mendel and the gene idea mendel’s discoveries extending medelian genetics mendelian inheritance...
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Mendel and the Gene Idea
Mendel’s DiscoveriesExtending Medelian GeneticsMendelian Inheritance in
Humans
Mendel’s Discoveries
Experimental and quantitative approach
Law of segregation Law of independent
assortment Roles of probability Discovered the
behavior of genes
Law of Segregation
Allele pairs segregate during gamete formation and randomly recombine during fertilization
Predicted by Punnett square
Some useful genetic vocabulary Homozygous Heterzygous Phenotype Genotype Monohybrid cross Dihybrid cross
Testcross Dominant Recessive P F2
F1
Law of Independent Assortment
Each pair of alleles segregates independently of other gene pairs during gamete formation
Roles of Probability
Role of multiplication
The probability that two independent events will occur simultaneously is the product of their individual probabilities
Role of addition The probability of an
event that can occur in two or more independent ways is the sum fo the separate probabilities of of the different ways
Beyond Mendel
Incomplete dominance Codominance Multiple alleles Pleiotropy Epistasis Polygenetic inheritance
What is a dominant allele?
Dominance does NOT determine relative abundance!
Recessive alleles have no message Recessive product is overwhelmed by
product of dominant allele Recessive product inhibited by
dominant product
Mendelian Inheritance in Humans
Difficult to study Few offspring Generation-20 yrs Breeding
experiments frowned upon
Understanding comes from family pedigrees
Human Disorders
Recessive lethals Dominant lethals Multifactorial
disorders
Sickle Cell Disease-Video
http://www.hhmi.org/biointeractive/media/DNAi_sicklecell-lg.mov
Technology and Genetics
Role of genetic counseling
Carrier recognition Newborn screening Fetal testing
1) chorionic villus sampling
2) amniocentesis
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