A2.1 Origin of cells Flashcards
Outline the conditions that are thought to have existed on prebiotic Earth, including atmosphere, temperature, UV radiation, volcanic activity and asteroid bombardment.
Ammonia and methane in the atmosphere
no ozone layer
Subject to a lot of bombardments
Many volcanic eruptions
Higher levels of UV radiation
Temperature extremely hot
Loads more volcanoes
State that the conditions of prebiotic Earth may have caused a variety of carbon compounds to form spontaneously.
Because of prebiotic earth’s conditions it is likely that it caused the spontaneous formation of carbon compounds.
Discuss the challenges of defining matter as living or nonliving.
The challenges of defining matter as living or nonliving is that whatever rule they set there was an exception.
Discuss the reasons why cells are considered to be living.
Cells are considered to be living because it is able to use energy to sustain itself in a highly ordered state
Discuss the reasons why viruses are considered to be non-living.
They aren’t made of cells
Can’t keep themselves stable
Do not grow
Can’t replicate
Can’t perform independent metabolism
Outline the intermediate stagesneeded for the evolution of the first cells on prebiotic Earth.
- Inorganic compounds
- Organic monomers
- Polymer
- Self-replication
- Formation of Cell
Discuss limitations in testing hypotheses about the evolution of the first cells.
Conditions on early earth were very different, impossible to replicate with certainty
Well preserved fossils are rare
Methods used to estimate dates of first living cells have ranges of uncertainty
Outline the methodology, results and conclusion that can be drawn from Miller and Urey’s experiments into the origin of biologically relevant carbon compounds.
The Miller-Urey experiment was done to see whether simple carbon compounds can form from inorganic compounds. To do this they recreated the conditions of pre-biotic earth.
Discuss the benefits and limitations of the Miller-Urey apparatus as a model for a natural phenomena.
It was able to replicate conditions that weren’t directly observable
They couldn’t include every single possible variable
Outline the cause and consequence of the spontaneous formation of membranes and vesicles by amphipathic molecules such as fatty acids and phospholipids on prebiotic Earth.
Spontaneous formation of membranes and vesicles were formed from amphipathic molecules like phospholipids and fatty acids because they contain both a hydrophilic and hydrophobic side. This allowed cell membranes to develop meaning that the cells could then have an internal chemistry that was different from the outside chemistry, an important step in the origin of cells
State that modern cells use DNA as the genetic material and enzyme proteins as catalysts of metabolism.
Modern cells use DNA as the genetic material and enzyme proteins as catalysts of metabolism
List properties of RNA that suggest it was the first genetic material.
- RNA can act as catalysts for their own replication
- RNA is formed from inorganic sources
- RNA can catalyze essential biochemical reactions
- RNA that functions as a catalyst are called ribozymes which form peptide bond between amino acids during translation.
Compare the genetic stability of RNA and DNA.
The sugar phosphate bond in DNA makes it chemically more stable than RNA
Outline the ribosomal ribozyme as a type of RNA that is still used as a catalyst.
Ribosomal ribozyme is used to catalyze specific reactions in a similar way to that of protein enzymes.
Define LUCA.
LUCA (Last Universal Common Ancestor) is the last living organism that all living organisms today descended from
