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Microbiology > 9.Pili, Inclusions, Ribosomes and Genetic material > Flashcards

9.Pili, Inclusions, Ribosomes and Genetic material Flashcards

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Biology 101 flashcards
1
Q

What are fimbriae and pili

A

Proteic filaments protruding from the outer membrane of Gram - bacteria. Short, thin and slender and are present in more then one per cell

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2
Q

What’s the function of fimbriae and pili

A

Adhesion to other bacteria, other organisms or surfaces

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3
Q

Why is adhesion of fimbriae and pili molecule-specific

A

Because of specific adhesion proteins

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4
Q

What is the shape of fimbriae and what are they made of

A

They are short, slender tubes with helical shape
They are made of polymers of protein known as pilin

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5
Q

Where are adhesion proteins located in fimbriae

A

At the end for mediating cell adhesion

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6
Q

What are fimbriae used for

A

Forming multicellular structures like pellicle( on liquid) or biofilm(on solid)

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7
Q

What are pili similar to

A

To fimbria and are usually referred as ‘‘longer’’ filaments

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8
Q

What are pili and what are they made out of

A

Proteic filaments made of pilins

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9
Q

What functions can pili have

A

DIfferent pili can have different function in the cell(ex: adhesion to surfaces, cell aggregation, DNA transfer)

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10
Q

Are Archaeal pili similar to bacterial pili

A

Yes, but with differences in protein composition and some structural specificities

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11
Q

What’s twitching motility caused by?

A

type IV pili, elongating and retracting and therefore ‘dragging’ the cell

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12
Q

What are type IV pili made out of

A

Proteic units(pilins), polymerized at the base of the structure, in the plasma membrane

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13
Q

Are type IV pili both in Gram + and Gram- bacteria

A

Yes

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14
Q

What are specialized pili used for in Gram - bacteria

A

Specialized pili(sex pili) are used by Gram - bacteria for mating with other bacteria and transferring DNA

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15
Q

Where are sex pili created

A

In bacteria carrying conjugate plasmids(ex: F plasmid)

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16
Q

who can target specialized (sex) pili

A

Phages

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17
Q

What’s cytoplasm and what does it contain

A

Cytoplasm-part of the cell inside the plasm membrane. It consists of: cytosol, cytoskeleton, inclusion bodies, gas vesicles, nucleoid, plasmids, ribosomes

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18
Q

What’s cytoplasm made out of

A

Aqueous solution of several molecules and some organized structures. It’s extremely viscous

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19
Q

Is cytoplasm similar in both archaea and bacteria?

A

Yes

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20
Q

Are there cytoskeletal proteins in bacteria

A

Yes

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21
Q

What’s the function of cytoskeletal proteins in bacteria

A

-participate in cell division
- determine cell shape
-grant localization to proteins or other molecules

22
Q

What’s exception to the rule that bacteria don’t have complexes with bi-layer membranes

A

Photosynthetic and nitrifying bacteria have groups of vesicles or tubular membranes in the cytoplasm, sometimes connected to the cell membrane
These vesicles contain large amount of proteins involved in energy production or conservation

23
Q

Who has chlorosomes

A

Photosynthetic green bacteria

24
Q

What do chlorosomes contain

A

Photosynthetic pigments, bacteriochlorophylls C,D,E

25
Q

Where are chlorosomes located in the cell

A

They are closely associated with cytoplasmic membrane (inner face) by a basal plate and allow green bacteria to be distinguished from other photosynthetic bacteria

26
Q

What are inclusion bodies

A

Inclusion bodies- aggregates of organic or inorganic substances in the cytoplasm

27
Q

What kind of structure can inclusion bodies have

A

Crystal or amorphous

28
Q

Where can inclusion bodies be located inside a cell

A

-floating free in the cytosol
-encapsulated in a proteic shell
-enclosed in a single-layer phospholipidic membrane

29
Q

What functions can inclusion bodies have

A

Several, including nutrients storage and osmotic pressure control

30
Q

What are examples of storage inclusions

A

-Glycogen granules(storage of glucose)
-Sulphur globules
-Poly-phosphate granules
-PHB granules

31
Q

What are PHB granules

A

Poly- β-hydroxybutyrate, part of more general group of poly-hydroxyalkonate granules, storage of organic carbon. They have proteic single-layer shell

32
Q

What are some other types of inclusion bodies

A

-Carboxaysomes- storage of CO2 and enzymes for sugar synthesis, allow CO2 fixation in cyanobacteria and other specialized bacteria
-Magnetosomes- aggregates of magnetite or greigite arranged in linear chain. They provide specialized bacteria(magnetotactic bacteria) orientation with Earth’s magnetic field. They can recognize north, south and down-direction, useful to determine depth of aquatic environment

33
Q

What are gas vesicles used for

A

They appear in bacteria that live in liquid environment and that need floating capabilities

34
Q

What are characteristics of gas vesicles

A

They are made of proteins only, have tubular shape and are permeable to gas only. They are usually arranged in groups, forming large structures of ‘Gas Vacuoles’

35
Q

What is gas vesicles’ dimension and contribution to floating determined by

A

Extracellular pressure

36
Q

What are ribosomes

A

Specialized sites for protein synthesis (translation)

37
Q

Where can ribosomes be located inside the cell

A

In the cytoplasm or attached to plasma membrane (for synthesis of envelope associated proteins)

38
Q

What are ribosomes made out of

A

Proteins and ribosomal(r)RNA

39
Q

How many structural units does bacterial ribosome have and how can it be divided

A

70S
It has two subunits:
1. large 50S
2. small 30S

40
Q

What do large and small subunits of bacterial ribosome contain

A

large-23S and 5S rRNA
small-16 S rRNA

41
Q

Do bacterial subunits contain proteins

A

Yes, a lot (>50), many common to eukaryotes

42
Q

How many structural units does archaeal ribosome have and how is it devided

A

70S
large 50S
small 30S

43
Q

What to large and small subunit or archaeal ribosome contain

A

large: 23S and 5S rRNA; some Archaea have 5.8 S rRNA(like eukaryotes)
small: 16S rRNA

44
Q

Do archaeal ribosomes have proteins that are common with bacteria only

A

no

45
Q

What are 3 main groups that ribosomal proteins can be divided into?

A
  1. Universally conserved r-proteins that with the rRNA form common core;
    2) Domain specific r-proteins (ex: bacteria-specific and eukaryote-specific; no archaea specific has been recognized)
    3) R-proteins exclusively shared between archaea and eukaryotes ( also called archaea/ eukaryote-specific, A/E- specific)
46
Q

Are r-proteins evenly distributed in the ribosome

A

No. Most of them are located on the solvent side of the subunits, leaving the subunit interface side to be dominated by rRNA

47
Q

What function do r-proteins have

A

In ribosome biogenesis and ensuring optimal functioning of the ribosome. They have a role in stabilizing intrasubunit network, in forming the subunit contacts during protein synthesis and are docking sites for translation factors and other ribosome associated proteins during translation

48
Q

What’s difference between prokaryotic mRNA and eukaryotic mRNA

A

Prokaryotic has several translation start sites while eukaryotic has single translation start site

49
Q

What shape is chromosome in bacteria

A

It has 1-2 copies/cell, usually circular and rarely linear
It’s essential

50
Q

Line up the 3 kingdoms from the largest to the smallest size of genome

A

Eukarya
Bacteria
Archaea

Microbiology (20 decks)

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