Topic 2 - Earth's History Flashcards
What are the three main domains of the Tree of Life?
& what is it based off of?
- Eukarya, Bacteria, Archaea
- mostly from highly conserved DNA sequences (genes encoding ribosomal RNA)
What are the 2 defining features of life? (biologists view)
- Ability to capture energy
2. Ability to use that energy to replicate (make copies) - ability to evolve
What were the 2 earliest milestones critical for the emergence of life?
- the first organic molecules (sugars, amino acids, purines, pyrimidines)
- first self-replicating polymers (RNA - ability to self-replicate and catalyze)
- the RNA world
History of Earth and the Fossil Record
1. When did the universe emerge?
14 billion years ago
History of Earth and the Fossil Record
2. When did the solar system emerge?
4.6 billion years ago
History of Earth and the Fossil Record
3. When was the first evidence of cellular life?
3.7 billion years ago
History of Earth and the Fossil Record
4. When was the first evidence of multicellular life?
640 million years ago
History of Earth and the Fossil Record
- What is the general order of earth’s history and the fossil record?
14 bill – 4.6 bill – 3.7 bill – 640 mill
Universe - solar system - cellular life - multicellular life
What where the 4 major events for early evolution?
- Genetic Code
- Cells
- 2 Important Biochemical Pathways
- Linear Chromosomes
What was the importance behind the evolution of the genetic code?
- nearly universal
- provided a link between nucleic acids and proteins
allows for early catalytic capability of building blocks and link to a LUCA
What advantages did the formation of cells bring? (2)
- formation of membranes (self-assembling lipid bilayers)
- compartmentalization (reactions could not occur in open environments)
1. concentrate all reactants & catalysts to increase reaction rates
2. increased reaction surface area
3. protect reaction from competition
What were the two early biochemical pathways?
- Autotrophic (CO2 fixing) allowing photosynthesis
- Aerobic respiration pathways (increased atmospheric O2 levels)
What were some advantages to these two early biochemical pathways?
- using elements around them to synthesize molecules of life
- switch from heterotrophic to autotrophic organisms leading to more complex carbon compounds
- a by product of photosynthesis
What did linear chromosomes allow evolution to progress?
- bacterial chromosomes only have 1 OoR meaning replication was slow and limited in size
- compared to a linear chromosome allowing multiple OoR (rapid) and an increase in size of chromosome to carry more information
What are 3 distinguishing features of Eukarya?
- cytoskeleton
- 1 of several linear chromosomes
- membrane-bound organelles
What was the origin of organelles?
Mitochondria and Chloroplasts descended from bacteria via Endosymbiosis
- engulfed smaller organisms and prevented them from collapsing establishing a symbiotic relationship with them
How can we establish the endosymbiotic relationship?
- through the ancestral and symbiont and tracking the movement of chromosomes between them
- certain algae lack the photosynthetic capability and engulf a symbiont with this ability
Are Eukarya a monophyletic group?
- there may have been several independent origins of eukaryotic-like cells
- evidence indicate eukarya evolved from a single common ancestor
What 2 points were essential attributes necessary for the multicellularity of cells?
- gene regulation (cell differentiation) - since different cells now have different functions
- Cell-cell communication (about cell positioning and state of differentiation) - chemical signalling
What is an important note about cancer?
- cancer can only evolve in cells with gene regulation
What was the first milestone in the evolution of complex life?
Separating genes (forming membranes) – lead to compartmentalization – lead to larger more complex genomes
What was the second milestone in the evolution of complex life?
Separate unicells to symbiotic unicells – eukaryotic cells – formation of symbiotic organelle and the transfer of genes between them
What was the third milestone in the evolution of complex life?
formation of multicellular organisms – evolution of a cell, tissue differentiation, and somatic/germ cells
What does the fossil record include? and how accurate is it?
- fossils only occur in sedimentary rock
- probability of fossilization depends on species and habitat
- fossil must occur near exposed or near-exposed strata
- estimate <1% of once living species are known as fossils
- they indicate life @ that time NOT a time period
What is radiometric dating?
- measures the decay of certain radioactive elements in minerals that form in igneous rock
What are examples of radioisotopes?
- U235 – Pb207 (700 mill)
- K40 – Ar40 (1.3 bill)
- C14 – N14 ( 5700 years)
What is one catch between igneous and sedimentary rock?
Fossils only form in sedimentary rock, however radiometric dating is an estimate using that rock type - thus the best radiometric dating is done using sedimentary rock wedged between two layers of igneous rock
When was the Archaean Era?
2.5 billion years ago
What originated from the Archaean Era, changed and allowed life to take off?
