CH. 3 Prokaryote Cell Structure & Function Flashcards

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1
Q

What are the basic chemical composition of a bacterial cell and the proportions of chemicals? What are the features all prokaryotic cells possess? Which are variable characteristics?

A

Water - 70%
Proteins - 16%
RNA - 6.7%
Cell Envelope - 5% (peptidoglycan, membrane phospholipids, etc.)
DNA - 1%

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2
Q

What is the role of hopanoids in prokaryotic cell membranes?

A

Stabilizes membranes by controlling fluidity and permeability and strengthen the bacterial cell envelope

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3
Q

What is group translocation and ABC transporters? What form of transport is this?

A

ABC transporters transport amino acid and carbohydrate transport; expends ATPs to transport

Group translocation: modification of substrate during transport; the source substrate is continually moving down its gradient

They are both ACTIVE transport

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4
Q

What are active transport, passive transport, and osmosis?

A

Active Transport: requires energy to move molecules against their gradient concentration

Passive Transport/Diffusion: simple/facilitated; molecules move based on their concentration (high to low)

Osmosis: diffusion of water; water molecules move towards area of high SOLUTE concentration (bacteria maintain a hypertonic cell interior; water diffuses in)

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5
Q

How do the membrane lipids of Archaea differ from typical prokaryotes?

A

Archaea
- hydrocarbon chains are terpenoids (from isoprene)
- ether link (C-O-C) hydrocarbons to glycerol

Typical Prokaryotes
- phospholipid head group
- saturation/unsaturation of fatty acids
- cyclization of fatty acids

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6
Q

How does the cell envelope structure of Mycobacteria species differ from that of Gram‐negative and Gram‐positive bacteria?

A

Mycobacteria contains mycolic acids in addition to the peptidoglycan layers

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7
Q

Describe the structure of a prokaryotic cell wall (what is its chemical composition?)

A

Made of peptidoglycan (murein) -> a polymer of disaccharides, glycan, cross-linked with peptide tetramers

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8
Q

Compare and contrast the differences/similarities in the cell envelopes of Gram‐negative and Gram‐positive bacteria.

A

Gram-Positive:
- thick cell wall (multiple peptidoglycan layers and teichoic acids)
- s-layer (made of glycoprotein and is in-between the peptidoglycan and glycosyl)

Gram-Negative:
- thin cell wall (1-2 peptidoglycan layers) and is bridged to the outer membrane via murein lipoprotein
- lipoproteins connected with peptidoglycan and outer membrane
- lipopolysaccharide layer (LPS)

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9
Q

What is the nucleoid? How is DNA organized in here? How would you describe a bacterial chromosome?

A

A single, circular, double-stranded DNA; organized in loops (bacterial chromosome)

DNA is organized by supercoiling (DNA gyrase)

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10
Q

What does polysome or polyribosome formation refer to? What are the components required for this process?

A

It refers to transcription and translation

Some components required are DNA, RNA, proteins, and ribosomes

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11
Q

What is a replisome?

A

A protein complex that is responsible for carrying out DNA replication at the ori site

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12
Q

How is a bacterial chromosome copied? Describe the basic steps of the DNA replication process, starting with where replication is initiated.

A

DNA replication begins at the ori site where 2 replication forks and replisomes forms

Bidirectional replication continues where the replisomes synthe4size the DNA at each fork

Z-ring forms by FtsZ -> septation and cell division

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13
Q

What is septation?

A

The partition (a septum) that splits the envelope into two daughter cells

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14
Q

What element comprises the bacterial cytoskeleton? How does these function in bacteria? How is the cytoskeleton involved in cell division & septation?

A

FtsZ Protein - determines the cell diameter and forms a “z-ring” for cell division

MreB Protein - guides cell wall synthesis

CreS Protein (crescentin) - curves the inner side of crescent-shaped bacteria

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15
Q

To what does “polar aging” refer? How would you describe this? Of what significance is it?

A

Refers to two cell poles that differ in their origin and age which signifies that cells of different polar ages may differ in resistance to antibiotics

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16
Q

What are specialized structures of phototrophic bacteria? What are their functions?

A

Thylakoids: inner cell membrane foldings packed with photosynthetic components

Carboxysomes: protein-covered bodies containing Rubisco (also chemoautotrophs)

Gas Vacuoles: to maintain proper depth

17
Q

What are intracellular inclusions? List and describe the different types found in bacteria. Which are energy storage types?

A

Metachromatic granules: inorganic phosphate

Polysaccharide granules: glycogen, starch

Sulfur granules: oxidation of H2S (insoluble granules)

Lipid inclusions: PHB

18
Q

What are the functions of pili/fimbriae?

A

Involved with bacterial conjugation and attachment to the surface and motility

Ex. biofilm formation

19
Q

What is a sex pilus?

A

Where the male bacterium connects with the female bacterium for conjugation (transfer DNA)

20
Q

What is twitching motility?

A

A type of bacterial movement where the pilus extends and retracts

21
Q

What are nanotubules and what is their function?

A

They are cell envelope extensions that connect the cytoplasm between different cells

Function is to share proteins, mRNA between members of same/different species

22
Q

How does bacterial motion occur via a flagellum (or flagella)?

A

Rotary motion (clockwise rotations = “tumbles”)

23
Q

What is chemotaxis?

A

The ability of organisms to move toward or away from specific chemicals

24
Q

How does a slime layer differ from a capsule? What does a capsule provide?

A

Capsules are more organized and tightly associated compared to slime layer

Capsules provide bacterial adhesion to surfaces

25
Q

What is endotoxin?

A

They are lipopolysaccharides (LPS) where they are released when bacteria die