Microbiology Section 1

Front 1

What is the cell theory of life?

Back 1

Concept developed by Schwann. All organisms are composed of cells.

Front 2

What is pasteurization?

Back 2

Exposing food to enough heat to destroy microorganisms without affecting quality.

Front 3

What is the germ theory of disease?

Back 3

Disease is caused by microorganisms. Lister.

Front 4

What are Koch's postulates?

Back 4

1. MO is found in diseased animals but not healthy animals.
2. MO can be grown in pure culture.
3. Healthy animals are made sick by the MO.
4. You can re-isolate the MO from these animals.

Front 5

What did Tyndall do?

Back 5

Helped dispel the idea of spontaneous generation. Invented tyndallization (which destroys MOs with pressure).

Front 6

About how many bacteria in the oral cavity?

Back 6

2 x 10^7

Front 7

A bacterial ribosome is defined as__S. What two subunits does it have?

Back 7

70
Subunits: 50S and 30S

Front 8

Prokarya are defined by what they do not have, namely ____. This is why Pace thinks the term is outdated.

Back 8

nuclei

Front 9

Bacteria ribosomal RNA is defined as ___S.
What two subunits does it have?

Back 9

16
subunits: 23S and 5S

Front 10

What are the three domains? Which two have the closest evolutionary origin?

Back 10

Eukarya, Archaea, and Bacteria

E and A are closest in origin

Front 11

What RNA is used to classify bacteria? Which section is variable?

Back 11

the 16S rRNA. The middle is variable.

Front 12

Eubacteria lack ___ in cell membranes.

Back 12

sterols

Front 13

Which organelles are thought to have evolved from bacteria?

Back 13

mitochondria and chloroplasts (endosymbiotic theory)

Front 14

What kinds of lipids are in bacteria?

Back 14

only simple phospholipids

Front 15

What kinds of ribosomes do eukaryotes have?

Back 15

80S (and some 70S from ribosomes)

Front 16

Do eukaryotes or prokaryotes display colinearity? What is it?

Back 16

Prokaryotes do. Means number of amino acids is proportional to the nucleotides. (Eukaryotes have introns)

Front 17

Do viruses translate/transcribe RNA or DNA?
Do they have lipids?

Back 17

No.; It is POSSIBLE for them to have a lipid coat, but this is not a biological membrane.

Front 18

Why aren't bacteria giant?

Back 18

Once the volume to surface area ratio gets too high, it is difficult for a cell to function.

Front 19

Do bacteria have ribosomes? Do viruses?

Back 19

Bacteria have ribosomes (70S) and viruses don't.

Front 20

Do bacteria have DNA/RNA? Do viruses?

Back 20

Bacteria have both. Viruses have one or the other, but never both.

Front 21

Four basic steps of the Gram stain.

Back 21

1. Crystal violet
2. Iodine (fixing in +)
3. acetone/alcohol (washing from -)
4. safranin

Front 22

What's the difference between classification and taxonomy?

Back 22

taxonomy is the study of classification

Front 23

What did Carl Linnaeus start?

Back 23

the binomial system of nomenclature

Front 24

After performing the Ziehl-Neelson stain, the acid-fast bacteria are stained ____.

Back 24

RED

Front 25

The biggest acid-fast genus is ____. Species of this genus cause what two major diseases?

Back 25

Mycobacterium
leprosy and tuberculosis

Front 26

Almost all Gram + cocci n the oral cavity are ___.

Back 26

Streptococcus

Front 27

Almost all Gram - spirochetes in the oral cavity are ___.

Back 27

Treponema (all spirochetes in general are Gram -)

Front 28

Almost all Gram - cocci in the oral cavity are ____.

Back 28

Veillonella

Front 29

A star shaped colony indicates ____.

Back 29

Aggregatibacter actinomycetemcomitans

Front 30

Gram - rods with a black/brown colony from the oral cavity are usually one of what two things?

Back 30

Bacteroides species or Porphyromonas gingivalis

Front 31

Does Aggregatibacter actinomycetemcomitans have catalse? How can you tell?

Back 31

It does have catalase! It bubbles when you add hydrogen peroxide.

Front 32

Why are Bacteroides black in colonies?

Back 32

melanin

Front 33

What is notable about Serratia marcesens?

Back 33

It is blood red in culture because of a pigment called prodigiosin.

