9/18 Prokaryotes Flashcards
Prokaryotes:
* Exist almost everywhere, including places where _____________________
* Biomass outweighs all eukaryotes combined by at least __________
- eukaryotes cannot
- 10x
Prokaryotes:
Functions:
* Break down organic material in dead plants and animals
* Release ________ used by plants
* Make ________________ available to most life forms
* O2 in atmosphere came from photosynthetic __________
- CO2
- Nitrogen(N)
- bacteria
Prokaryotes:
Both __________________________ to humans
* Important to produce some _____________
* Chemical reactions in industry
* Used for pharmaceutical products
* Bioremediation of _______________ sites
- beneficial and harmful
- foods
- polluted
3 Domains of LIFE:
1. _________
2. _________
3. _________
- Bacteria
- Archaea
- Eukarya
Shared Characteristics of the 3 domains:
1st tick:
1. _________
2. _________
3. _________
1.DNA
2.Ribosomes
3.Plasma membrane
Shared Characteristics of the 3 domains:
2nd tick:
1. _________
2. _________
Prokaryotes lack these
1.Nucleus
2.Membrane bound organelles
Prokaryotic genomes:
* Prokaryotes genomes ________, simpler than eukaryotes
* 1/1,000 as much DNA as a eukaryote
* 5,000 genes vs. 50,000 in eukaryotes
* DNA condensed in nucleoid region of cytoplasm
* Similar to nucleus but _________________________
* Single, circular, double-stranded DNA chromosome
- are smaller
- no membrane
Prokaryote Reproduction:
* Prokaryotes grow and adapt ____________________
* Reproduce ________________ via binary fission
* No ______________________
* A single cell in favorable conditions will produce a
colony of offspring (1012 cells in 24 hrs!)
- rapidly
- asexually
- meiosis
Binary Fission steps:
1. Circular chromosome ________
2. Copies of ____ separate as cell enlarges
3. Plasma membrane and cell wall _________ into two cells
- replicates
- DNA
- separate
When conditions unfavorable, some bacteria form endospores
(____________ condition)
Cytoplasm and chromosome dehydrate Encased by 3 layers
Resistant to
1. _____________
2. Drying
3. _____________
4. Antibiotics
5. Various chemical
disinfectants
Can survive for _________________
years in this dormant state!
- dormant
- heat
- radiation
- thousands
Genetic Diversity?
- ___________________________ but…
- Several mechanisms to combine genes between
individuals - These are called horizontal gene exchange
- Allows genetic transfer between prokaryotes
- lack meiosis
Genetic Diversity:
1. Transformation: a cell absorbs and integrates
fragments of _________ from the _________________
2. Conjugation: one cell directly transfers genes to
_________________________
3. Transduction: ____________ transfer genes between
prokaryotes
- DNA from the Environment
- another cell
- viruses
Domain Bacteria:
Bacteria differentiated with Gram stain
* Gram-positive
– Retain dyes (purple and red)
– Appear _____________
– ___________ cell wall
* Gram-negative
– Only retain red dye
– Appear _____________
– ________ cell wall
- purple
- thick
- pink/red
- thin
Gram-positive (Gram+) bacteria – ______________, thicker
cell walls, large amounts of peptidoglycan in a thick cell wall
- simpler
ram-negative (Gram-) bacteria – __________________,
less peptidoglycan, thinner cell wall
* Outer membrane ______________ cell wall
* Contains lipopolysaccharides (carbohydrates
bonded to lipids)
- more complex
- outside
Among pathogenic bacteria:
* Gram- more ____________________ than Gram+
* Outer membrane protects ____________ pathogens from
defenses (immune system) of their hosts
* Gram- bacteria more ____________ than Gram+ to antibiotics
* Outer membrane impedes entry of antibiotics
- threatening
- Gram-
- resistant
Bacteria also differentiated by three basic shapes
1. _______– round
2. ________- rod
3. ________- spiral
- Cocci –
- Bacilli
- Spirilli
Domain Bacteria
* Outnumber all other organisms on Earth
* _________________ species identified
* Habitats range from land, aquatic, to parasitic
* Remarkable metabolic diversity allows them to live almost anywhere
* Biomass outweighs all eukaryotes combined by at least ________
1.10,000
2. 10x
Significance to Humans
* Some cause __________________________
– MRSA
– Bacterial meningitis
- disease
Significance to Humans
* Provide ___________, chemicals and _______________
– Fermented meats (salami)
– Lactobacillus and Streptococcus (both bacteria) produce yogurt
* Geochemical processes (carbon and nitrogen
cycles)
– Nitrogen fixation
– Photosynthesis
- food and medicines
Cyanobacteria
* _______________ bacteria
* _________________________
* Called “blue-green algae”
* May be responsible for _________________________ into the
primitive atmosphere (3.5bya)
* Photosynthetic and unicellular or colonial
* Common in freshwater, moist soils, oceans, bare rock
- Gram-
- Photosynthesize
- introducing oxygen
Cyanobacteria
* Produce hepatotoxins and neurotoxins
* Neurotoxins are highly toxic
* Hepatotoxins damage ___________
* Low, chronic exposures may
cause liver cancer
- liver
Domain Archaea
Formerly considered _____________________
* Unique rRNA base sequences
* More closely related to ________________________
* _________________________ environments
- bacteria
- eukarya than bacteria
- extreme environments
Archaea Structure and Function
* Plasma membranes have unusual lipids
* Diverse cell wall types (polysacharride, protein, or absent)
* Some are methanogenic (make methane)
* Anaerobic areas (swamps and marshes)
* Intestinal tracts of animals
* Most are chemoautotrophs
* Inorganic compounds (no carbon) to produce
energy
* None are _________________________
_____________________ to cause infectious disease
- photosyntheic
- not known
Types of Archaea:
Methanogens
* Anaerobic environments
(without ________________)
* Produce methane from hydrogen
gas and carbon dioxide
- oxygen
Types of Archaea
Halophiles
* Require ____________
concentrations for growth (12-15%)
* Great Salt Lake, Dead Sea,
hypersaline soils
Thermoacidophiles
* Reduce sulfides and survive best at
temperatures above 80oC
* pH of 1 or 2
- high salt
Viruses (not a __________________)
* Segments of DNA or RNA
wrapped in protein coat
* Not considered __________
1. Cannot ___________on their own
(hijack host’s cells to replicate)
2. ______________ (no cells ,
organelles, or cytoplasm)
3. Do not grow
4. No _____________(requires a host)
* Viruses come from host genes
that somehow ____________
host & acquired a protein coat
* Parasitic chemica
- prokaryote
- alive
- reproduce
- acellular
- metabolism
- escaped
