2004 James E. Mickle and Patricia M. Aune
1. Define and discuss the following terms and concepts: DNA, chromosome, homologous
chromosome, gene, allele, phenotype, genotype, dominant, recessive, homozygous,
heterozygous, gamete formation, and Punnet squares.
2. Understand the concept of karyotyping.
3. Recognize traits in humans that appear to be controlled by a single gene and determine how
to assign a phenotype and genotype for these traits.
4. Construct a family tree/pedigree following 2 traits for 2 to 3 generations.
5. Explore the concept of continuous and discontinuous variation.
: Read Special Preparation at the end of this lab unit and Chapter 9 and Sections 11.
7 and 13.2 (2
ed.), Ch. 9 and Sections 11.5, 8.19 (3
ed.) or Ch. 9 and Sections 11.7 and
ed.) or Chapter 9 and Sections 8.12 and 8.19 (5
ed.) and in Campbell
This entire lab unit with all tables filled in and questions answered, including group data
submitted to http://webct.ncsu.edu, a karyotype, a family pedigree, and one photograph.
Genetics is the study of heredity, the process by which biological information is passed from
generation to generation. It is general knowledge that we inherit some of our traits from our
mothers and others from our fathers. Sometimes a trait seems to skip a generation and a child
shows a trait not seen in their own parents, but is seen in their grandparents or another relative.
In this laboratory unit, we are going to examine the basic concepts of inheritance, explore some
basic traits in order to appreciate the differences between individuals, and produce a pedigree
(family tree) following 2 inherited traits.
Before we look at actual traits, we need to understand the basic concepts and vocabulary of
inheritance. Inherited information is found within the
DNA (Deoxyribonucleic Acid)
of our body
cells. DNA is what makes you genetically distinct from anyone else (except in the case of
identical twins). DNA includes the information for obvious traits such as hair color and tongue
rolling, as well as for more subtle information that regulates important biochemical processes
within our bodies. DNA is a large molecule that can be tightly condensed into smaller packages
. As humans, we have 23 pairs of chromosomes: 23 of these
chromosomes come from our mothers (from her egg) and the other 23 chromosomes come from
our fathers (from his sperm). It is in the union of egg and sperm that a new individual with 23
pairs of chromosomes is created and the overall chromosome number of 46 is maintained. If
chromosomes are missing or damaged, all of the information contained within that DNA will be
missing from the new individual. This can result in a serious and/or fatal condition.