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Flashcards in Exam 2 Deck (77):
1

How do you prepare a smear

1.aseptically a thin film of a specimen is spread on a slide
2. Film is air dried
3. then heat fixed (adhere and kills things on slide)

2

what is staining?

procedure that use dyes to add color to microbes or cellular structures

3

what are dyes?

chemicals added to microbes

4

what are basic dyes?

have positivity charged ions that help them adhere to negatively charged bacteria
Ex. Crystal Violet, Methylene Blue, and Safranin

5

What are acidic dyes?

have negative charged ions that are attracted to background
bacteria appears colorless against a stained background
Ex. Nigrosin

6

What is a simple stain?

use 1 dye
determine shape and arrangement

7

what is differential stain

places bacteria into categories

8

what are special stains?

stains specific part of microbes
Ex. ENDOSPORE STAIN, Negative Stain, and Flagellar Stain

9

how do you make a gram stain?

1. make smear
2. Crystal Violet --> 1 min
3. Rinse with water
4. Iodine --> 1 min
5. Decolorize with ethyl alcohol
6. rinse with water
7. Safarrin --> 1 min
8 rinse with water
9. blot dry

10

Gram positive bacteria appears
Why?

purple
Ex. bacillus
have many peptiodglycan and they retain primary dye

11

gram negative bacteria appears
why?

red/pink
Ex. E. Coli
have few peptidoglycan that allow decolorization of primary dye and adherance to the counterstain

12

how do you make an acid fast stain?

1. make smear
2. carbolfucshin --> microwave --> 1 min
3. cool and decolorize with acid alcohol
4. rinse with water
5. methylene blue -- 30 seconds
6. rinse with water
7. blot dry

13

Acid Fast positive bacteria appears
why?

bright red
waxy material called mycolic acid
Once heated carbolfuchsin are applied and not decolorized with alcohol and appear read

14

Acid Fast negative bacteria appears
whY?

blue
if bacteria doesnt contain mycolic acid carbolfuchsin is decolorized with acid alcohol and methylene blue adheres

15

What are the steps for endospore stain?

1. make smear
2. Malachite green --> microwave --> 1 min
3.cool rinse with water
4. Safranin --> 45 seconds
5. Rinse with water
6. blot dry
*view on oil immersion lens

16

What are the results of spore stain?

if spore present --> green ( can be inside or out of cell)
bacteria cell --> red
Ex. of positive Bacillus and Clostridum

17

what are the reasons for the spore stain results?

spore are resistant to mild heat but heating in the microwave allows them to open --> absorb malicite green stain

bacteria cells are decolorized with water and counter stain adheres (red) to cell

18

what are the steps for a negative stain?

1. mix bacteria with Nigrosin on one end of slide
2. Use second slide, spread suspension over entire slide
3. Air dry

19

what are the results for Negative Stain?

used to determine capsules (structures that surround cell wall)

if capsule is not present it wont accept the stain and will appear as light spots against a dark background

20

prokaryotic characteristics

DNA not in a membrane (no nucleous)
very small
cell wall have peptidoglycan
no membrane bound organelles
Ex. bacteria

21

eukaryotic characteristics

DNA in a membrane (nucleous)
larger and more complex
not all have cell wall bu most
membrane bound organelles
Ex. Human, plant , and fungi

22

what are some similarities in prokaryotic and eukaryotic cells?

contain carbohydrates, protein, lipids, and nucleic acids
use chemical reaction to metabolize food build protien and store energy
contain cells

23

what is the size of prokaryotes?