Front 34

What are some ways to identify bacteria by products?

Back 34

1. their products of fermentation
2. their acid profiles
3. their fatty acid profiles
4. their protein profiles
5. their antigen profiles

Front 35

What are biotypes?

Back 35

classifications based on fermentation reactions

Front 36

What are serotypes?

Back 36

classifications based on immunospecific reactions (antigen/antibody)

Front 37

How does neutral red work?

Back 37

If the bacteria ferments lactose, the lactate will neutralize the red color. (this is a "biotype")

Front 38

What are two typical tests for serotype?

Back 38

ELISA. Adding fluorescent antibodies to a bacteria and seeing if they fluoresce.

Front 39

Steps in ELISA.

Back 39

1. antigens added
2. first antibody added
3. second antibody (attached to a dye) is added

Front 40

What is API?

Back 40

Automated phenotypic identification. Strips that you inject your bacteria into and then incubate. Pretty neat.

Front 41

What's the difference between Gram negative and Gram positive bacteria?

Back 41

Negative have a smaller PG layer. They also have an outer membrane.

Front 42

On a Gram - bacteria, the ___ is between the inner membrane and the outer membrane.

Back 42

periplasmic space

Front 43

Why are bacterial membranes described as tripartate?

Back 43

With the electron microscope, there are three layers.

Front 44

What kind of bacteria have enclosing membranes?

Back 44

acid-fast (I'm not sure why I made this question and I don't know what it means, but I'm leaving it in case I find out)

Front 45

What is unique about the genus Mycoplasma?

Back 45

It lacks PG. It can absorb sterols into its membrane. In these ways, they're like eukaryotes. (MYCOPLASM /= MYCOBACTERIA)

Front 46

What are the three parts of PG?

Back 46

1. Glycan backbone (NAG and NAM)
2. tetrapeptide side chain
3. amino acid cross-links

Front 47

What is NAM? NAG?

Back 47

N-acetyl muranic acid (found only in bacteria). N-acetyl glucosamine

Front 48

How are NAG and NAM linked?

Back 48

beta-1,4 disaccharide linkages

Front 49

What are the conformations of the aas in the tetrapeptide side-chain? What does it end in?

Back 49

Usually L, then D, then L/D, then D. It always ends in D-alanine.

Front 50

Does the tetrapeptide chain attach to NAG or NAM?

Back 50

NAM

Front 51

The cross bridge of PG connects what to what?

Back 51

D-alanine (position 4), to an amino acid in position 3 on a different glycan backbone.

Front 52

What is the amino acid in position 3 in the tetrapeptide chain? What's unique about it.

Back 52

Usually D,L-diaminopimelic acid. It's unique because it's diamino, dicarboxy, allowing it to make 3 peptide bonds, which makes crosslinking possible.
Abbreviation: meso-DAP

Front 53

What doesn't the D-alanine in position 4 have to be diamino dicarboxy?

Back 53

It only has to make two peptide bonds. Think about it.

Front 54

What's the difference between the structure of PG in Gram - and +?

Back 54

Gram - has less cross-linking. In Gram +, all the NAMs are linked.

Front 55

What happens to a eukaryotic cell under hypertonic conditions? Hypotonic?

Back 55

hypertonic: plasmolysis
hypotonic: cytolysis

Front 56

What structural feature most explains bacteria's ability to live in weird places?

Back 56

The cell wall. Keeps them from lysing/shrinking. It's also resistant to detergent and heat.

Front 57

Where does lysozyme cut the cell wall?

Back 57

It cleaves between NAG and NAM. (Many host cell defenses target PG)

Front 58

What is the major surface polymer of (all and only) Gram positive bacteria?

Back 58

Lipoteichoic acid (LTA)

Front 59

The hydrophilic portion of LTA is composed of alternating phosphates and one of what two sugars?

Back 59

glycerol or ribitol

Front 60

What is the major surface polymer of (all and only) Gram - bacteria?

Back 60

LPS (lipopolysaccharide, aka endotoxin)

Front 61

What are the three parts of LPS.

Back 61

1. Lipid A (in membrane)
2. Core polysaccharide (short. maybe 4-5 sugars)
3. O-polysaccharide (aka O-antigen)

Front 62

What is the composition of the O-antigen?

Back 62

It's got about 4 sugars that repeat many times.

Front 63

Why is the O-polysaccharide helpful for serotyping?

