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BIMM 120 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

What are the 6 shapes of Cell Morphology

A

Coccus, Rod, Spirillum, Spirochete, Budding and Appendaged (Stalk and Hypha) and Filamentous Bacteria

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2
Q

Why do cells tend to be small

A

Cells tend to be small in order to increase their surface to volume ratio, which allows faster growth rate, support greater nutrient exchange, evolve faster, and adapt better to changing environments

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3
Q

What is the cytoplasmic membrane in Bacteria

A

Very thin, 6-8 nm, it is the barrier that separates cytoplasm from the environment. It is a highly selective barrier (phospholipid bilayer). Contains embedded proteins, is stabalized by hyudrogen bonds and hydrophobic interactions to make it somewhat fluid.

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4
Q

What does it mean that the membrane is highly selective

A

It can uptake and concentration of specific metabolites and excretion of waste products through the use of transport proteins

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5
Q

What is the general structure of the phospholipid bilyaer

A

Has a glycerol backbone and fatty acid tails that form the hydrophobic layer (non-polar), barrier to hydrophilic polar and charged molecules

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6
Q

Where are the hydrophobic and hydrophilic regions

A

The hydrophilic regions are the glycerophosphates and are on the outside of the membrane. The hydrophobic regions are the fatty acid tails and are on the inside of the membrane

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7
Q

Describe the glycerophosphate component of the membrane

A

It is a glycerol backbone connected to a phosphate group which is connected to ethanolamine

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8
Q

What are integral membrane proteins

A

Proteins that appear on both sides of the cytoplasmic membrane (firmly embedded in the membrane)

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9
Q

What are peripheral membrane proteins

A

One portion is anchored in the membrane

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10
Q

What are the functions of membrane proteins

A

Membrane proteins work to transport molecules into and out of cells, perform energy-transformation reactions, motility, and sensing the environment/signaling

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11
Q

What are membrane-strengthening lipids

A

Sterols and Hopanoids

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12
Q

What are sterols

A

Rigid, planar lipids found in eukaryotic membranes, not in bacteria, and strengthen and stabilize membranes

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13
Q

What are hopanoids

A

They are structurally similar to sterols and present in the membrane of many bacteria

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14
Q

Compare Archaeal Membranes with Bacteria and Eukarya Membranes

A

They have ETHER linkages in their phospholipids while bacteria and eukarya have ESTER linkages (between glycerol and fatty acids/isoprenes). Archaeal lipids lack fatty acids and have iseoprenes instead. Their major lipids are glycerol diethers and tetraethers and can exist as a lipid monolayer, bilayer, or mixture

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15
Q

What is a phytanyl membrane structure

A

Only has a glycerol diether at one end. Glyercol diether can be recognized by the extra methyl group along the chain of carbons

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16
Q

What is a biphytanyl membrane structure

A

Have two two glycerol diethers on both ends (Diglycerol tetraethers)

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17
Q

What is a crearchaeol membrane structure

A

Glycerol on both ends and kinks in the isoprene chain (cyclopentanes)

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18
Q

What is the difference between a phytanyl structure and a biphytanyl structure

A

The phytanyl structure has a glycerophostphate at one end but the biphytanyl has a glycerolphosphate on both ends. There is no gap in the biphytanyl membrane (a monolayer)

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19
Q

Describe the permeability of the membrane

A

It doesn’t allow for the movement of any charge or any large charged molecules through the membrane unless active transport is used. It functions as a gateway for transport of nutrients into, and wastes out of the cell. It also prevents leakage of molecules in the cell.

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20
Q

What is active transport

A

Proteins can accumulate nutrient solutes against a concentration gradient by expending energy

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21
Q

What is a protein anchor

A

Holds the transport proteins in place on the membrane. Site of many proteins that participate in transport, bioenergetics, and chemotaxis

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22
Q

What is energy conservation

A

Site of generation and use of the proton motive force. Membrane maintains a H+ gradient across the membrane. Positive outside (H+) and Negative inside (OH-)

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23
Q

Describe simple diffusion rate

A

Solute will diffuse down its concentration gradient. The more solute there is outside the cell, the faster the solute will enter the cell, at a linear rate, no saturation effect

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24
Q

Describe carrier mediated transport rate

A

Metabolites that need to be brought in via transport have rapid transport because proteins are specialized for pumping it into the cell, the rate of entry will rise very rapidly as amount of sugar increases outside the cell, but at some point all the transporter proteins will be busy and the metabolites outside of the cell will have to wait until one is free in order to enter the cell.

