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BMSC 210 > BMSC210 CH3.3 > Flashcards

BMSC210 CH3.3 Flashcards

1
Q

What are the distinguishing characteristics of prokaryotic cells?

A

Small, simple, lack a nucleus or membrane-bound organelles

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2
Q

What are the internal and external structures of prokaryotic cells?

A

Cell wall, plasma membrane, cytoplasm, ribosomes; pili, flagella, capsule

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3
Q

How do prokaryotic cells differ from eukaryotic cells?

A

Prokaryotic cells lack a nucleus or membrane-bound organelles

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4
Q

What is cytoplasm?

A

gel-like substance composed of water and dissolved chemicals

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5
Q

What is a plasma membrane?

A

membrane that surrounds the cytoplasm

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6
Q

What are chromosomes?

A

genetic blueprints of the cell

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7
Q

What are ribosomes?

A

organelles for protein production

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8
Q

What are the two largest categories of cells?

A

Prokaryotic cells and eukaryotic cells

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9
Q

What is the main difference between prokaryotic cells and eukaryotic cells?

A

Presence or absence of nucleus and nuclear membrane

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10
Q

Which domains do prokaryotic microorganisms belong to?

A

Archaea and Bacteria

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11
Q

Which domain do eukaryotic organisms belong to?

A

Eukarya

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12
Q

How does the size of eukaryotic cells compare to prokaryotic cells?

A

Eukaryotic cells are larger

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13
Q

Do prokaryotic cells have membrane-bound organelles?

A

No, generally lacking

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14
Q

What are the structures typically associated with prokaryotic cells?

A

cell membrane, chromosomal DNA, ribosomes, cell wall

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15
Q

What is the role of the cell wall?

A

Protects the cell from changes in osmotic pressure

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16
Q

Which types of organisms have a cell wall?

A

Most prokaryotes and some eukaryotes

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17
Q

What is osmotic pressure?

A

Differences in solute concentration on opposing sides of a semipermeable membrane

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18
Q

What can pass through a semipermeable membrane?

A

Water

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19
Q

What can’t pass through a semipermeable membrane?

A

Solute molecules

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20
Q

What is osmosis?

A

Diffusion of water

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21
Q

Which way does water diffuse in osmosis?

A

From low concentration to high concentration

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22
Q

What happens to the concentrations on both sides in osmosis?

A

They become equal

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23
Q

What is the name for extreme osmotic pressure on a cell?

A

Osmotic shock

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24
Q

How is the external environment of a cell described?

A

Isotonic, hypertonic, or hypotonic

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25
Q

What is an isotonic medium?

A

Solute concentrations are approximately equal inside and outside the cell.

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26
Q

What happens in a hypertonic medium?

A

Solute concentration outside the cell exceeds that inside the cell. Water moves out of the cell.

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27
Q

What happens in a hypotonic medium?

A

Solute concentration inside the cell exceeds that outside the cell. Water moves into the cell.

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28
Q

What can happen to a cell in a hypotonic medium?

A

The cell can swell and potentially burst.

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29
Q

What is tonicity?

A

The ability of a cell to withstand changes in osmotic pressure

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30
Q

Why are cells with a cell wall better able to withstand changes in osmotic pressure?

A

They can maintain their shape

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31
Q

What advantages do cell walls provide prokaryotic cells?

A

Cell walls provide shape, structural support, and protection against osmotic stress.

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32
Q

What is the nucleoid in prokaryotic cells?

A

The nucleoid is the region within prokaryotic cells where the circular, haploid chromosome is located.

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33
Q

Where is prokaryotic DNA and DNA-associated proteins concentrated?

A

Nucleoid region

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34
Q

Which domains of life possess ribosomes?

A

All three domains - bacteria, archaea, and eukarya

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35
Q

What are ribosomes made of?

A

Proteins and ribosomal RNA (rRNA)

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36
Q

What is the size of prokaryotic ribosomes?

A

70S

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37
Q

What is the size of eukaryotic cytoplasmic ribosomes?

A

80S

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38
Q

What does ‘S’ stand for in 70S and 80S?

