Sarah Margareta Ibrahim▯ Monday, January 7th 2013
BIOL 202 - Basic Genetics
Lecture #1 - Introduction
Reading: Ch. 1 (p.1-25)
Conferences begin on Jan. 21st - 1.5 hours/week (see schedule on myCourses)
Textbook: Introduction to Genetic Analysis 10th ed.
Midterm Exam: Thursday 21 February 6-8pm (will be 1.5 hours long)
Midterm Exam (all multiple choice) - 35% (Lectures 1-14)
Final (multiple choice and short answer) - 65% (Lectures 15-37)
Overview of Genetics
• Biologists are interested in how organisms function. They ask
questions about biological function.
• Biologists use a reductionist approach.
• A geneticist searches for mutations (in natural populations or
a mutation that they may create in some way with chemicals
or with radiation). These mutations disrupt function.
Geneticists learn about function by studying mutations. You
can learn something by comparing the mutant form of the
organism and non-mutant organism and through this you can
infer some things - this is called genetic dissection.
• Lets say youʼre interesting in curing a genetic disease, if you
know what that gene does, you might be able to develop a
therapy based on substituting for individuals who have a
mutation that causes that disease.
• Molecular biology gave us the tools for geneticists to manipulate the code and allowed cell
biology/biochemistry to communicate with genetics.
Approaches in Genetics
1. Forward Genetics
We look for natural
mutations. Make crosses
between phenotypes that
differ and look at offspring
ratios. We look for the
genetic control of that trait -
does it look like its controlled
by a single gene? Does it
look like its controlled by
many genes? Does it even
have a genetic basis? So in
a nutshell: make crosses
between genes, note
offspring ratio and infer the
molecular and developmental
differences which could lead you to identifying the DNA sequence. Weʼre going forward from
the different forms (form the mutations) down to the DNA sequences.
▯ 1 Sarah Margareta Ibrahim▯ Monday, January 7th 2013
2. Reverse Approach
You start out with a particular mutation -
could a be a mutation tot the code itself
ie. you could induce a mutation with a
chemical compound in a particular
region of the genome, in a particular
DNA sequence OR you could mess
around with the transcript of that DNA
sequence (so the mRNA) OR you could
mess with the protein. So now that
youʼve done something to the message:
does it have an effect on the
phenotype? In many cases it has no
effect on the phenotype or just a very
subtle effect. But in some cases it has a