are prokaryotes a clade?
no
what defines bacteria?
they are called “prokaryotes” because:
because of what they lack :
- nuclei
- cellular organelles
prokaryotes are typically much __ than ____
much smaller than eukaryotes
most prokaryotes have: (3)
- cell walls
- circular chromosomes
- reproduce via binary fission
prokaryotes are immensly ___ and found ___
diverse and found everywhere
Prokaryotes are immensely diverse, and are found everywhere
* Incredibly numerous:
The estimated number of
prokaryotes in one handful of fertile
soil is greater than the number of
people who have ever lived
Prokaryotes are immensely diverse, and are found everywhere
Incredibly diverse:
there are more species of prokaryotes in 10 grams of soil than there are species of animals on earth
~7 million animal species, 1 to 100 million prokaryote species
How do we determine prokaryotic “species”?
(2)
- Prokayotes reproduce asexually
- Most species of prokaryotes are impossible to
grow and observe in a lab
can we use the biological species concept to define prokaryotic species?
yes
We can use the ___
for prokaryotic species
ecological species concept
How do we determine prokaryotic “species”?
Metagenomics is
revealing clustering of genetic similarities in prokaryotes that: (2)
- We have classified as species
- Live in the same environment
All organisms are trying to solve the same basic problems (3)
- Reproduction
- Obtaining resources
- Surviving current and future conditions (i.e. “avoid harm”)
how do prokaryotes avoid harm?
cell wall
nearly all prokaryotes have :
bacteria have:
archaea have:
CELL WALLS
Bacteria: peptidoglycan
Archaea: lack peptidoglycan; polysaccharides + proteins
the cell walls maintain ___ and ____
maintains structure and protects from outside
how do bacteria avoid harm other than cell wall?
CAPSULES
role of the capsule : (3)
- Aids in cell adhesion to other cells,
- protects against dehydration,
- helps prevent attacks by the immune system
in many prokaryotes the capsule is:
Sticky layer of polysaccharides or proteins
how do bacteria avoid harm?
other than capsule or cell wall
endospores
the endospore preserves:
preserves the cell’s genetic material in times of extreme stress
__% of prokaryotes do not ___ under their own power
most of them:
50% of prokaryotes do not move under own power
they use a flagella
the flagella of ___, ___ and ___ have likely evolved ____
Flagella of bacteria,
archaea, and eukaryotes
likely evolved
independently
binary fission is:
reproduction without SEX
how is binary fission different from mitosis? (3)
No spindle, centrioles,
dance of the
chromosomes
