483 Lecture Notes - Lecture 5: Zygosity, Genetic Disorder, Quantitative Trait Locus
5 Jun 2018
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LECTURE 5 Mendelian inheritance
What is a trait?
Character: a heritable feature that varies among individuals. e.g. eye colour
Trait: a variant of a particular style. e.g. blue eyes
Attributes are not inherited directly; they appear during • development
Information for features is encoded in genes
What is a gene?
Gene: –a sequence of DNA
–a hereditary unit –occupies a specific location on chromosome
–determines a characteristic in organism
• The expression of genes, along with environmental factors, identify the traits observed.
Gregor Mendel
•Mendel was a monk in Brno in the 1860s – studied mathematics, physics and chemistry
• interested in how traits are inherited
• chose garden peas (Pisum sativum) for his inheritance experiments
Gregor Mendel
•Why peas? –Many easily‐distinguishable varieties – Proliferate –Reproduction can be
controlled •self‐ or cross‐fertilise
•both parents knew
Mendel: methods
•Mendel developed ‘true‐breeding’ varieties –When two identical true‐breeding individuals are
crossed, all offspring have the same characteristics as the parents
–Using true‐breeding pea varieties allowed him to study the inheritance of one trait at a time
• Mendel crossed two different true‐breeding varieties together
• Then, he passed their offspring (the F1 generation
Mendel: results
Monohybrid cross: • Parents –identical except for one character
–each true‐breeding for their trait
• F1 –all purple flowers
• F2 ––75% purple25% white
Mendel: discussion
• Alleles did not blend but remained as discrete units of inheritance (e.g. purple or white
flowers).
• Only one allele was expressed in the trait observed. Even where the two alleles for a gene
were different.
find more resources at oneclass.com
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Document Summary
Character: a heritable feature that varies among individuals. e. g. eye colour. Trait: a variant of a particular style. e. g. blue eyes. Attributes are not inherited directly; they appear during development. A hereditary unit occupies a specific location on chromosome. Determines a characteristic in organism: the expression of genes, along with environmental factors, identify the traits observed. Gregor mendel: mendel was a monk in brno in the 1860s studied mathematics, physics and chemistry, interested in how traits are inherited, chose garden peas (pisum sativum) for his inheritance experiments. Many easily distinguishable varieties proliferate reproduction can be controlled self or cross fertilise: mendel developed true breeding" varieties when two identical true breeding individuals are. Using true breeding pea varieties allowed him to study the inheritance of one trait at a time: mendel crossed two different true breeding varieties together. Each true breeding for their trait: then, he passed their offspring (the f1 generation.