Back 63

The repeating sugars vary from bacteria to bacteria, so the antigens that respond to each one will be different.

Front 64

Describe Lipid A.

Back 64

Two phosphorylated NAGS with FAs attached. Lipid A is the TOXIC PORTION of LPS.

Front 65

LTA attaches to the ___ and passes out through ___.

Back 65

cytoplasmic membrane; PG

Front 66

LPS attaches to the ____.

Back 66

outer membrane

Front 67

How does LPS create an asymmetrical membrane?

Back 67

The outer leaflet of the outer membrane is composed mainly of the FAs and sugars of lipid A, while the inner leaflet of the outer membrane is generic phospholipid.

Front 68

What's the structure of a porin? What's the biggest thing that can get through it?

Back 68

It's a trimer. A pentasaccharide can get through it.

Front 69

Like Gram positive bacteria, ____ have a cytoplasmic membrane and PG, but no outer membrane.

Back 69

acid-fast bacteria

Front 70

What is the most important surface compound of acid-fast bacteria? Describe it.

Back 70

Mycolic acid. It's large and very waxy and excludes water. It makes growth difficult.

Front 71

A shiny, glistening colony might indicate the presence of what?

Back 71

A thick glycocalyx

Front 72

Falgella are composed of ___, while pili are composed of ____.

Back 72

flagellin; pilin

Front 73

What are the protein surface appendages?

Back 73

flagella and pili

Front 74

Flagella are used for ____, while pili are used for ____.

Back 74

motility; adhesion (including mating)

Front 75

E. coli has a single flagellum. These are called ___.

Back 75

polar flagella

Front 76

When bacteria have more than one flagellum, they are called ____.

Back 76

peritrichous flagella

Front 77

How does a bacteria change direction?

Back 77

The flagellum (or flagella bundle) changes its direction of rotation.

Front 78

What kinds of bacteria have axial filaments? What are they?

Back 78

Spirochetes. Axial filaments are flagella that give spirochetes their corkscrew movement.

Front 79

O-polysaccharide is sometimes called ____, and flagella are sometimes called ____. Capsules are sometimes called____.

Back 79

O-antigen; H-antigen; K-antigen

Front 80

Why do obligate anaerobes die in the presence of O2?

Back 80

They cannot eliminate superoxide anions. They don't have the enzyme superoxide dismutase.

Front 81

Autotrophs do not require what?

Back 81

organic carbon. They use only CO2 (e.g. blue-green).

Front 82

What do superoxide anions do?

Back 82

they inhibit DNA (OK. Not sure, but I think they bind the two strands of DNA together...?)

Front 83

Heterotrophs require ____.

Back 83

an organic source of carbon

Front 84

Bacteria that grow at high temperature are called? Medium temp? Cold temp?

Back 84

High: thermophiles
Medium: mesophiles
Cold: psychrophiles

Front 85

What is heterotrophic CO2 fixation?

Back 85

The use of inorganic carbon for growth by heterotrophs (~5-10%)

Front 86

How does glycerol get through the cytoplasmic membrane?

Back 86

diffusion (this is rare and only for small molecules)

Front 87

How do glucose, fructose, and sucrose get through the cytoplasmic membrane?

Back 87

the phosphotransferase system (PTS)
[active transport]

Front 88

What are the two kinds of passive transport across the cytoplasmic membrane?

Back 88

simple diffusion or facilitated diffusion (as through a permease)

Front 89

Describe active transport by a permease.

Back 89

The permease goes through a conformation change. Once the molecule is inside, it is phosphorylated by ATP (usually), so it can't get out.

Front 90

Superoxide anions are broken down by _____ into _____, which can further be broken down by ___ or _____.

Back 90

superoxide dismutase; hydrogen peroxide; catalase; peroxidase

Front 91

How does sugar get through the 3 layers of the Gram - bacteria?

Back 91

facilitated diffusion through outer membranes, can pass through PG, and is actively transported across the cytoplasmic membrane.

Front 92

What is the permease for glucose?

Back 92

Enzyme IIGlu

Front 93

Unlike other active transport systems, the PTS system uses ___ for phosphorylation instead of ATP.

Back 93

PEP

Front 94

____ takes the phosphate from PEP and puts it on ___. (re: PTS)

Back 94

Enzyme I; HPr (histadine-rich protein

Front 95

HPr brings phosphate to ___, which brings it to ___, which transfers it to the sugar as it enters.

