Unit One: Life on Earth Flashcards
What is said to be life’s origin?
various meteorite strikes
What meteorite has been said to fall from mars to earth with extraterrestrial life?
ALH84001
4 +3/4 lbs, formed by molten lava
What are the two types of life?
1. Biotic (living)
2. Abiotic (non-living)
What are the biotic characteristics of viruses
- nucleic acids
- ability to reproduce and replicate
- ability to evolve and adapt
What are the abiotic characteristics of viruses
- cannot synthesize their own proteins
- cannot live without host attatchment
- cannot reproduce
What are the characteristics of all life forms?
- Display orderly fashion
- Harness and utilize energy for mechanical purposes
- Reproduction
- Responding to stimuli
- Homeostasis
- Growth and Development
- Evolution
What are some characteristics of the earth
- earth is 4.6 billion years old
- first prokaryotes: 3.5 billion years
- first eukaryotes: 2.0 billion years
- dinosaur extinction: 65 million years
- modern humans: 150,000 years
What are the 4 classes of molecules
- Nucleic Acids (DNA, RNA, ATP)
- Proteins (amino acids)
- Lipids (fats)
- Polysaccarhides (carbohydrate)
What are the 3 hypothesis’ to early years of earth
- Reducing Atmosphere
- Deep Sea Vents
- Extraterrestrial Origin
Reducing Atmosphere Hypothesis (1)
- beginning (primordial) atmopshere
- water vapour (H2, CO2, NH3, CH4)
- almost complete absence of O2
What is the Oparin-Haldane Hypothesis
- early atmosphere was reducing (eliminating O2 and O3)
- simple organic molecule formation
- amino acids first –> complex polymers
- molecule development through UV light
What is the confirmed modern atmospheric content
- oxidizing atmosphere
- high levels of O2 prevents formation of complex molecules
Deep Sea Vents Hypothesis (2)
- complex organic molecules originated on ocean floor through deep sea vents
- cracks near volanic activity
- produces nutrient rich water
- NH3, CH4, H2S
Extraterrestrial Origin Hypothesis (3)
- key organic molecules originated from outer space
- organic molecules: carbon based
- carbonaceous chondrites: meteorites with organic molecules
Earliest Form of Life: Heterotrophs
- heterotrophs
- organisms containing organic molecules
- consumers
- earliest forms were considered anerobic
Earliest Form of Life: Autotrophs
- autotrophs
- contain carbon from environment (inorganic form CO2)
- photoautotrophs additionally use light as an energy source
What is Organic Photosynthesis
- light to support various functions
- increase in atmospheric oxygen
What evidence points to proof of organic photosynthesis
- banded iron
- striped red rock sediment
- red on striped rock sediment come from rust
Where did the source of O2 come from in organic photosynthesis
- photosynthetic prokaryotes + cyanobacteria
- extract electrons from H2O
- liberates O2
- relies on oxidation of water for electrons
What was the VERY first organism on planet Earth
- protists
- 200,000 eukaryotes
- mostly unicellular
- not animals, plants, or fungi
- paramecium, aemoba
What are Fossil Records
- only direct evidence from millions of years ago
- represents a small fraction of existed life
- fossils form in sedimentary rocks
What are Fossil Records
- only direct evidence from millions of years ago
- represents a small fraction of existed life
- fossils form in sedimentary rocks
What are Strata
- layers of sediments
- particles setting on the bottom of water bodies
- lowest layer = oldest
- fossil formation and preservation
- hard tissues, unconsumable
- lack of oxygen prevents decomposition
ex: tree resin, ice glace
What are some examples of Fossil Records
- Petrified Wood
- Sedimentation
- Strata
- Mosquitoes in Amber
- Mammoth in Permafrost
What are the 3 Trees of Life
- Eukarya
- Bacteria
- Archea
What does LUCA stand for?
Last Universal Common Ancestor
all life descends from a common ancestor
What are the Common Features in the Tree of Life
- Lipid Bilayer: made up of lipid molecules + semi-permable membranes (selective entrance)
- Genetic System based on DNA: cell “blueprint”
- System of Information Transfer: DNA to RNA
- System of protein assembly: “central dogma”
- Protein Reliance: enzymes, channels, structures
- ATP as energy currency: continual resynthesis
- Break of Glucose: fuel composition for ATP resynthesis