microbial cell structure

5 major groups of microorganisms

bacteria, fungi, protozoa, algae, viruses

3 kingdoms of life

bacteria, archea, eukaryota

bacteria have a larger…

surface area to vol ratio

can viruses be viewed using light microscope ?

no - electron

diameter range of eukaryotic cells

10 - 200um

1mm = ?µm

1000

protozoa

single celled eukaryotes

diameter of Saccharomycetes (fungi)

5um

diameter range of prokaryotic cells

0.2 - 700µm

viruses can only replicate within

cytoplasm of host

2 types of bacterial cell wall

gram pos or neg

gram pos

one thick cell wall multiple layers of peptidoglycan

teichoic and lipoteichoic acids

gram neg

2 layers with single peptidoglycan layer

LPS and porins

bacterial cell walls composed mainly of

peptidoglycan (murein)

peptidoglycan is composed of…

• N-acetylglucosamine (NAG)

• N-acetylmuramic acid (NAM)

• amino acids

what % of gram pos is peptidoglycan

60 - 90

how thick are gram pos cell walls ?

30-60nm

role of teichoic acid in gram pos mem

bound to NAM of PG

helps cross-link PG chains and adhere to surface

what

porins

transmembrane proteins

channels for movement of hydrophilic low-molecular weight substances

1nm diameter hole

porins are composed of how many identical polypeptides

3

periplasm

space between cytoplasmic and outer membranes

15nm wide

contains digestive enzymes, transport proteins and chemoreceptors

cytoplasmic/plasma mem

found in both gram pos and neg

8-10nm wide

phospholipid bilayer with embedded proteins

highly selective permeable barrier

what stains are used to differentiate between gram pos and neg

crystal violet and safranin

gram pos stains

purple - retain crystal violet

gram neg stains

pink/red - lose crystal violet, retain safranin counterstain

inclusion bodies

particles of aggregated proteins

nucleoid

chromosome region

single circular closed loop of double stranded supercoiled and highly condensed DNA

no membrane

ribosomes absent

ribosomes

granular appearance

small and large subunits

some antibiotics work by preventing protein synthesis at ribosome eg. tetracycline

plasmids

nonessential DNA molecules

loop of 5-100 genes

replicate independently of host chromosome

transfer genetic traits between bacteria - conjugation

antibiotic resistant genes

bacterial DNA replication is

bi-directional

binary fission

form of asexual reproduction where a single cell divides into two identical daughter cells

what major microorganism groups are eukaryotic

fungi, algae, protozoa

nucleus can be viewed

under light microscope without staining

nucleolus

site of ribosome and protein synthesis

fungi reproduce via

spores - asexual or sexual

saprotrophic

dead or decaying organic matter

symbiotic

mutually beneficial relationship

commensal

one organism benefits, and the other is neither helped nor harmed

cell wall of fungi is composed of

chitin and glucan

in cell mem of fungi cholesterol is substituted with

ergosterol

protozoa

simple microorganisms

live in/on organism of another species - heterotrophic

can cause direct/indirect harm to host