Theme A: A2 Cells - A2.1 Origin of Cells Flashcards
possible components of earth’s early atmosphere
1) it was thick with water vapour and other compounds by volcanic eruptions
2) the gases, especially CO2 and CH4 present in higher concentrations than today, allowed UV light to penetrate Earth’s atmosphere and retain heat resulting in high surface temperature
3) free oxygen was not present. had it been, it would have formed a layer of ozone in the upper regions of the atmosphere, thus blocking UV radiation + high temps
formation of carbon compounds
Earth’s early atmospheric components coupled with high surface temperatures and lightning, followed by a gradual cooling, resulted in the spontaneous formation of carbon compounds. this spontaneous formation occurred during the unique conditions of Early Earth that are not evident today.
3 main principles of cell theory
1) all organisms are composed of 1 or more cells
2) cells are the smallest unit of life
3) all cells come from pre-existing cells
stages of cell evolution
1) synthesis of small organic molecules (monomers / carbon compounds) from abiotic (non-living) molecules
2) small organic molecules joining to form large chain molecules (polymers)
3) polymers becoming enclosed by membrane-like structures, creating a protective homeostatic environment that separates them from their surroundings
4) development of self-replicating molecules, allowing inheritance and control of biological functions
enzyme
proteins that act as biological catalysts by accelerating chemical reactions. they are carbon compounds, thus they always contain carbon and hydrogen atoms (usually along with other elements)
inorganic compounds
Chemical compounds that generally do not contain carbon-hydrogen (C-H) bonds. They are often associated with non-living matter, though some inorganic compounds, such as water (H₂O), salts (NaCl), and carbon dioxide (CO₂), are essential for life processes. Inorganic compounds include minerals, salts, metals, and substances like oxygen and water.
organic compounds
Typically contain carbon-hydrogen (C-H) bonds and are mostly associated with living organisms. Examples include carbohydrates, proteins, lipids, and nucleic acids. with this, it can be said the carbon is the keystone element of life.
Miller-Urey experiment
conducted in 1953 by Stanley Miller and Harold Urey to simulate early Earth conditions and test the hypothesis of abiogenesis (the natural process by which life arises from non-living matter).
The experiment demonstrated that organic molecules, such as amino acids, could form from simple inorganic compounds - by recreating a premordial soup of water, methane, ammonia, and hydrogen - when exposed to energy sources like electric sparks (simulating lightning). This supported the idea that life’s building blocks could have originated in Earth’s early atmosphere.
primordial soup
a water based sea of simple organic molecules
the Earth’s mantle
an intermediate layer surrounded by the exterior crust and resting on the core
vesicles
Small membrane-bound sacs composed of a lipid bilayer that transport and store substances within a cell or between cells
ribozymes
type of RNA that are highly active today in catalysing activities. it speeds up chemical reaction, like allowing faster development of peptide bonds which are essential for protein synthesis.
major stages in the origin of life
- early Earth
- abiotic chemical compounds
- small organic molecules
- polymers of organic molecules
- protocell
- cell
fossils
remains/traces of past life, mostly originating from teeth, bones, and shells or the hard parts of an organism. some fossils also represent trials, footprints, and even soft body parts.
half-life
time it takes for half a radioactive isotope to change into another stable element