A

Svedberg unit

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39
Q

What is the difference between bacterial and archaeal ribosomes?

A

Different proteins and rRNA molecules

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40
Q

How are archaeal ribosomes similar to eukaryotic ribosomes?

A

More similar than bacterial ribosomes

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41
Q

What are the sizes of prokaryotic ribosomes?

A

30S (small subunit) and 50S (large subunit)

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42
Q

What are inclusions?

A

Cytoplasmic structures that store excess nutrients

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43
Q

What is the function of magnetosomes in magnetotactic bacteria?

A

Align along a magnetic field

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44
Q

What are endospores?

A

Structures that protect the bacterial genome in a dormant state

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45
Q

What are the characteristics of vegetative cells compared to endospores?

A

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.

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46
Q

What is the process by which vegetative cells transform into endospores?

A

Sporulation

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47
Q

What is the first step in the process of sporulation?

A

Formation of a septum

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48
Q

During sporulation, what does the septum do?

A

Divides cell asymmetrically

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49
Q

What is a forespore during sporulaton?

A

Copy of cell’s chromosomes

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50
Q

What forms around the cortex during sporulation?

A

Protein spore coat

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51
Q

What happens to the DNA of the mother cell during sporulation?

A

Disintegrates

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52
Q

What is the final stage in the maturation of an endospore?

A

Formation of an outermost exosporium.

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53
Q

When is the endospore released during sporulation?

A

Upon disintegration of the mother cell.

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54
Q

How are the endospores visualized in staining?

A

Malachite Green spore stain

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55
Q

How long can endospores persist in a dormant state?

A

Up to thousands of years

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56
Q

What happens to endospores when living conditions improve?

A

They undergo germination

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57
Q

What happens to the cell after germination?

A

It becomes metabolically active again

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58
Q

What are some clinically significant endospore-forming gram-positive bacteria?

A

B. anthracis, C. tetani, C. difficile, C. perfringens, C. botulinum

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59
Q

What is the function of an endospore?

A

Survival under unfavorable conditions

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60
Q

What is the function of a cell wall in prokaryotic cells?

A

Provides structural support.

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61
Q

What is meant by selective permeability?

A

Allows some molecules to enter or leave the cell while restricting others.

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62
Q

What is the plasma membrane structure of most bacterial and eukaryotic cell types?

A

Bilayer composed mainly of phospholipids and proteins

63
Q

What type of linkages are found in the phospholipids of the plasma membrane of most bacterial and eukaryotic cells?

A

Ester linkages

64
Q

What is the structure of the bacterial plasma membrane?

A

Phospholipid bilayer with embedded proteins

65
Q

How do archaeal plasma membranes differ from bacterial and eukaryotic plasma membranes?

A

Formed with ether linkages instead of ester linkages

66
Q

What is the difference between archaeal phospholipids and those of bacterial and eukaryotic cells?

A

Archaeal phospholipids have branched chains

67
Q

What are some functions of proteins in prokaryotic plasma membranes?

A

Cell-to-cell communication, sensing environmental conditions, pathogenesis (in bacteria)

68
Q

What is the function of glycoprotein and glycolipid complexes?

A

Allowing the cell to interact with the external environment

69
Q

Where do glycoproteins and glycolipids extend from?

A

The surface of the cell

70
Q

What is one of the most important functions of the plasma membrane?

A

Control transport of molecules into and out of the cell

71
Q

What are membrane transport mechanisms responsible for?

A

Transporting molecules across the plasma membrane

72
Q

What is the purpose of maintaining internal conditions within a certain range?

A

Maintain homeostasis

73
Q

What is the process by which molecules move from a higher concentration to a lower concentration?

A

Simple diffusion

74
Q

What is simple diffusion also known as?

A

Passive transport

75
Q

What molecules can cross the membrane bilayer directly by simple diffusion?

A

Carbon dioxide

76
Q

What type of molecules need the help of carriers or channels in the membrane?

A

Charged molecules and large molecules

77
Q

What is the process called when molecules are ferried across the membrane?

A

Facilitated diffusion

78
Q

What are aquaporins?

A

Family of membrane proteins

79
Q

What do aquaporins provide channels for?

