Prokaryotic Cell Structure Flashcards Preview

Microbiology > Prokaryotic Cell Structure > Flashcards

Flashcards in Prokaryotic Cell Structure Deck (45)
1

Prokaryotic envelope in Gram positive bacteria

glycocalyx, external cell wall, cell membrane

2

Prokaryotic envelope in Gram negative bacteria

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

3

capsule function

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

4

Gram negative characteristics

outer membrane and periplasm

5

outer membrane

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

6

bilayer with space

inner layer- phospholipid, similar to cell membrane
outer layer- lipopolysaccharide, toxic to humans

7

porins

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

8

periplasm

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

9

External cell wall

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

10

external cell wall composition

peptidoglycan

11

peptidoglycan

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

12

bacteria lacking external cell wall outside plasma membrane

Mycoplasma, some Archaebacteria

13

Mycobacterium

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

14

Appendages

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

15

flagella

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

16

flagella patterns

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

17

flagella parts

filament and bend, basal body

18

filament and bend

extends from surface, orients flagella in environment

19

basal body

anchors flagella to plasma membrane, rotates flagella

20

pili (fimbriae)

shorter, thinner than flagella
most Gram negatives have pili

21

adhesion pili

adhere to surfaces

22

sex pili

join cells during bacterial conjugation (plasmid transfer)

23

axial filiments (endoflagella)

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)

24

cell membrane composition

phospholipids and proteins

25

membrane exterior

phosphate groups
hydrophilic
soluble in water

26

membrane interior

hydrophobic
insoluble in water

27

membrane proteins

peripheral or integral

28

peripheral membrane proteins

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

29

fluid mosaic model

phospholipids and proteins move laterally in membrane

30

selective permeability

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

31

membrane folds on itself to

increase surface area
contains more ATP synthesizing proteins for respiration or photosynthesis

32

Is there cholesterol in prokaryotic cell membranes?

NO
but Mycoplasma have membrane steroids

33

Cytoplasm contents

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

34

nucleoid

where DNA is located in cell

35

bacterial DNA

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

36

ribosomes

site of protein synthesis

37

inclusions

storage granules containing different materials

38

metachromatic granules

Corynebacterium diphtheriae
store phosphate for ATP synthesis

39

polysaccharide granules

glycogen or starch

40

lipid granules

fat, used to make ATP
Mycobacterium, Bacillus, Spirillum

41

Endospores

most resistant structure known in nature
ensures survival during unfavorable conditions

42

sporulation

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

43

small section of cytoplasm

forespore- forms endospore

44

large section of cytoplasm

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

45

Archaebacteria

cell walls composed of protein or pseudomurein
some lack external cell walls