BIOL 180 Lecture 14: BIOL 180 - Lecture 14 - DNA, Genes, and More
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Biology 180 w/ Prof. Scott Freeman
Kane 130 MTWThF 1:30-2:20
October 15, 2018
Lecture Topic: DNA, Genes, Mutations, and Alleles
How Do We Get Mutations?
We learned that independent assortment is the random combinations of genes
on chromosomes that occurs during meiosis, sex cell division.
• Genetic Linkage is an exception to independent assortment
o This is the process in which two or more genes will generally stay together
because they are in close proximity on the same chromosome
o Traits that are generally inherited together
• Sex Linkage is similar to genetic linkage, however the chromosome that the
genes are on is the sex chromosomes
o X or Y
An autosome is a non-sex chromosome
A gamete is a sex chromosome
• Certain diseases can be either x-linked or y-linked
o Meaning there can be diseases that are sex specific
Another definition for a gene:
• The basic hereditary unit that is passed from parents to offspring which describes
which traits the offspring will have
Before, we learned that an allele is a different form of a gene
But what does that mean?
• The allele is an alternative form of the gene due to mutation
o You would see this allele on the same place on the chromosome as the
gene was before
o Mutation: the change of the structure of a gene by means of deleting,
inserting, or rearranging specific genes on the chromosome
▪ This can happen through the three main sources of genetic
variation (which all occur during metaphase 1 during meiosis 1!!)
• Crossing over
• Independent assortment
• Segregation
