Unit 5 Flashcards
1
Q
Eukaryotes and Prokaryotes main difference
A
Eukaryotes Have a clearly defined nucleus
2
Q
Eukaryotes ribosome
A
80S
3
Q
Prokaryotes ribosome
A
70S
4
Q
Division of prokaryotes
A
Binary fission
5
Q
Size bacteria
A
10⁻⁶ m
6
Q
Where are located the sterols
A
Plasma membrane of eukaryotes
7
Q
Size virus
A
10⁻⁹m
8
Q
Shapes bacteria
A
Coccus
Bacillus
Coccobacillus
Vibrio
Spirillum
Spirochete
9
Q
Pleomorphism
A
Bacteria changes the size and shape according to environment (pH)
10
Q
Arrangement Cocci
A
Single (coccus)
Pair ( diplococci)
Tetrads
Irregular cluster (Staphylococci)
Chains ( streptococci)
Cubical (Sarcina)
11
Q
Which type of bacteria has the greatest variety in arrangement
A
Coccus
12
Q
Sarcina
A
Cubical
13
Q
Staphylococci
A
Irregular clusters (grapes)
14
Q
Streptococci
A
Chains
15
Q
Bacilli arrangement
A
Bacillus
Diplobacilli
Streptobacilli
Palisades
16
Q
Streptobacilli
A
➖➖➖
Chain
17
Q
Palisades
A
/\/\/
18
Q
Arrangement spirilla
A
Sometimes in chains
19
Q
Bright field microscope
A
Bright background
Dark image
20
Q
Dark field
A
Black background
Bright specimen
21
Q
Black background
Bright specimen
A
Dark field
22
Q
Phase contrast microscope
A
Bright structures
Green background
To see internal components
23
Q
Bright structures
Green background
To see internal components
A
Phase contrast microscope
24
Q
Fluorescence microscope
A
Black background
Fluo stained structures
25
Black background
Fluo stained structures
Fluorescence microscope
26
Electron microscope
Grey background
White structure
3D
To see viruses and organelles
27
Why staining
Increase contrast
28
Smear technique
Take sample of the cells, spread in crystal slide and air dry it
Heat fixation so that the cells are not removed when washing
Or chemicals to preserve subcellular structures and morphology
29
3 types procedures for microscope
Direct fresh preparations
Stained smears
Special procedures ( electron microscope)
30
Differential or complex stain
Primary dye and counterstain
- Gram staining
- Ziehl Neelsen
31
Gram stain procedure function
Differentiate the structure and chemical composition of the cell wall
➡️identification and classification of bacteria
32
Steps Gram stain procedure
1st dye, crystal violet, wash
Mordant (lugol): help fixation
Decolorizer : ethanol-acetone. Critical step. Removed the first dye in some bacteria
Conterstain : Safranin
33
Gram - color
Pink red
34
Gram + color
Dark purple
35
Obligated structures in Prokaryotes
Cell wall (except mycoplasma)
1 Chromosome
Plasma membrane
Cytoplasmic matrix
36
Where is the bacterial chromosome located
Nucleoid
37
Cell wall properties
Exclusive to bacteria
Semi-rigid layer outside the plasma membrane
Target of some antibiotics
Determine type of stain used Gram/Ziehl-Neelsen
Contains antigenic components ( LPS, teichoic acids
38
What bacteria doesn’t have a cell wall
Mycobacteria
39
Composition cell wall
Main : peptidoglycan=murein
40
Peptidoglycan
- Peptides
- Glycan: NAM-NAG-NAM
Overall : NAM and NAG are linked by glycosidic bonds
1 Tetrapeptide ( peptide cross links) on each NAM, link NAMs together form a chain to another
41
Peptide
Small protein
42
Synonym glycan
Polysaccharide
43
NAM and NAG are linked by
Glycosidic bonds
44
Why are lysozymes effective
They break the glycosidic bonds between NAM and NAG
45
Gram + cell wall
Thick and rigid wall of peptidoglycan
Lots of techoic acids crossing the peptidoglycan
No outer membrane
No lipopolysaccharide
46
Gram - cell wall
Thin peptidoglycan layer
Outer membrane (only for gram -)
Periplasmic space
Transmembrane proteins (porins)
47
Outer membrane Compo
Made of phospholipids, proteins (porins), and Lipopolysaccharide LPS endotoxin
48
Lipopolysaccharide compo
Lipid A
Core polysaccharide
O side chain
49
Periplasmic space
Between the outer membrane and the plasma membrane
50
Function porins
Diffusion hydrophilic molecules
51
Mycobacterias are also called
Acid fast bacteria AFB
52
Structure mycobacteria cell wall
Great amount of lipids
Mycolic acid layer (wax like lipid coat)
Arabino galactan polymer
53
What type of stain is used on mycobacteria
Ziehl-Neelsen stain
54
Ziehl-Neelsen stain stages
Heat 3 times to melt the wax
Carbol fuchsine (pink)
