{ Genetics Review

 Involves several different genes for one trait like eye color, skin tone and color, height (humans), wheat kernel color  These are called Polygenes Polygenic Inheritance

 Skin color has three alleles: ABC for dominant and abc for recessive  The darkest skin tone is AABBCC and the lightest is aabbcc  Possible gametes for both the mom and dad are: abc, abC, aBc, Abc, aBC, ABc, AbC, and ABC  Distribution of results will be a bell curve! Example

Punnett Grid

 Mendel’s laws worked with genes on separate chromosomes – Law of Independent Assortment  Many genes are found on a single chromosome and they will separate together with crossing over being a way to create ‘recombinants’ Linked Genes and Genetic Variety

 Occurs when there are linked genes – An offspring that possesses the characteristics from both parents as crossing over has occurred and the linked genes transfer between homologous chromosomes  The further apart the genes are on a chromosome, the better the chance of producing recombinant gametes and organisms Recombinant

Steps:  Denature the DNA – heat it to 95 o C, breaking the H bonds between the nucleotide bases  Annealing where the DNA is cooled and the Primers – small strands of DNA that bind to target DNA on the strand – bind to the complementary sequence and specify the DNA to be amplified  Heated now to the optimal temp – 72oC, so the DNA Polymerase extends the primers using the target DNA as the template  This process is repeated 20 – 35 times!! Exponential growth PCR

 Uses an electrical current to move negatively charged DNA particles through a current carrying Gel  They move due to size and charge  When stained they create a banded pattern and similarities between different samples indicate a familial relationship  Used in forensic studies and paternity testing Gel Electrophoresis and DNA Profiling

 Completed in 2003 – Mapped all the genes in Human DNA  Helps to give a better understanding of how particular changes in coding can cause particular results – genetic disorders  Identifies specific genes – synthetic human hormones are used to produce human insulin for diabetics  Genetic screening to identify specific diseases like sickle-cell anemia and Huntington’s Disease Human Genome Project

 Manipulation of particular genes for a specific purpose  Specific genes are located and extracted and then used to modify the genetic code of another species  An example is inserting the gene code for creating insulin into a bacterium  Restrictive enzymes cut the DNA sequence at particular nucleotide sequences then ligase enzymes join them to another DNA strand with the same sequence  Lab Activity on Tuesday Genetic Engineering

Cloning – Good or Bad?