Flashcards in Lecture 21 - Prokaryotes 1 Deck (74)
Where do prokaryotes thrive?
-even too acidic, salty, cold , or hot for other organisms
Are prokaryotes macroscopic or microscopic?
What are the two domains of prokaryotes?
What are the 3 elements of the tree of life?
Archaea are more closely related to ______ than to ________
What were earth's first organisms?
Are prokaryotes uni or multicellular?
unicellular, but some species form colonies
How small are most prokaryotic cells?
What are the 3 most common shapes of prokaryote cells?
1. spheres (cocci
2. rods (bacilli)
What is trichodesmium?
colonial marine nitrogen-fixing cyanobacterium
What is the important feature of nearly all prokaryotic cells?
What do cell walls do?
-maintains cell shape
-prevents it from bursting in a hypotonic environment
What are eukaryote cell walls made of?
What are bacterial cell walls made of?
What is peptidoglycan?
-network of sugar polymers
-cross-linked by polypeptides
What doe archaea contain? lack?
-polysaccharides + proteins
What is a gram stain used for?
to classify bacteria by cell wall composition
What will a gram-positive bacteria have?
-simpler walls with a large amount of peptidoglycan
What do gram-neg bacteria have?
-outer membrane that can be toxic
What do many antibiotics target? What do they do?
-damage bacterial cell walls
Which type are more likely to be antibiotic resistant?
What also covers many prokaryotes?
capsule (slime layer)
What is an endospore?
-seed that forms inside cell (with DNA)
-inactive, can remain viable in harsh conditions for centuries
What do fimbriae do?
-allow prokaryotes to stick to their substrate or other individuals in a colony
What are pili?
-longer than fimbriae
-allow prokaryotes to exchange DNA
What are taxis?
ability to move toward or way from a stimulus
What is chemotaxis?
-movement toward or away from chemical stimulus
How do motile bacteria propel themselves?
-flagella scattered about the surface or concentrated at one or both ends
What are flagella composed of?
-likely evolved independently