0.1 um ( 10 ^ -6) to 50 um in diameter

24

why is the size significant in prokaryotes?

all less space and food so can reproduce and adapt quickly

25

what is coccus shape?

spherical

26

what is bacillus shape?

rod

27

what is spirillum shape?

spiral

28

what is the plemorphic shape?

many shapes

29

what is strepto shape?

chain

30

what is the staphylo shape?

grape- like clusters

31

what is the diplo shape?

two (pair)

32

what is tetrad shape?

group of four

33

what is flagellum?

structure used for motility

34

what are monotrichous?

one flagellum at one end

35

what is amiphitrichous?

one flagellum on each end

36

what is lophotrichous?

turf of flagella at one or more ends

37

what is peritrichous?

flagella around entire surface

38

what is the movement of using flagellum?
run
tumble

rotation of flagella is clockwise or counterclockwise
move in one direction
stop and change directions

39

what is taxis?
positive
negative

movement toward or away from a stimulus
towards
away

40

what is chemotaxis?

movement involving chemical

41

what is phototaxis?

movement involving light

42

what is geotaxis?

movement involving gravity

43

what is fimbriae?

appendage that is shorter and straighter thatn glagella
2 to 100's per cell
used for attachement

44

what is pili?

longer than fimbriae
1 to 2 per cell
used in conjugation

45

what is glycocalyx?

made of polysaccharides
found outside cell well
cell protection

46

what are types of glycocalyx?

capsule
sime layer

47

what is a capsule?

glycocalyx firmly attached to cell wall
protects bacteria from phagocytosis

48

what is slime layer?

glycocalyx loosely attached to cell wall
protects from water loss

49

what is the prokarytoic cell wall like?

semiridgid structures outside cell membrane

50

what is the function of prokaryotic cell wall?

protection and give shape

51

what are things to know aobut prokaryotic cell walls?

can only be seen clearly with an electron microscope
site where many antibiotics damage bacteria

52

what is peptidoglycan?

main component of cell wall
it contains 2 monosaccharides
NAG ( N-acetylglucosamines)
NAM ( N-acetylmuramic)
amino acid for crossbridge

53

what is gram positive cell wall consist of?

25 - 30 layers of peptidoglycan
teichoic acid

54

what is teichoic acid?

acidic polysaccharide
give cell surgace a negative charge
prevents lyse

55

what is the gram negative cell wall consist of?

10 layers of peptidoglycan
no teichoic acid
contain additional wall layer called LPS outside peptidoglycan

56

what is LPS?

LipoPolySaccharide
layer is toxic to humans, is responsible for symptoms of infections and is resistant to many antibiotics

57

what is the cell membrane?

structure below cell wall
forms a phospholipid bilayer similar to eukaryotic cells

58

what is the function of cell membrane?

acts as selective barrier
site of ATP production

59

What is simple diffusion ?

movement of molecules from areas of high to low

60

what is osmosis?

diffusion of water across cell membrane high to low

61

what is a solute?

substance dissolved in a solvent
Ex. salt

62

what is a solvent

a liquid
Ex. water

63

what is solution

mixture of the two or more substance
Ex. Salt water

64

lower concentration of solutes ouside the wall would be?

hypotonic solution

65

what does hypotonic solution consist of?

higher concentration of water outside celle
water moves into the cell
Lysis could happen

66

higher concentration of solutes outside the cell is?

hypertonic

67

what does a hypertonic solution consist of?

higher concentration of water inside the cell
water moves out
crenation could happen

68

what is isotonic solution?

equal concentration of both solutes
cells remain intact

69

what is cytoplasm?

jelly-like substance found inside cell
80% is water
contains carb., proteins, lipids, and genetic material

70

what is a nucleoid?

cluster of genetic material

71

what are ribosomes?

structures directs protein synthesis
composed of 2 sub units
smaller than eukaryotic
very numerous in cells that are actively growing

72

what are inclusions?

large storage molecules made of
C
N
S
P
formed when these elements are abundant
not always present

73

what are endospore?

structure formed when nutrient are limited
contain thick cell walls
able to survive extreme environments conditions
(heat, lack of water, or exposure to chemicals)
can live for 25 million years

74

what happens to endospores when conditions are favorable again?

convert back to vegetative state

75

what is sporulation?

process of making spores

76

who has spores?

bacillus and clostridium

77

how are spores killed?

autoclave --> heat under pressure for 20 min