Genetics and Intelligence IGenes & Heritability

What does it mean for something to be

genetically controlled?

Hemoglobin

• Red blood cells• Oxygen carried by the

protein hemoglobin

Hemoglobin is a protein

• Complex molecule made of smaller units called amino acids

• Amino acids make peptide chains

• Chains bend and fold into 3 dimensions to make protein (e.g. myoglobin below).

• Proteins are essential to all of life» Catalyze reactions» Structural proteins » Cell signaling, immune responses, cell adhesion

DNA

• DNA can be thought of as a list of recipes for how to line up amino acids into proteins

• DNA made of nucleotides– Adenine, Cytosine, Thymine, Guanine (ATCG)– DNA in cells is strings of nucleotides

that sit together on chromosomes– Nucleotides read in threes– Segments of strings that code for

protein called genes

DNA and Genes and Proteins(protein recipe, list of “amino acid ingredients”)One wrong nucleotide and you get a different amino acid, potentially big effect on protein

Sickle Cell AnemiaA trait with strong genetic control

• C738H1166N812O203S2Fe

• Hemoglobin folds and fits into RBC and carries oxygen

• But, a mistake in nucleotide sequence (the gene/recipe) and hemoglobin doesn’t fold right.

Sickled cells block blood vessels body suffocates with long-term, severe

consequences, death

Phenylketonuria (PKU)

• Body lacks ability to metabolize phenylketones

• Recessive genetic disorder causes seizures, retardation, etc.

• Every child tested at birth

• Can be controlled through diet

Recessive genetic disorder?

You have two copies of each gene

1 from mom, 1 from dad

The Cancer Gene

Press Releases Sloan-KetteringNew Cancer Gene Identified

• Oncogene Plays a Critical Role in Tumor Formation

• January 20, 2005 • • NEW YORK - Scientists at

Memorial Sloan-Kettering Cancer Center (MSKCC) have identified a new cellular oncogene essential for the development of cancer…..

• But, lung cancer, one of leading cause of diseases in USA, is over-whelming caused by smoking

• People who have never smoked and die of lung cancer exist, but they are a small fraction of those who get lung cancer

The Gene for…..

Some genes seem to be more prevalent in people with certain behavioral traits, such as schizophrenia, manic-depression, compulsive gambling, alcoholism, homosexuality

?? What does this mean??

Genes + Environment = Phenotype

Genetics or Free Will?

• Atoms make up molecules, molecules make up DNA-chromosomes-genes-proteins

• Proteins make the world go ‘round’

• So at some level, everything is governed by our genes, but does that mean organisms have no free will?

Single Gene Traits Rare but cool examples can be found

Hygienic behavior in bees- behavior controlled two genes

Bees recognize and cut out infected and dead brood. Protects against foulbrood, chalkbrood and now Varroa mites

10% presence naturally

Dancing bees

Dancing tell nest mates location of resources

Waggle Dance

Dance type is caused by single gene and species specific

Genetic Expression: the plot thickens and the story gets complicated

1) Pleiotropy- one gene, multiple effects 2) Incomplete Dominance- pink carnations3) Environmental Effects- heat, pH, drought4) Epistasis- many genes interact to affect

one trait (human height)5) Codominance- multiple genes control

single trait (e.g. ABO blood group)

This is a Major Frontier of Science: the dynamics between genes and environment

Blood groups (codominance)

• Three possibilities of blood type– AA, AO Type A (can receive from A and O)– AB Type AB (can receive from A, B, AB or O)– BB, BO Type B (can receive from B and O)– OO Type O (and only receive from O)– O is universal donor because it doesn’t elicit attack from A or B– AB is universal recipient because it doesn’t attack anything

A and B are codominant; O is recessive to both

Genetics and Human Intelligence

We will be looking at the following:• How has human intelligence been studied? • How do science and politics mingle in the

conscious and unconscious minds of scientists?• Does ‘genetic basis for intelligence’ mean same

thing as born ‘smart’ or ‘dumb’?• What is race? • What is intelligence?• Debate: Can intelligence be measured in a

meaningful way?