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BIO900 Cellbiologi > Prokaryotic Cell Structure > Flashcards

Prokaryotic Cell Structure Flashcards

1
Q

Q: The shape of a bacteria may determine its …

A

A: Nutrient uptake, motility, reproduction & interaction with hosts or surfaces.

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2
Q

Q: The size of a bacteria may determine its …

A

A: Nutrient uptake, growth rate, survival/defense & metabolic efficiency

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3
Q

Q: What are the advantages of larger bacteria?

A

A: Greater capacity for nutrient storage, resistance to phagocytosis, contain more genetic material, may compartmentalize functions resulting in more efficient metabolism, better resilience in harsh environments.

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4
Q

Q: What are the disadvantages of larger bacteria?

A

A: Slower nutrient uptake, slower growth, slower reproduction, higher energy requirements, difficulty in diffusion-based processes.

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5
Q

Q: What are the advantages of smaller bacteria?

A

A: Efficient nutrient uptake, rapid growth and reproduction, lower energy requirements, quick adaptation to novel environments, greater mobility, harder to detect by “predators”

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6
Q

Q: What are the disadvantages of smaller bacteria

A

A: Limited nutrient storage, lacking structural complexity, vulnerability to environmental stress, lower antibiotic resistance, easy target in phagocytosis

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7
Q

Q: What are the characteristics of a membrane in the gel phase?

A

A: Low chain disorder, crystal packing, thick bilayer

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8
Q

Q: What are the characteristics of a membrane in the fluid phase?

A

A: High chain disorder, irregular packing, thin bilayer.

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9
Q

Q: What three types of glycerolipids commonly make up the bacterial membrane?

A

A: PG (glycerophosphatidylglycerol), PE (glycerophosphatidylethanolamine) , CL (cardiolipins)

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10
Q

Q: Which three types of lipids can form bacterial membranes, and which of these is most common?

A

A: Saccharolipids, Glycerophospholipids & Glycerolipids. Of these, glycerolipids are the most common.

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11
Q

Q: What is the function of hopanoids (bacterial steroids)?

A

A: Regulate membrane rigidity & mark microdomain boundaries

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12
Q

Q: Why do bacteria benefit from lipid diversity?

A

A: Lipid diversity aids in membrane fluidity & stability, regulating permeability, biofilm formation & resistance to toxins

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13
Q

Q: What is the structure of peptidoglycan in Gram (-) bacteria?

A

A: Single layer with a hexagonal structure & direct cross- links. Fewer connections than in Gram (+).

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14
Q

Q: What is the structure of peptidoglycan in Gram (+) bacteria?

A

A: Multiple layers with dense peptide cross-linking.

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15
Q

Q: Why do bacteria need cell walls?

A

A: Bacteria have a high internal solute concentration that creates osmotic pressure, which would cause the bacteria to burst in the absence of a cell wall.

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16
Q

Q: What is the Gram (-) outer membrane composed of?

A

A: The gram (-) bacterial membrane is an asymmetric bilayer composed of an outer and inner leaflet. The outer leaflet is composed of lipopolysaccharides (LPS). The inner leaflet is composed of phospholipids (PE/PG/CL).

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17
Q

Q: What is the main difference between the inner and outer layer of the Gram (-) bacterial membranes?

A

A: The presence of lipopolysaccharides in the outer leaflet.

18
Q

Q: What are the components of a lipopolysaccharide?

A

A: Lipid A, core polysaccharides, O-specific polysaccharides (O-antigens)

19
Q

Q: What is Lipid A?

A

A: A saccharolipid anchored in the outer membrane

20
Q

Q: What is a core polysaccharide?

A

A: A polysaccharide with 10-20 sugar subunits and sometimes a phosphate side group. Connects Lipid-A to O-antigen (O-specific polysaccharide)

21
Q

Q: What is an O-antigen (O-specific polysaccharide)

A

A: Chain of repeating sugars which influence membrane permeability & immune system recognition.

22
Q

Q: Outer membrane proteins are formed by …

A

A: β-sheets

23
Q

Q: Inner membrane proteins are formed by …

A

A: α-helixes

24
Q

Q: What are the four main types of outer membrane proteins (OMPs)?

A

A: Outer membrane protein F (OmpF), unspecific porins, substrate specific porins, TonB dependent transporters

25
Q

Q: What is the function of Outer membrane protein F (OmpF)?

A

A: OmpF acts as a molecular sieve, allowing smaller molecules to pass through the outer membrane while blocking larger ones.

26
Q

Q: What is the function of unspecific porins?

A

A: Unspecific porins allow for passive diffusions without binding any specific substrate

27
Q

Q: What is the function of substrate specific porins?

A

A: Substrate specific porins facilitate the passage of specific molecules through the outer membrane by binding to these

28
Q

Q: What is the function of TonB dependent transporters?

A

A: TonB dependent transporters are “mechano-activated” transporters that rely on the TonB system to actively transport complex molecules like iron or vitamin B12, by using energy from the inner membrane.

29
Q

Q: Does active transport occur in the outer membrane layer?

A

A: No, never.

30
Q

Q: What is the ratio of proteins to lipopolysaccharides in the outer membrane layer?

A

A: ~ 1 : 1

31
Q

Q: What is the periplasm?

A

A: The aqueous space between the inner and outer membrane in Gram (-) bacteria

32
Q

Q: What are S-layers and where are they located?

A

A: S-layers are crystalline layers that form a protective lattice around some bacterial and archaeal cells. They also act as a molecular sieve and provide support for the cell. In Gram (+) bacteria S-layers are found outside the thick peptidoglycan layer. In Gram (-) bacteria S-layers are found outside the outer membrane layer.

33
Q

Q: What are capsule slime layers and where are they located?

A

A: Capsule slime layers are layers composed of sugars and sometimes proteins. They surround some bacterial cells and prevent dehydration and are important for biofilm formation.

34
Q

Q: What subunits are bacterial ribosomes divided into?

A

A: Bacterial ribosomes are 70S ribosomes, divided into a 50S larger subunit and a 30S smaller subunit.

35
Q

Q: What are the two types of DNA in bacteria?

A

A: DNA in the bacterial chromosome & plasmid DNA.

36
Q

Q: What are the functions and traits of plasmid DNA?

A

A: Plasmid DNA is DNA in small, circular form that is replicated independently from the rest of the genome. Plasmid DNA typically confers a selective advantage such as antibiotic resistance and can easily be transferred between bacteria.

37
Q

Q: What are inclusions in bacterial cells?

A

A: Any non-native materials clustered up inside the cell such as PHAs or PHB which serve as carbon- and energy storage or gas vesicles which increase buoyancy in certain bacteria.

38
Q

Q: What is the function of flagella in bacteria?

A

A: Flagella enable movement for bacteria in aqueous environments

39
Q

Q: How do flagella enable a bacteria to change direction?

A

A: Through flagellar rotation which happens through an alteration in conformation of the C-ring

40
Q

Q: What is the function of pimbriae (sometimes called pili) in bacteria

A

A: Pimbraes primary function is attaching the bacterial cell to other surfaces. They have specific adhesion proteins in their tips which aid in this.

41
Q

Q: What is the function of conjugation pili?

A

A: Transfering genetic information, mostly plasmid DNA, between bacterial cells.

BIO900 Cellbiologi (15 decks)

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