Prokaryotes: Bacteria & Archaea Section 18.4

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

-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

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

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

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

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

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

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

Streptococci Streptobacilli Spirillum Diplococci Staphylococci Diplobacilli

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

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

GRAM NEGATIVE GRAM POSITIVE

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

Which is the gram-positive? B

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

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

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

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

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

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