May 26, 2010 What is the difference between a homologous structure and analogous structure? Which is good evidence of a common ancestor? What characteristics do humans display as embryos that are not shown in adults?

DAY 2 BIOCHEMICAL evidence

What is Biochemistry? Study of chemicals important to living things Examples: Enzymes Hemoglobin (protein that carries oxygen in blood) Hormones We can look at the sequence of amino acids to see how closely related things are More AAs in common = more closely related

What is Biochemistry? We will use the idea of antibodies/antigens to test for similarities among the 5 primates on our “no tail” side of our tree

Antigens Antibodies Carbs or proteins on outside of cells Used for recognition Antibodies Proteins produced in response to foreign antigens

1. Make antibodies against each type of blood (ex 1. Make antibodies against each type of blood (ex. Antibodies against human blood) Inject human blood into cow (since the blood is foreign, it is the antigen) Cow produces antibodies against foreign blood

2. Remove antibodies from cow We now have antibodies against human blood, called anti-Human antibodies

3. Use antibodies to test blood (our lab) Inject antibodies into primate If clot forms, then animals are closely related because they must have similar shaped antigens on their cells.

IN OUR LAB: Anti H = antibodies against human blood (should form clot with human blood and close relatives b/c these antibodies have the shape that fits with human antigen). Antibodies are yellow, blood is red

Evidence # 3 DNA Cut/separate DNA into fragments Similar fragments = close relationship