bacteria and antibiotic resistance

Question 1

what are the three classifications of bacteria

Answer 1

1) bacillus- rod shaped
2) coccus- spherical
3) spirillum- spiral
4) gram positive= stain purple
5) gram negative= stain pink

Question 2

what are bacteria cell walls made of

Answer 2

peptidoglycan /murien

Question 3

outline the cell wall structure of a gram negative bacteria

Answer 3

1) thinner layer of murein with a protective outer layer of lipopolysaccharides

Question 4

outline the cell wall structure of gram positive bacteria

Answer 4

one thick layer of murine

Question 5

why do gram positive bacteria stain purple

Answer 5

thick layer of murine

they stain purple as the cell wall retain the crystal violet die which appears purple

Question 6

why do gram negative bacteria stain pink

Answer 6

protective layer of lipopolysaccharides and lipoproteins outside cell wall
during staining it doesn’t retain crystal violet dye
when washed the protective layer is lost
therefore thinner murine layer retains the pink counter stain

Question 7

what is the difference between broad spectrum bacteria and narrow

Answer 7

1) effective against a wide range of pathogenic bacteria usually effecting common processes such as protein synthesis
2) only effective against a few types of bacteria affecting specific processed such as cell wall formation

Question 8

define bacteriostatic

Answer 8

slows down or stops bacterial growth

Question 9

define bactericidal

Answer 9

kills bacteria

Question 10

outline how penicillin works against bacteria

Answer 10

= narrow spectrum, bactericidal = gram positive only

1) affects the formation of cross linkages in peptidoglycan when the new cell wall is formed as the cell grows
2) the cell wall is weakened so cell will burst due to osmosis
3) doesn’t effect gram negative as the protective outer layer

Question 11

outline tetracycline

Answer 11

bacteriostatic, broad spectrum = inhibits protein synthesis

1) prevents the translation of mRNA during protein synthesis
2) competibley inhibits second binding site on 30s ribosome so tRNA cant bind

Question 12

outline how antibiotic resistance can occur

Answer 12

1) bacteria show genetic variation in their resistance to antibiotics
2) this could be a result of a random mutation
3) this enables their survival allowing them to pass on their resistant DNA to non-resistant ones during sexual reproduction through conjugation via pili
4) when antibiotics are given non-resistant ones die leaving the resistant ones still alive
5) antibiotics acts as a selection agent

Question 13

what increases the likelihood of antibiotic resistance

Answer 13

1) over prescribed for trivial infections
2) individuals don’t complete the full course of antibiotics
3) over use in farming