The Origin of Life Beginning of Life Earth

The Origin of Life

Beginning of Life… • Earth formed 4. 6 billion years ago • 3. 9 billions years ago, Earth began cooling • Around 3. 5 billion years ago, the first organisms appeared.

Earth’s Early Atmosphere • Contained hydrogen cyanide (HCN), carbon dioxide (CO 2), carbon monoxide (CO), nitrogen (N), hydrogen sulfide (H 2 S) and water. • Which important element is missing? Why do you think it’s missing?

How did life form? • Hypothesis 1: Life came from other living things (Biogenesis) • Hypothesis 2: Life was produced from nonliving matter (Spontaneous Generation)

Spontaneous Generation Franciso Redi designed experiment to test the idea of spontaneous generation. Two jars: One with rotting meat and no lid One with rotting meat and a cloth covering Developed maggots and flies No maggots or flies

Perhaps, it was something in the air… Louis Pasteur filled an Sshaped flask with nutrient broth and boiled it. The design of the flask allowed air to get to broth, but not microorganisms. After ONE year, no microorganisms entered the broth.

Miller-Urey experiment proposes how organic compounds could have formed from simpler compounds. electrodes “atmosphere” water “ocean” heat source amino acids

The oldest known fossils are a group of marine cyanobacteria. – prokaryotic cells – added oxygen to atmosphere – deposited minerals

Eukaryotic cells may have evolved through endosymbiosis. • Endosymbiosis is a relationship in which one organism lives within the body of another. • Mitochondria and chloroplasts may have developed through endosymbiosis.

The evolution of sexual reproduction led to increased diversity. • Genetic variation is an advantage of sexual reproduction. • Sexual reproduction may have led to the evolution of multicellular life.

Evolution did a number on this guy!

• Evolution is change over time – Explains how descendants differ from ancestors.

• A species is a group of organisms that can reproduce and have fertile offspring. Fertile Infertile

Father of Evolution – Charles Darwin • There are four main principles to theory of natural selection. – Adaptation – Overproduction – Variation – Descent with modification

• Natural selection - process where individuals with inherited beneficial adaptations produce more offspring than others. -Survival of the Fittest!! • Adaptations are traits that increase an organism’s chance to survive. -Malaria and Sickle Cell Anemia

• Variation is a difference in a physical trait. – Galápagos finches with different beaks suited for different seeds – Blood type in humans – A, B, AB and O – Mutation is a change in the DNA sequence

Artificial selection is the selection of specific traits for breeding. Does artificial selection increase or decrease variation? ? Examples of artificial breeding: Horses (racing), Dogs (purebreds), and Cows (milk)

• Overproduction occurs when more offspring of a species are produced than can possibly survive.

Thomas Malthus Theorized human population would run out of living space and food if population continued to grow. Factors prevent populations from growing out of control: war, famine and disease. Darwin realized that applied even more to plants and animals.

• Descent with modification is the principle that each living species has descended, with changes, from other species over time. • Heritability is the ability of a trait to be passed down.

Lamarck’s Inheritance of Acquired Traits Use or disuse of organs could determine the size or even elimination of organs

Evidence from Comparing Anatomy Homologous structures – similar evolution (during development), different functions Analogous structures – evolved separately, similar functions Different functions, similar bone structure Wings of a pterosaur, bat and bird

Evidence from Comparing Anatomy Vestigial organ – organ that serves no useful function in an organism

Macroevolution Large-scale evolutionary patterns and processes over long periods of time.

Different Types of Evolution – Divergent and Adaptive Radiation Divergent - Two or more related species becoming more and more different. Adaptive radiation – species that evolve into several different forms living in different ways.

Different Types of Evolution Convergent – organisms independently evolve similarities when adapting to similar environments. Human hand Fly wing Wings of a pterosaur, bat and bird Mole foot Bat wing

Different Types of Evolution - Coevolution • Coevolution can occur in competitive relationships, sometimes called evolutionary.

Opposite to Evolution – Extinction Species that has died out. More than 99% of all species are now extinct.

Types of Adaptations – Camouflage (Crypsis) Adaptation that allows an organism to blend in with its surrounding environment.

Types of Adaptation - Mimicry Copying the appearance or behavior of another organism to avoid predators.