Genetics summary – VU BMS 2020/2021
Simone Zweers
Reference: Brooker, Genetics: Analysis and prinicples, 7th edition
Chapter 25: Genetic basis of cancer
1
, Genetics summary – VU BMS 2020/2021
Simone Zweers
Reference: Brooker, Genetics: Analysis and prinicples, 7th edition
- Cancer is a disease characterized by uncontrolled cell division
- It is a genetic disease at the cellular level
- More than 100 kinds of human cancers are known
o These are classified according to the type of cell that has become
cancerous
o 10% as inherited trait
- Carcinogens = environmental agents that increase the likelihood of
developing cancer
25.1: Overview of cancer
- Most originate from a single cell, cancerous growth can be considered to be
clonal
- At the cellular and genetic level, cancer is usually a multistep process
o Begins with a precancerous genetic change benign growth =
goedaardig, followed by additional genetic changes, progresses to
cancerous cell growth
- When cells have become cancerous, the growth is described as malignant
cells are invasive (can invade healthy tissue) and metastatic (can
migrate to other parts of the body)
- Two affects of genetic changes that lead to cancer
o Oncogene = mutant gene that is overexpressed and contributes to
cancerous growth
o Tumor-suppressor gene = gene that prevents cancers. A loss-of-
function mutation in a tumor-suppressor gene can allow cancerous
growth to occur
25.2: Oncogenes
- Proto-oncogene = a normal, nonmutated gene that has the potential to become an
oncogene
o To become an oncogene, it incurs a mutation that causes its expression to be
abnormally high (gain of function)
- Three possible effects of fain of function mutation that produces an oncogene
o The amount of the encoded protein is greatly increased
o A change occurs in the structure of the encoded protein that causes it to be
overly active
o The encoded protein is expressed in a cell type where it is not normally
expressed
Oncogenes have gain-of-function mutations that may affect proteins involved in cell division
pathways
- Cell in G1 may accumulate molecular changes that cause it to advance through the rest
of the cell cycle
- Growth factors are signaling molecules that coordinate cell division
- Epidermal growth factor EGE, secreted from endocrine, stimulates epidermal cells to
divide
- Binds to receptor activation of intracellular signaling pathway changes gene
transcription, activated. The proteins promote progression through the cell cycle cell
stimulated to divide
- Oncogenes commonly encode proteins that function in cell-signaling pathways related to
cell division
2
Simone Zweers
Reference: Brooker, Genetics: Analysis and prinicples, 7th edition
Chapter 25: Genetic basis of cancer
1
, Genetics summary – VU BMS 2020/2021
Simone Zweers
Reference: Brooker, Genetics: Analysis and prinicples, 7th edition
- Cancer is a disease characterized by uncontrolled cell division
- It is a genetic disease at the cellular level
- More than 100 kinds of human cancers are known
o These are classified according to the type of cell that has become
cancerous
o 10% as inherited trait
- Carcinogens = environmental agents that increase the likelihood of
developing cancer
25.1: Overview of cancer
- Most originate from a single cell, cancerous growth can be considered to be
clonal
- At the cellular and genetic level, cancer is usually a multistep process
o Begins with a precancerous genetic change benign growth =
goedaardig, followed by additional genetic changes, progresses to
cancerous cell growth
- When cells have become cancerous, the growth is described as malignant
cells are invasive (can invade healthy tissue) and metastatic (can
migrate to other parts of the body)
- Two affects of genetic changes that lead to cancer
o Oncogene = mutant gene that is overexpressed and contributes to
cancerous growth
o Tumor-suppressor gene = gene that prevents cancers. A loss-of-
function mutation in a tumor-suppressor gene can allow cancerous
growth to occur
25.2: Oncogenes
- Proto-oncogene = a normal, nonmutated gene that has the potential to become an
oncogene
o To become an oncogene, it incurs a mutation that causes its expression to be
abnormally high (gain of function)
- Three possible effects of fain of function mutation that produces an oncogene
o The amount of the encoded protein is greatly increased
o A change occurs in the structure of the encoded protein that causes it to be
overly active
o The encoded protein is expressed in a cell type where it is not normally
expressed
Oncogenes have gain-of-function mutations that may affect proteins involved in cell division
pathways
- Cell in G1 may accumulate molecular changes that cause it to advance through the rest
of the cell cycle
- Growth factors are signaling molecules that coordinate cell division
- Epidermal growth factor EGE, secreted from endocrine, stimulates epidermal cells to
divide
- Binds to receptor activation of intracellular signaling pathway changes gene
transcription, activated. The proteins promote progression through the cell cycle cell
stimulated to divide
- Oncogenes commonly encode proteins that function in cell-signaling pathways related to
cell division
2
