9.Pili, Inclusions, Ribosomes and Genetic material

Question 1

What are fimbriae and pili

Answer 1

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

Question 2

What’s the function of fimbriae and pili

Answer 2

Adhesion to other bacteria, other organisms or surfaces

Question 3

Why is adhesion of fimbriae and pili molecule-specific

Answer 3

Because of specific adhesion proteins

Question 4

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

Answer 4

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

Question 5

Where are adhesion proteins located in fimbriae

Answer 5

At the end for mediating cell adhesion

Question 6

What are fimbriae used for

Answer 6

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

Question 7

What are pili similar to

Answer 7

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

Question 8

What are pili and what are they made out of

Answer 8

Proteic filaments made of pilins

Question 9

What functions can pili have

Answer 9

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

Question 10

Are Archaeal pili similar to bacterial pili

Answer 10

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

Question 11

What’s twitching motility caused by?

Answer 11

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

Question 12

What are type IV pili made out of

Answer 12

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

Question 13

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

Answer 13

Yes

Question 14

What are specialized pili used for in Gram - bacteria

Answer 14

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

Question 15

Where are sex pili created

Answer 15

In bacteria carrying conjugate plasmids(ex: F plasmid)

Question 16

who can target specialized (sex) pili

Answer 16

Phages

Question 17

What’s cytoplasm and what does it contain

Answer 17

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

Question 18

What’s cytoplasm made out of

Answer 18

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

Question 19

Is cytoplasm similar in both archaea and bacteria?

Answer 19

Yes

Question 20

Are there cytoskeletal proteins in bacteria

Answer 20

Yes

Question 21

What’s the function of cytoskeletal proteins in bacteria

Answer 21

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

Question 22

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

Answer 22

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

Question 23

Who has chlorosomes

Answer 23

Photosynthetic green bacteria

Question 24

What do chlorosomes contain

Answer 24

Photosynthetic pigments, bacteriochlorophylls C,D,E

Question 25

Where are chlorosomes located in the cell

Answer 25

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

Question 26

What are inclusion bodies

Answer 26

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

Question 27

What kind of structure can inclusion bodies have

Answer 27

Crystal or amorphous

Question 28

Where can inclusion bodies be located inside a cell

Answer 28

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

Question 29

What functions can inclusion bodies have

Answer 29

Several, including nutrients storage and osmotic pressure control

Question 30

What are examples of storage inclusions

Answer 30

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

Question 31

What are PHB granules

Answer 31

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

Question 32

What are some other types of inclusion bodies

Answer 32

-*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

Question 33

What are gas vesicles used for

Answer 33

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

Question 34

What are characteristics of gas vesicles

Answer 34

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'

Question 35

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

Answer 35

Extracellular pressure

Question 36

What are ribosomes

Answer 36

Specialized sites for protein synthesis (translation)

Question 37

Where can ribosomes be located inside the cell

Answer 37

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

Question 38

What are ribosomes made out of

Answer 38

Proteins and ribosomal(r)RNA

Question 39

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

Answer 39

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

Question 40

What do large and small subunits of bacterial ribosome contain

Answer 40

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

Question 41

Do bacterial subunits contain proteins

Answer 41

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

Question 42

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

Answer 42

70S large 50S small 30S

Question 43

What to large and small subunit or archaeal ribosome contain

Answer 43

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

Question 44

Do archaeal ribosomes have proteins that are common with bacteria only

Answer 44

no

Question 45

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

Answer 45

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)

Question 46

Are r-proteins evenly distributed in the ribosome

Answer 46

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

Question 47

What function do r-proteins have

Answer 47

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

Question 48

What's difference between prokaryotic mRNA and eukaryotic mRNA

Answer 48

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

Question 49

What shape is chromosome in bacteria

Answer 49

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

Question 50

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

Answer 50

Eukarya Bacteria Archaea