Topic 2: Bacteria

Question 1

What determines the morphology of bacteria?

Answer 1

1) Nutrient uptake efficiency: surface to volume ratio
2) Movement: spirals allow for proffiecient movement in viscous or turbulent fluids
3) Gliding motility (filaments): cyanobacteria: rod shaped, all move into one formation

Question 2

Morphology types

Answer 2

Circle: COCCUs
Rod: Bacillus
Comma Shaped: Vibrio
Spiral: Spirillium
Pleiomorphic: varied shapes, could have rods, spheres,

Question 3

Multicellular Morphology Organizations

Answer 3

1) Hyphae : branching filaments of cells
2) Mycelia ( tufts of hyphae)
3) Trichomes: Smooth unbranched chain of cells (kinda like worms)

Question 4

Prokaryote size

Answer 4

0.2 um to >700 um
: rod shaped are 0.5um to 4 um wide
1-15 um long

Question 5

Eukaryote size

Answer 5

10->200 um

Question 6

Why is there a minimum size

Answer 6

Need to fit genome, proteins and ribosomes in there

Question 7

What are the advantages of being small

Answer 7

Higher surface to volume ratio: greater rate of nutrient/waste exchange per unit volume
-supports faster growth and metabolic rate
smaller radius better than bigger radius!
-longer better than shorter!

Question 8

Where are very small cells common?

Answer 8

In marine environments because low nutrient levels in ocean so need better nutrient absorbance

Question 9

Nucleoid

Answer 9

where dna is in bacteria
-largest region
-no membrane around nucleoid region, chromosomes and dna replication machinery are just there

Question 10

How is DNA compressed

Answer 10

1) Use of Cations (Mg+, K+): shield negative charges on sugar-phosphate (PO4-) backbone
2) Small Positive Proteins: bind to chromosome to maintain condensed structure
3) Topoisomerase: modify structure of dna by SUPERCOILING, causing it to twist on itself multiple times
Remember: no histone proteins or membrane around nucloid

Question 11

Cytoplasm tings

Answer 11

-stew of macromolecules (tRNA, mRNA, rRNA, proteins, ribosomes)
-inclusion bodies and micro-compartments are also present
Inclusions (dont have membrane):
-Sulfur globules: sulfur storage for energy, sulfur used for energy or to accept electrons
-Polyhydroxybutrate granules: carbon storage
Micro-compartments:
-Gas vesicles: buoyancy control, cyanobacteria have it,
-Carboxysomes: location of carbon fixation reactions (RUBISCO), this reaction of co2 into sugars happens within here “photosynthesis dark reaction”, rubisco is enzyme, doesnt work very well which is why it has to be close to co2 (needs high conc) for it to work in this compartment
-Magnetosomes: Organelle associated with direction finding
think compass
sphere filled with magnitite in a chain
Motile Aquatic bacterium want this cause it points them to bottom of lake with sediment that has high nutrients and less oxygen (good for anaerobes)

Question 12

What is MREb

Answer 12

a cytoskeletal protein
-actin homolog
-polymer that foms helical shape all along, next to plasma membrane
-BUILDS SHAPE INTO ROD
-allows fo flexibility

Question 13

FtsZ

Answer 13

A cytoskeletal protein
-tubulin homolog
-cell has z ring at some point in division, everything needed for division is on there
-without fitsZ, cell will become filamentou-> longer without dividing
-fitsZ essential for division

Question 14

What is the default cell shape? Why?

Answer 14

Sphere, cause we dont have gene to make rod.

What makes it rod? MREb protein

Question 15

ParM

Answer 15

-cytoskeletal protein
-involved with moving things specifically plasmids
-subunits bind togethe at plasmids to make a longer polymer (cubes join together) which is the parM
-plasmids are seperated as the parM subunits keep adding on to lengthen the parM
-polymerization requires atp
-parM polymer dissociates, and the plasmids are sepeated

Question 16

Cell envelope

Answer 16

consists of eveything surrounding the cytoplasm: including plasma membrane, cell wall and outer membane if present

Question 17

Roles of plasma membrane

Answer 17

Capturing energy: electron transport chain, respiration/photosynthesis, can be used to derive enegy for motion
2) holding sensory systems: proteins in membrane can detect environmental changes and alter gene expession as a result, sned signmals to have specific responses
3) permeability barrier but not structural barier

Question 18

How does the hydrophillic head of phospholipid bind to the hydrophobic tail?

Answer 18

Ester Linkages

Question 19

What has more fluidity: unsaturated fatty acids or saturated fatty acids

Answer 19

unsaturated due to their double bond; modifying double bond and number of them modify fluidity

Question 20

Hopanoids

Answer 20

Sterol like molecules found in the plasma membrane
-help with stability across temperature ranges
-give rigidity
-found in some bacteria but not all

Question 21

How does h20 go acoss plasma mem

Answer 21

through aquaporin protein chambers

Question 22

Facilitated diffusion

Answer 22

moves down concentration grad from high to low
-no energy required due to the use of the leveraging of the concentation gradient

Question 23

Symport

Answer 23

Type of co-transport where energy needed (active transport)
-both molecules move the same way, one up gradient though and one down

Question 24

Antiport

Answer 24

Another type of cotransport, one molecule moves out (high to low) , one moves in (low to high)

Question 25

ABC Transport

Answer 25

Type of active transport
-ATP binding cassette
-move particle against conc gradient
-requires energy in the form of atp
HOW IT WORKS:
Nutrient binds to a protein, move to channel, bind/interacts to channel, channel opens due to hydrolysis of atp, nutrient moves in

Question 26

Protein Secretion

Answer 26

-how do we get proteins out?
-proteins are tagged when they are synthesized, tagged with secB whichprevents the protein from folding before it is sent out, other sec proteins build a channel that allows the protein to be secreted out of, excitory protein they are threaded thriough channel and protein is allowed to fold when outside
-USE ATP TO OPEN CHANNEL

Question 27

Cell Wall

Answer 27

-protects cell from lysis and mechanical forces (protective barrier)
-gives cell their shape
-crosslink of peptidoglycan units (proteins + sugars = suit of armour)

Question 28

Peptidoglycan Subunits

Answer 28

NAG (n-acetylglusamine) and NAM (n-acetyl muramic acid) NAM looks almost same except extra acid piece
-Small peptide chain attached to NAM
-Nam peptide chain crosslinked to another nam peptide chain
GRAM NEG: crosslink of NAM is peptide bond
GRAM POS: crosslink of NAM is pentaglycine interbridge

-crosslinks are not perfect, there are holes, and over-crosslinks which is why it is a mechanical barrier not a pemeability barrier

Question 29

D-amino acid speciality

Answer 29

unique to cell walls, L-isomes are nomal, D are weid, just brick blocks essentially
-D are stereoisomers of L