6.3.1, 6.3.2 Bacteria structure, physiology and replication

Name of arrangement of pairs of circles

Diplococci

Name of arrangement of chains of circles

Streptococci

Name of arrangement of pairs of circles

Diplococci

Name of arrangement of chains of circles

Streptococci

Name of arrangement of clusters of circles

Staphylococci

Name of rod arrangement

Bacilli

Name of oval rod arrangement

Coccobacilli

Which 2 parts of the bacteria are useful for antigenic typing?

Outer membrane (in gram -ve bacteria only, via O polysaccharide) and flagellum protein

Use of fimbriae

Attachment to other cells

Use of pili

Attachment to fellow bacterial cells for conjugation (DNA exchange)

A

cytoplasm

B

flagellum

C and type

ribosomes (70S- 50S + 30S)

D

nucleoid

E

plasma (cell surface) membrane

F

cell wall

G

capsule

H

plasmid

I

pili

Components of bacterial capsule

Polysaccharides

Describe the 2 components of peptidoglycan.

• Disaccharide backbone (N-acetylglucosamine and N-acetylmuramic acid)

• Polypeptide chain

What enzymes make bacterial cell wall crosslinks?

Transpeptidase

Describe the structure of a gram +ve bacterial envelope. (2)

• Many peptidoglycan layers

• Techoic acid- maintains rigidity

Describe the structure of a gram -ve bacterial envelope. (1)

• Thin peptidoglycan layer

• Presence of outer membrane

Describe the resulting colours of a gram staining test for and where the 2 results come from.

• +ve purple- crystal violet trapped in peptidoglycan cell wall

• -ve pink- safranin stains left because crystal violet escapes

Which structure is used for the electron transporters on bacteria?

Plasma (cell surface) membrane

Which 2 structures are often targeted by antimicrobials?

• DNA (nucleoid)- easy to get to once inside cell

• 70s ribosomes- different from eukaryotic

List the 4 phases of a bacterial growth curve.

• Lag- bacterial adjustment to surroundings, no growth

• Log- exponential growth

• Stationary- growth plateaus due to environmental limitations

• Decline- bacteria use up available nutrients and start dying off

Which 2 bacteria have endospores?

Clostridium, bacillus

Process of forming endospore

Sporulation

Role of endospore

Highly resistant body to enable dormancy for a long time

Process of reversing endospore to vegetative cycle

Germination

List the 4 types of culture media.

• Complete- grows everything

• Selective- selects against specific bacteria

• Differential- different bacteria show differently

• Enrichment- enhances specific bacterial species

Describe how MacConkey medium is both selective and differential. (2)

• Fermentable carbohydrate- only bacteria that can process it survives

• Acid produced via fermentation changes colour of medium

Appearance of strict aerobe bacteria in culture

Remains at surface of medium

List the 4 types of oxygen requirement.

• Strict aerobe

• Obligate anaerobe

• Facultative anaerobe (can do both)

• Microaerophil (requires only a bit of oxygen)

Appearance of obligate anaerobe bacteria in culture

Sinks to bottom of medium

Appearance of facultative anaerobe bacteria in culture

Remains in all depths of culture

Appearance of microaerophil bacteria in culture

Sit in middle of medium