharide diphosphate
  4. Lipid A
  5. Fatty acids

37

Synthesis of LPS (3 steps)

  1. Core (monosaccharide) added to lipid A on Inner surface of inner membrane -- Lipid A flips to periplasmic space
  2. Repeat unit is made in cytoplasm and carried to Periplasmic space by bactoprenol (and added to lipid A core)
  3. LPS moves to Outer membrane via bridging proteins

38

Bacterial species may alter what part of LPS?

O antigen

 

these define SEROTYPES (strains)

39

____ lack O antigen, and instead produce variant form of LPS called ________

Neisseria

Lipooligosaccharide

40

Bacteria contain polysaccharide capsule (except ______. What does it have instead?)

Bacillus anthracis

 

It has poly D-Glu

41

Purposes of capsule (glycocalyx)

Adhesion to surfaces (Strep mutans – uronic acids)

Anti phagocytic (Strep pneumoniae)

Immune mimic (NmB, EcK1 – sialic acid)
 

42

Function of Pili/Fimbriae

  1. Hold together during conjugation
  2.   Attach cells to surfaces (Streptococcal M protein is a minor protein at tips of pili)
  3.  Antigenic - cells can vary antigens to evade host defenses (antigenic variation in N. gonorrhoeae)
  4. Motility (twitching... alternate extension and retraction)

43

Flagella structure

Filament composed of flagellin*

 

*H antigen

44

Location of flagella is...

species specific

45

How does locomotion by flagella occur?

repulsion of charges from proton flow           through Mot A/B proteins

46

What is a C ring?

switch that allows rotation to change direction

47

Conformations of C ring

  1. CCW = cell swims
  2.   CW = cell tumbles randomly

  this allows chemotaxis, a sensing of chemical gradients TEMPORALLY (not spatially)

48

What are S-Layers? Who are they especially prominent in?

Single crystalline protein that surrounds some cells

(esp. prominent in Archaea)
 

49

Function and characteristic of S-layers

(one of each)

  1. Molecular sieve (anti-complement)
  2. Variations in lattice arrangement are characteristic of the species

50

Flagella filament (propeller) is connected at the ______

Hook

(universal joint)