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25
What are the three major classes of transport systems in prokaryotes
Simple Transport, Group Translocation, and ABC System
26
What is Simple Transport
Uses a pre-existing gradient of one molecule (H+ ion) to drive the transport of another molecule. The H+ gradient across the membrane proves the energy required to pump the transported substance across the membrane. The H+ ion goes through the transport protein (out to in) and the energy that is lost is used to pump the solute. Energy is required for symporter and antiporter.
27
What is Group Translocation
The transport protein allows the molecule to cross the membrane, and once it gets inside the cell, the molecule undergoes a covalent modification (phosphate group added) Energy is required to modify the molecule
28
What is ABC System
ATP Binding Cassette. There are periplasmic binding proteins that bind the solute, delivers it to the transporter, and the transporter pumps it into the cell using ATP
29
What are the 3 simple transport events
Uniporters, symporters, and antiporters
30
What are uniporters
Not Active Transport. Molecule goes down concentration gradient and DOES NOT require energy. It has a specificity for the molecule being transferred, binds and releases molecules without actually pumping it. Facilitates the diffusion of molecule
31
What are symporters
Active Transport. Molecule is coupled with the movement of another molecule into the cell. The energy of the H+ ion going down its concentration gradient is coupled with pumping something in the cell, the solute
32
What are antiporters
Active Transport. H+ ion enters the cell and the solute leaves the cell, one of them needs to be supplying energy. The H+ ion moves down its concentration gradient to supply the energy needed to pump the solute out of the cell
33
In the ABC System what are the periplasmic binding proteins
Proteins in the periplasmic membrane space that bind to the substance being transported and delivers it to the transporter. Periplasmic binding proteins have high substrate specificity. Hydrolysis of the ATP changes the shape of the transport protein so that it can pump the molecule into the cell
34
What are translocases
They are responsible for exporting proteins through membranes and inserting proteins into membranes
35
What is the sec translocase system
Responsible for most exported proteins (sec for secretion)
36
What is the type III secretion system
It is common in pathogenic bacteria, secreted proteins translocated directly from bacterial cell into host cell. The secreted proteins alter the host cells in ways that benefit the pathogen
37
What is peptidoglycan
A strong layer that provides strength to cell wall and it is composed of polysaccharide backbone and peptide side chains. The polysaccharide monomers are joined by glycosidic bonds and the peptide side chains (cross-links) are joined by peptide bonds
38
What are the polysaccharide backbone monomers of peptidoglycan
NAG or G and NAM or M (Modified Sugars-the acetyl group is added on) Modified sugar can avoid hydrolysis that breaks down sugar, will always alternate GMGMGMG. the M sugar has a short sidechain (4 AA's) and the M sugar is involved in forming cross-links (covalent bond between the AA sidechains)
39
What are the peptides in peptidoglycan
Short amino acid chains, attached to the sugars, usually Lysine or DAP involved in crosslinks. Gram + and Gram - bactueria are cross-linked differently.
40
What is lysozyme
An enzyme that attacks peptidoglycan at particular positions in the polysaccharide backbone and damages the cell wall, a way of killing bacteria
41
Describe Gram + cell walls
Contain up to 90% peptidoglycan, multiple/thick layers of it, also common to have teichoic acids embedded in the cell wall
42
What are lipoteichoic acids
Lipoteichoic acids are teichoic acids covalently bound to cell membrane lipids, they act as anchors between the cell wall and the membrane
43
What is responsible for the differences in the Gram stain reaction between Gram + and Gram - bacteria
Structural difference between the cell walls
44
Describe Gram - cell walls
Total cell wall contains only about 10% peptidoglycan. Most of cell wall is composed of an outer membrane with Lipopolysaccharide LPS layer
45
What does LPS consist of
Lipid A, Core polysaccharide, and O-polysaccharide
46
What is endotoxin
The lipid A portion of LPS can be toxic to animals if released into blood by lysis of bacteria
47
What are porins
In Gram -, integral membrane channels for movement of hydrophillic low-molecular weight molecules. The outer membrane is also selectively permeable but much less so than the inner membrane. Lets small molecule pass the outer membrane and when in the periplasm, if there are transporters present, it can enter the cell
48
What is the periplasm
Space located between cytoplasmic and outer membranes, contains many soluble proteins that produces a gel-like consistency
49
Describe the cell walls of Archaea
