1.5 The origin of cells Flashcards
What is abiogenesis?
The theory that living cells arose from non living matter
What is one of the four key stages of abiogenesis to do with simple organic molecules?
There was non living synthesis of simple organic molecules
What was the non living synthesis of simple organic molecules from?
Primordial inorganic molecules
During one of the four key stages of abiogenesis what did the simple organic molecules assemble into?
More complex polymers
During one of the four key stages of abiogenesis what did certain polymers form the capacity to do?
Self replicate
During one of the four key stages of abiogenesis what does the self replicating polymers enable?
Inheritance
During one of the four key stages of abiogenesis what were the molecules packaged into and with?
Membranes with an internal chemistry different from their surroundings
What demonstrated the non living synthesis of simple organic molecules?
The miller-Urey experiment
What did the miller urey experiment recreate?
The postulated conditions of pre-biotic earth
What did miller urey use to create pre biotic earth?
A closed system of flasks and tubes
In the miller urey experiment what did they do to water and why?
Water was boiled to vapour to show the high temperatures of earths original conditions
In the miller urey experiment what was the vapour mixed with and why?
Gases such as H2, CH4, NH3 to create an atmosphere without oxygen
In the miller urey experiment, what happened to the vapour exposed to gases and why?
An electrical charge to recreate lightning as an energy source
In the miller urey experiment, what happened to the mixture with an electrical discharge?
It was left to cool for a week
In the miller urey experiment, what happened after it was left for a week?
The condensed mixture was analysed and found to have traces of simple organic molecules
Name three types of conditions needed for the chemical processes that contributed to the initial formation of biological life?
Reducing atmosphere
High temperatures
Electrical Discharge
Why cant cells arise independently by abiogenesis?
As the specific conditions needed do not commonly exist on modern earth
What is the only way cells can be formed?
By the division of pre existing cells
What is biogenesis?
The principle that living things only arise from other living things by reproduction
Who is credited with the law of biogenesis?
Louis Pasteur
What did Louis pasteur demonstrate?
Emergent bacteria growth in nutrient broths were due to contamination by pre existing cells
In Louis Pasteurs experiment, were where broths stored?
In vessels with swan neck ducts
In Louis Pasteurs experiment, why were swan neck vessels used?
To prevent external dust particles to pass
In Louis Pasteurs experiment, what happened to the broths and why?
Boiled to kill any micro organisms present
In Louis Pasteurs experiment, where did the growth occur?
If the flasks were broken open as they were exposed to the outside contaminents
What did the louis pasteur experiment conclude?
That emergent bacterial growth came from external contaminants and did not spontaneously occur
What is an endosymbiont?
A cell which lives inside another cell with mutual benefit
Where is believed that eukaryotic cells evolved from?
Early prokaryotes that were engulfed by phagocytosis
What happened to the engulfed prokaryotic cell?
Remained undigested as it contributed a new function to the engulfing cell
Over generations, what happened to the engulfed cell?
Lost some of its independent utility and became an organelle
What are two organelles suggested to have arisen via endosymbiosis?
Mitochondria and chloroplasts
What is evidence that supports the extracellular origins of mitochondria and chloroplasts?
Membranes
Antibiotics
Division
DNA
Ribosomes
How are membranes evidence of endosymbiosis?
Some organelles have double membranes
outer membrane may be vesicular in origin
How are antibiotics evidence for endosymbiosis?
They are susceptible to antibiotics which indicates organelles may have bacterial origins
How is division evidence for endosymbiosis?
Reproduction occurs via a fission-like process
How is DNA evidence for endosymbiosis?
Has own DNA which is naked and circular like prokaryotic DNA structure
How is ribosomes evidence for endosymbiosis?
Have ribosomes which are 70s in size like prokaryotes
