2.  Genes are chemical factors in DNA that determine traits.  Examples: Hair color, eye color, skin color, height, windows peak, tongue rolling, tongue folding, attached ear lobes, widow’s peak, hitchhiker’s thumb, etc  Alleles  Different forms of genes  For example: There are different alleles for eye color

3.  Principle of dominance  Some alleles are dominant and some are recessive  Dominant genes win out of recessive genes.  You receive 1 form a gene from each parent, so you have two genes.  If you receive two dominant genes you will express the dominant trait.  If you receive one dominant gene and one recessive you will express the dominant trait.  You must receive two recessive genes to express the recessive trait.

4.  Punnett squares are used to determine a genetic cross.  You receive one gene from your mom in the egg and one gene your father in the sperm. Depending on the gene passed down you can have different combinations.

5.  Homozygous  two identical alleles for a trait  Heterozygous  two different alleles for a trait  Phenotype  Expressed physical characteristics  Genotype  Actual genetic makeup  Organisms can have the same phenotype, but different genotypes

6. Genes for different traits can segregate independently during the formation of gametes (sperm/egg, remember meiosis?)

9.  Not all traits show pattern of dominant and recessive alleles!  Incomplete Dominance  Neither allele is completely dominant  Crossing white and red flowers (pink flowers)  Codominance  Both alleles contribute to the phenotype  White feathered chicken and black feather chicken (speckled chicken)  Multiple Alleles  More than two possible alleles exist  Human blood type (A, B, O)  Polygenic Traits  Traits controlled by two or more genes  Skin color

10. INCOMPLETE DOMINANCE CODOMINANCE AND MULTIPLE ALLELES

11.  Consists of two long chains of nucleotides twisted into a double helix  Consists of the genetic information for an organism  Nucleotide contains a base  4 bases in DNA  Adenine (A)  Thymine (T)  Cytosine (C)  Guanine (G)  Base pairing in DNA  “A” pairs with “T”  “C” pairs with “G”  Bonded with hydrogen bonds  Sugar-phosphate backbone

12.  How much DNA is in an organism?  E. coli (bacteria) contains 4,639,221 base pairs  Humans contain over 3,000,000,000 base pairs per cell.  The human body has 50 to 75 trillion cells.  75,000,000,000,000

15.  http://learn.genetics.utah.edu/content/begin /traits/predictdisorder/. http://learn.genetics.utah.edu/content/begin /traits/predictdisorder/

16.  Chromatin is DNA wound tightly into coils.  If we didn’t store DNA in this manner it would be difficult to store over 3 billion base pairs.

17.  Karyotype  Photographs of chromosomes are cut out and grouped together in pairs  Sex Chromosomes  Determine individuals sex  Males have one X and one Y  Females have two X sex chromosomes  Autosomes  All chromosomes besides sex chromosomes

19.  Let’s try to make a Karyotype.  http://learn.genetics.utah.edu/content/begin /traits/karyotype/. http://learn.genetics.utah.edu/content/begin /traits/karyotype/

20.  Karyotypes can help identify genetic disorders such as Down syndrome (trisomy 21), turner syndrome, and klinefelter’s syndrome (there are many more disorders that can be identified using karyotypes.)  Example of nondisjunction which causes trisomy 21. http://learn.genetics.utah.edu/content/begin /traits/predictdisorder/. http://learn.genetics.utah.edu/content/begin /traits/predictdisorder/