Lecture 22 - Cancer Genetics and Quantitative Genetics

Describe pBRCA 1 and pBRCA 2

Tumor suppressor genes. Mutations in these are associated with hereditary breast and ovarian cancer. They are involved in DNA repair in human cells

What are the 3 main categories of cancer causing genes?

1. Oncogenes

2. Tumor suppressor genes

3. DNA repair genes (indirect)

Examples of oncogenes

1. v-src

2. c-ras

Examples of tumor suppressor genes

1. pRB

2. p53

Examples of DNA repair genes

1. pBRCA1

2. pBRCA2

Telomerase

An enzyme that produces telomeres to “extend” the life of chromosomes. Cancer cells are considered immortal because of telomerase activity that allows them to divide forever

Describe the pathway to invasive cancer

Usually requires mutations in several different genes which suggests cells have redundant systems for preventing uncrontrolled division

Polygenic traits

When complex characteristics involve multiple genes

Multifactorial traits

Environmental factors that may influence a characteristic

Oxytocin gene

Encodes a small peptide hormone that is released by the pituitary gland

Describe how a mutation in the oxytocin gene affects mice

1. Mice with homozygous mutant oxytocin gene do NOT produce oxytocin (recessive null alleles)

2. Mutant male mice do NOT appear to recognize or bond with females they interacted with

Vasopressin

Peptide hormone that is produced by the pituitary gland that regulates blood pressure and water balance. Associated with monogamy and polygamy

Monogamy

Many receptors that is associated with long term bonding with a mate, high levels of paternal behavior, and intense aggression towards strangers for defense of territory, nest, and mate

Polygamy

Fewer receptors and results in multiple mates, and lack of paternal and territorial behavior

Why is vasopressin labeled the “cheating gene”

Gene is associated with difficultiees in marriage and emotional bonding when the allele is associated with polygamy

Self fertilization

Contributes to loss of variability. Self fertilization of heterozygotes results in a 50% loss of heterozygotes each generation

Polygenic trait variation in inbred lines

With inbred lines, variation is due to the environment