Prokaryotes Flashcards
What are the 3 domains of life
- Bacteria
- Archaea
- Eukarya
What are prokaryotes
Prokaryotes: Bacteria and Archaea
- small
- unicellular
- some colonies
- no membranes bound organelles (mitochondria, chloroplast… )
What are the 3 main shapes of prokaryotes
cocci = spherical
bacilli = rod-shaped
spirochete = spiral
What are some general anatomy features of prokaryotes
Have cell walls + capsules to protect the cell membrane
Fimbriae adhere to other cells
flagella for locomotion
RNA + DNA in single chromosomes and or “rings” called plasmids
What are Archaea
- similar in form to bacteria
- associated with extreme environments and habitats
- sisters to eukaryotes
Where can you find prokaryotes
Prokaryotes can be found in diverse environments from the Antarctic to hydrothermal vents
What are the different types of autotrophs
Autotrophs:
1. Photoautotroph: energy from light, carbon from CO2, HCO3- or other compounds, found in plants, protists, photosynthesizing bacteria, etc
- Chemoautotroph: energy from inorganic materials like H2S, NH3, Fe2+, carbon from CO2, HCO3-, or others. Found in certain protists
What are the different types of heterotroph
- Photoheterotroph: energy from light, carbon from organic compounds, found in aquatic and salt loving prokaryotes
- Chemohaterotroph: energy and carbon from organic compounds, found in animals, fungi, many protists, many prokaryotes
What are the 3 types of Symbiosis
- Parisitism
one party benefits at expense of others (includes pathogens)
- Commensalism
2+ organisms coexisting, neither party is harmed
- Mutualism
Both parties benefit
How many prokaryotes are there
prokaryotes make up around half of earth’s biomass, around 6 x 10^30 cells
How do prokaryotes mainly reproduce
They reproduce mainly through binary fission, which is a type of vertical gene transfer
what is conjugation
- Conjugation
- One prokaryotes passes genetic material to another through a type of gene bridge
What is transformation
- Transformation
- a prokaryote absorbs nucleic acid from the environment
what is transduction
- Transduction
- nucleic acid transmitted by viruses
What are the three types of primary horizontal gene transfer in prokaryotes
Conjugation,
Transformation,
Transduction.
Where are viruses on the tree of life
on our 3 domain tree of life, we have bacteria, eukaryotes containing plants, animals, fungi, and groups of protists, and archaea. But where are viruses?
well Viruses are not considered living, so they are not on the tree of life.
How might we define life
We might define life as anything that can or has the following characteristics:
- reproduction or replication
- structural order (cells)
- consumption and conversion of energy
- regulation of internal processes (homeostasis)
Why are viruses alive
Viruses meet the first characteristic but aren’t made of cells, don’t consume / convert energy, and don’t demonstrate homeostasis.
What might viruses illustrate
They might illustrate possible paths to the origins of life on earth, though since they are dependant on living cells, they are not the same as pre-cell lifelike things
What is the structure of a virus
small segment of nucleic acid
covered in a capsid and protein coat
Invade a host cell to replicate its nucleic acid sequence using the cells “machinery”
What is the replication cycle of viruses
- Attaches to a living cell
- Injects its nucleic acid into the cell
- the viral DNA or RNA takes over the cell
- It forces the cell to synthesize viral genomes and proteins (the building blocks of viruses)
- these components self assemble into new viruses
- the new viruses burst out of the cells
what are prions
a “selfish” protein
they can replicate themselves at the expense of cellular life
Causes diseases like mad cow
no nucleic acid, but they force other proteins to match their form
When did earth form and when did life begin
the earth formed around 4.5 billion years ago, but for the first 500 million years it was inhospitable during a time dubbed the Hadeon Eon
Prokaryotes emerged in the Archaen Eon, around 3.7-3.5 billion years ago.
what environment did early life start in
At this point the atmosphere contained no ozone and little oxygen, but it did have lots of UV, ammonia, and methane.
Life probably started in a warm ocean soup of carbon, nitrogen, and hydrogen.
what affects did prokaryotes have on the earth
Nitrogen fixing prokaryotes converted the unusable atmospheric nitrogen to usable forms, this makes up the base of the ecosystem.
Cyanobacteria and other photosynthesizers caused the 1st mass extinction when they “rapidly” increased the amount of oxygen in the atmosphere
what are 6 biotech uses of prokaryotes
Through gene editing technology like Crisper we can do a number of useful things
- make allergy free / better food
- green fuel
- eradication of disease
- bioremediation
- synthesizing materials
- storing data in DNA hard drives
what is the LTEE
LTEE (Long Term Evolution Experiment)
began in 1988 and still ongoing
12 populations of E.Coli were set up to feed on a glucose food source
everyday (equating to around 6-7 generations) 1% of each population were transferred to a fresh medium
Several lines evolved an interesting adaptation: the ability to feed on the wast product citrate.