Decolorizer : HCl + alcohol
Methylen blue
Acid fast bacteria get stained the first time and don’t get discolored because of the wax
55
Functions of cell wall
Gives shape, rigidity and elasticity
Protection from osmotic lysis
Protection from toxic substances
Anchor for flagella
Support for glycocalyx when present
Involved in adhesion (to infect a cell) and aggregation
56
Plasma membrane composition
Phospholipidic membrane
Bilayer of lipids contains most of the time hopanoids
Proteins crossing the membrane
PBPs on the outer side
57
PBP function
Involved in peptidoglycan synthesis
58
How are mycoplasma genus different
They have sterols instead of hopanoids in their plasma membranes (like eukaryotes)
59
What is the name of the bacteria that has sterol in its membrane
Mycoplasma genus
60
Function plasma membrane
Retains cytoplasm
Protection from osmotic stress
Transport : Selective permeable barrier ( waste, secretions, nutrient intake)
Location of metabolic processes ( respiration, photosynthesis, synthesis of wall constituents)
Contains receptor molecules to detect and respond to chemical signals
61
Cytoplasmic matrix synonym
Cytosol
62
Cytoplasmic matrix definition
No organelles, just soluble components like enzymes, vitamins, DNA, etc
Largely water
Cytoskeleton
Ribosomes 70S
63
Ribosomes
Made of ribosomal RNA and protein
2 sub units
64
Bacterial chromosome
Prokaryotes are haploid
No nucleus
Single circle of double stranded DNA
Supercoiled DNA due to enzymes like topoisomerase, gyrase or HU proteins
Fibrillar appearance
65
Haploid
1set of chromosomes
66
Facultative structures for Prokaryotic cells
Plasmids
Glycocalyx (capsule & slime layer)
Flagella
Fimbriae/pili
Endospore
67
Plasmids
Double stranded circle of DNA
Exist independently of the chromosome
Not required for growth and reproduction
Confer selective advantage such as drug resistance, toxin production
Moves horizontally or vertically between bacteria
Not attached to plasma membrane ➡️sometimes lost during division
68
Glycocalyx
Supplementary coat, mucus
Protects the cell and help for adhesion to environment
2 types
69
What are the two types of glycocalyx
Slime layer
Capsule
70
Description Slime layer
Loose shield
Unorganized layer of extra cellular material
Easily removable
71
Description Capsule
Bound more tightly to the cell
Denser, thicker, more organized
Not easily washed off
72
Function Capsule
Anti-phagocytic structure
Helps to adhere to surfaces
Protects from bacterial viruses and most hydrophobic toxic materials
Protects from desiccation cells and anti microbial agents
73
Function Slime layer
Can enclose many bacterias into a biofilm
Protects from environment (dessiccation, antibiotics)
Protects from loss of nutrients
Allows bacteria to adhere to smooth surfaces (like medical devices)
74
Dessiccation
Loss of water
75
Flagella Function
Cell mobility
Role in pathogenesis
Antigenic properties
76
Flagella description
Helical filament appendage
Attached to plasma membrane
Made of the protein flagellin
77
Types of bacteria according to flagella
Monotrichous
Lophotrichous
Amphitrichous
Peritrichous
78
Monotrichous
1 flagella
79
Amphitrichous
1 Flagella located on opposite sides of bacteria
80
Lophotricous
Several flagella on one side
81
Peritrichous
Several flagella everywhere on the plasma membrane
82
Where is the flagella attached
Plasma membrane
83
Fimbrae and pili
Filament appendages shorter and thinner than flagella
Attached to plasma membrane
Made of the protein pilin
Don’t provide locomotion (except twitching mvt of pseudomonas)
84
Where are attached Fimbriae and pili
Plasma membrane
85
Types of Fimbriae and pili
Fimbriae (common pili)
Sex pili
86
Fimbriae
Short, thin, hair like appendages
Involved in bacterial adherence
87
Sex pili
Larger than Fimbriae
Required for bacterial mating
88
Synonym bacterial mating
Bacterial conjugation
89
Meaning bacterial conjugation
Transfer of plasmids
90
Endospores
In some gram+ bacteria
Special resistant, dormant structures
Resistance to environmental stresses such as lack of nutrients, UV, gamma radiation, chemical disinfectant, dessiccation.
91
Difference spirochete and spirilla
Spirilla is more rigid
92
Function of hopanoids
Similar to sterols
Fluidity
