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Microbiology > 14: evolutionary relatedness > Flashcards

14: evolutionary relatedness Flashcards

1
Q

What are the 4 differences between prokaryotes and eukaryotes?

A

prokaryotes = no nucleus, mRNA is not stable, no membrane-bound structures, one circular piece of DNA

eukaryotes = nucleus, mRNA is stable, membrane-bound structures, multiple strands of DNA

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2
Q

What are the two steps of gene expression?

A

transcription and translation

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3
Q

What happens when a gene is expressed?

A

a protein gets made

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4
Q

what is transcription?

A

making and RNA copy of a gene

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5
Q

What is translation?

A

using the instructions on the mRNA to make a protein

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6
Q

Where does transcription take place in eukaryotes? and translation?

A

nucleus and cytoplasm (transcript must leave nucleus to be translated)

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7
Q

Why does gene expression take longer in eukaryotic cells?

A

a transcript cannot be translated as the transcript is being made. (it’s compartmentalized)

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8
Q

Why is gene expression faster in bacteria?

A

they do not have a nucleus, so they can start translating a transcript even before it is finished (not compartmentalized)

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9
Q

What other domain does not contain a nucleus? Are bacteria haploid or diploid?

A

Archaea; haploid

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10
Q

Who is able to turn off gene expression more quickly? Why is that?

A

Bacteria; prokaryotic mRNA is degraded more quickly (lasts only few minutes)

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11
Q

How does bacteria use their short half life of mRNA to their advantage?

A

they can respond more quickly to environmental changes, can turn genes off and on faster.

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12
Q

What organism deals w rapid switches in the environment?

A

Vibrio cholerae

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13
Q

What does cholera toxin cause? What does it result in? What does it have an impact on?

A

excessive watery diarrhea; severe dehydration and death; the enzyme adenylate cyclase

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14
Q

Where else was adenylate cyclase mentioned?

A

edema toxin

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15
Q

What type of toxin is cholera toxin?

A

AB toxin

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16
Q

How does cholera toxin enter the cell?

A

V. cholerae in the intestines releases cholera toxin, which binds to a receptor on the intestinal cell

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17
Q

What happens after the cholera toxin binds to the cell receptor?

A

The A subunit gets inside the cell and modifies G protein, causing unregulated adenylate cyclase activity so lots of cAMP is made.

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18
Q

What is G protein? What happens after it is modified?

A

a cellular protein; leads to unregulated adenylate cyclase activity so a lot of cAMP is made

19
Q

What happens after excessive amounts of cAMP are made? (cholera toxin mechanism)

A

causes the chloride channel to pump out excess chloride ions into the lumen; water follows. Sodium in the lumen is also blocked from getting into the cell.

20
Q

what two ions are involved in the mechanism of action of cholera toxin?

A

chloride ions (out) and sodium (can’t get back in)

21
Q

What is cAMP, what makes it it? and what does it do in our cells?

A

a second messenger; made by cellular adenylate cyclase; controls fluid balance in the cell

22
Q

cAMP is generated from what? and made by what enzyme?

A

ATP; adenylate cyclase

23
Q

How does cAMP regulate fluid balance?

A

by controlling ion channels

24
Q

What controls adenylate cyclase?

A

G protein

25
Q

in cAMP the sugar is __________ and the phosphate is bonded to the ___________ and _________ carbon.

A

ribose; 5’ ; 3’

26
Q

What is used when treating cholera pts?

A

cholera cot

27
Q

what does evolution involve?

A

changes to the genetic material in the chromosome

28
Q

what has an impact on number of replication events per given time?

A

number of chromosomes distributed during cell division

29
Q

bacteria are ________ so they do not spend a lot of time organizing chromosomes during cell division, so they replicate _________ __________ than eukaryotes.

A

haploid; more often

30
Q

How often does E. coli replicate?

A

every 20 min

31
Q

what is mutation rate?

A

number of mutations per replication event

32
Q

which type of cell has more mutation rates?

A

both types have the same mutation rate

33
Q

Which type of cell has more replication events?

A

bacteria

34
Q

Bacteria have more replication events, therefore…

A

more opportunities for mistakes being made during replication

35
Q

eukaryotic cells have fewer replication events, therefore…

A

fewer opportunities for mistakes to be made

36
Q

bacterial cells have more ________ _________, so they have more __________ in a shorter period of time even though both typed have the same _________ ___________

A

replication events; mutations; mutation rate

37
Q

Why do bacteria undergo evolution more quickly?

A

because they have more replication events causing more mutations

38
Q

Why do bacteria have more replication events?

A

the cell division process is less complicated and faster than mitosis in eukaryotes

39
Q

what is cell division in bacteria cells called?

A

binary fission

40
Q

when else does evolution occur in bacteria? (besides a mutation)

A

when a bacterium gains a plasmid from another organism, or a bacteria is infected w a bacteriophage

41
Q

What happens in prokaryotes when a mutation occurs in a gene? What does it cause? Why is this?

A

it cannot be covered up or masked, so they are more likely to have an impact; speeds up evolutionary process; because it’s haploid

42
Q

What happens in eukaryotes when a mutation occurs? What does it cause? Why is this?

A

it can be masked by a normal gene on a chromosome in the same pair; slows down evolution; it’s diploid

43
Q

what is the driving force for evolution?

A

mutation

Microbiology (16 decks)

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