Concept 27.1: Structural and functional adaptations contribute to prokaryotic success (to slide 11)

Flashcards from Concept 27.1 of Pearson's Campbell Biology, Twelfth Edition.

Prokaryotic adaptations

For survival, includes:

• Small size and rapid reproduction

• Rapid mutation rate

• Diverse adaptations

• Rapid evolution

Prokaryotes

Single-celled organisms that make up domains Bacteria and Archaea

• Most abundant organisms on Earth due to their adaptations to diverse and extreme environments

• Usually 0.5 to 5 micrometers, smaller than the 10 to 100 micrometers of eukaryotes

• Form three main shapes of spheres, rods, and spirals

Colonies

Collections of prokaryotes that form for growth

Cocci

One of the three shapes of prokaryotes taking the form of spheres

Bacilli

One of the three shapes of prokaryotes taking the form of elongated rods

Cell wall

In bacteria, this maintains shape and protects the cell

• Prevents bursting in a hypotonic environment as water rushes in to a solute-heavy cell

• Still vulnerable to plasmolysis in hypertonic environments, enabling salt to be used as a preservative to cause water loss in cells

• Contains peptidoglycan, a network of sugar polymers linked by polypeptides

Plasmolysis

The breakdown of a cell’s cytoplasm

• Occurs in hypertonic environments within bacteria, especially when surrounded by solutes like salt

Peptidoglycan

A substance found in most bacterial cell walls containing a network of sugar polymers cross-linked by polypeptides

• Not present in human cells, thus making targeting this substance not harmful in medications combating gram-positive bacteria

Gram stain

Cell staining method used to classify bacteria by cell wall composition either into gram-positive or gram-negative categories

Gram-positive bacteria

Bacteria that show up on a gram stain as purple and have simpler walls with a thick layer of peptidoglycan

Gram-negative bacteria

Bacteria that show up on a gram stain as pink, with less peptidoglycan, more complex cell walls, and an outer membrane containing lipopolysaccharides

• Typically more resistant to antibiotics due to most targeting peptidoglycan