A

Facilitated diffusion of water

80
Q

What is the process called when cells move molecules against concentration gradients?

A

Active transport

81
Q

What is a major difference between passive and active transport?

A

Active transport requires energy

82
Q

What are the three general types of active transport in bacteria and archaea?

A

Coupled Transport, ATP-binding cassette transporters, Group Translocation

83
Q

What is the driving ion in symport and antiport in bacteria and archaea?

A

Proton

84
Q

In symport, does the driving ion move in the same direction as the substrate for transport?

A

Yes

85
Q

What is antiport?

A

Driving ion and substrate move in opposite directions

86
Q

What are ATP-binding cassette transporters?

A

Protein superfamily that transports substrates using ATP energy

87
Q

What does ABC stand for in ABC-transporters?

A

ATP-binding cassette

88
Q

What type of energy do ATP-binding cassette transporters use?

A

Energy of ATP hydrolysis

89
Q

What are the three components of an ABC transporter?

A

1) Membrane-spanning carrier proteins, 2) ATP binding peripheral proteins, 3) Substrate-binding protein

90
Q

Where is the substrate-binding protein located in Gram-negative bacteria?

A

Periplasm

91
Q

Where is the substrate-binding protein located in Gram-positive bacteria?

A

Outside of cell membrane

92
Q

What types of molecules do ABC transporters import?

A

Ions, amino acids, peptides, sugars, hydrophilic molecules

93
Q

What do exporters in gram-negative bacteria transport?

A

Lipids and some polysaccharides

94
Q

What is the PTS system?

A

Transfer of phosphate from PEP to sugar carriers.

95
Q

What is the role of the membrane component of the PTS system?

A

Phosphorylates the sugar as it enters the cell.

96
Q

What are some prokaryotic cells that have membrane structures for photosynthesis?

A

Cyanobacteria and photosynthetic bacteria

97
Q

What is the major component of bacterial cell walls?

A

Peptidoglycan

98
Q

What is the structural composition of peptidoglycan?

A

Long chains of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

99
Q

What gives peptidoglycan its two-dimensional tensile strength?

A

Formation of peptide bridges

100
Q

Why are antibiotic drugs designed to interfere with peptidoglycan synthesis?

A

To weaken the cell wall and make bacterial cells more susceptible to osmotic pressure

101
Q

How do certain cells of the human immune system recognize bacterial pathogens?

A

By detecting peptidoglycan on the surface of a bacterial cell

102
Q

What enzymes do these cells use to destroy the bacterial cell?

A

Lysozyme

103
Q

What are the two common types of cell wall structures that the Gram staining protocol differentiates?

A

Gram-positive and Gram-negative

104
Q

What is the external layer found in bacteria of the family Mycobacteriaceae?

A

Waxy mycolic acids

105
Q

Why are bacteria with mycolic acid layer referred to as acid-fast?

A

Acid-fast stains are needed to penetrate the mycolic acid layer for microscopy

106
Q

What are the two common cell wall structural types in bacteria?

A

Gram-positive and Gram-negative.

107
Q

How would you describe the structure of Gram-positive cell walls?

A

Gram-positive cell walls have a thick layer of peptidoglycan with embedded teichoic acid.

108
Q

What are the three layers of Gram-negative cell walls?

A

Inner membrane, peptidoglycan layer, outer membrane

109
Q

How are acid-fast cells stained?

A

Red by carbolfuschin

110
Q

What is the second lipid bilayer called in Ingram-negative cells?

A

Outer membrane

111
Q

Where is lipid A located in a gram-negative bacterial cell?

A

Embedded in the outer membrane

112
Q

What are the components of the outer membrane of a gram-negative bacterial cell?

A

Lipopolysaccharide (LPS)

113
Q

How does the cell wall structure of archaea differ from bacteria?

A

Archaeal cell walls do not contain peptidoglycan; instead, they contain pseudopeptidoglycan or glycoproteins/polysaccharides.

114
Q

What is pseudopeptidoglycan (pseudomurein)?

A

A polymer similar to peptidoglycan found in archaeal cell walls.

115
Q

What are glycocalyces?

