Chapter 20.2 Prokaryotes Flashcards
What is a prokaryote?
smallest and most abundant microorganisms that are unicellular and lack a nucleus
Where is prokaryote DNA located?
in the cytoplasm
Where is eukaryote DNA located?
in a membrane-bound nuclear envelope
Domain Bacteria
(Kingdom Eubacteria)
- the larger of the two domains
- surrounded by a cell wall that protects from injury and determines its shape
- cell walls contain peptidoglycan
- some bacteria (ie. E. coli) have a second membrane outside the peptidoglycan wall that makes the cell especially resistant to damage
- live in wide range of environments
What is peptidoglycan?
a polymer of sugars and amino acids
Domain Archaea
(Kingdom Archaebacteria)
- cell walls lack peptidoglycan
- membranes contain different lipids
- archaea and eukaryotes are more closely related to each other than bacteria
- live in harsh/extreme environments
- methanogens
- halophiles
- thermoacidphiles
What are methanogens?
bacteria that can live in swamps, lake sediment, animals’ guts and produce methane gas (greenhouse gas)
- live in places with little or no oxygen
What are halophiles?
bacteria that live in very salty habitats like the Dead Sea, seawater-evaporating ponds for salt production
What are thermoacidphiles?
bacteria that live in acid, hot conditions, like hot springs, deep-sea volcanic vents
How do prokaryotes vary in their structure and function?
prokaryotes vary in their size and shape, in the way they move, and in the way they obtain and release energy
Describe the size of prokaryotes.
range in size from 1 to 5 micrometers (smaller than most eukaryotic cells)
What are the three different shapes of prokaryotes?
- bacilli: rod-shaped
- cocci: spherical
- spirilla: spriral and corkscrew-shaped
Describe the movement of prokaryotes.
some do not move at all, some are propelled by a flagella, some glide slowly along a layer of slimelike material they secrete
Describe the nutrition and metabolism of prokaryotes.
store chemical energy in the form of fuel molecules (sugars), this energy is released during cellular respiration, fermentation, or both
What is a photoautotroph?
organism that carries out photosynthesis in a manner similar to that of plants
What is a chemoautotroph?
organism that makes food from chemical reactions such as ammonia
What is a decomposer?
organism that takes in organic molecules and then breaks them down
What is a photoheterotroph?
organism that uses light energy in addition to processing organic molecules