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Chapter 3 Flashcards

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1
Q

Why is it important that cells have high surface area to volume ratio

A

It increases nutrient uptake and diffusion of molecules across the cell
The bigger the cell the more energy expended to move things across the cell

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2
Q

What is the cell envelope and what is it made of

A

Layers that surround the cell
Made of plasma membrane and cell wall and sometimes another additional layer such as capsule or slime layer

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3
Q

What molecules move across the cell easiest

A

Small, non polar

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4
Q

What are some plasma membrane functions

A

Innermost membrane that encompasses the cytoplasm
Selectively permeable that takes nutrients and eliminates waste
Interacts with external environment
Required for all living organisms

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5
Q

What are hydrophilic lipids

A

Contain polar ends that interact with water

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6
Q

What are hydrophobic lipids

A

Non polar rails that are insoluble in water and interact with each other

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7
Q

What are peripheral membrane proteins

A

Loosely connected to membrane and can be easily removed

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8
Q

What are integral membrane proteins

A

Amphipathic proteins that are embedded within the membrane and not easily removed
Hydrophobic part is buried in the membrane and hydrophilic interacts on the outside

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9
Q

What are hopanoids

A

Hydrophobic molecules similar to cholesterol that give structure and intengrity to the plasma membrane
They increase structural rigidity for bacteria

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10
Q

What are functional membrane micro domains

A

Platforms used for protein complex assembly

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11
Q

What are macronutrients

A

Required in large amounts
Found in organic molecules
Contain cations that contribute to activity and stability of molecules and cell structures

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12
Q

What are micronutrients

A

Required in small amounts
Can support microbial growth and works to assist enzyme catalysis and maintain protein structure

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13
Q

What are growth factors

A

Organic compounds required for survival

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14
Q

What are siderophores

A

Secreted by bacteria, work with ferric iron for transport into cell
They hold onto iron until needed

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15
Q

Why is iron so crucial for bacteria

A

It is usually a limiting nutrient for many bacteria
No iron means no enzyme functionality

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16
Q

Why is the cell wall essential to bacteria in regards to osmosis

A

Water goes in and will explode to the bacteria without the cell wall
The cell wall pushes back on osmotic stress

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17
Q

What is peptidoglycan

A

Mesh like polymer that has two alternating sugars, NAM and NAG
they have helical shape and their chains are cross linked by peptides for strength

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18
Q

What is direct cross link

A

Connecting carboxyl group and amino groups between amino acids

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19
Q

What are indirect cross link

A

Peptide inter bridge may form

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20
Q

What is gram positive

A

Stains purple, thick peptidoglycan
Can be monoderm which is having a singular membrane

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21
Q

What is gram negative

A

Stains pink or red
Thin peptidoglycan and outer membrane
Has diderm which has plasma membrane and outer membrane

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22
Q

Why does penicillin work against gram positive

A

Because it has a larger peptidoglycan layer than gram negative

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23
Q

What does the peptidoglycan structure look like

A

Mesh like polymer that forms long strands from its polymers
NAG and NAM alternate
Strands have helical shape and are cross linked with peptides for strength