A

Sugar coats exterior to the cell wall

116
Q

What are the two important types of glycocalyces?

A

Capsules and slime layers

117
Q

Where is a capsular polysaccharide layer located?

A

Outside of the cell wall

118
Q

How is a slime layer different from a capsular polysaccharide layer?

A

A slime layer is loosely attached and easily washed off

119
Q

What is the function of glycocalyces?

A

Allow cells to adhere to surfaces

120
Q

What is the significance of biofilms?

A

Provide protection to microbes

121
Q

How do biofilms protect cells?

A

Prevent desiccation and hinder immune responses

122
Q

What are capsules?

A

Organized layer of polysaccharides

123
Q

What is the role of a capsule in a microbe’s pathogenicity?

A

Capsule makes it difficult for phagocytic cells to engulf and kill the microorganism.

124
Q

Which bacterium is known for producing a capsule that aids in its pathogenicity?

A

Streptococcus pneumoniae

125
Q

Why is staining capsules for microscopy challenging?

A

Capsules are difficult to stain; negative staining techniques are used.

126
Q

How can capsules be used?

A

To help identify specific pathogenic strains.

127
Q

What is an S-layer composed of?

A

A mixture of structural proteins and glycoproteins.

128
Q

What are filamentous appendages in bacterial cells?

A

Protein appendages that extend outward and allow interaction with the environment

129
Q

What are the filamentous appendages that can attach to other surfaces, transfer DNA, or provide movement?

A

Fimbriae, pili, and flagella.

130
Q

What do fimbriae commonly refer to?

A

Short bristle-like proteins projecting from the cell surface by the hundreds.

131
Q

What is the function of fimbriae?

A

Enable cell attachment to surfaces and other cells.

132
Q

Why is adherence to host cells important for pathogenic bacteria?

A

Colonization, infectivity, and virulence.

133
Q

What are pili?

A

Longer protein appendages aiding in attachment to surfaces.

134
Q

What is the function of the F pilus or sex pilus?

A

Important in DNA transfer between bacterial cells.

135
Q

What are two protein appendages that bacteria may produce?

A

Fimbriae and pili

136
Q

What is the function of flagella?

A

To move cells in aqueous environments

137
Q

What are bacterial flagella composed of?

A

Flagellin protein subunits

138
Q

What is the function of bacterial flagella?

A

Spin in solution like propellers

139
Q

Where is the motor for the flagellum located?

A

Basal body embedded in the plasma membrane

140
Q

What connects the basal body to the filament of the flagellum?

A

Hook region

141
Q

Do gram-positive and gram-negative bacteria have the same basal body configuration?

A

No, they have different configurations due to differences in cell wall structure

142
Q

What is the arrangement of flagella in a bacterium with a singular flagellum?

A

Monotrichous

143
Q

What is the arrangement of flagella in a bacterium with a flagellum or tufts of flagella at each end?

A

Amphitrichous

144
Q

What is the name for flagella that cover the entire surface of a bacterial cell?

A

Peritrichous flagella.

145
Q

What are the main components of a bacterial flagellum?

A

Basal body, hook, and filament

146
Q

Can flagellated bacteria have different arrangements of their flagella?

A

Yes

147
Q

What are four common flagella arrangements of bacteria?

A

Monotrichous, amphitrichous, lophotrichous, peritrichous

148
Q

What are some environmental signals that bacteria respond to?

A

Light, magnetic fields, chemical gradients

149
Q

What is chemotaxis?

A

Movement in response to a chemical gradient

150
Q

How are flagella arranged in peritrichous bacteria?

A

All bundled together in a streamlined way

151
Q

What is the overall effect of runs and tumbles when an attractant exists?

A

Movement towards higher concentration

152
Q

What is the name of the pattern where movement is more random when no chemical gradient exists?

A

Biased random walk

153
Q

How do bacteria achieve directional movement?

A

By changing the rotation of their flagella

154
Q

What happens to flagellar rotation in the absence of a chemical gradient?

A

Cycles between counterclockwise (run) and clockwise (tumble) with no overall directional movement.

BMSC 210 (24 decks)

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