Lecture 1- Bacteria And Fungi

Question 1

Tree of life

Answer 1

-bacteria and archaea - prokaryotes
-fungi, algae, Protozoa- eukaryotes
-viruses- viruses

Question 2

Cell wall

Answer 2

-prevents osmotic lysis
-made of peptidoglycan (in bacteria)

Question 3

Peptidoglycan

Answer 3

-consists of strands of alternating repeats of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM/NAMA)
-NAMA strands cross-linked via the short peptides
-number of sheets of peptidoglycan present depending on the bacteria

Question 4

Gram stain

Answer 4

Gram + = blue/purple (coccus shaped)
*thick peptidoglycan, techoic acids, in acid-fast cells, contains mycolic acid
*lipotheichoic acid links to plasma membrane
*wall teichoic acid links to peptidoglycan
*may regulate movement of cations
*polysaccharides provide antigenic variation= may change immune responses of individuals
Gram - = pink/red (rod shaped)
*thin peptidoglycan, no teichoic acids, outer membrane
-fundamental differentiation between bacteria
-cell wall structure

Question 5

Gram-negative outer membrane

Answer 5

-contains lipopolysaccharides, lipoproteins and phospholipids
-protection from phagocytes, complement and antibiotics
-proteins form channels through membrane

Question 6

Lipopolysaccharide (LPS)

Answer 6

Composed of:
-lipid A
-core polysaccharide
-O-specific polysaccharide
-lipid A endotoxin properties

Question 7

The capsule

Answer 7

-polysaccharide layer outside of the cell
-mediates adherence to surfaces
-provides protection against phagocytes and antimicrobial agents
-secondary function
-most common in gram - bacteria but gram + also have them

Question 8

Plasma membrane

Answer 8

-phospholipid bilayer
-peripheral, integral and transmembrane proteins

Question 9

Prokaryotic ribosomes

Answer 9

-assemble proteins from amino acids based on mRNA
-difference between prokaryotic and eukaryotic ribosomes

Plasmids- prokaryotes
-small circular or linear DNA molecules, carry unessential genes, can confer pathogenic/therapeutic properties and are transferable between bacteria

Question 10

Endospores

Answer 10

-some bacteria can
-highly resistant survival structures produced by some gram +ve bacteria
-highly dehydrated
-contains essential macromolecules
-calcium dipicolinate + small acid-soluble proteins

Question 11

Flagella

Answer 11

-outside cell wall
-made of chains of flagelin
-attached to a protein hook
-anchored to the wall and membrane by the basal body

Question 12

Fungi

Answer 12

-eukaryotic
-aerobic or facultatively anaerobic
-most are decomposers; like polymers
-deed via absorbing nutrients; excrete extracellular enzymes

Question 13

Structure, Yeasts, moulds, dimorphism and spores

Answer 13

3 types of structure; filamentous, unicellular and both= dimorphic

Yeasts; unicellular fungi, Candida species more common pathogens; thrush and candida auris

Moulds; fungal biomass consists of hyphae, generate spores

Dimorphism; pathogenic dimorphic fungi are yeast at 37c and mold like at 25c

Spores; many fungi all produce spores, very small and easily dispersed, many wind dispersed
-exposed to spore all the time; immune status that determines infection, environmental factors= temperature and humidity

Question 14

Candida infections

Answer 14

-common fungal infection
-may be superficial or systemic
-associated with flora disruption and immune issues