Microbial Cell Structure and Function Flashcards
1
Q
Bacterial habitats
A
Terrestrial and aquatic
2
Q
How do bacteria reproduce? What is the term for this type of reproduction?
A
Reproduce asexually, called binary fission
3
Q
Size range of bacteria
A
0.3-100 micrometers
4
Q
Average size of bacteria (E. coli cell)
A
4 micrometers
5
Q
Thiomargarita size
A
Greater than 100 micrometers
6
Q
Coccus
A
Spherical shape
7
Q
Diplococcus
A
Pairs of cocci (spheres)
8
Q
Streptococcus
A
Chains of cocci (spheres)
9
Q
Staphylococcus
A
Grape-like clusters of cocci (spheres)
10
Q
Tetrads
A
4 cocci in square
11
Q
Bacillus
A
Rod shape
12
Q
Vibrio
A
Curved rod shape (crescent moon or comma)
13
Q
Spirillum
A
Rigid helical shape
14
Q
Spirochete
A
Flexible helical shape
15
Q
Pleomorphic
A
Variable shape
16
Q
Hyphae
A
Long filaments formed by some bacteria and many fungi
17
Q
Mycelium
A
Network of hyphae
18
Q
Deinococcus genus
A
Form tetrad shape
Radiation resistant
19
Q
Mycoplasma genus
A
Form pleomorphic shape
Plasma membrane, but no cell wall
20
Q
Shape of E. coli
A
Bacillus
21
Q
Surface to volume ratio and size of cells
A
Smaller cells, higher surface to volume ratio
22
Q
Advantages to small size of bacteria
A
More efficient nutrient uptake
Faster growth
23
Q
Cell envelope: 3 components
A
Plasma membrane
Cell wall
Layers outside cell wall
24
Q
Plasma membrane encompasses what?
A
Cytoplasm
25
Selectively permeable membrane
Plasma membrane is selectively permeable
| Makes sure that only necessary compounds are brought into cell
26
Main site of energy generation in bacterial cell
Plasma membrane
27
What structure enables energy generation in plasma membrane?
Electron transport chains
28
Function of transport systems in bacterial cell
Bring nutrients into cell
29
Function of signal transduction systems in plasma membrane
Sense and respond to environment
30
Components of fluid mosaic model of plasma membrane
```
Lipid bilayers (polar heads and nonpolar tails)
Floating proteins
```
31
Lipids of bilayer have what type of bonds?
Flexible ester bonds
32
Term for molecules having both polar and nonpolar components
Amphipathic
33
Type of molecules that stabilize plasma membranes of eukaryotes
Sterols
34
Type of molecules that stabilize plasma membranes of bacterial cells
Hopanoids (similar to sterols)
35
Hopanoids are found in what fuel source?
Petroleum
36
Functions of bacterial cell wall
Maintain shape
| Protection from toxic substances and osmotic lysis
37
Osmosis definition
Movement of water from more dilute to more concentrated environment
38
Bacteria are often found in what kind of osmotic solutions?
Hypotonic (concentration of solute inside cell is greater than concentration of solute outside cell)
39
Gram positive bacteria stain what color?
Purple
40
Gram negative bacteria stain what color?
Pink
41
Peptidoglycan: what it makes up and what are its components
Makes up cell walls of bacteria
Components: two alternating sugars (N-acetylglucosamine, NAG, and N-acetylmuramic acid, NAM) which are crosslinked by alternating D- and L-amino acids
42
Bond that connects N-acetylglucosamine and N-acetylmuramic acid in peptidoglycan
Beta-1,4 glycosidic bond
43
Lysozymes target which part of peptidoglycan?
Beta-1,4 glycosidic bond
44
What form are amino acids generally found in? What is the advantage to peptidoglycan having both forms?
