Download Pedigree

14. Pedigrees/ Human Genetics
Fruit Fly- Drosophila melanogaster, used by scientists to
study genes and heredity.
 Advantages of Fruit Flies
 Short Life Span
 Small and easy to maintain
 8 Chromosomes
Human Chromosomes- 46 total (23
pairs)
 Autosome- 22 pairs of non-sex cells determining
traits.
 Sex Chromosomes- one pair of chromosomes
determining gender.
Karyotype
 Karyotype- picture of all the chromosomes lined up
during metaphase taken about half way through
pregnancy used to determine a chromosomal
abnormality. (blood cells)
Determining Sex
 Male- XY
 Female- XX
 Sex-Linked Traits- traits caused by genes that are
located on the sex chromosomes.
 Ex. Color Blindness, Pattern Baldness, Hemophilia
 Why Males are affected more than females
 X chromosome is larger than Y chromosome so it
holds more genes. Both X’s must have gene to be
expressed in females whereas only one X in a male
must have gene to be expressed.
Pedigree Analysis
 Pedigree Analysis- diagram of a family history that
shows how one trait is passed through several
generations.
 *Used by healthcare workers to help parents
determine the likelihood of passing on genetic
disorders.
 Symbols of a Pedigree
 O = Female
 = Male

 / = Affected female/ male

 ___ = Marriage

= Offspring
Rules of a Pedigree
 Fill in the shaded people with homozygous recessive
(rr).
 The non-shaded in people will receive at least one
capital.
 Determine the second letter on the non-shaded in
people by looking at parents, siblings and children