Unit 1 Evolution Lucy Australopithecus afarensis Charles Darwin

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Unit 1: Evolution Lucy Australopithecus afarensis

Unit 1: Evolution Lucy Australopithecus afarensis

Charles Darwin 1859

Charles Darwin 1859

How did life arise?

How did life arise?

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2.

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2. Complex biomolecule(s) capable of replication 3. A membrane enclosure 4. Selection & evolutionary change

Formation of the elements in stars PBS Video Local copy • PBS link to

Formation of the elements in stars PBS Video Local copy • PBS link to the Video NOVA. Origins: back to the beginning. Chapter 5

Clicker question on video Build up of the element iron causes a star to

Clicker question on video Build up of the element iron causes a star to die. What happens when a star dies? a. b. c. d. This is a dead end for the star which will be overcome by the birth of new stars with greater energy. The dead star explodes and the energy generated overcomes barriers imposed by the concentration of iron allowing other higher elements to be formed. Dead stars by chance impact with other stars allowing them to regenerate and energize. The dead star is not actually dead as it has a “broth” whose chemicals can be utilized to make new compounds.

Clicker question on video Data from the Hubble Telescope show remarkable images of the

Clicker question on video Data from the Hubble Telescope show remarkable images of the Eagle Nebula. Scientific data based upon the study of the Eagle Nebula are consistent with which of the following statements? a. b. c. d. Stars developing in the Eagle Nebula will overcome our solar system within a billion years. The Eagle Nebula is a beautiful rendition of fireworks and star development that has no impact on our understanding of the development of our own solar system. Because the elemental composition in the areas within the Eagle Nebula where stars are forming is similar to that of our sun, it is possible that conditions for life could be repeated in these new solar systems. The Eagle Nebula is a representation of an older group of solar systems very far away from our solar system and what we see in the telescopic images is the death of an older set of stars where the light images are just reaching us.

Were building blocks of life present? 1. All elements are forged in the interior

Were building blocks of life present? 1. All elements are forged in the interior of stars – when a star explodes in a supernova elements blasted into space. 2. Many carbon-based molecules including CN, CH 3, CO 2, amino acids, and precursors of nucleotides brought to Earth by asteroids & comets. 3. Early oceans were a chemical factory for rich array of organic molecules.

Most Common Elements in Living Organisms? carbon (C) oxygen (O) hydrogen (H) nitrogen (N)

Most Common Elements in Living Organisms? carbon (C) oxygen (O) hydrogen (H) nitrogen (N) calcium (Ca) phosphorous (P) potassium (K) sulfur (S)

Formation of Solar System, Earth & Life • Our solar system formed about ____

Formation of Solar System, Earth & Life • Our solar system formed about ____ years ago. 4. 5 -4. 6 BYA • The Earth’s surface had cooled sufficiently for oceans to form by ~ _____ years ago. 4. 0 BYA • The first fossil evidence of life is about _____ years old. 3. 7 -3. 8 BY

Stanley Miller Experiments • 1953, 23 year old Stanley Miller sets up an experiment

Stanley Miller Experiments • 1953, 23 year old Stanley Miller sets up an experiment to mimic early Earth environment in a flask. The flask contained water vapor, H 2, CH 4, and NH 3. For energy he used heat and a sparking device to mimic lightning. After a week, he found specific organic compounds, amino acids, the building blocks for proteins.

Organic Compounds Hydrogen & other elements covalently bond to carbon to form: • Carbohydrates

Organic Compounds Hydrogen & other elements covalently bond to carbon to form: • Carbohydrates • Lipids • Proteins • Nucleic Acids

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2.