- it is the origin of cellular life
- lead to the diversification of archaea and bacteria
- two biological pathways evolved: photosynthesis and autotrophic pathways and aerobic respiration
When was the Proterozoic Era?
2.5 billion years ago till about 542 million years ago
What was the significant evolution accompanying the Proterozoic Era?
- origin of eukaryotes
- origin of multicellular organisms
- the oldest fossil around 640 million years ago
- but there was little detail to determine structures but we did see a burst of life
What time period does the Paleozoic Era encompass?
between 542-251 million years ago
Name the 6 Periods encompassed in the Paleozoic Era in order to the most recent
COS-DC-P Cambrian Ordovician Silurian Devonian Carboniferous Permian
Name the key traits of the Cambrian Period?
- introduced many phyla (especially marine), including algae and JAWLESS vertebrates
Name the key traits of the Ordovician and Silurian Periods?
- diversification of animal groups, earliest land plants emerged, and JAWED fishes
Name the key traits of the Devonian Periods?
- BONY fishes
- invertebrates (trilobites, ammonoids)
- insects
- seed plants
What are the key traits from the Carboniferous Period?
- abundant land plants (mosses and liverworts, early vascular plants, seed plants)
- winged insects
amphibians and reptilians - this formed the present day coal beds used
What are the key traits of the Permian Period?
- diversification of fishes, insects and other animals groups
- earliest form of mammal-like vertebrates
What is a challenge faced by the early plants?
- to avoid desiccation
- to have structural support
What are the remaining 2 Eras and there periods in order to the most present?
Mesozoic (250-65 million years ago)
- Triassic, Jurassic, Cretaceous
Cenozoic (65 million to present)
- Tertiary, Quarternary
What is one defining feature of the Mesozoic Era?
- it is well inhabited by plants and animals
What are the key points from the Triassic Period?
- seed plant domination on land
- first dinosaurs emerged
- first mammals appeared
What are the key points from the Jurassic Period?
- “Marine Revolution”
- radiation of dinosaurs
- first birds and flowering plants
What are the key points from the Cretaceous Period?
- radiation of mammals, birds, and flowering plants
- coincidentally
Birds vs their Ancestors
- birds are theropod dinosaurs/ transition from feathered dinosaur to birds
- increased brain size?
Two groups from which all dinosaurs evolved from?
- Ornithischia
2. Saurischia
What are the seven differences of birds compared to their ancestors?
- no teeth
- larger brain with fused skull bones
- reduction of digits of the forelimb
- fusion of pelvic bones
- fewer tail vertebrae
- enlarged, keeled sternum
- reinforcing processes on the ribs
Who where the ancestors to the birds?
Saurischian theropod dinosaurs
What were the other 3 differences between mammals and their synapsid vertebrate ancestors and their ancestors?
- hair: allowed thermal regulation
- mammary glands and changes in diet and their masculature
How many years before present did the tertiary and quaternary periods occur?
- Tertiary: 65 million to 5.3 million
- Quaternary: 2.56 million years till present
What were the defining features of the tertiary period of the Cenozoic Era?
- cooling climate
- radiation of modern groups (mammals, birds, snakes, teleost fishes, flowering plants)
- diversification of pollinating insects
What are the defining features of the quaternary period of the Cenozoic Era?
- consists of the Pleistocene-Holocene Periods
- glaciation and lowered sea levels
- extinctions occurring
- and the rise of hominins
What are 2 significant points that dictated what the Cenozoic Era appeared like?
- groups were recognizable at the beginning of this period
- there was enough variation in the landscape that continental localization affected the climate
Evolution of Primates (and Humans)
What was the order of evolution to humans?
First primates First monkeys First apes First hominins Earliest Homo H. erectus Modern H. sapiens
What is the timeline for the first primates?
- primates during the early Cenozoic Era (Paleocene)
- moneys during the Oligocene period
- apes during the miocene period
around 22 million years ago
What was the first timeline of the first hominins?
Sahelanthropus - late Miocene 6 million years ago
Australopithecus - later on 3.5 million years ago
What was the first timeline of the first Homo species?
- earliest Homo during the late Piocene and early Pleistocene around 1.9 million years ago
- H. erectus was around 1.6 million years to 200,000 years ago
- H. sapiens was around 170,000 years ago
Name the order of evolution from chimpanzees to homo sapiens.
Chimpanzee Australopithecus afarensis Australopithecus africanus Homo habilis Homo erectus Homo neaderthalensis Homo sapiens
Name the 5 Eras in order from oldest to present day, including their important Periods.
APP-MC
- Archaean
- Proterozoic
- Paleozoic: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian
- Mesozoic: Triassic, Jurrassic, Cretaceous
- Cenzoic: Tertiary and Quaternary
