BIOL1003 Lecture Notes - Lecture 4: Dwarfism, Hbb, Phenylalanine
Mendelian Genetics
Blending Inheritance
The belief that offspring carry a blend of characteristics of both parents- inheritance
is a process of averaging the phenotypes of both parents- doesn’t work
If it did happen, we would all look exactly the same
There is a massive amount of diversity- because individual traits act as individual
particles on material entities (chromosomes), not merged into each other
Two genes can be put together that weren’t together in the parents and can create
new phenotypes
Some hidden traits only emerge under certain stimuli and environmental conditions
Particulate Inheritance
Gregor Mendel
1822-1884
1865- two talks at a scientific meeting: Experiments in Plant Hybridisation but never
wrote a scientific paper
In charge of monastery garden- began counting peas and creating crosses, looked at
inheritance of traits and characteristics
Began to cross garden peas (Pisum Sativum) with each other
First got true-breeding lines by spending
year making sure they only gave the
same type of offspring
Limited gene flow- no self pollination as
he cut off the carpel of some plants and
the stamen of others
Could see that it wasn’t blending of characteristics
as all the offspring from purple and white true-
breeders were purple, resembling only one parent
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This rebuked the idea that women didn’t have
any contribution to the traits of the offspring
Looked at lots of
characteristics
Mendel’s observations
1. The phenotype is determined by heritable factors (genes)
2. Alternate forms of genes are responsible for variation in inherited characteristics
(alleles)
3. For each character an organism inherits 2 genes, one from each parent
4. If two alternative forms of a gene are present, one is fully expressed (dominant) and
the other completely hidden (recessive)
5. The two genes for each character segregate during gamete production
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The belief that offspring carry a blend of characteristics of both parents- inheritance is a process of averaging the phenotypes of both parents- doesn"t work. If it did happen, we would all look exactly the same. There is a massive amount of diversity- because individual traits act as individual particles on material entities (chromosomes), not merged into each other. Two genes can be put together that weren"t together in the parents and can create new phenotypes. Some hidden traits only emerge under certain stimuli and environmental conditions. 1865- two talks at a scientific meeting: experiments in plant hybridisation but never wrote a scientific paper. In charge of monastery garden- began counting peas and creating crosses, looked at inheritance of traits and characteristics. Began to cross garden peas (pisum sativum) with each other. First got true-breeding lines by spending year making sure they only gave the same type of offspring.
