Lecture 8 - Shapes, Arrangement, and Glycocalyx

Question 1

How does penicillin kill bacteria?

made from molds commonly found in homes

Answer 1

By interfering with the ability to synthesize the cell wall. Bacteria lengthen, but cannot divide. Eventually, the weak cell wall ruptures.

Question 2

Prokaryotes

cell walls made of what?

-one circular chromosome

Answer 2

bacteria and archaea

peptidoglycan (murein) - bacteria
archaea - psuedomurein

Question 3

Eukaryotes

cell walls made of?

-paired chromosomes in nuclear membrane

Answer 3

animals, plants, fungi (yeasts and molds), and protists - much larger than prokaryotic cells

polysaccharide cell walls (only in a few eukaryotes - most do not have cell walls)

Question 4

Porkaryotes don’t have _______ , but archaea have ________ -like proteins.

Answer 4

Histones, histone-like

Question 5

Most bacteria are _________ (exist as one cell), and ________ (think shape).

Answer 5

unicellular, monomorphic (one cell shape)

Question 6

Pleomorphic bacteria

Answer 6

meaning they have the ability to alter their shape or size in response to the environment

ex. H. pylori chronic superficial gastritis (ulcers)

Question 7

Shapes of bacteria

Answer 7

bacillus (rod-shaped)

• diplobacillus (just two linked)
• streptobacillus (chain)

coccus (sphere)

• diplococcus (pair)
• tetrad (group of 4)
• staphylococcus (cluster)
• streptococcus (chain)

spiral

• vibrio (comma-shaped)
• spirillum - helical, but ridgid
• spirochete - helical, and flexible (resemble flagella)

Question 8

Other shapes that are unusual

Answer 8

star-shaped (stella), rectangles (haloarcula), or arranged in several tetrads, or even some take on long filamentous chains that resemble fungi

Question 9

Most bacteria secrete some sort of _________ an outer viscous covering of fibers extending from the bacterium that is outside of the cell wall. Extracellular polysaccharide allows cells to _______.

Answer 9

glycocalyx (sugary/sticky coat)

attach

Question 10

Two types of glycocalyx

Answer 10

Slime layer, capsule

Question 11

Capsule

Answer 11

extensive, tightly bound accumulation of gelatinous material adhering to the cell wall

• neatly organized, hard to remove, firmly attached to cell
• encapsulated pathogenic bacteria are typically more difficult for phagocytic cells of the immune system to recognize and destroy

Question 12

Slime layer

Answer 12

glycocalyx appears unorganized and more loosely attached, easy to remove

Question 13

Glycocalyx aids bacteria by:

Aids in _________ formation.

Answer 13

preventing dessication (drying), but two most important are:

• enables certain bacteria to resist phagocytic engulfment by white blood cells in the body or protozoans in soil and water
• glycocalyx also enables some bacteria to adhere to environmental surfaces (rocks, root hairs, teeth, etc), which will lead to colonization of that surface

BIOFILM - ability to adhere to surfaces will aid in biofilm formation and the ability to cause disease (pathogenesis)