BMSC210 CH3.3 Flashcards
1
Q
What are the distinguishing characteristics of prokaryotic cells?
A
Small, simple, lack a nucleus or membrane-bound organelles
2
Q
What are the internal and external structures of prokaryotic cells?
A
Cell wall, plasma membrane, cytoplasm, ribosomes; pili, flagella, capsule
3
Q
How do prokaryotic cells differ from eukaryotic cells?
A
Prokaryotic cells lack a nucleus or membrane-bound organelles
4
Q
What is cytoplasm?
A
gel-like substance composed of water and dissolved chemicals
5
Q
What is a plasma membrane?
A
membrane that surrounds the cytoplasm
6
Q
What are chromosomes?
A
genetic blueprints of the cell
7
Q
What are ribosomes?
A
organelles for protein production
8
Q
What are the two largest categories of cells?
A
Prokaryotic cells and eukaryotic cells
9
Q
What is the main difference between prokaryotic cells and eukaryotic cells?
A
Presence or absence of nucleus and nuclear membrane
10
Q
Which domains do prokaryotic microorganisms belong to?
A
Archaea and Bacteria
11
Q
Which domain do eukaryotic organisms belong to?
A
Eukarya
12
Q
How does the size of eukaryotic cells compare to prokaryotic cells?
A
Eukaryotic cells are larger
13
Q
Do prokaryotic cells have membrane-bound organelles?
A
No, generally lacking
14
Q
What are the structures typically associated with prokaryotic cells?
A
cell membrane, chromosomal DNA, ribosomes, cell wall
15
Q
What is the role of the cell wall?
A
Protects the cell from changes in osmotic pressure
16
Q
Which types of organisms have a cell wall?
A
Most prokaryotes and some eukaryotes
17
Q
What is osmotic pressure?
A
Differences in solute concentration on opposing sides of a semipermeable membrane
18
Q
What can pass through a semipermeable membrane?
A
Water
19
Q
What can’t pass through a semipermeable membrane?
A
Solute molecules
20
Q
What is osmosis?
A
Diffusion of water
21
Q
Which way does water diffuse in osmosis?
A
From low concentration to high concentration
22
Q
What happens to the concentrations on both sides in osmosis?
A
They become equal
23
Q
What is the name for extreme osmotic pressure on a cell?
A
Osmotic shock
24
Q
How is the external environment of a cell described?
A
Isotonic, hypertonic, or hypotonic
25
What is an isotonic medium?
Solute concentrations are approximately equal inside and outside the cell.
26
What happens in a hypertonic medium?
Solute concentration outside the cell exceeds that inside the cell. Water moves out of the cell.
27
What happens in a hypotonic medium?
Solute concentration inside the cell exceeds that outside the cell. Water moves into the cell.
28
What can happen to a cell in a hypotonic medium?
The cell can swell and potentially burst.
29
What is tonicity?
The ability of a cell to withstand changes in osmotic pressure
30
Why are cells with a cell wall better able to withstand changes in osmotic pressure?
They can maintain their shape
31
What advantages do cell walls provide prokaryotic cells?
Cell walls provide shape, structural support, and protection against osmotic stress.
32
What is the nucleoid in prokaryotic cells?
The nucleoid is the region within prokaryotic cells where the circular, haploid chromosome is located.
33
Where is prokaryotic DNA and DNA-associated proteins concentrated?
Nucleoid region
34
Which domains of life possess ribosomes?
All three domains - bacteria, archaea, and eukarya
35
What are ribosomes made of?
Proteins and ribosomal RNA (rRNA)
36
What is the size of prokaryotic ribosomes?
70S
37
What is the size of eukaryotic cytoplasmic ribosomes?
80S
38
What does 'S' stand for in 70S and 80S?
Svedberg unit
39
What is the difference between bacterial and archaeal ribosomes?
Different proteins and rRNA molecules
40
How are archaeal ribosomes similar to eukaryotic ribosomes?
More similar than bacterial ribosomes
41
What are the sizes of prokaryotic ribosomes?
30S (small subunit) and 50S (large subunit)
42
What are inclusions?
Cytoplasmic structures that store excess nutrients
43
What is the function of magnetosomes in magnetotactic bacteria?
Align along a magnetic field
44
What are endospores?
Structures that protect the bacterial genome in a dormant state
45
What are the characteristics of vegetative cells compared to endospores?
Vegetative cells are sensitive to extreme temperatures and radiation, gram-positive, have normal water content and enzymatic activity, and are capable of active growth and metabolism. Endospores are resistant to extreme temperatures and radiation, do not absorb Gram stain, are dehydrated with no metabolic activity, and are dormant with no growth or metabolic activity.
46
What is the process by which vegetative cells transform into endospores?
Sporulation
47
What is the first step in the process of sporulation?
Formation of a septum
48
During sporulation, what does the septum do?
Divides cell asymmetrically
49
What is a forespore during sporulaton?
