1.1 Bacteria: structure and classification

Question 1

Eukaryote

Answer 1

an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus

Question 2

Prokaryote

Answer 2

a microscopic single-celled organism that​ has neither a distinct nucleus with a membrane nor other specialized organelles

Question 3

Answer 3

Eukaryote

Question 4

Answer 4

Prokaryote

Question 5

Eukaryotes and prokaryotes both have?

Answer 5

Cell membran + cytoplasm + DNA

Question 6

Have a nucleus and membrane bound​ organelles?

Answer 6

eukaryotes

Question 7

no-membrane bound organelles, no nucleus

Answer 7

prokaryote

Question 8

large, complex cells

Answer 8

eukaryotes

Question 9

small, simple cells

Answer 9

prokaryotes

Question 10

Gram Staining process:

Answer 10

1. Crystal​ violet
2. iodine
3. alcohol (decolorization)
4. safranin (counterstain)

Question 11

morphology and color are based on

Answer 11

cell wall structure

Question 12

Answer 12

gram negative

Question 13

Answer 13

gram positive

Question 14

Answer 14

Pairs (diplococci)

Question 15

Answer 15

Chains (streptococci)

Question 16

Answer 16

Clusters (staphylococci)

Question 17

rods =

Answer 17

bacilli

Question 18

The first steps to identification…

Answer 18

Question 19

Flagella:

Answer 19

• present in some bacteria
• involved in motility and chemotaxis

Question 20

Fimbriae / Pili:

Answer 20

• Predominantly found in Gram-negative bacteria
• Shorter, straighter, and thinner than flagella

Fimbriae: attachment to surfaces, including other cells
Pili: join bacterial cells for conjugation (DNA transfer)

Question 21

Capsule:

Answer 21

• polysaccharides
• confers mucoid appearance to colonies
• protection from phagocytosis, antimicrobials
• enhances adherances

Question 22

play a part in enveloping the cell?

Answer 22

cell wall
outer membrane
plasma membrane

Question 23

cell wall:

Answer 23

maintain bacterial shape
- prevent cell from osmotic lysis
- extends as needed while volume of cell increases

Question 24

Is a target for antimicrobials?

Answer 24

cell wall ( not present in eukaryotes)

Question 25

the cell wall is made up of?

Answer 25

peptidoglycan

Question 26

Unusual case, doesn't​ve a cell wall?

Answer 26

Mycoplasma spp antimicrobials targeting​ this cell wont work

Question 27

bacterial envelope: gram-positive​

Answer 27

- many layers of peptidoglycan - technic​ acid: provides rigidity​ and used for antigentic typing

Question 28

bacterial envelope: gram-negative

Answer 28

- thin peptidoglycan - outer membrane

Question 29

Gram +: alcohol

Answer 29

dehydrates PG = more permeable

Question 30

Gram -: alcohol

Answer 30

dissolves crystal violet and makes holes in thin PG = crystal violet washed out

Question 31

crystal violet enters via

Answer 31

cell walls

Question 32

what does iodine do?

Answer 32

binds crystal violet = to big to leave cell wall

Question 33

Phospholipid bilayer:

Answer 33

- Hydrophilic head - Hydrophobic tails - Only small lipid-soluble compounds can enter the cell by passive diffusion - Transporters/porins​ for transport of other molecules

Question 34

outer membrane =

Answer 34

LPS

Question 35

outer membrane function:

Answer 35

- Protect from phagocytosis - Barrier to antimicrobials e.g. penicillins * & enzymes, detergents, bile salts etc

Question 36

Plasma (cytoplasmic) membrane

Answer 36

- Encloses the cytoplasm - Phospholipid bilayer and proteins - Permeability barrier with transport systems for selective transport of substances in and out of the cell (selective permeability) - Bacterial respiration (ATP synthesised using electron transporters on membrane) - Anchor for external structures - Target for disinfectants and antimicrobials

Question 37

cytoplasm:

Answer 37

- Facilitate chemical reactions and to dissolve solutes - Contains cell components (e.g. nucleoid and ribosomes) - aqueous solution to macromolecules, small molecules, and inorganic ions

Question 38

site of protein synthesis?

Answer 38

ribosomes