Back 95

Enzyme II; Enzyme III

Front 96

In the PTS, sucrose binds to ____ on the cell membrane. Unlike glucose, sucrose does not have an ____.

Back 96

Enzyme IIScr; Enzyme III

Front 97

What are the soluble cytoplasmic components of the PTS? Which enzymes are in the membrane?

Back 97

HPr and Enzyme I. Enzyme IIs are in the membrane.

Front 98

What is the name for the bacterial glycolytic pathway?

Back 98

The Embden-Meyerhoff-Parnas (EMP) pathway

Front 99

The EMP breaks glucose down to ___.

Back 99

pyruvic acid

Front 100

What are the three general stages of the EMP?

Back 100

1. phosphorylation
2. splitting
3. redox

Front 101

What are the products of EMP?

Back 101

Net 2 ATP, 2 NADH, 2 pyruvic acid

Front 102

If glucose-6-P enters the PPP instead of the EMP, it will be converted first to 6-phosphogluconolactone, and ultimately will become building blocks for ___.

Back 102

nucleic acids

Front 103

What are the products of the pentose phosphate pathway?

Back 103

1 net ATP, 1 NADH, 2 NADPH, a C4 product

Front 104

Anaerobic bacteria (and facultative bacteria) will take pyruvate and make what?

Back 104

alcohol, acid, and CO2

Front 105

Aerobes (and facultative bacteria) take pyruvate and make what?

Back 105

carboxylic acid intermediates and ATP

Front 106

What process is coupled to the reduction of pyruvate to lactate (C3)?

Back 106

the oxidation of NADH back to NAD+

Front 107

During alcoholic fermentation, pyruvate is generally converted to ___, with ___ as an intermediate.

Back 107

ethanol (C2); acetaldehyde (C2)

Front 108

What kinds of bacteria are homolactic and heterolactic?

Back 108

Both Streptococcus and Lactobacilli can be both

Front 109

(Re: fermentation) Fusobacterium produce ____. Veillonella produce ____.

Back 109

butyric acid; propionic acid

Front 110

Do aerobic bacteria use the TCA cycle?

Back 110

Yes, but it's modified. It's not complete. They don't have all the enzymes.

Front 111

What are the main products of TCA?

Back 111

NADH2 and intermediates for amino acid biosynthesis

Front 112

In bacteria the ETC is in the ____. Protons are pumped ___ the cell. As protons rush back ___, they create energy.

Back 112

cytoplasmic membrane; out of; in

Front 113

What is the chemiosmotic hypothesis?

Back 113

The idea that the proton gradient across the membrane allows ATP synthesis

Front 114

What TCA enzyme is notably inactivated in anaerobic conditions?

Back 114

a-ketoglutarate oxidase (which typically converts it to succinyl-CoA)

Front 115

Do facultative bacteria completely stop TCA in the absence of O2?

Back 115

No. It still makes some of the intermediates. It uses different enzymes.

Front 116

During heterotrophic CO2 fixation, where is the carbon used?

Back 116

It is used to make oxaloacetate from pyruvate for TCA. (NB: ATP is generated from CO2 fixation.)

Front 117

What is horizontal (lateral) gene transfer?

Back 117

Gene transfer from one MO to another. (No sex, no children.)

Front 118

What are the consequences of lateral gene transfer?

Back 118

Genetic plasticity allow MOs to evade host defenses and acquire resistance to antimicrobial agents.

Front 119

What are the three types of mobile genetic elements?

Back 119

1. plasmids
2. transposons
3. bacteriophages

Front 120

Little circles of DNA that are separate from the bacterial chromosome are called ____.

Back 120

plasmids

Front 121

What is the "copy number" of a plasmid?

Back 121

It determines the number of copies of the plasmid that the bacteria will make.

Front 122

What are bacteriocins?

Back 122

Plasmids that code for proteins that kill other bacteria.

Front 123

What is an F-factor?

Back 123

A plasmid that codes for the sex pilus (fertility factor).

Front 124

What is a colicin?

Back 124

A type of bacteriocin coded by a plasmid that is toxic to E. coli.

Front 125

What's the main difference between a plasmid and a transposon?

Back 125

Plasmids are circular. Transposons are linear. (NB: both are dsDNA)

Front 126

What is on the ends of the transposon?