Copy of cell's chromosomes
50
What forms around the cortex during sporulation?
Protein spore coat
51
What happens to the DNA of the mother cell during sporulation?
Disintegrates
52
What is the final stage in the maturation of an endospore?
Formation of an outermost exosporium.
53
When is the endospore released during sporulation?
Upon disintegration of the mother cell.
54
How are the endospores visualized in staining?
Malachite Green spore stain
55
How long can endospores persist in a dormant state?
Up to thousands of years
56
What happens to endospores when living conditions improve?
They undergo germination
57
What happens to the cell after germination?
It becomes metabolically active again
58
What are some clinically significant endospore-forming gram-positive bacteria?
B. anthracis, C. tetani, C. difficile, C. perfringens, C. botulinum
59
What is the function of an endospore?
Survival under unfavorable conditions
60
What is the function of a cell wall in prokaryotic cells?
Provides structural support.
61
What is meant by selective permeability?
Allows some molecules to enter or leave the cell while restricting others.
62
What is the plasma membrane structure of most bacterial and eukaryotic cell types?
Bilayer composed mainly of phospholipids and proteins
63
What type of linkages are found in the phospholipids of the plasma membrane of most bacterial and eukaryotic cells?
Ester linkages
64
What is the structure of the bacterial plasma membrane?
Phospholipid bilayer with embedded proteins
65
How do archaeal plasma membranes differ from bacterial and eukaryotic plasma membranes?
Formed with ether linkages instead of ester linkages
66
What is the difference between archaeal phospholipids and those of bacterial and eukaryotic cells?
Archaeal phospholipids have branched chains
67
What are some functions of proteins in prokaryotic plasma membranes?
Cell-to-cell communication, sensing environmental conditions, pathogenesis (in bacteria)
68
What is the function of glycoprotein and glycolipid complexes?
Allowing the cell to interact with the external environment
69
Where do glycoproteins and glycolipids extend from?
The surface of the cell
70
What is one of the most important functions of the plasma membrane?
Control transport of molecules into and out of the cell
71
What are membrane transport mechanisms responsible for?
Transporting molecules across the plasma membrane
72
What is the purpose of maintaining internal conditions within a certain range?
Maintain homeostasis
73
What is the process by which molecules move from a higher concentration to a lower concentration?
Simple diffusion
74
What is simple diffusion also known as?
Passive transport
75
What molecules can cross the membrane bilayer directly by simple diffusion?
Carbon dioxide
76
What type of molecules need the help of carriers or channels in the membrane?
Charged molecules and large molecules
77
What is the process called when molecules are ferried across the membrane?
Facilitated diffusion
78
What are aquaporins?
Family of membrane proteins
79
What do aquaporins provide channels for?
Facilitated diffusion of water
80
What is the process called when cells move molecules against concentration gradients?
Active transport
81
What is a major difference between passive and active transport?
Active transport requires energy
82
What are the three general types of active transport in bacteria and archaea?
Coupled Transport, ATP-binding cassette transporters, Group Translocation
83
What is the driving ion in symport and antiport in bacteria and archaea?
Proton
84
In symport, does the driving ion move in the same direction as the substrate for transport?
Yes
85
What is antiport?
Driving ion and substrate move in opposite directions
86
What are ATP-binding cassette transporters?
Protein superfamily that transports substrates using ATP energy
87
What does ABC stand for in ABC-transporters?
ATP-binding cassette
88
What type of energy do ATP-binding cassette transporters use?
Energy of ATP hydrolysis
89
What are the three components of an ABC transporter?
1) Membrane-spanning carrier proteins, 2) ATP binding peripheral proteins, 3) Substrate-binding protein
90
Where is the substrate-binding protein located in Gram-negative bacteria?
Periplasm
91
Where is the substrate-binding protein located in Gram-positive bacteria?
Outside of cell membrane
92
What types of molecules do ABC transporters import?
Ions, amino acids, peptides, sugars, hydrophilic molecules
93
What do exporters in gram-negative bacteria transport?
Lipids and some polysaccharides
94
What is the PTS system?
Transfer of phosphate from PEP to sugar carriers.
95
What is the role of the membrane component of the PTS system?
Phosphorylates the sugar as it enters the cell.
96
What are some prokaryotic cells that have membrane structures for photosynthesis?
Cyanobacteria and photosynthetic bacteria
97
What is the major component of bacterial cell walls?
Peptidoglycan
98
What is the structural composition of peptidoglycan?
Long chains of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
99
What gives peptidoglycan its two-dimensional tensile strength?
Formation of peptide bridges
100
Why are antibiotic drugs designed to interfere with peptidoglycan synthesis?
To weaken the cell wall and make bacterial cells more susceptible to osmotic pressure
101
How do certain cells of the human immune system recognize bacterial pathogens?
By detecting peptidoglycan on the surface of a bacterial cell
102
What enzymes do these cells use to destroy the bacterial cell?
Lysozyme
103
What are the two common types of cell wall structures that the Gram staining protocol differentiates?
