Prokaryotic Cell Structure Part II

Question 1

Some structures extend beyond the cell envelope in bacteria and archaea. Name 3. What are 4 functions of these?

Answer 1

Fimbriae, Pili, Flagella

protection, attachment to surfaces, horizontal gene transfer, cell movement

Question 2

what is a flagella?

what are its functions?

Answer 2

Threadlike, locomotor appendages extending outward from plasma membrane and cell wall
Functions:motility and swarming behavior
attachment to surfaces
may be virulence factors

Question 3

what are the 5 patterns of flagella distribution

Answer 3

Monotrichous – one flagellum
Polar flagellum – flagellum at end of cell
Amphitrichous – one flagellum at each end of cell
Lophotrichous – cluster of flagella at one or both ends
Peritrichous – spread over entire surface of cell

Question 4

what is taxis?

Answer 4

directed cell movement in response to some stimulus

Question 5

what is chemotaxis?

Answer 5

movement towards a chemical attractant or away from a chemical repellent

Question 6

describe prokaryotic cytoplasm

Answer 6

Cytoplasm - material bounded by the plasmid membrane
Cytoplasm - ~ 90 – 94 % water; dissolved solutes (ions, sugars, amino acids, etc); somewhat viscous; cytoskeleton ? (+/-); cyclosis ?; contains many enzymes and ribosomes

Question 7

describe prokaryote cytoskeleton

Answer 7

Network of fibrous proteins within cytoplasm
Homologs of all 3 eukaryotic cytoskeletal elements have been identified in bacteria and 2 in archaea
Functions are similar as in eukaryotes
Role in cell division, protein localization, and determination of cell shape

Question 8

what are the two types of intracytoplasmic membrane? describe

Answer 8

1) Cell membrane infoldings
observed in many photosynthetic bacteria
analogous to thylakoids of chloroplasts
reactions centers for ATP formation
observed in many bacteria with high respiratory activity
2) Anammoxosome in Planctomycetes
organelle – site of anaerobic ammonia oxidation

Question 9

what are inclusions?

Answer 9

membrane bound storage structures containing granules of organic or inorganic material that are stockpiled by the cell for future use

Question 10

what are the functions of having inclusions?

Answer 10

Storage of nutrients, metabolic end products, energy, building blocks
Glycogen storage
Carbon storage 	
poly-β-hydroxybutyrate (PHB) 
Phosphate - Polyphosphate (Volutin)
Amino acids - cyanophycin granules

Question 11

slide 33

Answer 11

RIBOSOMES

Question 12

what are plasmids?
what do they do?
what do they contain?

Answer 12

1.) Extrachromosomal DNA
-found in bacteria, archaea, some fungi
-usually small, closed circular DNA molecules
2.) Exist and replicate independently of chromosome
-episomes – may integrate into chromosome
3.) Contain few genes that are non-essential
confer selective advantage to host (e.g., drug resistance)

**LOOK AT SLIDE 37 and 38

Question 13

what is a Bacterial Endospore?

what is its function?

Answer 13

-Complex, dormant structure formed by some bacteria in various locations within the cell
-Function is to survive extreme environments for the organism
Resistant to numerous environmental conditions
heat
radiation
chemicals
desiccation

Question 14

describe the endospore structure (4)

Answer 14

• Spore surrounded by thin covering called exosporium
• Thick layers of protein form the spore coat
• Cortex, beneath the coat, thick peptidoglycan
• Core has nucleoid and ribosomes

Question 15

what makes an endospore so resistant? (4)

Answer 15

Calcium (complexed with dipicolinic acid)
Small, acid-soluble, DNA-binding proteins (SASPs)
Dehydrated core
Spore coat and exosporium protect