Amino acids are usually in L-forms
| D-forms aren't usually recognized by enzymes
45
Direct crosslinking of amino acids in peptidoglycan
Transpeptidation
| Caused by chemical reaction
46
Indirect crosslinking of amino acids in peptidoglycan
Peptide interbridges
47
Difference between gram positive and gram negative bacteria
Gram positive: thick peptidoglycan wall
| Gram negative: thin peptidoglycan wall with outer membrane (lipid bilayer)
48
Periplasmic space
Space between plasma membrane and outer membrane
| Large in gram negative, but small in gram positive
49
Teichoic acids
Polymers of glycerol and ribitol
| Provide stability to gram positive cell walls
50
Lipopolysaccharides (LPS): where found
Part of outer membrane of gram negative bacteria
51
Porins
Molecules in outer membranes of gram negative bacteria
| Form pores
52
3 parts of lipopolysaccharides (LPS)
```
Lipid A (embedded in membrane)
Core polysaccharide
O side chain (sticks out)
```
53
Functions of lipopolysaccharide (LPS)
Protection from host defenses
Attachment
Stability
54
What part of lipopolysaccharides (LPS) can vary?
O antigens (E.coli O157)
55
Lipid A can perform what function?
Endotoxin: causes fever and septic shock
56
Capsules: what are they, what are they made up of, features
Layer outside cell wall
Made up of polysaccharides
Organized, not easily removed
57
Slime layers: what are they, what are they made up of, features
Layer outside cell wall
Made up of polysaccharides
Diffuse, unorganized, easily removed
58
S layers: what are they, what are they made up of, features
Layer outside cell wall
Made up of protein
Organized
59
Do all bacteria have outside layers?
No
60
Capsules and S layers are common in what types of organisms?
Bacteria (gram positive and negative), Archaea
61
Bacillus anthracis has what type of outside layer?
Capsule
62
Outside layer functions
Attachment
| Protection from chemicals, dessication, bacteriophages, and host immune responses
63
Neisseria meningitidis: what it causes and what type of outside layer it has
Bacteria that causes meningitis
| Has capsule
64
What is suspended in cytoplasm?
Inclusions, chromosome, and ribosomes
65
What is cytoplasm mainly composed of?
Water
66
Inclusion function
Storage of nutrients
67
Two types of carbon inclusions
Glycogen
| Poly-beta-hydroxybutyrate (PHB) granules
68
What is poly-beta-hydroxybutyrate (PHB) used to make?
Biodegradable plastic
69
Phosphate inclusion
Polyphosphate (metachromatic) granules
70
Sulfur inclusion
Sulfur globules
71
What type of bacteria has sulfur globules?
Thiomargarita
72
Carbon and nitrogen inclusion
Cyanophycin granules (chains of amino acids)
73
Gas vacuoles: function
Control buoyancy
74
What type of bacteria have gas vacuoles?
Cyanobacteria (photosynthetic bacteria)
| Aquatic bacteria
75
Magnetosomes: composition and function
Inclusions made from magnetite or greigite (iron-containing) chains
Act as magnets, orienting bacteria to north and south, helping them to find nutrients
76
Thylakoids: what type of bacteria have them, and what are they?
Cyanobacteria have thlakoids
| Photosynthetic membranes that contain clorophyll
77
Carboxysomes: what are they, and what bacteria have them?
Microcompartments
| Found in Cyanobacteria and other CO2 fixing bacteria
78
Carboxysomes: what shape are they, and what are they composed of?
Polyhedral shape
| Protein shell
79
What 2 enzymes are inside carboxysomes, and what do they do?
Carbonic anhydrase: converts carbonic acid to CO2
| RubisCO: adds CO2 to ribulose 1, 5 bisphosphate (RuBP), forming 3-phosphoglycerate (PGA)
80
RubisCO's reaction is the first key reaction of what process?
Calvin cycle: fixing CO2 into carbohydrate
81
CO2 fixation is energy demanding. Where do Cyanobacteria gain the energy for CO2 fixation?
Photosynthesis
82
What molecule transcribes DNA into mRNA?
RNA polymerase
83
What molecules translate mRNA into protein?
Ribosomes
84
In bacteria and archaea, do transcription and translation occur simultaneously or at different times?
Simultaneously
85
Nucleoid
Region of bacterial cell that contains chromosome
86
Bacterial chromosome features: shape, number per cell, membrane enclosed or not
Closed circular dsDNA (some bacteria have linear chromosomes)
Typically 1/cell (some bacteria have more than one)
Not membrane enclosed
87
Plasmids: size/shape, do they replicate with chromosome, what types of genes do they carry
Small, closed circular DNA
Exist and replicate independently of chromosome
May carry genes that are advantageous to survival
88
Conjugative plasmid
Can be transferred from one bacterium to another
89
R plasmid
Conjugative plasmid that confers resistance to antibiotics
