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Microbial Metabolism Flashcards

1
Q

In prokaryotes where is the cytoplasmic membrane located?

A

surrounding the cell

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2
Q

In eukaryotes what does the inner membrane of consist of?

A

mitochondrion

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3
Q

In respiration, a terminal electron acceptor is

A

used to consume donated electrons

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4
Q

What is oxygen commonly used as in aerobic microorganisms?

A

used as the acceptor

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5
Q

What is fermentation used by?

A

organisms that cannot perform respiration to consume electrons

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6
Q

When is fermentation used?

A

when oxygen is not available

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7
Q

What does an obligate anaerobe lack?

A

genes for the proteins of electron transport chain

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8
Q

What are fermentation products useful for?

A

identifying enteric bacteria

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9
Q

What is the central dogma of molecular biology?

A

DNA» Transcription (RNA)» Translation (Protein)

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10
Q

What is not in Prokaryotic Transcription and Translation, but is present in Eukaryotes?

A

mRNA is not processed and it does not contain introns

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11
Q

In Prokaryotes, translation occurs when?

A

translation of mRNA starts as it is being transcribed

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12
Q

In eukaryotes where is the mRNA transported so that it can be translated?

A

out of the nucleus so it can be transcribed in the cytoplasm

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13
Q

In Eukaryotes mRNA is….

In Prokaryotes mRNA is often…

A

Monocistronic: translation begins at the first AUG
Polycistronic: translation usually begins at the first AUG that follows a ribosome binding site

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14
Q

What is true about Prokaryotic gene regulation?

A

some genes are constitutively expressed

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15
Q

Most prokaryotic genes are

A

modulated

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16
Q

Repressors

A

bind to the DNA between the promoter and transcriptional start site, thus blocking RNA pol

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17
Q

Activators

A

interact with the promoter region to facilitate RNA pol binding

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18
Q

During the “off setting” what is bound?

A

the repressors

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19
Q

During the “on setting” what is bound?

A

The activators

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20
Q

What is the lac operon

A

a sensing pathway for lactose

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21
Q

What must you have for the expression of a gene that metabolizes lactose in culture media?

A

The presence of lactose and absence of glucose

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22
Q

What are the steps for turning on the LAC operon

A
  1. As Glucose levels drop cyclic AMP (cAMP) increases
  2. cAMP binds to catabolite activating), allowing it to bind to the promoter
  3. Allolactose, an isomer of lactose, binds to the lac repressor, preventing from binding to the DNA
  4. RNA pol binds to the DNA and begins mRNA synthesis
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23
Q

What are cAMP and CAP together?

A

they become an activator together

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24
Q

Permease

A

Protein involved in permeability, allows the glucose to get into the cell

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25
What happens to the lac operon when Glucose is present and lactose is not present?
Transcription is not activated AND blocked; Because there are low glucose levels there are low cAMP levels and CAP cannot bind, repressor is bound to operator blocking polymerase
26
What happens in the lac operon when glucose is present and lactose is present?
Transcription is not activated; low cAMP; CAP cannot bind. The inducer, allolactose, prevents repressor from binding to the operator
27
What happens in the lac operon when: No Glucose | No Lactose?
Transcription is activated but blocked; High cAMP; CAP/cAMP complex binds to the activator site. Repressor is bound to operator, blocking polymerase
28
What happens in the lac operon when; No Glucose | Lactose Present?
High cAMP; CAP/cAMP complex binds to activator binding site. Allolactose (inducer) prevents repressor from binding to the operator
29
What is Gene 1 in the lactose operon?
Lac Z B-galactosidase
30
What is Gene 2 in the lactose operon
Lac Y B-galactoside permease
31
What is Gene 3 in the lactose operon?
Lac A B-galactoside transacetylase
32
Antibiotic resistance is a
genetic event
33
What is MRSA
methicillin- resistant Staphylococcus aureus
34
Is S.aureus Gram + or Gram -
Gram +
35
What is now used instead of methicillin to treat Staphylococcus aureus?
Vancomycin
36
What does it mean to be haploid?
one chromosome: one copy of everything: Bacteria have haploid genes
37
What do mutations in bacterial genes alter?
alter the genotype and phenotype
38
What is the genotype?
DNA-level information encoded by the genome
39
What are phenotypes usually controlled by?
proteins by alteration of amino acid composition
40
What are the two types of mutations?
Induced | Spontaneous
41
What are Spontaneous mutations?
mutations during normal cellular processes
42
What are the three types of Spontaneous mutations?
``` Nucleotide base substitution (point mutation) Deletion or insertion of nucleotides Transposable elements ("jumping genes" ```
43
What causes induced mutations?
Chemicals and radiation can INDUCE mutations
44
What enzymes are expressed during times of stress? and what do these enzymes do?
Mutases, they increase rates of mutations
45
What do all DNA polymerases have?
inherent mutation rates
46
What would not occur without mutations?
Evolution and organisms being well-equipped to adjust to changes in their environment
47
What three events does evolution require?
``` Genetic Variation (mostly random: mutations) The variations must be heritable Natural selection of those traits most suitable for environment ```
48
What are cells that are receptive to DNA?
competent
49
What does the process of becoming competent require?
protein synthesis
50
What do competent cells have the ability to do? What is this process called and what can it lead to?
permit DNA to pass through their cell walls and membranes: termed Transformation and can lead to acquisition of new genes
51
What can be induced artificially and play a large role in biotechnology?
Competent cells
52
What is transduction? What is an example of this?
Transfer of Genetic Material from one species to another: ex: Bacteriophages (bacterial viruses)
53
What are plasmids?
circular molecules of DNA: look like a bacterial chromosome
54
What do plasmids frequently contain?
Virulence factors; contribute to disease susceptibility: Antibiotic resistance Toxins
55
What are plasmids routinely used for in biotechnology?
gene cloning and recombinant protein production
56
Why are plasmids considered promiscuous?
they can disseminate between species of bacteria
57
What is conjugation
direct transfer of plasmids (or chromosomes) between bacteria
58
What acquire plasmids by random chance rather than conjugation?
Competent cells
59
What are the four steps of Conjugation?
1) Contact between donor cell (F+) and Recipient cell (F-) is mediated by a sex pilus, a tubular structure 2) The plasmid becomes mobilizes by an enzyme that cleaves the plasmid 3) One strand of the plasmid is transferred tot he recipient, presumably through the pilus 4) The copies of the plasmids are used as templates for DNA synthesis
60
What are Transposons?
Jumping Genes; copy themselves and then leave: | Self replicating DNA molecules
61
Where do transposons occur?
Virtually ALL organisms
62
What frequently happens when transposons jump?
They take adjacent genes with them, such that integration in another cell leads to the introduction of novel genetic information.
63
In General the process of protein transcription followed by translation would be faster for...
Prokaryotes
64
You place bacteria in a phenol red lactose broth. A change in broth color from yellow indicated that the bacteria can utilize the sugar source. In this situation you can conclude that:
Allolactose is present in the broth

Micobiology (12 decks)

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