Week 3: Cellular Structures

Question 1

comonalities of prokaryotes & eukaryotes

Answer 1

all are composed of same biomolecules, all cells are membrane bound, all cells are fluid filled with cytoplasm, both have ribosomes

Question 2

smaller cells have a larger surface to volume ratio which means

Answer 2

they are more efficient at metabolism

Question 3

how do stains work

Answer 3

simple stain become positively charged in solution, they interact with the negatively charged plasma membrane which creates a contrast under the microscope

Question 4

strepto

Answer 4

long chains

Question 5

staphylo

Answer 5

grape like clusters

Question 6

glycocalyx

Answer 6

gel like polysaccharide layer that typically surrounds bacterial cells

Question 7

pili/fimbriae

Answer 7

protein fibers arranged in hollow, helical formation

Question 8

flagella

Answer 8

thin protein tubes longer than pili, spin like propeller enabling bacterial motility

Question 9

positive taxis

Answer 9

move towards a favourable stimulus

Question 10

negative taxis

Answer 10

move away from negative stimulus

Question 11

3 types of prokaryotic cell walls

Answer 11

gram +, gram -, acid fast

Question 12

gram + structure

Answer 12

largely composed of thick layer of peptidoglycan

Question 13

the penicillin family of antibiotics inhibit the formation of

Answer 13

pentaglycine bridges

Question 14

gram - structure

Answer 14

contain peptidoglycan, contain outer membrane of lipopolysaccharide

Question 15

LPS is recognized by the host sytem causing

Answer 15

fever and inflammation

Question 16

LPS is also called endotoxin which can result in

Answer 16

endotoxic shock if gram - bacteria die too rapidly

Question 17

basic stain (crystal violet)

Answer 17

adheres to negatively charged plasma membrane in all cell types

Question 18

iodine is applied

Answer 18

iodine CV bind forming large crystals attached to the cell membrane

Question 19

alcohol is applied followed by water

Answer 19

Alcohol dissolves the outer membrane in Gram negative cells and water washes
away the Iodine-CV complex

Question 20

basic stain (safranin) is applied

Answer 20

Adheres to the negatively charged plasma membrane in Gram negative cells.

Question 21

phospholipids

Answer 21

Unique structural property forces the hydrophobic tails
to point inwards, away from the watery cytoplasm and
extracellular fluid. Results in the formation of a bilayer
(two layers of phospholipids)

Question 22

peripheral proteins

Answer 22

Bound to the outer surface of the membrane; perform

various functions discussed later

Question 23

transmembrane proteins

Answer 23

Cross through both layers of the PM

Question 24

endospores

Answer 24

allow bacteria to persist in environmentally unfavourable conditions until more favourable conditions arise

Question 25

spore formation

Answer 25

First, the genetic material is replicated
• Unequal cell division occurs within the cell,
forming a septum between the two chromosomes
• The larger of the two compartments, then engulfs
the smaller compartment creating a double
membrane
• Peptidoglycan layers are constructed between the
two membranes and a protein coat is deposited on
top
• The cell lyses, releasing the endospore into the
environment