Back 126

inverted repeats

Front 127

The RNA or DNA of a bacteriophage is always contained in a ______.

Back 127

protein coat

Front 128

On a bacteriophage, there may be a ____ between the tail and the tail fibers. There may be a ____ between the head and the core.

Back 128

base plate; collar

Front 129

What is a capsomere?

Back 129

the protein coat on the genetic material of a bacteriophage

Front 130

What are Bradley groups?

Back 130

Different kinds of bacteriophages based on DNA/RNA, ds/ss, tail/no tail, long tail/short tail, etc.

Front 131

What are the three mechanisms of lateral gene transfer?

Back 131

1. transformation (naked dsDNA)
2. conjugation (plasmid or transposon)
3. transduction (bacteriophage)

Front 132

What are R strains and S strains?

Back 132

R = rough, no capsule
S= smooth, capsule

Front 133

In Griffith's experiments, why could inactive S strain make the R strain toxic?

Back 133

Because of transformation. Naked dsDNA from the lysed S strain incorporated into the R strain, inducing it to form capsule.

Front 134

What is the competence factor?

Back 134

A protein made by the cell that binds to other cells at high cell concentration. It turns on autolysin. (Re: transformation)

Front 135

What does autolysin do?

Back 135

It makes the membrane more permeable. (Re: transformation)

Front 136

What does nuclease do? (Re: transformation)

Back 136

It sits on the cell surface near pores and DNA-binding protein.

It degrades one strand of the dsDNA that enters the cell.

Front 137

What is competence-specific protein?

Back 137

It coats the ssDNA made by the nuclease in protein, allowing it to enter the cell and incorporate into the chromosome during transformation.
(NB: both DNA and the membrane are negative, so the protein allows the DNA to get through the membrane)

Front 138

What are the two cell types involved in conjugation?

Back 138

F+ donor cell (caries the F plasmid) and F- recipient cell (no F factor)

Front 139

What happens when the F+ attaches to the F-?

Back 139

The F pilus acts as a bridge and makes a copy of its plasmid for the F- cell.

Front 140

What is an Hfr cell?

Back 140

A high frequency recombinant cell. It's a cell that has incorporated a plasmid into its chromosome during conjugation.

Front 141

What is an F' cell?

Back 141

It is an cell that has received a plasmid during conjugation that has extra DNA in it from the Hfr.

Front 142

What is the last piece of DNA to pass to from the Hfr to the F-?

Back 142

The F gene, which is the incorporated plasmid.

Front 143

What are the two types of phages?

Back 143

virulent and temperate

Front 144

Virulent phages ___ the cell.

Back 144

lyse

Front 145

Virulent phages go through the ___ cycle. Temperate phages go through the ____ cycle.

Back 145

lytic; lysogenic

Front 146

Why is it called the lysogenic cycle?

Back 146

The prophage DNA is carried silently, but always has the potential to become lytic given the right stimulus.

Front 147

What is a good example of feed forward activation in S. mutans?

Back 147

When sucrose is found in excess, G6P activates pyruvate kinase. F16BP activates lactate dehydrogenase. T3P inactivates pyruvate formate lyase.

The overall effect is homolactic fermentation (the strongest acid).

Front 148

1. Pyruvate kinase
2. lactate dehydrogenase
3. pyruvate formate lyase

Back 148

1. PEP to pyruvate
2. pyruvate to lactate
3. pyruvate to other stuff (heterlactic fermentation)

Front 149

What does beta-glactosidase do?

Back 149

Breaks lactose into galactose and glucose

Front 150

What enzyme allows lactose to get into the cell?

Back 150

galactoside permease

Front 151

The lactose operon is an example of ___ and ___ control.

Back 151

negative; local

Front 152

What is the regulatory gene of the lactose operon?

Back 152

lacI. It makes the repressor, which is always expressed in the absence of lactose.

Front 153

What is the inducer of the lactose operon?

Back 153

lactose. It changes the conformation of the repressor, so it can no longer block the operator.

Front 154

What happens when the repressor is not bound to the operator (in negative control)

Back 154

It allows lacY, lacZ, and lacA to be transcribed. (These make galactoside permease, b-galactosidase, and transacetylase, which are needed for lactose catabolism.)

Front 155

What's the main difference with positive control?