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2. Complex biomolecule(s) capable of replication

Was RNA the original self replicating molecule? • Ancient viruses use RNA as genetic

Was RNA the original self replicating molecule? • Ancient viruses use RNA as genetic material, not DNA. Some are still common such as influenza and hepatitis C. • Further evidence lies in diverse role of RNA in all modern cells and discovery of catalytic functions. • Only RNA can initiate DNA replication. A bacterial ribosome: Green = protein Blue = RNA • RNA regulates gene expression, repairs genes, carries genetic information from DNA to ribosomes. • Ribosome, an ancient molecular complex that assembles proteins is made of RNA + protein. The RNA is part of the catalytic site for peptide bond formation.

“chicken & egg problem” for the origin of life: “DNA needed to make proteins

“chicken & egg problem” for the origin of life: “DNA needed to make proteins but proteins needed to make DNA” • Proteins known as enzymes catalyze reactions essential to cell's survival • Proteins were thought to be the only biological molecules capable of catalysis. • Ribozymes: Catalytic functions discovered • Altman & Cech (1982) discovered RNAs can act as catalysts for chemical reactions. These catalytic RNAs are known as ribozymes • Certain ribozymes called RNA replicases were also The Hammerhead Ribozyme found to catalyze their own synthesis

RNA World G C • All these lines of evidence suggest use of RNA

RNA World G C • All these lines of evidence suggest use of RNA by early life forms for genes AND replication preceded proteins and DNA • Later more stable and efficient molecules such as DNA and proteins evolved and replaced much of RNA’s functionality • In 1986 Harvard biologist Walter Gilbert called this idea the RNA World hypothesis T A RNA World Proto-cell

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2.

Ingredients for the Origin of Life 1. Basic elements & basic organic compounds 2. Complex biomolecule(s) capable of replication 3. A membrane enclosure 4. Selection & evolutionary change

Lipid Bilayer • Natural bilayers are made of phospholipids having a hydrophilic head &

Lipid Bilayer • Natural bilayers are made of phospholipids having a hydrophilic head & 2 hydrophobic tails. • When exposed to H 2 O spontaneously form a two-layered sheet with tails pointing toward the center • The cell membranes of all living organism are made of a lipid bilayer, as are membranes surrounding nucleus & other sub-cellular structures.

Formation of the Protocell • Self-assembly of Membrane • Permeability of Membrane • Division

Formation of the Protocell • Self-assembly of Membrane • Permeability of Membrane • Division of the Proto-cell

Animation of protocell division • http: //exploringorigins. org/protocells. html • This brings us to

Animation of protocell division • http: //exploringorigins. org/protocells. html • This brings us to the site and we want to look at the animation entitled “A protocell life cycle featuring RNA replication and vesicle growth. ”

How do protocells evolve? • Protocells encapsulated with higher RNA content outcompete protocells with

How do protocells evolve? • Protocells encapsulated with higher RNA content outcompete protocells with no or little RNA – They may grow by stealing membrane • RNA’s must be replicases and mutation rate will generate better versions and enhance competition with other protocells • Merging with other protocells can bring RNA with other capabilities into the protocell

Proto-Cell Competition & Evolution • Replication of RNA molecules within protocell creates osmotic gradient

Proto-Cell Competition & Evolution • Replication of RNA molecules within protocell creates osmotic gradient • Cell membrane stretches - grabs fatty acids from membranes of cells with lower RNA replication rates & hence lower osmotic gradients • Via this process cells with higher rates of RNA synthesis divide & grow faster than other cell types – eventually outcompete and take over • Competitive vesicle growth could have played role in emergence of Darwinian evolution at one gene-one cell level

Creation of artificial life • PBS Video link – Click “Launch video” button Local

Creation of artificial life • PBS Video link – Click “Launch video” button Local copy

Attendance Exercise Question Please answer the following question in about 5 -8 sentences using

Attendance Exercise Question Please answer the following question in about 5 -8 sentences using pen/pencil/paper. Make sure to indicate your name and please write legibly. When done, hand your (non -carbon) copy to Teaching Assistant. If it is indeed possible to create new life forms that resemble current microbial life forms or possibly to make entirely different microbial life forms from what developed naturally on Earth, should we? Are there dangers/advantages to following this line of experimentation?