Earth’s Early History

Origin of Eukaryotic Cells Eukaryotic cells have a nuclei, have complex organelles, have mitochondria Prokaryotic cells do not have a nuclei (simpler organisms)

Origin of Eukaryotic Cells Endosymbiotic Theory Symbiotic relationship between eukaryotic cells and the prokaryotic cells within them. Mitochondria and chloroplast were once prokaryotes Eukaryote ate them So mitochondria and chloroplast have their own DNA

Endosymbiotic Theory

Darwin’s Theory of Evolution Book: “The Origin of Species” 1859

Darwin’s Theory of Evolution “The Origin of Species” Evolution – All the changes that have transferred life over an immense time

Darwin’s Theory of Evolution Prior to Darwin 2 theories about how life on Earth prevailed: 1.Species do not change 2.That Earth was less than 10,000 years old (young)

Darwin’s Theory of Evolution Adaptation – (today) An inherited characteristic that improves an organism’s ability to survive and reproduce in a particular environment

Darwin’s Theory of Evolution Galápagos Islands Many important observations came from the Galápagos. Animals here were different from all other places

Darwin’s Theory of Evolution - Galápagos Islands Islands had many unique organisms They were different even between islands It was believed when they would migrate they would adapt to new environment

Darwin’s Theory of Evolution Darwin’s 2 Main Points: 1.Species of organisms living on Earth today descended from ancestral species. (Come from another species)

Darwin’s Theory of Evolution 2.Natural Selection is the mechanism for evolution Natural Selection Natural Selection – individuals with inherited characteristics best suited to the environment will live longer and leave more offspring on average than other individuals. Example: In savannah with tall trees there are giraffes with long and short necks. Which giraffes do you think will live longer? So if they live longer the will make more babies. So in the future there will be more of which type of giraffe? NATURAL SELECTION!!!

Fossils The preserved remains or markings left by organisms that lived in the past

Fossil Record The chronological collection of life’s remains in the rock layers Older rocks lower in the crust

Similarities in Structure Homologous Structures Homologous Structures – similar structures in species sharing a common ancestor

Similarities in Structure Forelimbs of all mammals consist of the same skeletal parts Function is different to adapt to different functions

Creation of New Species Speciation Speciation – the origin of a new species Why different species don’t mate: Temporal Isolation - reproduce at different Timing - different breeding seasons Behavior- different mating behaviors

Geographic Isolation and Speciation Convergent Evolution Convergent Evolution – process by which unrelated organisms adapt similar because they live in the same environment Mammals that feed on ants Book page 551

Gene Pool All alleles/DNA in all the individuals that make up a population What can change a gene pool: Genetic Drift- due to chance The Bottleneck Effect- disasters (Earthquakes, floods, droughts, fires, etc) Natural selection- good traits get passed on Gene flow- immigration and emigration

Natural Selection and Fitness Fitness Fitness – ability to reproduce (better genes lets you live longer = more babies with your genes)