Session 2: Introduction to Evolution Flashcards
What was Thomas Malthus’ theory of evolution?
That populations increased in size until checked by the environment, called the “struggle for existence” because organisms competed with each other.
What was Charles Lyell’s theory for Evolution?
The physical features of the earth were the result of slow geological processes that still occur today.
What was Jean Baptise Lamarck’s theory of evolution?
Individuals pass on acquired characteristics to their offspring. He was the first to propose that change over time was the result of natural phenomena and not divine intervention.
What was Darwin’s proposal?
Darwin proposed natural selection and also the theory that organisms had common ancestors.
What were the four main principles of Darwin’s Theory of Evolution: Evolution by Natural Selection?
- All species produce more offspring than the resources can support
- There is natural variation between individuals of a species
- Individuals with advantageous genotypes will be more likely to survive & produce offspring
- Over subsequent generations, the frequency of the advantageous genotype increases, leading eventually to evolution of the species
Define evolution.
The permanent genetic change (a change in allele frequencies) in a population of individuals over successive generations. It does not refer to changes occuring to individuals within their own lifetimes: populations evolve, not individuals.
What are the three basic “ingredients” for life?
A source of energy (sun and thermal vents), a carbon source, and liquid water.
What are the processes needed for the origin of life?
- The non-living synthesis of simple organic molecules (from primordial inorganic compounds)
- The assembly of these organic molecules into polymers
- The formation of polymers that can self-replicate (enabling inheritance)
- Packaging of these molecules into membranes with an internal chemistry different from their surroundings
What were the features of the primordial sea?
Life may have arisen in the primordial sea which has high volcanic activity, high UV radiation (thin atmosphere), lightning, water vapour, methane, ammonia, and hydrogen.
Describe the features of undersea thermal vents that made life possible.
gases, energy (heat), and a possible source of catalysts (metal sulfides) for life to develop.
What is panspermia?
The theory that life originated in microorganisms or chemical precursors, etc. in outer space. This theory is justified because some bacteria can survive in conditions similar to space, amino acids have been found in several meteorites, comets contain a variety of organic molecules (~20% of a comet’s tail is comprised of organic material), and a heavy bombardment about 4,000 million years ago may have delivered both organic compounds and water to early Earth.
Describe what RNA has to do with the first cells.
RNA molecules have the ability to act both as a blueprint and as a catalyst (enzyme). This characteristic offers a way around the “chicken-and-egg” problem that: Genes require enzymes to form and enzymes require genes to form. This is likely to have led to the first cells.
What are the two relevant properties of RNA?
- RNA can self-replicate. RNA is able to store information in a sequence of four nucleotides (similar to DNA). Short sequences of RNA have been able to duplicate other molecules of RNA accurately
- RNA can act as a catalyst: Modern cells use RNA catalysts (called ribozymes) to remove introns from mRNA and help synthesise new RNA molecules. In ribosomes, rRNA is found in the catalytic site and plays a role in
peptide bond formation
What would the first cells (ever) need?
A membrane separating the internal environment from the external environment, storage of specific biological molecules, and the ability to replicate.
What was the first evidence of life?
Microbial mats such as stromatolites are multilayered sheets formed by microorganisms such as archaea and bacteria. There is good fossil evidence of these mats that have been dated to at least 3.5 billion years old. Some of the best evidence comes from fossils found in Western Australia. Fossils can tell us about the environment that an organism lived in/if it changed/how much it changed.
