Review What have we learned so far in the preparation for

evolution? – 2. Age of the earth – evidence shows us the earth is at

about 4.5 billion years old.• Grand canyon -6 millions years old from erosion• Continental drift – 200 millions years – the rate at which

the continents spread would put them together 200 million years ago.

• Magnetic pole flip• Radiometric dating. – the oldest rocks we find are 3.5

billions years old. But the minerals in the rocks are 4.4 billions years old.

Genetics

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Gregor Mendel Father of Genetics Worked with peas

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Genes and terminology Gene – sequence of DNA that codes for a

protein and thus determines a trait A – adenine G – guanine T – thymine C – cytosine

AUACGCGCGCGCGTAUTAUAUATAU This animal is hairy

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Con. Alleles – one of a number of different forms

of a gene Dominant (T) and recessive (t) T and t represent two different alleles If a trait is expressed and the alleles are the same

it is homozygous TT = homozygous dominant tt = homozygous recessive Tt = heterozygous dominant

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Con. Phenotype is the outward expression of the

genes. Physical characteristics Genotype is the genes themselves T = tall over 5’2” t = short under 5’2” Example – Cross Tt and Tt in a Punnett

square

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Population – a group of organisms of the same species that live in a specific geographical area and interbreed Can you have a population of one. Go around the room and count the number of

visible populations. How many populations in the room

5 10 15 20 or somewhere in between?

What is evolution Def - Any change in the frequency of alleles in

poplulations of organisms from generation to generation.

Allele frequency is how often the gene is expressed. Ie. If we were to count the number of people with black

hair in the class. #? Is it possible that allele frequency could change in the

population That is all evolution is! If the allele frequency is changing – then the population is

evolving.

Theory – def