Evolution 1

The beginning: 

• 13.7 billion years ago The big bang 

• 4.6 billion years ago formation of earth 

• Elements,molecules, amino acids, proteins 

• 3.5 billion years ago first life 

• Unicellular organisms, bacteria

• Endosymbiosis theory

• DNA

History of earth 

Hadean and archean 4.6-2.5) cant find to rock to date back to this time because of how worm it was  the first rock date back at the time were it finally started to cool down 

Arcia ( in between bacteria and eukaryotic cells )is thought to be the first living organism because they thrive in harsh conditions 

Geological times scale 

To get an appreciation of the numbers of years 

How did organic molecules come too:

The condition present at the time could make organic molecules from inorganic molecules 

Four processes of life:

• The non-living synthesis of simple organic molecules 

           -All life built of amino acids

           -Early earth only had inorganic matter 

• The assembly of these organic molecules into polymers(many) (bigger molecules)

           -organisms are organised 

           -organic molecules had to be connected 

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• The origin of self-replicating molecules that made inheritance possible (need some kind of inheritance)

           -for something to be considered ‘alive’ it has to be able to replicate 

           -today, DNA is mostly used but can not do it without enzymes 

           -some RNA can self-replicate 

• Packaging of molecules into membranes with an internal chemistry different from their surroundings (need protection of the membrain)

           -many compounds dissolve in water 

           -formation of a membrane 

• Unicellular eukaryotes 

-endosymbiosis theory 

            Mitochondria that can transform chemically bound energy at ATP (cellular respiration) are believed to have originated from free-living prokaryotic organisms that entered into a symbiotic relationship with ancestral eukaryotic cells.

-Chloroplasts that can absorb light energy to chemically bound energy (photosynthesis)

Mitochondria and chloroplasts are a cell within a cell and it it is thought a cell ‘ate’ another but kept it alive 

Evolution 2 Natural selection

• Evolution theory- the cumulative change in heritable characteristics of a population

• Modern biology-a change in the allele frequency in population over time

• Gene pool- all the genetic information present in reproducing population

• Allele frequency-how frequent a specific variation of a gene is in a population

• Allele-one of the alternative forms of the same gene

• new alleles come from mutation and they disappear when the last living organism carrying it dies

• the change in allele frequency in the gene pool over time is evolution

• evolution works on population

Lamarck’s evolution theory

• the organ that is being frequently will have stronger development while the ones that are not used will be weakened

• learnt behavior can be inherited

  Darwin’s evolution theory

• life is adaptive to different environments-Darwin’s finches

• the better adapted to the environment the higher the chances of survival and reproduction

  Natural Selection

• most populations produce more than the environment can support

• this leads to struggle for survival

• individuals within the same species differ in their characteristics-genetic variation

• depending on the environment characteristic can be beneficial or non-beneficial

• different species have different ancestry

• works on individuals

  Buzzwords:

• variation-difference in traits among individuals in a population

• hereditary-passing of traits from parents to offspring

• selection-process where certain traits become more common because they help survival

• time- key factor of evolution

Conditions of Evolution

The heritable characteristics in individuals give them different viability(fitness)

Fitness:

Viability can refer to:

-behavior

-tolerance

-color

-form etc

• the traits that can affect the size and viability of the offspring

Signs of evolution

Fossils

the oldest 3.5 bil

if an organism is embedded in sand, clay or udstone it can be fosselized or leave an imprint before it decays

easiest to preserve are the hard parts such as skeletons shells and tree trunks

since new layers will be placed on top of the old ones u can determent the age

index fossils- species that are specific to a certain time era and common over large areas. can help detainment the age

Radiometric methods

• determining age

• half life-when half of the atoms have decayed

Similarities in body structure

• animals are divided into different groups based on their form

• small organs which have lost their initial function

Homologous and Analogous organisms

• Homologous- same origin different function

• Analogous-different origin but same function

Similarities in fetal development

• organisms with a common ancestor share similar looking embryos

Biological similarities

• every organisms is made of: proteins, carbohydrates,DNA.RNA

• genetic code is the same

• the more closely related, more similarities in DNA and proteins

Bio Geography

• some organisms have limited areas that they can live in

• set climates give organisms specific traits

• endemic species

Mechanism of evolution

• no goal or agenda

• genetic variation

• natural selection

• speciation

Variation-Mutation

• change in the DNA

• can be caused from: radiation,chemicals,virus, infections or cell division

• has to happen is the sex cell for it to be inherited

• don’t have to be beneficial or dangerous

• it’s a mistake in replication

• can have no consequences on the individual

• does not occur due to need

-Mutations gives variation

-Some genotypes might be good in one environment but bad in another

Different forms of natural selection

• Directional selection

  -adaptations to a changing environment

• Stabilizing selection

  -in a stable environment

• Divergent evolution

  -moving away from each other

• Convolution

  -pollination,preditor-pray

• Genetic drift

  -a temporary decrease in population size which then recovers

  -a change in the allele frequency in population due to chance

  -can make positive alleles disappear from the population

• Artificial selection

  -man made, no regard for the organisms and what benefits said organism

  -only benefits humans
  

  Speciation

  How ?

• Changes in the environment

• Geographical isolation

• movement to isolated areas

• hybrids

  Barriers between gene pools:

• geographical isolation- physical barrier

• temporal isolation-mating at different seasons

• behavioral isolation- different habits and courtships

Endemic species

• speciation due to isolation (usually on island)

• ex:lemurs, giant turtles