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BrooklynMessersmith Chap 27 (Comparison of the Three Domains of Life…
BrooklynMessersmith Chap 27
Major Nutritional Modes
heterotroph
chemoheterotroph
Types or organisms: Many prokaryotes (for example, Clostridium) and protists; fungi; animals; some plants
energy source: organic compounds
carbon source: organic compounds
photoheterotroph
energy source: light
Carbon Source: organic compounds
Types of organisms: Unique to certain aquatic and salt-loving prokaryotes (for example, Rhodobacter, Chloroflexus)
autotroph
chemoautotroph
energy source: inorganic compounds such as NH3
Carbon Source: cO2, hcO3-, or related compound
Types of organisms: Unique to certain prokaryotes (for example, Sulfolobus)
phototroph
energy source: light
Carbon Source: cO2, hcO3-, or related compound
Types of organisms: photosynthetic prokaryotes (for example, cyanobacteria); plants; certain protists (for example, algae)
Comparison of the Three Domains of Life
Archaea
Membraneenclosed organelles: absent
peptidoglycan in cell wall: absent
nuclear envelope: absent
rnA polymerase: Several kinds
initiator amino acid for protein synthesis:
methionine
Membrane lipids: Some branched hydrocarbons
introns in genes: present in some
histones associated with DnA: present in some species
circular chromosome: present
response to the antibiotics streptomycin and chloramphenicol:
Growth not inhibited
Growth at temperatures above 100°c: some species
Eukarya
Membraneenclosed organelles: present
peptidoglycan in cell wall: absent
nuclear envelope: present
rnA polymerase: Several kinds
initiator amino acid for protein synthesis:
methionine
Membrane lipids: Unbranched hydro- carbons
introns in genes: present in some
circular chromosome: absent
Growth at temperatures above 100°c: no
histones associated with DnA: present
response to the antibiotics streptomycin and chloramphenicol: Growth not inhibited
Bacteria
Membraneenclosed organelles: absent
peptidoglycan in cell wall: present
nuclear envelope: absent
rnA polymerase: One kind
initiator amino acid for protein synthesis: formylmethionine
introns in genes: very rare
Membrane lipids: Unbranched hydro- carbons
circular chromosome: present
Growth at temperatures above 100°c: no
histones associated with DnA: absent
response to the antibiotics streptomycin and chloramphenicol:
Growth usually inhibited
Eukaryote v Prokaryote
Prokaryote
circular chromosomes
Compartmentalization: lacks membrane enclosed organelles
nucleoid
prokaryotic ribosomes are slightly smaller than eukaryotic ribosomes and differ in their protein and RNA content
binary fission
Eukaryote
linear chromosomes
Compartmentalization: has membrane enclosed organelles
nucleus
mitosis and meiosis
contains organelles such as endoplasmic reticulum, Golgi apparatus, etc.
Prokaryotes
Shape
Bacilli- rod shaped prokaryote
Cocci- spherical prokaryotes, Resembles bunches of grapes, can appear in long chains.
Spiral-range from comma-like shapes to loose coils.
Cell Wall
Cell Wall- maintains cell shape, protects the cell, prevents it from bursting into a hypotonic environment
Gram positive- bacteria have relatively simple walls composed of a thick layer of peptidoglycan
gram negative- bacteria have less peptidoglycan and are structurally more complex
The cell wall of many prokaryotes is surrounded by a sticky layer of polysaccharide or protein. This layer is called a capsule if it is dense and well-defined
certain bacteria develop resistant cells called endospores when they lack water or essential nutrients
improves. Finally, some prokaryotes stick to their substrate or to one another by means of hair-like appendages called fimbriae
prokaryotic cells reproduce by binary fission.
a single prokaryotic cell divides into 2 cells, which then divide into 4, 8, 16, and so on.
Under optimal conditions, many prokaryotes can divide every 1–3 hours; some species can produce a new generation in only 20 minutes
prokaryotic populations can consist of many trillions of individuals—far more than populations of multicellular eukaryotes, such as plants or animals.