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Micro Exam 2 > 4: Microbial Growth III > Flashcards

4: Microbial Growth III Flashcards

(60 cards)

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1
Q

Binary Fission

A

parent cell spits into 2

each daughter has one old and one new strand of DNA

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2
Q

Division time

A

can take 20 minutes to over 24 hrs

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3
Q

type of growth caused by binary fission

A

Logarithmic growth (2^n, where n is number of generations)

each new cell becomes 2 new cells and so on

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4
Q

if unchecked at this rate… e coli could

A

exceed earth’s weight in 2 days

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5
Q

why haven’t bacteria eaten the world?

A

they eventually run out of food

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6
Q

Growth phases of bacteria

A

Lag phase
Log Phase
Stationary Phase
Death Phase

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7
Q

Lag phase

A

bacteria not growing, but adjusting to environment
preparing to use up food in environment
change protein expression to divide

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8
Q

Log phase

A

2^n
binary fission
growth unchecked

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9
Q

Stationary Phase

A

Running low on nutrients… only metabolize to stay alive

not growth, just maintenance of numbers

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10
Q

Death phase

A

Not enough food to maintain life
bacteria due
some cannibalize each other

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11
Q

Division time depends on…

A

Nutrient Source!

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12
Q

how nutrients affect bacterial growth

A

glucose is favored carbon source, bacteria grow quickly

lactose less preferred carbon source

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13
Q

what if you have 2 carbon sources (glucose and lactose)

A

glucose preferred, so used first, grow fast: steep line
glucose used: lag phase. take time to adapt to new environment (lactose). synthesize metabolites needed to metabolize glucose.
Lactose: another log phase

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14
Q

Ways to measure bacterial growth

A

Optical Density

Serial Dilution and Plating

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15
Q

Optical Density (OD)

A

based on light absorbance… 600 nm wavelength
instant measurement based on absorbancece

if lots of bacteria in the tube, they will scatter the light. more absorption of light, less light is transmitted

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16
Q

Drawback of OD

A

doesn’t tell you a number

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17
Q

Serial Dilution and Plating

A

gives you an actual number

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18
Q

DNA replication… the strands

A

are not identical
are complementary: matched by base pairing

know the sequence of 1 strand? figure out the other

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19
Q

DNA in bacteria

A

is a closed circle

2 replication forks, 2 leading and 2 lagging strand

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20
Q

the genetic info is carried…

A

on a single strand

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21
Q

base pairing

A 
hydrogen bonds connect bases
3 bonds (GC) means more stable
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22
Q

sugar backbones of antiparallel strands

A

opposite! the double bonded oxygen on the phosphate is on the opposite side
5’: oxygen points toward top
3’: oxygen points toward bottom

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23
Q

what provides the energy for the reaction of adding a base?

A

hydrolysis of the phosphate bonds

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24
Q

how many DNA strands are around during replication

A

4… 2 parent, 2 new

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25
DNA polymerase
adds free nucleotides to 3' end. (copies DNA 5' to 3') MUST have primer to start (RNA or DNA) Proofreading ability Can degrade RNA (RNase activity)
26
whats important about the free hydroxyl and where does it need to be?
3' end needs a primer must be a free hydroxyl
27
helicase
opens RNA polymerase to put down primer other enzymes stabilize the replication fork lagging strand has to wait for DNA to be unwound to keep going
28
where MUST the new nucleotide be added
3' END!!!!!!!
29
what adds the RNA primer so that DNA replication can start?
RNA polymerase
30
bacteria: EACH replication fork as a leading and lagging strand
1 origin of replication: 2 replication forks they go in opposite directions lots of things happen to happen (including unwinding) at the end to put them back together
31
Leading/Lagging with 2 forks
if its leading on one fork, its lagging on the other
32
what is PCR?
tool for targeting and amplifying specific DNA sequences
33
what is required for PCR
single stranded DNA "primers"
34
types of Horizontal Transfer of DNA
Recombination Conjugation Transduction Transposition
35
Horizontal DNA transfer
acquisition of new DNA NOT from parent cell... usually smaller than chromosome
36
What enzyme does PCR use?
DNA Polymerase
37
verticle DNA transfer
DNA replication linked to cell division
38
why use PCR
to study genes... which are much smaller than the total DNA of the cell... ex. shig toxin: 2,000 bases out of 5 million in e. coli
39
what do the DNA Primers do in PCR
are DESIGNED to direct DNA poly to a particular sequence and copy it a ton of times to make lots of copies
40
how are copies made using PCR (equation)
2^n
41
what does PCR do?
uses DNA polymerase in a very specific way. copy just the small piece you want
42
Recombination
(transformation) uptake SIMILAR DNA sequence DNA out there in environment... taken up and put into genome NO VECTOR needed "naked" DNA
43
Conjugation
Transfer DNA using type IV secretion (bacterial sex) plasmid usually used to transfer DNA DNA transferred BETWEEN bacteria can carry antibiotic resistance plasmids between cells
44
Transduction
uptake of DNA by phage | movement by viruses
45
Transposition
jumping DNA usually genes that have sequence on end that allow it to move around usually within same cell.... but can move out of the crhomosome and become a plasmid
46
Conjugation... cell "types"
need a donor (F+) cell with a plasmid and a recipient (F-) cell donor replicates the plasmid then moves it into the recipient
47
Why does F+ make pili and F- doesn't
plasmid of F+ codes for pili F- doesn't have plasmid (yet) when injected with pili... F- can get the instructions for making pili
48
What else do we need to do to complete binary fission?
SPLIT THE CELL
49
how do baccili grow?
by elongation. gets to good size, repressors of DNA rep diluted so crhomosomes are copied and cells divide
50
How does it know how to grow?
growth is a function of increased cell mass have enough cell mass (DNA, RNA, protein) to make a second cell
51
what else grows during DNA growth?
plasma membrane and cell wall
52
Contractile rings
form in middle of cell directs cell division scar helps hold bacillus in palce during new round of growth
53
Ring Scars
from where daughters divided previously made of proteins help new cell stay together and keep its shape
54
2 main proteins of contractile rings
FtsZ: like tublin MreB: like actin both PROTEINS they may form spirals that may help rod shape stay in place
55
FtsZ
like tublin
56
MreB
like actin
57
DNA segregatin
just before contractile ring closes, DNA segregated into each daughter cell replication and division are tightly linked
58
Antibotic Resistance Transfer
conjugation plasmids Bacteriodes fragilis plsamid is a conjucation plasmid (RFT) that has resistance to 4 antibiotics
59
what is a main way antibiotic resistance genes are transferred?
plasmids
60
how transduction works
phage infects cell, puts its genome in bacterial chromosome for replication sometimes the phage takes some bacterial DNA from the host and puts it into its next host

Micro Exam 2 (8 decks)

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