Prokaryotic Cell Structure

Question 1

Prokaryotic envelope in Gram positive bacteria

Answer 1

glycocalyx, external cell wall, cell membrane

Question 2

Prokaryotic envelope in Gram negative bacteria

Answer 2

glycocalyx, outer membrane, periplasm, external cell wall, cell membrane

Question 3

capsule function

Answer 3

1. protection against phagocytosis
2. prevent dehydration- movement of nutrients out of cell, toxins into cell
3. adhesion- stick to surfaces, teeth, intestines
4. virulence- ability of pathogen to cause disease

Question 4

Gram negative characteristics

Answer 4

outer membrane and periplasm

Question 5

outer membrane

Answer 5

barrier against polar and non-polar molecules
only water, gases pass
resists phagocytosis, excludes toxins, antibiotics, enzymes, dyes

Question 6

bilayer with space

Answer 6

inner layer- phospholipid, similar to cell membrane

outer layer- lipopolysaccharide, toxic to humans

Question 7

porins

Answer 7

semipermeable channels spanning outer membrane
allows some materials into cell, excludes others
E. coli alters porin diameter as environment changes
porin diameters decrease when toxin levels increase

Question 8

periplasm

Answer 8

space between outer membrane and plasma membrane- includes cell wall
viscous- contains enzymes and binding proteins
enzymes- digest nutrients into units capable of crossing cell membrane
binding proteins- facilitate material movements across membrane

Question 9

External cell wall

Answer 9

protects cell, maintains cell shape, withstands changes in turgor pressure

Question 10

external cell wall composition

Answer 10

peptidoglycan

Question 11

peptidoglycan

Answer 11

polysaccharide chains composed of repeating sugars (NAG, NAM) and amino acids
thick peptidoglycan in Gram positive- many layers
thin in Gram negative- few layers

Question 12

bacteria lacking external cell wall outside plasma membrane

Answer 12

Mycoplasma, some Archaebacteria

Question 13

Mycobacterium

Answer 13

acid fast bacteria
cell wall contains my colic acid- waxy
resists destaining and treatments
tuberculosis, leprosy

Question 14

Appendages

Answer 14

1. flagella
2. pili (fimbriae)
3. axial filiments

Question 15

flagella

Answer 15

organelles of motion

move toward or away from stimulus (photo, chemo, aero, magneto)

Question 16

flagella patterns

Answer 16

1. monotrichous- single, polar; E. coli
2. amphitrichous- single or more at both ends; Rhodospirillum
3. lophotrichous- 2 or more at one end; Vibrio
4. peritrichous- occur over entire surface; Proteus, Salmonella, Bacillus

Question 17

flagella parts

Answer 17

filament and bend, basal body

Question 18

filament and bend

Answer 18

extends from surface, orients flagella in environment

Question 19

basal body

Answer 19

anchors flagella to plasma membrane, rotates flagella

Question 20

pili (fimbriae)

Answer 20

shorter, thinner than flagella

most Gram negatives have pili

Question 21

adhesion pili

Answer 21

adhere to surfaces

Question 22

sex pili

Answer 22

join cells during bacterial conjugation (plasmid transfer)

Question 23

axial filiments (endoflagella)

Answer 23

modified flagella in Spirochetes
flagella arise at end of each cell
spirals around cell under outer membrane
allows membrane through viscous environments (mud, mucous membranes)

Question 24

cell membrane composition

Answer 24

phospholipids and proteins

Question 25

membrane exterior

Answer 25

phosphate groups
hydrophilic
soluble in water

Question 26

membrane interior

Answer 26

hydrophobic

insoluble in water

Question 27

membrane proteins

Answer 27

peripheral or integral

Question 28

peripheral membrane proteins

Answer 28

exterior- receptors, enzyme reaction sites, adherence, cell recognition
internal- form passive or active channels, active carriers through membrane, signal transduction

Question 29

fluid mosaic model

Answer 29

phospholipids and proteins move laterally in membrane

Question 30

selective permeability

Answer 30

molecule size
lipid solubility
charge on molecule
presence of specialized channels, surface area

Question 31

membrane folds on itself to

Answer 31

increase surface area

contains more ATP synthesizing proteins for respiration or photosynthesis

Question 32

Is there cholesterol in prokaryotic cell membranes?

Answer 32

NO

but Mycoplasma have membrane steroids

Question 33

Cytoplasm contents

Answer 33

water (80%), ions, enzymes, sugars, DNA, ribosomes, inclusions

Question 34

nucleoid

Answer 34

where DNA is located in cell

Question 35

bacterial DNA

Answer 35

single, long, circular, double stranded DNA
outside nucleoid
carries few genes- replicate independently of nucleoid
provides resistance to antibiotics and toxins
produces unusual enzymes, pigments

Question 36

ribosomes

Answer 36

site of protein synthesis

Question 37

inclusions

Answer 37

storage granules containing different materials

Question 38

metachromatic granules

Answer 38

Corynebacterium diphtheriae

store phosphate for ATP synthesis

Question 39

polysaccharide granules

Answer 39

glycogen or starch

Question 40

lipid granules

Answer 40

fat, used to make ATP

Mycobacterium, Bacillus, Spirillum

Question 41

Endospores

Answer 41

most resistant structure known in nature

ensures survival during unfavorable conditions

Question 42

sporulation

Answer 42

endospore form in response to environmental change
DNA divides into 2 equal parts
cytoplasm divides into 2 unequal parts

Question 43

small section of cytoplasm

Answer 43

forespore- forms endospore

Question 44

large section of cytoplasm

Answer 44

secretes thick peptidoglycan and protein wall around forespore
endospore germinates when conditions improve

Question 45

Archaebacteria

Answer 45

cell walls composed of protein or pseudomurein

some lack external cell walls