Heaphy 2 Bacteria

Question 1

Common properties of all cell types:

x5

Answer 1

• highly organised, cytoplasmic membrane
• growth and reproduction
• DNA as hereditary information, express genes by transcription and translation
• cellular metabolism, use energy to transform simple materials into cellular structures
• Redox reactions generates electrochemical gradient (H+) used to make ATP.

Question 2

1920s Chatton

Answer 2

Chatton reported that bacteria do not have nuclei.

Question 3

Stanier & van Niel (1962)

Answer 3

proposed eukaryote (true nucleus) for animal and plant cells, prokaryote (before nuclei) for bacteria.

Question 4

RING OF LIFE

Answer 4

An anaerobic Archaea engulfed an aerobic Bacteria, eventually
giving rise to the Eukaryotes

Question 5

prokaryotic/eukaryotic divide

Answer 5

• nuclei, nuclear membrane around DNA-histone complexes (chromosomes); prokaryotes no nucleus, DNA tightly coiled with associated RNA and proteins (nucleoid).
• membrane-bound organelles (chloroplasts, mitochondria, endoplasmic reticulum, Golgi apparatus, vacuoles); prokaryotes do not, although specialised groups have internal membranes where ATP is generated (e.g. photosynthetic bacteria).

Question 6

Transcription and translation differ

Answer 6

eukaryotes, transcription in nucleus, translation in the cytoplasm; in prokaryotes the two processes occur concurrently.

Question 7

Bacterial cell walls contain

Answer 7

peptidoglycan (murein), a polymer specific to prokaryotes

Question 8

plant cells and some eukaryotic micro-organisms cell walls contain

Answer 8

cellulose; animal cells do not have cell walls.

Question 9

prokaryotic ribosomes:

Answer 9

70S (50S & 30S)

Question 10

eukaryotic ribosomes:

Answer 10

80S (60S & 40S)

Question 11

endospores:

Answer 11

for surviving hostile conditions, germinate to vegetative cells when conditions improve.

Question 12

Some aquatic photosynthetic bacteria have

Answer 12

gas vesicles of protein rather than lipid membranes (adjust buoyancy, maintain optimum depth for light capture).

Question 13

• Christian Gram 1884

Answer 13

• Heat-fix to glass slide, stain crystal violet (purple), wash.
-Potassium iodide added, ethanol rinse, counterstain with safranin (red).

Question 14

Gram-positive bacteria result on Gram stain

Answer 14

Ethanol rinse doesn’t affect cell wall =cells remain purple

Question 15

Gram-negative bacteria result on Gram stain

Answer 15

the outer and plasma membranes dissolve in alcohol, purple stain washed away and safranin counterstains red.

Question 16

peptidoglycan :

Answer 16

makes up the rigid framework of the Gram-positive wall: the primary polymer.
• additional macromolecules, secondary polymers, can be attached to the primary framework

Question 17

Gram-positive bacteria walls

Answer 17

are thicker, 20-50 nm stronger and contain more peptidoglycan than Gram-negative walls.

Question 18

Gram-negative bacteria walls

Answer 18

outer membrane, capsule attached to peptidoglycan.

Question 19

Periplasmic space:

Answer 19

Gap between membrane and cell wall. Full of enzymes, transport proteins

Question 20

Periplasm:

Answer 20

consists of periplasmic space and peptidoglycan