Cell structure of microorganisms

Question 1

What size are bacteria?

Answer 1

Range between ~0.3 to 5 um

Question 2

What are the three basic groups of bacteria?

Answer 2

Cocci
Bacilli
Spirochetes

Question 3

What are the different ways that cocci can be observed?

Answer 3

Pairs (diplococci)
Chains (streptococci)
Grapelike clusters (Staphylococci)

Question 4

What are the defining features of eukaryotes?

Answer 4

True nucleus with multiple chromosomes surrounded by a nuclear membrane

Contains organelles

80S ribbosomes

Question 5

What are the defining features of prokaryotes?

Answer 5

A single, long, circular double stranded DNA tightly coiled into a nucleoid

Cytoplasm contains only ribosomes (70s)

Cell membrane is covered by a thick protective cell wall

Metabolic functions in cell membrane, not organelles

Question 6

What is the bacterial cell wall made of?

Answer 6

Peptidoglycan, which forms a multi-layered, 3 dimensional structure

Question 7

How can peptidoglycan be destroyed?

Answer 7

Penicillins, cephalosporins and vancomycin inhibit peptidoglycan synthesis by inhibiting tripeptidase which links tetrapeptides together

Lysozymes cleave the peptidoglycan backbone by breaking its glycosyl bonds

Question 8

Upon gram staining how do you determine whether the bacterium is gram positive or negative?

Answer 8

Gram negative bacteria are pink

Gram positive bacteria are purple

Question 9

What are the features of gram positive bacteria?

Answer 9

Composed predominantly of peptidoglycan (90% of the cell wall) which provides lots of strength.

Also contain teichoic acid within the peptidoglycan layers which contribute to rigidity, cell division and protection against environmental factors

Question 10

What are the features of gram negative bacteria

Answer 10

More components

Peptidoglycan only makes up 5-10% of the cell wall

Porins which allow substances to enter the cell

Lipid bilayer

Contain lipopolysaccharide

Several functions including host response to pathogenic gram negatives

Question 11

What is lipopolysaccharide (LPS)

Answer 11

An endotoxin found in gram negative bacteria which is responsible for many features of disease such as fever and shock

Question 12

Features of the plasma membrane

Answer 12

Selective permeability with proteins embedded into the membrane acting as channels or carriers

Energy production