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BI1004 - the dynamic cell > Prokaryote cell structure > Flashcards

Prokaryote cell structure Flashcards

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1
Q

How are prokaryotes useful for food?

A

Food preservation (heat, cold, radiation, chemicals), fermented foods.

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2
Q

How are prokaryotes useful in agriculture?

A

N2 fixation (N2–2NH3), legumes (bacteria from root nodules), rhizobium.

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3
Q

What is the nutrient cycling in agriculture?

A

NH3 — N2 — NO3-

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4
Q

How are prokaryotes used in animal husbandry?

A

Rumen — cellulose or animal protein using CO2 + CH4.

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5
Q

How can prokaryotes be useful in humans?

A

Gut microbiota.

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6
Q

How can prokaryotes be important in energy and environment?

A

Mathanogenic bacteria.

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7
Q

How are prokaryotes useful in biotechnology?

A

Genetically modified organisms, production of pharmaceuticals and therapeutic chemicals, gene therapy for certain diseases.

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8
Q

What are the three main categories to the phylogenetic tree of life?

A

Domain bacteria, domain archaea, domain eukarya.

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9
Q

What is the basic bacteria cell structure?

A

Nucleus, cell wall (murien), capsule, plasmid, cytoplasmic membrane, 70s ribosomes, depot substances, attachment Pili, outer membrane, flagella.

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10
Q

In what type of bacteria is the outer membrane only present?

A

Gram-negative bacteria.

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11
Q

What depot substances are present in bacteria?

A

Metaphosphates and glycogen.

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12
Q

What are the different shapes of bacteria?

A

Micrococci, diplococci, streptococci, staphylococci, sarcina, rod-shaped, spirilla, vibrios.

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13
Q

What is a major limiting factor on single-celled organisms?

A

Surface area : volume ratio.

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14
Q

What are the external structures for bacteria?

A

Flagellum, pilus, nucleoid, plasma membrane, cell wall, capsule, ribosomes.

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15
Q

What are the two fundamental components of the cell membrane?

A

Hydrophilic head (polar) and hydrophobic tail (non-polar).

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16
Q

What do bacterial membranes consist of?

A

Saturated or monosaturated fatty acids and do not normally contain sterols.

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17
Q

How are bacterial membranes fluid and dynamic?

A

Lipids move, flip and can be modified.

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18
Q

What do some bacteria have in regards to cell membrane?

A

Some have double membranes which have implications for recognition and function.

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19
Q

What are the different types of proteins that can be found within the cell membrane?

A

Peripheral membrane protein, transmembrane proteins, integral membrane proteins.

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20
Q

What are the four major differences of archaeal membranes to bacteria?

A

Hydrophobic side chains composed of isoprene, branches hydrocarbon chains, attached to glycerol by ether linkages, glycerol is chiral.

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21
Q

What is the role of the cell membrane?

A

Permeability barrier, protein anchor, energy production and conservation.

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22
Q

How do cell membranes act as a permeability barrier?

A

Aquaporins, selective control of substances across membrane, barrier to influx/efflux of water.

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23
Q

How do cell membranes act as protein anchors?

A

Orientation, concentration, association, recycling, recognition.

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24
Q

What is simple transport?

A

Driven by energy in proton motive force.