Back 155

The inactivated repressor binds at a different region of the operon to induce transcription.

Front 156

What are the four stages of the bacterial growth cycle?

Back 156

1. Lag
2. Log
3. Stationary
4. Death

Front 157

Antibiotics made by...
1. fungi
2. Gram +
3. Gram -

Back 157

1. beta-lactam
2. aminoglycoside
3. quinolone

Front 158

What is MIC?

Back 158

minimal inhibitory concentration required to inhibit bacterial growth

Front 159

What are the four mechanisms of action of antibiotics we looked at?

Back 159

1. inhibit cell wall synthesis
2. disrupt cell membrane
3. inhibit nucleic acid synthesis/replication
4. inhibit protein synthesis

Front 160

The second part of PG is a tetrapeptide, but when it is being synthesized, it's actually a ____, with the 4th and 5th aas being ____.

Back 160

pentapeptide; D-alanine

Front 161

What does D-cycloserine do?

Back 161

(1) Inhibits formation of the D-alanine-D-alanine bond in the pentapeptide.

Front 162

What antimicrobials prevent PG precursors from getting out of the cell?

Back 162

(1) vancomycin prevents transport across cell membrane.

(1) bacitracin prevents Carrier Lipid PP from dephosphoylating so it can't be recycled

Front 163

What does penicillin do?

Back 163

(1) prevents cleaving of the second D-alanine. Cross-links cannot be formed.

Front 164

Penicillin is a close analog of ___.

Back 164

D-alanyl-D-alanine

Front 165

What are the two families of antimicrobials that disrupt cell membranes (2)?

Back 165

a. polymyxins (for prokaryotic cells)
b. polyenes (interact with sterols -for eukaryotic cells, e.g. yeast)

Front 166

What are the four families of antibiotics that inhibit DNA replication/synthesis (3)?

Back 166

1. quinolones
2. metronidazole
3. rifamycins
4. sulfonamides

Front 167

What do quinolones do?

Back 167

(3) Inhibit DNA replication

Front 168

What do metronidazoles do?

Back 168

(3) Produce superoxide anion radicals to inhibit DNA replication.

Front 169

What do rifamycins do?

Back 169

(3) Inhibit DNA transcription by inhibiting RNA polymerase

Front 170

What do sulfonamides do?

Back 170

(3) block folic acid synthesis, which is needed for NA synthesis

Front 171

Which antibiotics inhibit protein synthesis by inhibiting 30S (4)?

Back 171

a. kanamycin
b. tetracycline
c. spectinomycin
4. streptomycin

Front 172

Which antibiotics inhibit protein synthesis by binding to the 50S (4)?

Back 172

a. chloramphenicol
b. erythromycin
3. clindamycin
4. lincomycin

Front 173

Ethambuton, isoniazid, and pyrazinamide are all what?

Back 173

Antiobiotics effective against acid-fast bacteria.

Front 174

What are the four general mechanisms of antibiotic resistance?

Back 174

1.Decrease cell permeability
2. Mutation to alter target site
3. Acquire gene to pump out antibiotics
4. Acquire genes to kill antibiotics

Front 175

Mutations in transpeptidase might cause ____ resistance.

Back 175

penicillin

Front 176

Mutations in PG structure might cause ____ resistance.

Back 176

vancomycin

Front 177

How might bacteria become resistant to tetracyclin?

Back 177

A ribosome protection gene or a tetracyline pump.

Front 178

What's the last line of defense against MRSA?

Back 178

vancomycin

Front 179

Mutated DNA gyrase would cause resistance to ___.

Back 179

quinolone

Front 180

Which enzyme destroys penicillin?

Back 180

beta-lactamase

Front 181

Over time, pneumococci have become resistant to ____.

Back 181

penicillin G

Front 182

Over time, both meningococci and gonorrhea have become resistant to _____. The antibiotic of choice for gonorrhea is now ____.

Back 182

sulfonamides; quinolones

Front 183

Enteric bacteria are often treated with ____, but many are becoming resistant.

Back 183

tetracycline

Front 184

Regarding operons, ____ genes are always expressed and code for the ____.

Back 184

constitutive; repressor

Front 185

What is catabolite repression?

Back 185

In the presence of glucose, genes that code for metabolic intermediates are repressed.

With a lack of glucose, the PTS activates cAMP, which activates these genes. This is an example of global control of several operons.