Brock Microobiology Chapter Six

Front 1

What are the five steps of Binary fission?

Back 1

1) DNA Replication

2) Cell Elongation

3) Septum Formation

4) Formation of Distinct cell walls

5) Cell Separation

Front 2

Fts Proteins (Filamentous Temperature Sensitive)

Back 2

cell division dependent on this

interact to form a "divisome"

Front 3

Divisome

Back 3

Division apparatus in the cell

orchestrates synthesis of new cytoplasmic membrane and cell material in both directions until the cell reaches twice its original size

Front 4

How is the divisome formed?

Back 4

formed by FtsZ proteins in a ring around the cell center

FtsA, FtsI, and ZipA are attracted to the ring structure and associate with FtsZ

Front 5

DNA replication occurs prior to what?

Back 5

FtsZ ring formation

Front 6

FtsK

Back 6

helps to pull apart daughter cells following elongation

Front 7

Min Proteins (Min C and Min E)

Back 7

assist FtsZ in finding precise center of the cell

Front 8

What are three characteristics of MreB?

Back 8

1) the major shape determining protein in prokaryotes

2) very similar to actin protein in eukaryotic cells

3) not found in coccus-shaped bacteria (default shape is spherical)

Front 9

Autolysic enzymes

Back 9

in divisome complex

create openings in the cell wall so that peptidoglycan can be distributed between daughter cells

Front 10

What does autolysin cut to make new peptidoglycan?

Back 10

It cuts pre-existing peptidoglycan and inserts peptidoglycan precursors (such as muramic acid and glucosamine)

Front 11

Bactoprenol

Back 11

lipid carrier molecule that helps in the insertion of glucosamine and muramic acid in new peptidoglycan

transports precursors across cell membrane for incorporation into the growing point of the cell wall

Front 12

Transpeptidation

Back 12

Final step of cell wall synthesis

formation of peptide cross links between muramic acid residues in adjacent glycan chains

Front 13

Penicillin

Back 13

inhibits transpeptidation

binds to Fts proteins and render them catalytically inactive

Front 14

Generation time

Back 14

the time required for cell population to double

Front 15

Exponential growth

Back 15

when the number of cells doubles during a regular time interval

Front 16

What are the four phases of exponential growth?

Back 16

1) Lag Phase

2) Exponential Phase

3) Stationary Phase

4) Death Phase

Front 17

Lag Phase

Back 17

may be brief or extended depending on history of culture and growth factors

Front 18

Exponential Phase

Back 18

may be brief or extended depending on nutrients

smaller cells grow faster than larger cells

Front 19

Stationary Phase

Back 19

do not increase or decrease in cell number

essential nutrients being used up and waste products are accumulating

Front 20

Death Phase

Back 20

Cells begin to slowly die off

Front 21

How is microbial growth measured?

Back 21

measured by the change in the number of cells over time

Front 22

Direct Count

Back 22

cell counts done microscopically mthat measure the total number of cells (living or dead) in a population

Front 23

Plate Counts

Back 23

only measures viable cells

Front 24

viable cell counts require one of which two culturing methods?

Back 24

1) Spread Plate method

2) Pour Plate method

Front 25

Minimum Temperature

Back 25

below this no growth occurs as cytoplasmic membrane malfunctions

Front 26

Optimal Temp

Back 26

growth is most rapid

Front 27

Maximum Temp

Back 27

above this growth is not possible as proteins denature

Front 28

What is the typical cardinal temperature range for microbes?

Back 28

30-40 degrees celsius

Front 29

What are the four temperature classes of microbes?

Back 29

1) Psychorophiles (low temp optima (4 deg C)

2) Mesophiles (midrange temp optima (39 deg C)

3) Thermophiles (high temp optima (60 deg C)

4) Hyperthermophiles (very high temp optima (88 deg C)

Front 30

Psychrotolerant microbes

Back 30

can grow at 0 deg C but growth optima is between 20-40 deg C

Front 31

How do psychrophiles adapt to their cold environment (four reasons)?

Back 31

1) Produce enzymes that function optimally at cold temperatures

2) higher ratio of a-helix to b-sheets in enzymes

3) higher content of polar versus hydrophobic amino acids in enzymes

4) cytoplasmic membranes have a higher content of unsaturated fatty acids, allowing membrane transport to proceed unhindered

Front 32

How do thermophiles adapt to their hot environment (four reasons)?

Back 32

1) have key amino acid changes in enzymes and proteins that prevent denaturation

2) increased number of ionic bonds between (+) and (-) charged amino acids

3) cytoplasmic membranes have a higher content of saturated fatty acids

4) proteins have highly hydrophobic interiors which prevents unfolding

Front 33

What are the three environmental factors that effect microbial growth?

Back 33

1) pH

2) Osmolarity

3) Oxygen

Front 34

Acidophiles

Back 34

Microbes that grow at a pH of <5

Front 35

Alkaliphiles

Back 35

Microbes that grow at a pH of >9

Front 36

Water Activity

Back 36

most microbes unable to cope in environments with low aw

in environments with low aw water flows out of the cell by osmosis causing the cell to dehydrate

Front 37

Halotolerant microbes

Back 37

tolerate environments with a low aw but do not grow well

Front 38

Extreme Halophiles

Back 38

grow in extremely salty environments (15-30% NaCl)

Front 39

Osmophiles

Back 39

grow in environments with high sugar concentration

Front 40

Xerophiles

Back 40

grow in very dry environments

Front 41

What are the three groups of aerobes?

Back 41

1) Obligative Aerobe

2) Faculative Aerobe

3) Microaerophillic

Front 42

What are the two types of anaerobes?

Back 42

1) Aerotolerant

2) Obligate

Front 43

What are the four toxic forms of oxygen?

Back 43

1) Singlet (1O2)

2) Superoxide anion (O2-)

3) Hydrogen peroxide (H2O2)

4) Hydroxyl radical (OH)

Front 44

What are the enzymes that destroy hydrogen peroxide?

Back 44

Catalase and Peroxidase

Front 45

What is the enzyme that destorys superoxide?

Back 45

Superoxide dismutase