biodiversity
Chapter 27. BACTERIA & ARCHEA
Overview:
Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms Masters of Adaptation
Most prokaryotes are microscopic, but what they lack in size they make up for in numbers
There are more in a handful of fertile soil than the number of people who have ever lived
They have an astonishing genetic diversity
Prokaryotes are divided into two domains: bacteria and archaea
Structural, functional, and genetic adaptations contribute to prokaryotic success
Most prokaryotes are unicellular, although some species form colonies
Prokaryotic cells have a variety of shapes
3 most common shapes of prokaryotes?
Spheres (cocci), Rods (bacilli), and spirals
Diversity of prokaryotes
Gram negative vs. gram positive bacteria (Fig. 27.3)
Gram + vs -
-: less peptidoglycan
-: outer membrane
-: lipopolysaccharides in outer membrane
Why are gram– more pathogenic?
Lipopolysaccharides are often toxic
Outer membrane protects against the body’s defences
Outer membrane impedes entry of antibiotics
Common antibiotics inhibit cross-linking of peptidoglycan, particularly in gram+
Motility
?
Most motile bacteria propel themselves by flagella that are structurally and functionally different from eukaryotic flagella
In a heterogeneous environment, many bacteria exhibit taxis, the ability to move toward or away from certain stimuli
Traditional View: proks. vs. euks.
Size
Nucleus
Organelles
Genetic material
Reproduction
Reproduction and Adaptation
Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hours
Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries
Prokaryotes can evolve rapidly because of their short generation times
Reproduction in Prokaryotes?
Fig. 12.12
Binary fission
Reproduction without sex
3 processes that produce recombinant DNA in prokaryotes
Prokaryotes have
Overview:
Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms Masters of Adaptation
Most prokaryotes are microscopic, but what they lack in size they make up for in numbers
There are more in a handful of fertile soil than the number of people who have ever lived
They have an astonishing genetic diversity
Prokaryotes are divided into two domains: bacteria and archaea
Structural, functional, and genetic adaptations contribute to prokaryotic success
Most prokaryotes are unicellular, although some species form colonies
Prokaryotic cells have a variety of shapes
3 most common shapes of prokaryotes?
Spheres (cocci), Rods (bacilli), and spirals
Diversity of prokaryotes
Gram negative vs. gram positive bacteria (Fig. 27.3)
Gram + vs -
-: less peptidoglycan
-: outer membrane
-: lipopolysaccharides in outer membrane
Why are gram– more pathogenic?
Lipopolysaccharides are often toxic
Outer membrane protects against the body’s defences
Outer membrane impedes entry of antibiotics
Common antibiotics inhibit cross-linking of peptidoglycan, particularly in gram+
Motility
?
Most motile bacteria propel themselves by flagella that are structurally and functionally different from eukaryotic flagella
In a heterogeneous environment, many bacteria exhibit taxis, the ability to move toward or away from certain stimuli
Traditional View: proks. vs. euks.
Size
Nucleus
Organelles
Genetic material
Reproduction
Reproduction and Adaptation
Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hours
Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries
Prokaryotes can evolve rapidly because of their short generation times
Reproduction in Prokaryotes?
Fig. 12.12
Binary fission
Reproduction without sex
3 processes that produce recombinant DNA in prokaryotes
Prokaryotes have