Bacterial Metabolism and Genetics

Question 1

Nutrients required by bacteria

Answer 1

CHONPS and trace metal salts

Question 2

What versions of C and N are most important?

Answer 2

Reduced Form

Question 3

Describe the shape of a bacterial growth curve based on temperature.

Answer 3

The curve leans with the highest point/optimum at higher temperatures

Question 4

What is the significance of the bacterial growth curve?

Answer 4

Increase in temperature by as little as 2 degrees causes a large drop in population – FEVER

Question 5

Three types of bacteria based on pH? Who is most common in the stomach? The body?

Answer 5

Acidophile, Neutralophile, Alkalophile
Acidophile
Neutralophile

Question 6

Circumstances in which an aerobe will grow?

Answer 6

O2

Needs an electron acceptor – O,N,S

Question 7

Circumstances in which an anaerobe will grow?

Answer 7

Grows in No O2

O2 forms radicals

Question 8

Circumstances in which facultative anaerobes grow?

Answer 8

Grows in O2, less well without O2

Have TCA and can ferm.

Question 9

Circumstances in which aerotolerant will grow?

Answer 9

Will grow with or without O2

Doesn’t use O2 anyway

Question 10

Circumstances in which microaerophile will grow?

Answer 10

Grows in O2 below 0.2 ATM

Needs O2, but too much makes radicals

Question 11

Oxygen sensitivity of more tissue?

Answer 11

Anerobic

Question 12

Oxygen sensitivity of lungs?

Answer 12

Aerobic

Question 13

Oxygen sensitivity of tonsils/back of throat?

Answer 13

Microaerophile

Question 14

Four phases of bacterial growth cycle?

Answer 14

Lag, Exponential, Stationary, Decline

Question 15

What stage are bacteria typically in the lab? In the body?

Answer 15

Exponential Phase.

Stationary Phase.

Question 16

What occurs during the lag phase?

Answer 16

Adaption to new nutrients

New enzyme synthesis/up-regulation

Question 17

What occurs in the exponential phase?

Answer 17

Growth and binary division

Question 18

What occurs in the stationary phase?

Answer 18

Crowding, Starvation or Toxic Conditions

Stress Genes Upregulated

Question 19

What occurs in the decline phase?

Answer 19

Cells begin to lyse.

Question 20

What occurs in bacterial latency?

Answer 20

No division, allows for hiding from immune response

“Persister cell”

Question 21

How do persister cells come about?

Answer 21

Turn off metabolism
Turn on dormancy pathways
No growing/dividing

Question 22

Role of persister cells in treatment?

Answer 22

Treating against persister cells leads to more rapid cure

Question 23

Describe the bacterial chromosome.

Answer 23

Circular
Stable w/out telomeres
Haploid (typically)
Associated with proteins (structural and regulatory)

Question 24

What are merodiploids?

Answer 24

Genes in multicopy in the bacterial chromosome

Question 25

Describe a plasmid?

Answer 25

Circular, smaller than chromosome | Can exist in hundreds of copies per cell

Question 26

What controls plasmid replication?

Answer 26

Cop proteins

Question 27

In a broad sense, how does bacterial transcriptional regulation occur?

Answer 27

Negative Regulation -- Protein Repressors | Positive Regulation -- Protein Activators

Question 28

Where do repressors bind?

Answer 28

Between promoter and gene

Question 29

Where do activators bind?

Answer 29

Upstream of promoters

Question 30

How do environmental signals modify gene regulation?

Answer 30

Small molecules alter the shape/bind to regulatory proteins

Question 31

Two types of environmental signals?

Answer 31

Induction and Repression

Question 32

What are two ways in which repression may work?

Answer 32

Trigger Active Repressors | Inactivate Inducer

Question 33

How does the lactose influence the lac operon?

Answer 33

Lactose present inhibits the lac repressor protein

Question 34

How does high glucose influence the lac operon?

Answer 34

High glucose will lead to low cAMP With low cAMP, minimal binding of Lac Inducer Transcription at low rate

Question 35

How does low glucose influence the lac operon?

Answer 35

Low glucose leads to higher cAMP levels | cAMP+CAP activator binds, induces great amount of lactase transcription

Question 36

What happens in bacterial transformation?

Answer 36

Uptake of unpackaged DNA

Question 37

What triggers bacterial transformation?

Answer 37

Competence pharomones/Quoromones are secreted as nutrients run out Quorum Sensing

Question 38

How might DNA transformation be induced?

Answer 38

High temperature opens membrane pores | CaCl2 shields DNA- charges and lets new DNA in

Question 39

How might one make bacteria transformation occur in a laboratory setting?

Answer 39

Gene gun, electroporation

Question 40

What is conjugation?

Answer 40

Natural Plasmid Transfer

Question 41

How does conjugation occur?

Answer 41

Cells with F+ plasmid generate sex pili that binds to receptors on F- pili

Question 42

What are Hfr cells?

Answer 42

Cells that in conjugation can transfer chromosomal genes

Question 43

How are chromosomal genes transferred with plasmids?

Answer 43

Following integration of F plasmid, adjacent chromosomes be come with the F plasmid with abnormal excision P' Plasmid

Question 44

Significance to chromosomal gene transfer in plasmids?

Answer 44

Can generate R-plasmids | Resistance genes pulled along with the plasmid

Question 45

What is transduction?

Answer 45

gene transfer mediated by imprecise excision or packaging of phage

Question 46

Difference between generalized and specialized transduction?

Answer 46

Generalized -- lytic phage -- could be any gene | Specialized -- lysogenic phage -- only genes near integration site

Question 47

What happens in bacterial gene replacement?

Answer 47

transferring genes integrate into host chromosome replacing native genes

Question 48

Homologous recombination is catalyzed by ____. What unique thing may happen to the DNA?

Answer 48

RecA | Inversions

Question 49

Where do inversions happen? Where do deletions occur?

Answer 49

Inversions -- Between Inverted Repeats | Deletions -- Between Direct Repeats

Question 50

How does recombination at dissimilar sequences occur?

Answer 50

transposons acting via transposases

Question 51

Difference between composite and non-composite transposons?

Answer 51

Non -- inverted repeats at end and transposase | Comp -- Complete IS elements at ends, genes in middle

Question 52

Two pieces of medical significance of plasmids

Answer 52

Antiobiotic resistance transfer | Interruption of genes resulting in mutation

Question 53

What are outer membrane vesicles?

Answer 53

Small vesicles that bud from outer membrane containing genetic elements and signalling molecules

Question 54

Why do we care about outer membrane vesicles?

Answer 54

Blebbing and budding with genes/proteins/virulence factors provides extra routes of transmission