No peptidoglycan, no outer membrane, contains pseudomurein in some archaea whereas other archaea lack pseudomurein.
50
What is pseudomurein
Polysaccharide similar to peptidoglycan, but different enough so that it is not attacked by lysozymes
51
Describe the surface layer of Archaea cell walls
Most common cell wall type among Archaea, consists of protein or glycoprotein (protein with sugar groups attached) and is in a paracrystalline structure that coats the entire cell (gives it its structure and shape)
52
Describe the capsules and slime layers of cell surfaces
Polysaccharide layers, may be think or thin, rigid or flexible, capsules are tougher and more rigid. Assist in attachment to surfaces, protect against immune system and phagocytosis and resist desiccation. The difference between the capsule and slime layers is that the slime layers are easily washed off and the capsules aren't, they have a little more structural integrity. Cells want to be sticky to remain in place of high nutrients
53
Describe Fimbriae structures
Filamentous protein structures that enable organisms to stick to surfaces or form pellicles. Proteins can form these large filmaents because some proteins are like legos that fit together with complementary surfaces and can assemble into a long structure
54
What are pellicles
Layers of cells formed by bacteria on liquids
55
What are pili
Filamentous protein structures, typically longer than fimbriae, assist in surface attachment, facilitate genetic exchange between cells (conjugation) and Type IV pili involved in twitching motility
56
What are gas vesicles
They confer buoyancy in planktonic cells, they are spindle-shaped gas-filled structures made of a protein shell, the number of them in cells are regulated to control buoyancy. Is hydrophillic outside and hydrophobic inside, gases are actually hydrophobic (non-polar) and they can come out of solution and fill up these vessicles.
57
What are endospores
They are differentiated cells resistant to heat, hardsh chemicals, lysozymes, and radiation. They are in the dormant stage of bacterial life cycle. They are for disperal via wind, water, or through animal gut and are only present in some gram + bacteria
58
What are the 3 endospore types
Terminal spores, subterminal spores, and central spores
59
Describe the life cycle of an endospore-forming bacterium
In a favorable environment, vegetative cells grow and divide, in an unfavorable environment, they form spores. Spores develop inside of a vegetative cell and a mature spore will break out when the mother cell lyses.
60
What is a flagellum
Protein structure for motility. Helical in shape and there are three different arrangements. It rotates and acts like a propeller going through a liquid environment
61
What are the 3 different arrangements of flagellum
Peritrichous (multiple flagella surrounding cell) Polar (just one flagella at one end) Lophotrichous (multiple flagella at one end)
62
What is gliding motility
Movement that is independent of flagella, slower and smoother than swimming, movement typically occurs along long axis of cell, requires surface contact, and the mechanisms are unclear (excretion of polysaccharide slime or gliding-specific proteins
63
What is twitching motility
Type IV pili extend, attach, and pull cell forward
64
What is taxis
Directed movement in response to chemical or physical gradients
65
What are the 5 different types of taxis and describe them
``` Chemotaxis: response to chemicals Phototaxis: response to light Aerotaxis: response to oxygen Osmotaxis: response to ionic strength Hydrotaxis: response to water ```
66
Describe chemotaxis
Its movement in response to chemicals. Bacteria respond to temporal, but not spatial, difference in chemical concentration. Attractants (food) and repellents (harsh chemicals) are sensed by chemoreceptor proteins in the cell membrane
67
What are chemoreceptor proteins
They are proteins in the cell membrane and sense proteins in the environment. They signal across the membrane in response to external liagnds to produce internal resposne
68
Describe the "Run and Tumble" behavior
When there is no attractant present, the cells exhibit random movement. They will go in a fairly straight line, stop, then head off into a new direction and repeat. When there is an attractant present, the cells exhibit directed movement. Longer runs in direction of attractant
69
How do you measure chemotaxis
Measured by inserting a capillary tube containing an attractant or repellent (or a control) into a medium of mobile bacteria. The tube with the attractant should have an increase in # of cells in the tube over time and the tube with the repellent should have the least # of cells in the tube over time. The control tube will have slightly more cells than the repellent tube.
70
Describe the Outer Membrane of a Gram - bacteria
There is a thin layer of peptidoglycan and the outer membrane is a lipid bilayer.
71
Describe the inner part of the outer membrane (lipid bilyar) in the Gram - bacteria
The inner part of the lipid bilayer contains phospholipids and lipoprotein
72
In the LPS what is lipid A