Gram-positive and Gram-negative
104
What is the external layer found in bacteria of the family Mycobacteriaceae?
Waxy mycolic acids
105
Why are bacteria with mycolic acid layer referred to as acid-fast?
Acid-fast stains are needed to penetrate the mycolic acid layer for microscopy
106
What are the two common cell wall structural types in bacteria?
Gram-positive and Gram-negative.
107
How would you describe the structure of Gram-positive cell walls?
Gram-positive cell walls have a thick layer of peptidoglycan with embedded teichoic acid.
108
What are the three layers of Gram-negative cell walls?
Inner membrane, peptidoglycan layer, outer membrane
109
How are acid-fast cells stained?
Red by carbolfuschin
110
What is the second lipid bilayer called in Ingram-negative cells?
Outer membrane
111
Where is lipid A located in a gram-negative bacterial cell?
Embedded in the outer membrane
112
What are the components of the outer membrane of a gram-negative bacterial cell?
Lipopolysaccharide (LPS)
113
How does the cell wall structure of archaea differ from bacteria?
Archaeal cell walls do not contain peptidoglycan; instead, they contain pseudopeptidoglycan or glycoproteins/polysaccharides.
114
What is pseudopeptidoglycan (pseudomurein)?
A polymer similar to peptidoglycan found in archaeal cell walls.
115
What are glycocalyces?
Sugar coats exterior to the cell wall
116
What are the two important types of glycocalyces?
Capsules and slime layers
117
Where is a capsular polysaccharide layer located?
Outside of the cell wall
118
How is a slime layer different from a capsular polysaccharide layer?
A slime layer is loosely attached and easily washed off
119
What is the function of glycocalyces?
Allow cells to adhere to surfaces
120
What is the significance of biofilms?
Provide protection to microbes
121
How do biofilms protect cells?
Prevent desiccation and hinder immune responses
122
What are capsules?
Organized layer of polysaccharides
123
What is the role of a capsule in a microbe's pathogenicity?
Capsule makes it difficult for phagocytic cells to engulf and kill the microorganism.
124
Which bacterium is known for producing a capsule that aids in its pathogenicity?
Streptococcus pneumoniae
125
Why is staining capsules for microscopy challenging?
Capsules are difficult to stain; negative staining techniques are used.
126
How can capsules be used?
To help identify specific pathogenic strains.
127
What is an S-layer composed of?
A mixture of structural proteins and glycoproteins.
128
What are filamentous appendages in bacterial cells?
Protein appendages that extend outward and allow interaction with the environment
129
What are the filamentous appendages that can attach to other surfaces, transfer DNA, or provide movement?
Fimbriae, pili, and flagella.
130
What do fimbriae commonly refer to?
Short bristle-like proteins projecting from the cell surface by the hundreds.
131
What is the function of fimbriae?
Enable cell attachment to surfaces and other cells.
132
Why is adherence to host cells important for pathogenic bacteria?
Colonization, infectivity, and virulence.
133
What are pili?
Longer protein appendages aiding in attachment to surfaces.
134
What is the function of the F pilus or sex pilus?
Important in DNA transfer between bacterial cells.
135
What are two protein appendages that bacteria may produce?
Fimbriae and pili
136
What is the function of flagella?
To move cells in aqueous environments
137
What are bacterial flagella composed of?
Flagellin protein subunits
138
What is the function of bacterial flagella?
Spin in solution like propellers
139
Where is the motor for the flagellum located?
Basal body embedded in the plasma membrane
140
What connects the basal body to the filament of the flagellum?
Hook region
141
Do gram-positive and gram-negative bacteria have the same basal body configuration?
No, they have different configurations due to differences in cell wall structure
142
What is the arrangement of flagella in a bacterium with a singular flagellum?
Monotrichous
143
What is the arrangement of flagella in a bacterium with a flagellum or tufts of flagella at each end?
Amphitrichous
144
What is the name for flagella that cover the entire surface of a bacterial cell?
Peritrichous flagella.
145
What are the main components of a bacterial flagellum?
Basal body, hook, and filament
146
Can flagellated bacteria have different arrangements of their flagella?
Yes
147
What are four common flagella arrangements of bacteria?
Monotrichous, amphitrichous, lophotrichous, peritrichous
148
What are some environmental signals that bacteria respond to?
Light, magnetic fields, chemical gradients
149
What is chemotaxis?
Movement in response to a chemical gradient
150
How are flagella arranged in peritrichous bacteria?
All bundled together in a streamlined way
151
What is the overall effect of runs and tumbles when an attractant exists?
Movement towards higher concentration
152
What is the name of the pattern where movement is more random when no chemical gradient exists?
Biased random walk
153
How do bacteria achieve directional movement?
By changing the rotation of their flagella
154
What happens to flagellar rotation in the absence of a chemical gradient?
Cycles between counterclockwise (run) and clockwise (tumble) with no overall directional movement.
