Domain Bacteria (Lec. 10)

Question 1

Describe the structure and function of peptidoglycan.

Answer 1

Compound of disaccharides linked by transpeptidase; found in bacterial cell walls; maintains a cell’s shape and rigidity; protects the cell from osmotic pressure.

Question 2

Compare and contrast Gram-positive and Gram-negative bacterial cell walls.

Answer 2

Gram positive: plasma membrane + thick peptidoglycan layer; more susceptible to antibiotics but more resistant to osmotic pressure.
Gram negative: plasma membrane + thin peptidoglycan layer + lipid membrane with endotoxins in it; less susceptible to antibiotics but more prone to osmotic pressure

Question 3

Discuss the function and composition of bacterial capsules

Answer 3

Polysaccharides that cover the bacterial cell; help with adherence

Question 4

Discuss the function and composition of flagella

Answer 4

Made of flagellin; help with motility

Question 5

Discuss the function and composition of fimbriae.

Answer 5

Short bristle-like protein-based structures that help with adherence

Question 6

Discuss the function and composition of pili.

Answer 6

Longer than fimbriae, help with twitching motility, maybe adherence, and conjugation

Question 7

Discuss the function and composition of endospores.

Answer 7

Produced when environmental conditions become unfavorable; durable capsules that contain a bacterium’s DNA, ribosomes, and dipicolinic acid which helps to maintain dormancy.

Question 8

Define oligotroph

Answer 8

An organism that can live in an environment that offers very low levels of nutrients

Question 9

Define serovar/serotype

Answer 9

A distinct variation within a species of bacteria or virus or among immune cells of different individuals (differ in antigens)

Question 10

Define biovar/biotype

Answer 10

A group of microorganisms that have the same genetic makeup but different biochemical or physiological characteristics

Question 11

Define coryneform

Answer 11

Gram positive anaerobic actinobacteria commonly found on human skin.

Question 12

Define pleomorphic

Answer 12

Having more than one distinct form

Question 13

Given the phylum, identify whether it contains Gram positive or Gram negative bacteria

Answer 13

Proteobacteria: Gram negative
Bacteroidetes: Gram negative
Chlamydiae: Gram negative
Fusobacterium: Gram negative
Spirochaetes: Gram negative
Firmicutes: Gram positive
Actinobacteria: Gram positive

Question 14

Identify the phyla, order, and genera that contain acid-fast bacteria

Answer 14

Actinobacteria (phylum); order Mycobacteriales; genera Mycobacterium and Nocardia

Question 15

Identify the phyla, order, and genera that contain filamentous bacteria

Answer 15

Phylum Actinobacteria; orders Actinomycetales (genus Actinomyces), Streptomycetales (genus Streptomyces), and Mycobacteriales (genus Nocardia)