Lecture 2 Exam 1 Flashcards
What is needed for life as we know it?
- information storage: a genotype and phenotype
- energy acquisition and utilization
- reproduction
Describe the RNA World Hypothesis
- DNA can store and transmit information but not preform biological work
- proteins can preform biological functions but not propagate
- RNA can store info and do biological work - ribozyme has genotype and phenotype
- RNA is the only known molecule that carries genetic info and can catalyze chemical reactions
- However self replicating RNA has not been demonstrated or discovered
What is the primordial/prebiotic soup?
- The oparin-haldane model
1. assemble simple molecules assemble into building blocks for complex polymers
2. assemble polymers that can store information and catalyze reactions
3. add membranes and an energy source to make a living organism
What is the experiment by Stanley Miller?
Demonstrated that many of the compounds necessary for life could be produced in a “prebiotic” atmosphere
- formaldehyde, hydrogen cyanide, purine, pyrimidines, amino acids, sugars
What is panspermia?
- the idea that life can be distributed throughout the universe and can be spread through extraterrestrial meteorites
What is special about the murchison meteorite?
- sugars were found on it
- purine and pyrimidine compounds found on it are indigenous components of the meteorite
- this means that the components of the genetic code were already present in the early solar system and may have played a key role in life’s origin
How old are the…
Universe
solar system and earth
oldest known rocks on earth that contain life
living things
Universe: 16 billion
solar system and earth: 4.6 billion
oldest known rocks on earth that contain life: 3.7-3.8 billion
living things (fossils): 3.2-3.5 billion
What is known about the last universal common ancestor (cenancestor)?
- predates 2 billion years because of fossil evidence of cyanobacteria
Why is it that not all genes have the same evolutionary history, when seen in phylogenetic trees?
- recombination of cells (independent histories)
- lateral gene transfer
Describe igneous, sedimentary and metamorphic rock. Which one is where most fossils are found?
- igneous: created from molten material
- sedimentary: deposition and solidification of sediments
- metamorphic: results from the transformation of igneous or sedimentary rock under high pressures and temperatures
- most fossils are found in sedimentary rock because animals/plants are more likely to be found where sediment is likely to shelter them
Superposition is…
- younger rocks are deposited on older rocks (superposition)
What is absolute dating?
- unstable atoms such as uranium eventually change into stable atoms such as lead. The original version is called a parent atom and the new version is called a daughter atom
- Assumption 1: The original number of unstable atoms can be known
- Assumption 2: The rate of change was constant
Assumption 3: The daughter atoms were all produced by radioactive decay
Which elements are better for absolute dating?
- the shorter the half life, the more accurate the dating
What are some principles for biological dating with tree rings
- first cells in spring are large and get smaller through the growing season
- growth stops at the onset of cold weather
- widths of the rings indicate growing conditions
- good conditions, rain, produce wide ring
- bad conditions, drought, produce narrow rings
-allows the estimation of climatic occurrences such as rainfall
Describe the Continental drift theory
- proposed by alfred wegener and not fully accepted until seafloor spreading was validated
- plate tectonics is the theory that earth’s outer shell is divided into several plates that glide over the mantle, the rocky inner layer above the core
- 3 different types
- divergent: the plates are moving apart (produces ocean floor)
- convergent: the plates are moving towards each other
- transform fault: the plates are grinding past each other
