(37) Bacterial Ultrastructure

Front 1

define bacterial ultrastructure

Back 1

the subcellular composition of the cell which includes the cytoplasm, cytoplasmic organelles, cell envelope, and appendages

Front 2

how is the bacterial ultrastructure best observed?

Back 2

transmission electron microscopy

Front 3

____________ is much more important than morphology with regard to the physiology of the organism and is a function solely of cell envelope ultrastructure

Back 3

Gram reactivity

Front 4

why is the small size of prokaryotic cells necessary?

Back 4

small size is necessary to permit adequate exchange across the cytoplasmic membrane, thereby allowing for efficient transport of nutrients in and excretion of metabolic end products, extracellular enzymes, exotoxins, and such

Front 5

where is energy metabolism found in prokaryotes?

Back 5

cytoplasmic membrane in the absence of mitochondria and chloroplasts

Front 6

where is the DNA of prokaryotes found?

Back 6

genomic DNA exists freely within the cytoplasm in the absence of a membrane bound nucleus

Front 7

what are the intracellular contents of a prokaryotic cell?

Back 7

cytoplasm
ribosomes
nucleiod
inclusion bodies
endospores (certain gram positives only)

Front 8

what is found in the cell envelope of a prokaryote?

Back 8

cytoplasmic membrane
peptidoglycan (murein) layer
outer membrane (gram negative only)
Periplasmic space (periplasm, gram negative only)

Front 9

what are the types of appendages that can be found on a prokaryotic cell?

Back 9

flagella
fimbraia
capsules

Front 10

what are the major groups of prokaryotes?

Back 10

bacteria

Front 11

do prokaryotes have a nucleus?

Back 11

NO

Front 12

describe the chromosomes present in prokaryotes?

Back 12

single
circular DNA haploid genome

Front 13

Are mitochondria, golgi bodies, and endoplasmic reticulum found in bacteria?

Back 13

NO

Front 14

describe the ribosomes found in bacteria vs. those found in eukaryotic cells.

Back 14

Eukaryotic cell: 80S (60S+40S)
Prokaryotic cell: 70S (50S + 30S)

Front 15

does the cytoplasmic membrane of bacteria contain sterols?

Back 15

NO

Front 16

Describe the cell wall of a bacteria.

Back 16

is a complex structure containing protein, lipids, and peptidoglycans

Front 17

Is prokaryotic reproduction sexual or asexual?

Back 17

Asexual (binary fission)

Front 18

Describe the differences between eukaryotic and prokaryotic respiration.

Back 18

Eukaryotic respiration: mitochondria
Prokaryotic respiration: via cytoplasmic membrane

Front 19

what is the gram reactivity of a bacteria based on?

Back 19

the gram reactivity differentiation is based on peptidoglycan thickness and outer membrane presence

Front 20

what will be seen in an EM of a gram positive bacteria?

Back 20

cell wall
cell membrane

Front 21

what will be seen in the EM of a gram negative bacteria?

Back 21

cytoplasmic membrane
outer membrane
cell wall (murein layer)

Front 22

what is found in the Gram Positive cell wall?

Back 22

Peptidoglycan: glycan chains of GlcNAc and MurNAc cross-linked by peptide bridge
Teichoic acid: polyribital phosphate or glycerol phosphate cross-linked to peptidoglycan
Lipoteichoic acid: lipid linked teichoic acid

Front 23

what is found in the Gram Negative cell wall?

Back 23

Peptidoglycan: thinner version of that found in the gram positive bacteria
Periplasmic space: enzymes involved in transport, degradation, and synthesis
Outer membrane: phospholipids with saturated fatty acids
Proteins; porins, lipoprotein, transport proteins
LPS: lipid A, core polysaccharide, O antigen

Front 24

what is the function of the cytoplasm in the ultrastructure of the bacteria?

Back 24

cytoplasm is a water solution of endogenous mineral salts, cofactors, enzymes, metabolic intermediates, and other intracellular solutes surrounded by the cytoplasmic membrane

Front 25

define protoplast

Back 25

cell membrane + cytoplasm

Front 26

what are the most important cellular organelles of a bacteria?

Back 26

nucleiod
ribosomes

Front 27

describe the cell envelope in a gram positive bacteria

Back 27

cytoplasmic membrane + peptidoglycan

Front 28

describe the cell envelope in a gram negative bacteria

Back 28

cytoplasmic membrane, peptidoglycan, periplasmic space, outer membrane

Front 29

what are the macromolecules unique to the bacterial cell envelope?

Back 29

Peptidoglycan
LPS (endotoxin)
Teichoic acids
Lipoteichoic acids

Front 30

describe the peptidoglycan found in the cell envelope of a bacteria

Back 30

one huge, rigid complex network composed of glycan chains covalently crosslinked to short peptides which surround the entire prokaryotic protoplast

Front 31

what inhibits biosynthesis of the cell envelope?

Back 31

biosynthesis is inhibited by the antibiotic penicillin which competitively inhibits transpeptidase which catalyzes the cross linking reaction

Front 32

what degrades the glycan chain?

Back 32

hydrolytic enzyme lysozyme which is present in all secretory fluids

Front 33

what functions as the rigid layer of the cell envelope?

Back 33

Peptidoglycan (murein)

Front 34

what are the functions of the peptidoglycan in the bacterial cell envelope?

Back 34

1. confer cell shape
2. protect underlying protoplast from mechanical damage
3. protect underlying protoplast from bacteriolysis in hypotonic environments due to plasmoptisis
4. Grow inward at cell midpoint to form septum during transverse binary fission

Front 35

describe the Lipoplysaccharide found in the bacterial cell envelope

Back 35

LPS is an endotoxin
It is an extremely complex molecule which forms the outer leaflet of the GRAM-NEGATIVE outer membrane with three major regions:
1. Lipid A
2. Core oligosaccharide
3. O antigen

Front 36

what are the functions of LPS in the bacterial cell envelope?

Back 36

to confer unique impermeability properties to the outer membrane thereby allowing it to act as an outer protective barrier.
responsible for somatic (o) serotypes of gram NEGATIVE bacteria

Front 37

what size of molecule can diffuse through the LPS layer of a gram negative bacteria?

Back 37

< 700 Da diffuse thru porins, while large hydrophobic molecules are excluded

Front 38

describe one way that the LPS part of the cell envelope helps to identify bacteria strains.

Back 38

Recent salmonellosis from contaminated peanut butter involved all cases representing the same O serotype out of thousands of possibilities. So the epidemiology was quite easy to figure out.

Front 39

where are Teichoic and Lipoteichoic acids found in the cell envelope?

Back 39

Polyalcohol phosphate polymer compounds either covalently attached to peptidoglycan or embedded in the cytoplasmic membrane of GRAM POSITIVE bacteria.

Front 40

what confers somatic (O) serotype antigenicity to gram positive bacteria?

Back 40

the highly substituted regions with various sugars and amino acids with Teichoic and Lipoteichoic acids.