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25
What is group translocation?
Chemical modification of transported substance driven by phosphoenolpyruvate.
26
What is the ABC system?
Periplasmic binding proteins are involved and energy comes from ATP.
27
What important role do cell membranes have in orientation?
In production of energy.
28
How is energy produced in prokaryotes?
Movement of protons into cell drives rotation of ATP synthase, catalyses fusion of ADP+Pi into ATP, highly conserved in all organisms.
29
How is energy produced in prokaryotes?
Movement of protons into cell drives rotation of ATP synthase, catalyses fusion of ADP + Pi into ATP, highly conserved in all organisms.
30
What is the structure of ATPase like in all organisms?
All very similar.
31
What is the role of the cell wall and why?
Stops cell from popping, due to turgor pressure caused from high conc of dissolved solutes in bacteria cells.
32
What does the gram stain identify?
Two groups of bacteria - gram positive and gram negative.
33
How do the different groups of bacteria react to the gram stain?
Gram positive bacteria retain the crystal violet stain and so look purple, gram negative bacteria do not retain the stain.
34
What are the key steps of gram staining?
Flood heat fixed smear with crystal violet 1min (all purple), add iodine solution 1min (all purple), decolorise with alcohol 20sec (-ve cells colourless), counter stain with safranin for 1-2min (-ve cells pink/red).
35
What is the cell wall composition of gram positive bacteria?
Peptidoglycan and membrane - thick cell wall outside membrane.
36
What is the cell wall composition of gram negative bacteria?
Outer membrane, periplasm, peptidoglycan, membrane - thin cell wall inside between two membranes with periplasm in middle.
37
What is gram positive cell wall like compared to rest of cell? What does this provide?
Looks quite thin but robust, good target for antibiotics, several target integrity so bacteria explode.
38
What are the cell walls and other membranes of the gram negative bacteria like?
Cell wall capable of supporting cell, outer membrane has complex structure.
39
What is peptidoglycan composed of?
Repeating units of two sugar derivatives N-acetylglucosamine and N-acetylmuramic acid and small number special amino acids.
40
Where has peptidoglycan only found?
In cell walls of specie of bacteria - never found in cell walls of archaea or eukarya.
41
How is peptidoglycan used in E.coli?
Sheets of peptidoglycan can surround cell, formed from individual strands lying adjacent to one another.
42
What can glycosidic bonds connecting sugars not provide?
Rigidity in all directions.
43
What are chains of peptidoglycan cross linked by?
Amino acids by way of a peptide inter bridge.
44
What does cross linkage only occur of?
Amino group of diaminopimelic acid (DAP) to the carboxyl group of the terminal D-alanine.
45
What % of cell wall is peptidoglycan in gram -ve bacteria?
>10%.
46
What % of gram +ve cell wall is peptidoglycan and what else is present?
>90% - also teichoic acid present in small amounts.
47
What varies for amino acids between species?
Kinds and number.
48
What is an unusual feature in gram bacteria to do with amino acids?
Presence of two amino acids that have the D configuration = D-alanine and D-glutamic acid.
49
What form are the usual cellular proteins?
L-enantiomeric form.
50
Other than peptidoglycan and cytoplasmic membrane, what are extra components of gram positive cell wall that are embedded in?
Wall-associated protein, teichoic acid, lipoteichoic acid.
51
What are teichioc acids in gram +ve cell walls?
-ve charged acids partially responsible for -ve charge of cell surface, can bind to Ca2+ and Mg2+.
52
What is the lipopolysaccharide layer (LPS)?
The outer membrane of gram negative cell wall termed this for containing lipopolysaccharide complexes formed from linkage of lipid and polysaccharides.
53
What are the two components of the structure of lipopolysaccharide for gram -ve bacteria?
Core polysaccharide and the O-polysaccharide.
54
What is the lipid portion of the lipopolysaccharide called?
Lipid A.
55
What is KDO?
Ketodeoxyoctonate.
56
What does Lipid A contain?
Caproic, lauric, myristic, palamitic, steric acids.
57
In what way is the archaeal cell wall highly variable?
Polysaccharide similar to peptidoglycan called pseudopeptidoglycan, beta1-3 glycosidic linkages not 1-4, alternating repeats of NAG and NAT.
58
What do the wide range of different wall types for archaeal cells depend on?
Habitat and environmental stresses, structure depends on environmental stress being addressed.
59
What are secretory secretion systems?
Complicated multi-protein structures that are embedded in membrane and act as either movement, recognition or secretory structures.
60
What is the role of flagella, fimbriae and pili?
Used for movement and attachment.
61
What is a pilus used for?
To transfer genetic information in form of a plasmid between two bacterial cells.
62
What are the three types of positions of flagella and what is their significance?
Peritrichous, polar, lophotrichous - positioning determines how bacteria moves, how fast and how much energy required.
63
What are characteristics of flagella?
Helical shaped, when flattened show constant distance between adjacent curves called wavelength, characteristics for any given species.
64
How is the whip like movement of flagella produced?
Series of rings embed base in membrane, fli proteins cause rotation, body spins from base rotating.
65
What does Mot protein do?
Uses electrostatic charge changes to drive rotation of ring structures.
66
What is the most common cell wall type among archaea?
Paracrystalline surface layer (S-layer) - consists of protein or glycoprotein, has hexagonal symmetry.
67
What are capsules and slime layers, where are they found?
Gel-like capsule around the cell, form tight matrix over cell, usually several times larger than cell, constantly replenished as cell grows, polysaccharides and proteins.
68
What are capsules and slime layers used for?
Attachment to surfaces and biofilms, preventing desiccation.
69
What are cell inclusions?
Energy reserves or storage of structural substances, enclosed by a thin lipid membrane, may contain storage carbs, phosphates and sulfur.
70
What do some species contain to allow cells to show magnetotaxis?
Magnetosomes.
71
What are gas vesicles?
Found in bacteria, cyanobacteria and archaea, may act as buoyancy aides, may be spherical or spindle shaped.
72
What is the bacterial cytoskeleton, where is it found?
Recently found in rod-like bacterial cells, similar protein to actin in human micro filaments.
73
How does DNA exist for bacterial chromosomes?
As a clumped nucleoid associated with protein core.
74
What is the bacterial genome and genes like?
Genome circular and densely packed with genes, genes tend to be located in clusters of genes involved in same process, regulated together.
75
How is the bacterial genome stored in bacteria?
Looped and packed together into the nucleosome but not surrounded by nucleus.
76
What is the composition of escherichia coli bacterial chromosomes?
4.68 mil base pairs of DNA, 4300 genes, 1900 different kinds of proteins, 2.4mil total protein molecules.
77
How much more DNA and genes do human cells have compared to bacterial?
1000 times as much DNA, about 5x as many genes.
78
What are plasmids?
Small circular piece of DNA, not chromosome, contains antibiotic resistance and metabolic genes, helps evolution and overcoming environmental problems.
79
How do plasmids exist and replicate?
Separately from main genome.
80
What are plasmids varying size?
1 kb to more than 1Mb.
81
What types of plasmids do some bacteria contain and what do some encode?
Many different types, encode toxins and other virulence characteristics.
82
How can plasmids be used for engineering in biotechnology?
Replicate when cell replicates, can clone a DNA sequence into plasmid, culture of bacteria will amplify gene.

BI1004 - the dynamic cell (11 decks)

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