lecture 2 Introduction and overview of prokaryotes and their cell structure

Question 1

what are the three domains

Answer 1

eukaryote
prokaryote
archaea

Question 2

what three things are properties of all cells

Answer 2

compartmentalization and metabolism
growth
evolution

Question 3

properties of some cells

Answer 3

mobility
differentiation
communicate

Question 4

typical size of a virus

Answer 4

0.01 - 0.2um

Question 5

typical size of a bacterium

Answer 5

0.2 - 5um

Question 6

typical size of a eukaryote

Answer 6

5 - 100um

Question 7

typical size yeast

Answer 7

5 - 10um

Question 8

typical size algae

Answer 8

10 - 100um

Question 9

typical size protozoa

Answer 9

50 - 1000um

Question 10

1um = _______mm

___________m

Answer 10

0. 001mm

0. 000001m (1x10^-6)

Question 11

what does a higher sa/v ratio in cells mean

Answer 11

faster rate of nutrient exchange compared to large cells

Question 12

what are some other benefits of being a smaller cell

Answer 12

faster growth

quicker evolution rates

Question 13

some basic features of eukaryotic cell structure

Answer 13

nucleus (membrane)
ER and SER
mitochondrion
golgi
chloroplast
ribosomes
cell wall
cytoplasmic membrane

Question 14

bacteria cell structure basic features

Answer 14

nucleoids/plasmids
ribosomes
inclusions
slimy capsule
cell wall
cytoplasmimc membrane
s-layer
flagellum

Question 15

what is the s layer

Answer 15

layer of proteinfunction not fully understood – crystalline

Question 16

membrane structure in bacteria

Answer 16

phospholipid bilayer

integral membrane proteins

Question 17

functions of the bacterial cell membrane

Answer 17

barrier
selective permeability
energy conservation (proton motive force)
site of photosynthesis and respiration
active transport

Question 18

functions of the cell wall

Answer 18

determines and maintains shape of bacteria

protects the cell from osmotic lysis

Question 19

what are the steps in the gram stain

Answer 19

Stain with crystal violet
Add iodine (forms a complex with crystal violet)
Wash with ethanol
Counterstain with safranin

Question 20

what colour are gram positive

Answer 20

purple dark blue

Question 21

why are gram positive bacteria purple and dark blue

Answer 21

thick petidoglycan that traps the crystal violet and is too deep for the alcohol rinse to penetrate which masks the safranin dye

Question 22

what colour are gram negative

Answer 22

pink

Question 23

why are gram negative pink

Answer 23

think layer of peptidoglycan that is washed by alcohol wash so safranin is not hidden so cell appeares pink

Question 24

what % of a gram positive cell wall is peptidoglycan

Answer 24

90%

Question 25

what % of a gram negative cell wall is petidoglycan

Answer 25

10%

Question 26

what are porins

Answer 26

proteins that allow hydrophilic small molecules to cross the outermembrane.

Question 27

what is the periplasm

Answer 27

contains several important enzymes involved in processing nutrients/substrates and chemoreceptors.

Question 28

what is the waxy capsule made of

Answer 28

polysaccharides

Question 29

benefits of a waxy capsue

Answer 29

protection from host defenses (e.g., phagocytosis)
• protection from harsh environmental conditions
(e.g., desiccation)
• attachment to surfaces

Question 30

what are slimes

Answer 30

Also slimes… (less rigid than capsule

Question 31

what are fimbriae

Answer 31

short,thin, hairlike, proteinaceous appendages (up to 1,000/cell)
– recognition and attachment to surfaces

Question 32

what are pili

Answer 32

similar to fimbriae except longer, thicker, and less numerous (1-10/cell), required for mating

Question 33

what is a polar flagellum

Answer 33

flagellum at end of cell

Question 34

what does it mean to be monotrichous

Answer 34

one flagellum

Question 35

what does it mean to be amohitrichous

Answer 35

one flagellum at each end of the cell

Question 36

what does it mean to be lophotrichous

Answer 36

cluster of flagella at one or both ends

Question 37

what does it mean to be peritrichous

Answer 37

flagella spread over entire surface of cell

Question 38

what is bacterial cytoplasm

Answer 38

gelatinous material inside the cell
• contains
- ribosomes (for protein synthesis) & nucleoid
- cellular inclusions (sometimes)
- macromolecules (proteins, RNA etc)
- organic molecules such as carbohydrates & lipids
- inorganic ions

Question 39

what is the nucleoid

Answer 39

• irregularly shaped region
• location of chromosome
– usually 1/cell
(sometimes 2)

Question 40

what are plasmids

Answer 40

usually small, closed circular DNA
molecules

• exist and replicate independently of
chromosome

• not required for growth and reproduction

• may carry genes that confer selective
advantage (e.g., drug resistance)

Question 41

what are cellular inclusions

Answer 41

Granules of organic or inorganic material 
that are reserved for future use
 eg –  glycogen - polymer of glucose units
	–  poly-β-hydroxybutyrate (PHB =
		polymers of β-hydroxybutyrate)
	–  polyphosphate granules
	–  sulphur granules
-magnetosomes

Question 42

what are gas vacuoles

Answer 42

in some aquatic bacteria

- enables cells to alter their mass and float

Question 43

what are endospores

Answer 43

made by some gram positive bacteria, a resistant asexual spore that develops inside some bacteria cells.

Question 44

survival forms in endospores

Answer 44

can survive 100s if not 1000s of years

- produced under unfavourable conditions (e.g.,when cells run out of nutrients

Question 45

endospores are highly resistant to

Answer 45

heat, drying, radiation and chemicals

Question 46

what does the calcium dipicolinate in endospores do

Answer 46

binds free water and helps dehydrate cell

Question 47

how long to endospores live?

Answer 47

forever

Halophilic bacteria in a ¼ billion (250 million) year old salt crystal