bacteria lecture 3

Question 1

bacteria have inclusion bodies what are these for

Answer 1

energy storage

Question 2

3 functions of a the plasma membrane of bacteria

Answer 2

1. permeability barrier to protect the cell from losing nutrients
2. protects from being harmed by environmental toxins/waste
3. large surface area for photosynthetic and respiratory functions

Question 3

Bacterial cell walls are made of peptidoglycan.

what are the 2 main types of bacteria cell walls indicated by the Gram stain technique

Answer 3

1. Gram positive=peptidoglycan>lipids
   - purple
   - thick cell wall made of peptidoglycan
2. Gram negative=lipids>peptidoglycan
   - pink
   - thin peptidoglycan layer between inner and outer membrane (lipid bilayer on top and under)

Question 4

3 types of appendages on the cell surface of bacteria

Answer 4

1. pili
2. fimbriae
3. flagella

Question 5

pilus

Answer 5

long hair-like structure used for attachment or to form a mating bridge between cells for exchange of genetic material e.g. conjugational plasmids

Question 6

fimbriae

Answer 6

shorter versions of pili used for attachment to substrate

Question 7

flagella

Answer 7

log, whip-like appendages which rotate in a corkscrew motion to propel bacteria forward

Question 8

capsule

Answer 8

• surrounds cell wall

- assists with attachment to surfaces and protection again dehydration/ host’s immune system

Question 9

endospore 4 characters

Answer 9

• produced when under environmental stress
• consists of bacterial DNA, small amount of cytoplasm and thick protective coat
• resistant to UV radiation, desiccation, high temp and chemicals
• lie dormant until favorable conditions arise

Question 10

binary fission

Answer 10

mother divides into 2 identical daughter cells

Question 11

what protein is essential for binary fission

Answer 11

protein FtsZ (Filamenting Temperature Sensitive mutant Z)

Question 12

4 steps of binary fission

Answer 12

1. DNA replication
2. DNA segregation
3. infolding of the cell membrane
4. synthesis of new cell wall

Question 13

bacterial are successful for 2 reasons

Answer 13

1. rapid growth rate

2. ability to transfer DNA through horizontal gene transfer (much quicker then going via generations)

Question 14

4 main cell shapes

Answer 14

1. spherical=cocci
2. rod shaped=bacilli
3. spiral=spirilli
4. filamentous=actinomycetes

Question 15

2 largest phyla of bacteria

Answer 15

1. firmicutes=gram+

2. proteobacteria=gram-

Question 16

bacteria that use radiant energy =

Answer 16

phototrophs

Question 17

photo-autotrophs use

Answer 17

sunlight and CO2

Question 18

if oxygen is present what kind of respiration do bacteria undergo

Answer 18

aerobic cellular respiration

Question 19

if oxygen is absent what kind of respiration do bacteria undergo

Answer 19

fermentation

Question 20

what are the 2 broad environmental importance of bacteria

Answer 20

1. they are decomposers and fixers

2. symbiotic relationships

Question 21

decomposers

Answer 21

breakdown dead organisms and plants thereby returning elements to the ecosystem

Question 22

fixers?

Answer 22

converting inorganic compounds to forms that can be used by other organisms

Question 23

Nitrogen cycle

Answer 23

• nitrifying and denitrifying bacterial interconvert N-containing compounds
• convert N2 to NH3 which can be used by other microbes

Question 24

carbon cycle

Answer 24

• carbon-fixers such as autotrophs convert CO2 to organic compounds
• whilst others oxidise organic compounds and release CO2

Question 25

2 types of symbiosis (+short def)

Answer 25

1. mutualism-both partners benefit

2. commensalism-one partner may benefit without harming the other (rare)

Question 26

3 examples of mutualism

Answer 26

1. Rhizobium bacteria and legume roots
   - bacteria supply N to plant
   - plant supplies organic carbon
2. cellulase-producing bacteria that live in the digestive systems of cows
3. colonies of bacteria in human intestinal tract where they assist with digestion and produce vitamins (especially B12 and K) which the body cannot produce itself

Question 27

bacterial biofilms

Answer 27

-survival mechanism as it provides protection against unfavourable environmental conditions.

Question 28

bacterial biofilms contribute to a negative thing

Answer 28

development of resistance against chemicals and antibiotics that are usually used to control them

Question 29

how does HGT affect evolution

Answer 29

the idea of a single ancestor giving rise to separate “branches” forming the “tree of life” may have to be revised to a network of life with interlinked”‘branches” where microbes have exchanged genes

Question 30

what types of genes are transferred

Answer 30

genes that give the organism immediate selective advantage over its competitors

Question 31

3 main methods of HGT

Answer 31

1. transformation
2. transduction
3. conjugation

Question 32

HGT via transformation

Answer 32

bacterial natural take up, or chemically induced to take up, bits of DNA from the environments and integrate it into their genome

Question 33

HGT via transduction

Answer 33

bacteriophages can infect bacteria and carry DNA from one host to another

Question 34

bacteriophage

Answer 34

bacterial virus

Question 35

HGT via conjugation

Answer 35

bacterial can mate with one another and transfer DNA from cell to cell via pili

Question 36

example of HGT

Answer 36

MRSA
Methicillin-Resistant-Straphylococcus aureus
-bacteria is resistant to a wide range of bacteria
-occurs widely in hospitals