BIOL 306 - Chapters Twenty-Two & Twenty-Three: Development Genetics & Cancer Genetics

Totipotent Cell

Cell with the potential to develop into any cell type

Determination

Cell becomes committed to particular cell fate

Developmental Stages & Associated Genes

• Establishment of main body axes: Egg-polarity genes

• Determination of number and polarity of body segments: Segmentation genes

• Establishment of identity of each segment: Homeotic genes

Hox Genes

Encode transcription factors that help determine identity of body regions

Apoptosis

Controlled and programmed cell death

Necrosis

Injured cells dying in uncontrolled manner

What produces a tumor?

Abnormal proliferation of cancer cells

Benign Tumor vs. Malignant Tumor

Benign Tumor: Tumor remains localized

Malignant Tumor: Tumor cells invade other tissues

Metastasis

Secondary tumors induced by tumors

What are factors contributing to cancer?

• Genetics

• Smoking

• Alcohol

• Obesity

• UV Radiation

Oncogenes vs. Tumor-Suppressor Genes

Oncogene: Mutated and dominant-acting stimulatory genes that cause cancer

Tumor-Suppressor Gene: Mutated and recessive-acting inhibitory genes that are inactive

Proto-Oncogene

Gene that is responsible for basic cellular functions in normal cells but becomes an oncogene when mutated

In a person heterozygous for a _________________ gene, loss of heterozygosity can lead to cancer

tumor-supressor

Progression through the G₂/M checkpoint is regulated by ______________

cyclin B

Cyclin B accumulates through what phase of mitosis?

Interphase

Increasing levels of cyclin B combine with __________ to produce inactive __________

CDK; MPF

Removing phosphates groups from __________ MPF produces __________ MPF

inactive; active

What events associated with mitosis does MPF bring about?

• Nuclear envelope breakdown

• Chromosome condensation

• Spindle assembly

What phases of mitosis is active MPF associated with?

• Anaphase

• Telophase

• Cytokinesis

• Interphase

Ras-Signal Transduction Pathway

Conducts signals from growth factors and hormones to the nucleus and stimulates the cell cycle

True or False: Mutations in the Ras-signal transduction pathway can contribute to cancer

True

Ras is activated when it binds to ________

GTP

Activated Ras actives ________, which activates ________, which activates

Raf, MEK, MAP kinase

When activated, MAP kinase moves into the ____________ and activates ________________________

nucleus; transcription factors

True or False: Epigenetic changes are reversible

True

True or False: Epigenetic changes are mutations

False: They are not

Alterations to ________________ or ________________ are seen in multiple cancers

DNA methylation; chromatin structure

True or False: Cancers often posses chromosomal abnormalities

How do retroviruses cause cancer?

• Mutate and rearrange proto-oncogenes

• Insert strong promoters near proto-oncogenes