1. Prokaryotes: Bacteria & Archaea
Section 18.4

2. Classification of Organisms
The three domains in the tree of life are
Bacteria, Archaea, and Eukarya.

3. -made up of Bacteria and Archaea
Prokaryotes…
-made up of Bacteria and Archaea
Domain Archaea
cell walls chemically different from bacteria
differences discovered by studying RNA
known for living in extreme environments
Domain Bacteria
one of largest groups on Earth
classified by shape, need for oxygen, and diseases caused

4. Prokaryotes are widespread on Earth.
can be grouped by their need for oxygen.
obligate anaerobes are poisoned by oxygen
obligate aerobes need oxygen
facultative aerobes can live with or without oxygen

5. Obligate anaerobes are poisoned by oxygen
Archaea that produce methane gas
Live in marshes, bottoms of lakes, digestive tracts of herbivores
Release nutrients from plants that animals can’t digest on own

6. Facultative anaerobes
Obligate aerobes
need oxygen
includes pathogens that cause:
tuberculosis
leprosy
Facultative anaerobes
Can survive whether oxygen is present or not

7. Archaea vs. Bacteria Archaea Bacteria Cell type Prokaryote # cells
Unicellular
Exterior
Cell wall & plasma membrane
Make-up of exterior
Made of lipids
Peptidoglycan in walls
Fun fact…
Live in extreme harsh conditions
Most diverse and widespread group

8. What is bacteria? Prokaryotes Single-celled organisms
Cell walls and plasma membranes; no membrane-bound organelles
DNA is circular in cytoplasm (no nucleus)
Many have plasmids

9. 3 most common shapes
Shape
Singular
Plural
Rod
Bacillus
Bacilli
Spiral
Spirillum
Spirilla
Sphere
Coccus
Cocci
Diplo- 2 cells; Staphylo- cluster of cells; Strepto- chain of cells

10. Streptococci
Streptobacilli
Spirillum
Diplococci
Staphylococci
Diplobacilli

11. Bacterial Structure All have: Some have: Cell wall endospores
Cell membrane capsules
Cytoplasm outer memb.

12. Cell Wall peptidoglycan Made of _____________________
(____________-_____________)
Makes up-
Gram (+): ___________ outer layer
Gram (-): __________ middle layer
protein
sugar
THICK
THINNER

13. GRAM NEGATIVE
GRAM POSITIVE

14. Thick or Thin layer ?
Stain Color?
Gram Positive
THICK
PURPLE
Gram Negative
THIN
RED

15. Which is the gram-positive?B

16. Cell Membrane
Lipid bilayer
Carry out respiration
In some: carry out photosynthesis

17. Cytoplasm Solution of ribosomes and DNA DNA= single closed loop
Some have Plasmids: small piece of genetic material that can replicate separately from the main chromosome

18. Flagellum vs. Pilus Flagellum: Made of proteins
Attached to plasma membrane and cell wall
long, whip-like
used for movement
Pilus:
short, thin, numerous
used for sticking to other prokaryotes

19. CAPSULE Outer covering Made of sugars Protect from harsh environments
Can stick to other cells

20. Endospores
Dormant structure
Only in Gram Positive bacteria
Thick outer covering
Protect DNA
Harsh environments (temperature, chemicals, radiation, drying…)

21. Genetic Recombination
Transformation: bacteria takes DNA from outside environment
Conjugation: 2 cells bind together using pili, transfer DNA
Transduction: virus obtains DNA from host bacteria, viruses replicate