Microbial Cell Structure (Lec. 3)

Question 1

Compare the cell structure of prokaryotes and eukaryotes.

Answer 1

Both have DNA packaged in different ways. Prokaryotes have a non-membrane-bound nucleoid and eukaryotes have a nucleus. There are no linear chromosomes (only circular chromosomes) or histones or mitochondria or chloroplasts in prokaryotes.

Question 2

Classify types of microbes as prokaryotic or eukaryotic.

Answer 2

Prokaryotic: Archaea and bacteria.
Eukaryote: protozoa, fungi, algae, helminths

Question 3

Describe the structure and function of peptidoglycan

Answer 3

Made out of two polysaccharides that are crosslinked and stacked on top of each other to form a cell wall. In Gram-positive bacteria, it is very thick and big, and although it’s still present in Gram-negative bacteria, it’s thin.

Question 4

Compare and contrast Gram-positive and Gram-negative bacteria in terms of cell walls/membranes.

Answer 4

Gram-positive has a thick PG layer and provides greater resistance to drying because of the thick cell wall but it’s also more susceptible to PG-targeting antibiotics.
Gram-negative has a thin layer of PG and an outer membrane which contains lipid A which provides extra protection from antibiotics but is more susceptible to drying.

Question 5

Discuss the structure and function of bacterial capsules

Answer 5

Usually made out of polysaccharides, prevent the bacteria from getting phagocytized by bacteriophages and eukaryotic cells. Also may help with adherence.

Question 6

Discuss the structure and function of bacterial flagella

Answer 6

Flagella in bacteria is made of tubulin and flagellin. Helps it move

Question 7

Discuss the structure and function of bacterial fimbriae

Answer 7

Short bristle-like structures that help with adherence

Question 8

Discuss the structure and function of bacterial pili

Answer 8

Much longer than fimbriae, help with motility, adherence, and sometimes with horizontal gene transfer in reproduction.

Question 9

Discuss evidence that supports the endosymbiotic theory of eukaryotic evolution

Answer 9

Chloroplasts and mitochondria both have their own unique DNA and their ribosomes can be affected by the same type of antibiotics that affect bacteria, and their membranes have lots in common with bacterial membranes.

Question 10

Differentiate prokaryotic and eukaryotic flagella

Answer 10

Flagellin for prokaryotes, microtubules for eukaryotes.