Topic 2B - Prokaryotic Structure and Function - Microbes

what is the bacterial cell wall composed of

• peptidoglycan

• rigid polysaccharide

• repeating units of NAG and NAM

• 4 amino acids

  • L-alanine

  • D-alanine

  • D-glutamic acid

  • diaminopimelic acid (L-lysine)

how does the bacterial cell wall provide shape

• cell wall defines the bacterial cell shape

• morphology

how does the bacterial cell wall provide protection

• provides protection and support from physical damage

how does the bacterial cell wall provide resistance to osmotic pressure

• prevents cell from rupturing due to osmotic pressure

what are 4 different kinds of bacterial cell walls

• gram positive

• gram negative

• mycobacteria

• fungi

what is part of bacterial cell walls in different quantities

• peptidoglycan

the gram positive cell wall:

• contains several layers of peptidoglycan

• acidic molecules are embedded in the cell wall

  • teichoic acid

  • lipoteichoic acid

what is teichoic acid

• acidic molecules embedded in gram positive cell walls

• not present in gram negative cell walls

• covalently linked to peptidoglycan

what is lipoteichoic acid

• acidic molecules embedded in gram positive cell walls

• covalently bonded to membrane lipids

what are the components of gram positive cell walls

• peptidoglycan

• periplasm

• plasma membrane

gram negative cell walls:

• contain a thin peptidoglycan

• also includes an outer membrane

• high concentrations of degradative enzymes and transport proteins

what are the components of gram negative cell walls

• outer membrane

• peptidoglycan (thin)

• periplasm

• plasma membrane

what is peptidoglycan

• rigid polysaccharide

• Repeating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

• With the amino acids L-alanine, D-alanine, D-glutamic acid, and diaminopimelic acid (or L-lysine)

what is NAG

• N-acetylglucosamine

what is NAM

• N-acetylmuramic acid

what are two ways to attack the bacterial cell wall

• lysozyme

• penicillin

how does lysozyme attack the bacterial cell wall

• found in human tears

• peptidoglycan cell walls are susceptible to attach by the action of lysozyme

• attacks the peptidoglycan backbone

• cleaves the bond between NAG and NAM

how does penicillin attack the bacterial cell wall

• antibiotic that can attack certain bacterial cell walls

• blocks a step in the biosynthesis of the cell wall

• the cell cannot grow, so it dies

How could the properties of penicillin and lysozyme be used in research or medicine?

• bacterial infection

what is the gram negative outer membrane composed of

• lipopolysaccharides (LPS) - tells what it is comprised of

• lipoproteins

• phospholipids

how does the gram negative outer membrane provide protection

• assists in evading phagocytosis and destruction by complement activation

• provides a barrier to

  • some antibiotics

  • digestive enzymes

  • detergents

  • heavy metals

  • bile salts

  • specific dyes

what are the porins on the gram negative outer membrane

• proteins embedded in the outer membrane

• act as channels that allow passage of essential molecules into the cell

what is the structure of LPS -

• has a polysaccharide portion and a lipid A portion

• polysaccharide is antigenic and provides a useful way to distinguish different serovars or serotypes

• lipid A considered synonymous with endotoxin (toxic in bloodstream causing fever and shock)

what is the pathogenicity of lipid A

• 
  

how was a synthetic cell created

• removed inner components

• added ribosomes to cells

• cell was functional

• 
  

what are the characteristics of the cytoplasm

• 80% water

• contains enzymes, carbs, lipids, inorganic ions

what is the cytoplasm

• cell substance that is contained within the plasma membrane

what is the nucleoid

• genetic material of a prokaryote

• bacterial chromosome consisting of a single, long continuous strand of DNA

  • circularly arranged

what is flagella

• long filamentous appendage that propels bacteria

• can be anchored to a cell in different locations

• allow for active movement

what is active movement

• allows cell to move one point to another