Lipid A connects lipids and fatty acids with sidechains to the membrane,at the bottom of the LPS layer and the lipids and fatty acids are in the "inner membrane"
73
In the LPS what is core polysaccharide
The Core polysaccharides are in the middle of the LPS layer
74
In the LPS what is O-polysaccharide
The outer most molecule and is what is recognized by the host so an immune response can occur. This varies between species and is what is used to identify a pathogenic bacteria. The sugars on the surface is what is recognized by the host so an immune response can occur
75
What are inclusion bodies in bacterial cells
There are inclusion bodies in bacterial cells where certain proteins or metabolic activities are concentrated
76
What are the carbon storage polymers in bacteria
PHB: A type of lipid that bacteria can store Glycogen: A glucose polymer storage
77
What are polyphosphates
Accumulations of inorganic phosphates in the bacterial cell
78
What are sulfur globules
Composed of elemental sulfur inside bacterial cell. Found in the periplasm of Gram - bacteria
79
What are magnetosomes
Magnetic storage inclusions. If a bacteria has a magnetosome, it can align with a magnetic field and tell up from down, the effect of gravity is so small on a cell that it can't really tell up from down so it requires a magnetsome
80
What are vegetative cells
Cells that are in the normal state of growing and dividing
81
What happens to vegetative cells if the conditions are unfavorable
It will trigger a genetic program of differentation and then a spore will begin to form inside of the "mother" cell (sporulating) and the spore will be released from the sporulating cell.
82
What causes the spore to germinate
When the conditions have become favorable again, the spore will germinate and germination will then give rise to a vegetative cell that will take up nutrients and grow and divide
83
Describe the inside of an endospore
The inside of endospores contain small acid-soluble proteins (SASPs) that protect the DNA genome from radiation, dessication etc
84
Describe the outside of an endospore
There is a multi-layer coat that protects the spore. Cortex, Core Wall, Spore Coat, and Exosporium
85
Describe the life cycle of endospores
Under unfavorable conditions a genetic program is triggered and results in an assymetric division, the small part of that dividing cell starts to become the spore (pre-spore) and is engulfed by the mother cell membrane. The mother cell lays down these extra layers for the endospore and the mother cell will lyse to release the spore into the environemnt
86
Describe how the flagella is attached to the cell
The flagella is anchored to the cell, it anchors to the membrane and the peptidoglycan.
87
What is the basal body
There are 4 rings that make up the basal body, are in the cell wall, and these rings are what causes movement for the flagella driven by the proton motive force.
88
How does the flagella move with the proton motor force
It is what causes movement for the flagella. The bacteria will act like the inner mitochondrial membrane, in that they pump H+ ions across the membrane, the outside of the cell has a high concentration of + charge and the inside of the cell hsa a high concentration of - charge. As the proton goes down their concentration gradient (from the outside to the inside) they move through the Mot protein which will use the energy from the protons to turn the rings that will cause the flagella to move.
89
What are the 3 types of bacterial motility
Twitching, Gliding, and Swimming
90
Why can bacteria only respond to temporal changes
Bacteria can't respond to a spatial gradient because they are so small that from one side of the cell to the other side they cant tell the difference of concentration when they are inside the gradient. Attractants and repellents are sensed by the cell to determine about how much attractant is present. The bacteria have a timing mechanism while they are moving around to re-measure the chemical in a temporal way of responding to the gradient. They have integral membrane proteins that have a receptor on one side where a chemical can bind and cause a change in shape of the protein so it effects the inside of the cell
91
In peptidoglycan what do the peptide bonds bond
They bond the cross links together between the layers of NAM and NAG
92
In peptidoglycan what do the glycosidic bonds bond
They bond the the NAM and NAG together in each layer
93
What are the 4 rings that are in the basal body of the flagella, list them from outside to inside
L ring, P ring, MS ring, and C ring
94
What is the L ring associated with
The LPS layer of the Gram - outer membrane
95
What is the P ring associated with
The peptidoglycan layer
96
What is the MS ring associated with
The outer half of the inner membrane. The gycophosphate backbone
97
What is the C ring associated with
The inner half of the inner membrane. The glycophosphate backbone
98
Where are the Mot proteins anchored
In the inner membrane of the cell

BIMM 120 (17 decks)

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