Chapter 5: Microbial Growth

Question 1

what are the reproductive strategies of eukaryotic microbes?

Answer 1

asexual (mitosis) and sexual (meiosis), haploid or diploid

Question 2

what is the reproductive strategy of bacteria and archaea?

Answer 2

haploid only,

asexual - binary fission, budding, filamentous

Question 3

what is cell division?

Answer 3

each daughter cell receives genetic material and sufficient copies of all other cell constituents to exist as an independent cell

Question 4

For both prokaryotes and eukayrotes, there two common ways cell division occurs. What are they and describe them

Answer 4

1.) Binary fission – cell gets roughly twice its size and then divides the genetic material and cytoplasm equally between the two cells.
2.) Budding – a piece of the cell, containing the genetic material but only a little cytoplasm, pinches off to form a new cell. It will then grow bigger
(slides 4 and 5)

Question 5

what is the cell cycle?

Answer 5

sequence of events from formation of new cell through the next cell division

Question 6

most bacteria divide by _________

Answer 6

binary fission

Question 7

for the bacterial cell cycle, two pathways function during cycle. What are they?

Answer 7

1. ) DNA replication and partition

2. ) Cytokinesis – division of cytoplasm and structures within

Question 8

most bacterial chromosomes are____

Answer 8

circular

Question 9

Most bacterial chromosomes have a ______ origin/s of replication – site at which replication begins

Answer 9

single

Question 10

in regards to the bacterial chromosomes, what is the Terminus?

Answer 10

site at which replication is terminated, located opposite of the origin

Question 11

in regards to the bacterial chromosomes, what is the Replisome?

Answer 11

group of proteins needed for DNA synthesis

Question 12

True or False: DNA replication proceeds in both directions from the origin

Answer 12

true

slides 8 and 9

Question 13

describe chromosome partitioning in bacteria (2)

Answer 13

1.) 2 daughter chromosomes are moved to opposite ends
2.) MreB (murein cluster B) – an actin homolog, plays role in chromosome segregation
-new origins associate with MreB tracks
-if MreB is mutated, chromosomes do not segregate
(slide 11)

Question 14

what is Septation?

Answer 14

• formation of cross walls between daughter cells

- several steps directed by several enzymes

Question 15

describe culture media (3)

Slide 14

Answer 15

1. ) Need to grow, transport, and store microorganisms in the laboratory
2. )Culture media is solid or liquid preparation
3. ) Must contain all the nutrients required by the organism for growth

Question 16

what are the three basis for classifications for culture media?

Answer 16

• chemical constituents from which they are made
• physical nature
• function

Question 17

for the chemical composition basis for classification, what are the 2 types? describe them

Answer 17

1. ) Defined or Synthetic
   - All components and their concentrations are known
2. ) Complex
   - Contain some ingredients of unknown composition and/or concentration

Question 18

what is minimal medium?

Answer 18

media containing minimal nutritional requirements for a particular microorganism; varies from microbe to microbe

Question 19

what is rich medium?

Answer 19

medium containing much more than minimal; may have proteins, amino acids, starches, monosaccharides, ion, lipids

Question 20

for the function basis for classification, what are the 4 types?

Answer 20

Supportive
Enriched
Selective
Differential

Question 21

describe Supportive or general purpose media

Answer 21

Support the growth of many microorganisms (rich media)

e.g., (TSA) tryptic soy agar (rich medium)

Question 22

describe enriched media

Answer 22

general purpose media supplemented by blood or other special nutrients
e.g., blood agar (TSA + sheep blood)

Question 23

describe selective media

Answer 23

Favor the growth of some microorganisms and inhibits growth of others (has inhibiting agent)

e. g., MacConkey agar
- selects for gram-negative bacteria
- Crystal violet is inhibiting agent for gram + bacteria

Question 24

describe differential media

Answer 24

Media which allows different microorganisms to grow differently
i.e., blood agar

Question 25

what is a pure culture?
what does it allow for?
what techniques are used?

Answer 25

• Population of cells arising from a single cell developed by Robert Koch
• Allows for the study of single type of microorganism in mixed culture
• Spread plate, streak plate, and pour plate are techniques used to isolate pure cultures

Question 26

describe a streak plate (2)

Answer 26

-Involves technique of spreading a mixture of cells on an agar surface so that individual cells are well separated from each other
(involves use of bacteriological loop_
-Each cell can reproduce to form a separate colony (visible growth or cluster of microorganisms)
(Slide 31)

Question 27

what is a spread plate? (2)

Answer 27

-small volume of diluted mixture containing
-approximately 30–300 cells are transferred
spread evenly over surface with a sterile bent rod
(slide 33)

Question 28

describe a pour plate (3)

Answer 28

-sample is serially diluted
-diluted samples are mixed with liquid agar
-mixture of cells and agar are poured into sterile culture dishes
(slide 34)

Question 29

what is growth?

Answer 29

Increase in cellular constituents that may result in:

• increase in cell number
• increase in cell size

Question 30

Growth refers to______ rather than _________

Answer 30

population growth; growth of individual cells

Question 31

slides 36-39

Answer 31

Make sure to look at these slides!

Question 32

Entry into stationary growth curve phase activates survival strategy. Name 3 things that happen

Answer 32

1. ) morphological changes
   e. g., endospore formation
2. ) Decrease in size, protoplast shrinkage, and nucleoid condensation
3. ) RpoS protein assists RNA polymerase in transcribing genes for starvation proteins

Question 33

for starvation response, Production of starvation proteins does what? (3 things)

Answer 33

increase cross-linking in cell wall
Dps protein protects DNA
chaperone proteins prevent protein damage

Question 34

Cells in the starvation response stage are called what?

Answer 34

Persister cells

• long-term survival
• increased virulence

Question 35

There are 2 alternate hypothesis regarding Senescence and Death Phase. What are they?

Answer 35

1.) cells are Viable But Not Culturable (VBNC)
-cells alive, but dormant, capable of new growth when conditions are right
2.) Programmed cell death
fraction of the population genetically programmed to die (commit suicide)
(slide 43)

Question 36

describe Generation (doubling) time (3)

Answer 36

• Time required for the population to double in size
• Varies depending on species of microorganism and environmental conditions
• Range is from 10 minutes for some bacteria to several days for some eukaryotic microorganisms

Question 37

What is exponential population growth?

Answer 37

Population is doubling every generation

Question 38

slide 47-50

Answer 38

yay end of powerpoint:)