Cultivation & Prokaryotic cell

medium(a)

nutrient solution used to grow microorganisms

sterilization

process of killing all microbes in or on objects

pure culture

culture containing a single kind of microbe

turbid

when a liquid medium becomes cloudy due to a microbe growing to a density

locations of macromolecules: proteins

flagellum, membrane, wall, cytoplasm

locations of macromolecules: nucleic acids

nucleoid, ribosomes

locations of macromolecules: polysaccharides

storage granules

locations of macromolecules: lipids

storage granules

structure of a phospholipid bilayer

1. hydrophilic region

2. hydrophobic region

   1. fatty acids

3. glycerophosphates

why do cell membranes carry a net negative charge?

phosphate head groups give the cell surface a net negative charge

sterols

a membrane strengthening agent

• in eukaryotes membranes due to lack of wall

• rare in prokaryotes - often absent

hopanoids

a membrane strengthening agent

• similar to sterols and present in many Bacteria

major ways archaeal membranes differ from bacteria

1. lipids of archaea contain ether bonds while bacteria contain ester bonds

2. side chain composition: bacteria has fatty acids while archaea has 5C hydrocarbon isoprene

protein associated with membrane: integral

embedded (one side, other side or throughout)

protein associated with membrane: transmembrane

throughout

protein associated with membrane: peripheral

surface associated, found on one side or the other

functions of the cytoplasmic membrane

1. permeability barrier

2. protein anchor

3. energy conservation

cytoplasmic membrane: permeability barrier

prevents leakage and functions as gateway for transport of nutrients into and wastes out of cell

cytoplasmic membrane: protein anchor

site of proteins that participate in transport, bioenergetics, and chemotaxis

cytoplasmic membrane: energy conservation

site of generation and dissipation of the proton motive force

importance of transport

reliance on diffusion wouldnt achieve intracellular concentrations necessary for biochemical reactions

transport proteins importance

• allows accumulation of solutes against a concentration gradient

• aid the uptake of solutes across the cytoplasmic membrane barrier

properties of transport systems

1. saturation effect

2. high specificity

3. tight regulation

transport systems: high specificity

one molecule or a group of closely related molecules

transport systems: tight regulation

biosynthesis of transport systems is tightly regulated by the cell

3 classes of transport systems

1. simple transport

2. group translocation

3. ABC systems

all require energy

simple transport

involves a membrane spanning transport protein

• driven by the energy in the proton motive force

group translocation

series of proteins

• chemical modification of the transported substance driven by phosphoenolpyruvate

ABC systems

3 components

symport reaction

type of coupled transport where a membrane protein moves two different substances in the same direction across a biological membrane at the same time

antiport reaction

type of coupled secondary active transport where a membrane protein moves two different molecules or ions in opposite directions across a cell membrane simultaneously

group translocation: the phosphotransferase system

transports sugars: glucose, mannose, fructose energy derived from breaking a high energy bond in PEP

ABC transporters

transports certain sugars, amino acids and inorganic nutrients

• binding proteins are involved and energy comes from ATP

transport: secretion

transport of proteins across membranes

• translocases (enzyme complexes)

• proteins include toxins and enzymes for degradation of large polymers

cell envelopes of bacteria: gram +

peptidoglycan and membrane

cell envelopes of bacteria: gram -

outer membrane, periplasm, peptidoglycan, and membrane

peptidoglycan

cell wall of bacteria

• Polymers of sugars:

  • M: N-Acetylmuramic acid (N-AM)

  • G: N-Acetylglucosamine (N-AG)

• crosslinked by peptide side chains

Lysozyme

digests cell wall

Cell wall vs low solute (hypotonic) solution

lysozyme digests wall and h2o rushes in, causing lysis

cell wall vs isotonic solute solution

lysozyme digests wall but water doesnt rush in = no lysis

• becomes a protoplast

pencillin

binds to and inactivates transpeptidases responsible for forming crosslinks in peptidoglycan

• cell wall growth becomes weak and causes lysis

Gram stain

forms insoluble crystal violet-iodine complex inside all bacterial cells

gram stain: gram + cells

thick cell wall traps dye in cell

gram stain: gram - cells

remains invisible unless they are counter stained

gram + phylas

Actinobacteria and Firmicutes

Mycoplasmas (Tenericutes)

wall-less

Mycobacteria

requires acid-fast stain

Obligate intracellular and spiral bacteria

too small, structurally distinct or physically hidden

Mycoplasmas (Tenericutes) - Bacteria

pathogenic bacteria

live in osmotic protect habitat

contain sterols in their membranes (extra rigidity/strength)

Thermoplasma - Archaea

tough cytoplasmic membranes