Flashcards in Evolutionary History of Life- Early Life & Diversification of Prokaryotes Deck (75)
What are the 4 stages of early cells?
1. Abiotic synthesis of organic molecules
2. Polymerization into macromolecules
3. Packaging into Protocells
4. Origen of self replicating molecules enabling inheritance
What are early organic compounds?
Water vapour condenses into oceans and volcanic gas
What produced many amino acids and other organic molecules?
A reducing environment and activation energy
What is abiotic synthesis of macromolecules?
Organic molecules that can spontaneously come from polymers just by dripping onto a hot substrate such as sand, clay or rock
What are Protocells?
Aggregates of abiotically produced organic molecules which are enclosed by a membrane or similar structure
What are liposomes?
Membrane-bound droplets that can form when lipid are added to water
What was the first inheritance molecule?
What were early Protocells?
Were likely more effective at using resources and therefore likely increase due to natural selection
Why is double stranded DNA more stable than RNA?
Larger genomes that can store much more information and more stable molecules and ensures few copying errors
What are prokaryotes?
They are mostly microscopic what they lack in size they make up in numbers. Number of prokaryotes in one handful of soil is greater than the number of people who have ever lived
What is Cyanobacteria?
The greatest impact of any organism in the history of earth
What are the three most common shapes of prokaryotic cells?
Spheres(cocci), rods (bacilli) and spirals(spirilla)
What is the crucial feature of nearly all prokaryotes?
Cell wall: maintains cell shape, provides physical protection and prevents the cell from bursting in a hypotonic environment. Made of peptidoglycan
What is the Gram stain?
It is used to classify many bacterial species into two groups based on cell wall composition. Gram-positive traps crystal violet and Gram negative the crystal violet is rinsed away revealing red dye
What is the capsule?
The cell wall of many prokaryotes that is covered by a sticky layer of polysaccharide or protein
What are pili or fimbriae?
They help prokaryotes stick to the substrate or other individuals in the colony
How do prokaryotes move?
Propel themselves by flagella
What does the typical prokaryotic genome consist of?
-Has less DNA than the eucaryotic genome
-Most of the genome consists of circular chromosomes
-Some species of bacteria also have similar rings of DNA called plasmids
What are the four models of nutrition ?
1. Phototroughs obtain energy from light
2. Chemotrophs obtain energy from chemicals
3. Autotrophs use carbon dioxide as a carbon source
4. Heterotrophs use organic nutrients to make organic compounds
What are the different metabolic relationship with O2?
-Obligate aerobes require oxygen
- Facultative anaerobes can survive with or without oxygen
- Obligate anaerobes are poisoned by oxygen
What is nitrogen metabolism?
What is nitrogen fixation?
Nitrogen is critical for building amino acids and nucleic acid's
Some prokaryotes convert atmospheric nitrogen into ammonia
What is metabolic cooperation?
Cooperation between prokaryotes that allows them to use environmental resources they cannot use as individual cells
How do prokaryotes reproduce?
By binary fission. Offspring are generally identical
What comes from genetic recombination?
- Additional diversity
- Prokaryotic DNA from different individuals can be brought together by transformation, transduction and conjugation
What is transformation? Transduction?
Transformation is when a prokaryotic cell can incorporate foreign DNA from the surrounding environment
Transduction is the movement of genes between bacteria by bacteriophages
What is conjugation?
Genetic transfer between bacterial cells. Sex pili allows cells to connect and pull together for DNA transfer
What is the F factor?
A piece of DNA that is required for the production of sex pili. The F factor can exist as a separate plasmid or have DNA within the bacterial chromosome
What are bacteria?
Include the mass majority of prokaryotes most people are aware of
What are proteobacteria?
Gram-negative bacteria that include photoautotrophs, chemoautptrophs, and heterotrophs