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24
Q

What is direct cross linking

A

Connecting carboxyl group and amino groups between amino acids

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25
What is indirect cross linking
Peptide inter bridge may form
26
What are gram positive cell walls mostly made of
Peptidoglycan and teichoic acid
27
What is teichoic acid
Polymers of glycerol that help maintain cell envelope Protects against environmental substances and binds to host cells to initiate infection Is negatively charged
28
What are gram negative cell walls composed of
Thin layer of peptidoglycan surrounded by outer membrane The outer membrane has lipopolysaccharides (LPS) No teichoic acid in gram negative
29
What does LPS consist of
Lipid A which is buried in the membrane Core polysaccharide which is a 10 sugar structure joined to lipid A O side chain which is a polysaccharide that extends outward from the core
30
What are some importances of LPS
Contributes to negative charge on cell surface Helps stabilize outer membrane structure Creates permeability barrier Hosts defense protection and acts as endotoxin Elicits strong immune response
31
What happens in hypotonic environments
Solute concentration outside cell less than inside cell so water moves in and cell swells Cell lysis occurs
32
What happens in hypertonic environments
Solute concentration outside cell greater than inside so water leaves and cell shrivels Plasmolysis occurs which is shrinking of cytoplasm
33
What are lysozymes
Part of immune system that breaks bonds between NAG and NAM
34
What are two ways that would cause a cell to lyse in hypotonic solution
Penicillin inhibits peptidoglycan synthesis Lysozymes break NAM and NAG bonds
35
What is the difference between cidal and static
Cidal is when a cell explodes and static is when a cell dies of old age
36
What is the glycocalyx
Polysaccharide extension that aids in attachment to solid surfaces Examples include the capsule and slime layers
37
What are capsules
Well organized layers made of polysaccharides that are bonded covalently and difficult to wash away They are visible in light microscope and can resist phagocytosis Can also protect from desiccation
38
What are slime layers
Polysaccharide layers that are unorganized and easy to wash away Slime may facilitate motility
39
What are s layers
Geometric patterns made of protein that aid in protecting from ion and ph fluctuations, osmotic stress, enzymes, and predation Maintain shape and rigidity of cell and promote adhesion to surface Protect from host defenses
40
What is a cytoskeleton
Protein filaments that polymerize to form functional filaments that extend to dimension of cell Participate in cell division, localize proteins, and maintain cell shape
41
What are some examples of bacterial cytoskeleton molecules
FtsZ which are many bacteria and from rings at center of dividing cell that constrict as daughter separates (very good at binary fission) MreB which are many rods and maintain shape by positioning peptidoglycan synthesis machinery CreS which maintains curve shape
42
What are intracytoplasmic membranes
Plasma membrane foldings Can be observed in photosynthetic bacteria or bacteria with high respiratory activity
43
Ask Annabelle about slide 38
Idk
44
What are carboxysomes
CO2 fixing bacteria Contain carbonic anhydrase that releases co2 into shell and accumulates in high concentration then rubisco makes sugar
45
What are micro compartments
Compartments for specific functions not bound to membranes
46
What are gas vacuoles
Involved in bacterial movement and provide buoyancy to aquatic bacteria
47
What are magnetosomes
Found in aquatic bacteria that magnetite particles for orientation in earths magnetic field
48
What are ribosomes
Site of protein synthesis 70s because 30s for small unit and 50 s for large unit
49
What is the nucleoid
Usually not membrane bound Chromosome and associated proteins found here Usually a closed, circular, double stranded dna molecule Supercoiling and associated proteins aid in folding and structure
50
What are plasmids
Extra chromosomal dna, usually small and circular Exist and replicate independently of chromosome
51
What are episomes
Plasmids that can integrate into a chromosome
52
What is the difference between pili/fimbriae and flagella
Pili and fimbriae are used for attachment Flagella aids in movement
53
Why are sex pili important
They are genetically encoded on plasmids and are required for conjugation They are specialized genes are allow for gene transfer
54
What is monotrochous
One flagellum
55
What is a polar flagellum
Flagellum at the end of a cell
56
What is amphitrichous
One flagellum at each end of a cell
57
What is lophotrichous
Cluster of flagella at one or both ends
58
What is peritrichous
Spread over entire surface of cell
59
What are the three components of a bacterial flagella
Filament which extends from cell surface to the tip Basal body which is embedded in the cell envelope Hook which is a short curved segment
60
How is flagella synthesized
Flagellin molecules transported through hollow filament Filament subunits self assemble with help of filament cap at the tip not the base
61
How do flagella move and what is the importance or directionality in regards to them
They rotate like a propeller If moving counterclockwise they run in forward direction If clockwise they tumble instead
62
What are spirochete and how do they move
Contain multiple internal flagella Move by corkscrew movement since multiple flagella form axial fibril which winds around cell and exhibits spinning and flexing movements
63
True or false: twitching and gliding is true motility
False, it’s Brownian movement which isn’t true motility
64
What is involved with twitching motility
Pili at the end of cell Short jerky motions Cells are in contact with each other and surfaces
65
What does gliding consist of
Smooth movements that don’t require appendages
66
What is chemotaxis
Movement toward a chemical attractant or away from chemical repellent In presence of attractant or repellant the tumbling frequency is reduced
67
What are chemoreceptors
Chemical attractants and repellants bind to them and transmit signals throughout chemo sensing system
68
What are bacterial endospores
Complex, dormant structures that are formed by some bacteria in response to nutrient depletion Can resist uv radiation, gamma radiation, chemical disinfectants
69
What is sporulation
Process of endospores formation Usually starts when growth slows due to lack of nutrients Produces dormant cell that can persist until nutrients are available and growth resumes

Micro (8 decks)

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