Cancer and Cloning Flashcards
What types of genes are changed (mutated) that usually give rise to cancer?
Genes that control the cell cycle.
Gene regulation systems that tend to go wrong during cancer are usually associated with what?
Embryonic development, the immune system, and many other biological processes.
Since cancer is related to things going wrong with many biological processes, does it benefit from other areas of biology as well as inform them?
YES
What are the types of genes (3) that regulate cell growth and division during the cell cycle? A change of any of these genes in what type of cell will result in cancer?
- Growth factors
- Growth factor receptors
- Intracellular molecules of signaling pathways
SOMATIC CELLS
What is the difference between an oncogene and proto-oncogenes?
Oncogene - a cancer-causing gene.
Proto-oncogenes - normal genes that code for proteins that stimulate normal cell growth and division, if a change occurs in these genes that makes it excessively active then it is turned into an oncogene, which may promote excessive cell division and cancer.
Describe the four changes to a proto-oncogene that can occur to make it into an oncogene?
- The gene is translocated to another locus with different controls, new promoter is much more active and expression is increased. Results in excess.
- A gene is amplified into multiple copies results in excess.
- Point mutation within a control element results in excess.
- Point mutation within the gene results in a Hyperactive protein or a protein that is resistant to degradation.
What is the function of tumor-suppressor genes? How could they contribute to cancer?
These encode proteins that inhibit abnormal cell division
A decrease in their normal activity can contribute to cancer.
Proto-oncogene encode for what pathways, while tumor-suppressor genes encode for what pathways?
Proto-oncogenes - growth-stimulating
Tumor-suppressor - growth-inhibiting
What is the Ras proto-oncogene? What is the function of the Ras protein? What is the importance of the Ras proto-oncogene in cancer?
This gene codes for Ras protein.
The Ras protein relays a signal from a growth factor that results in a cascade of protein kinases that turns on genes that code for proteins that stimulate the cell cycle.
A mutation often occurs that leads to a hyperactive Ras protein that issue the signals that lead to the protein kinase cascade itself. This mutation occurs in about 30% of human cancer.
What is the p53 gene? Where does it get its name? What is anohter name for it? What are its products functions? What is its significance in relation to cancer?
This is a tumor-suppressor gene
Gets its name because it’s protein product is 53,000 daltons.
Also called “guardian angel of the genome”
Its product: is a specific transcription factor that prmotes synthesis of cell cycle-inhibiting proteins. These proteins can turn on genes that are directly involved in DNA repair or activate apoptosis genes if the damage is irreparable.
A mutation in this gene that makes it nonfunctional can lead to excessive cell growth and cancer, a mutation in this gene is present in more than 50% of human cancers.
Look at this picture and understand the two ways that the cell cycle can be effected to cause cancer in relation to Ras and p53.
DO IT.
- Cell-cycle is overstimulated
- Cell-cycle not inhibited when it normally would be
Mutations that cause these two things generally lead to cancer.
..
Is one mutation in a somatic cell generally enough to cause cancer?
NO, usually 6 or more must occur before full cancer occurs.
Usually there is at least one active oncogene as well as a mutation or loss of several tumor-suppresor genes.
What is an example of a multistep model for development of cancer?
What are the steps?
COLORECTAL CANCER, 140,000 new cases and 50,000 deaths every year.
How does the fact that multiple genetic changes explain predisposition of cancers that run in families? What is an example of this?
An individual can inherit an oncogene or a mutant tumor suppressor allele which will increase the risk for certain types of cancer.
Mutations in the BRCA1 or BRCA2 gene occurs in at least 50% of inherited breast cancers. A woman who inherits one mutant BRAC1 allele has a 60% probability of developing breast cancer by 50.
What is one way that scientists have tested for genomic equivalence in plants to see if a somatic cell can develop into a new organism?
Seeing whether an isolated somatic cell of a carrot can develop into a new genetically identical organism.
Describe how John Gurdon used nuclear transplantation to test whether or not a differentiated animal cell nucleus can direct the development of a completely new organism. Results?
Two frog egg cells were enucleated (nucleus destroyed by being exposed to UV light), then the nucleus of a less differentiated frog embryo cell and a fully differenentiated from intestinal cell were inserted into one each of the enucleated frog egg cells.
The new egg cells were then activated to begin development.
RESULTS:
- The egg cell with the embryo nucleus donor developed fully into a tadpole.
- The egg cell with the intestinal nucleus donor stopped developing before the tadpole stage,.
Describe how the cloned sheep “Dolly” was made. Was there any complications?
This is a lamb that was cloned from an adult sheep via nuclear transplantation from a differentiated mammary cell into a donor sheeps enucleated egg cell.
Dolly had a premature death and had arthritis. This led to speculation that her cells were older than those of a normal sheep, possibly reflecting incomplete reprogramming of the original transplanted nucleus.
What is the difference between a totipotent and a pluripotent stem cell? What is an example of each?
Totipotent - able to differentiate into all cell types, EMBRYONIC STEM CELL
Pluripotent - can give rise to multiple but NOT ALL cell types, ADULT STEM CELL
What are two ways that plant and animals morphogenesis differ?
In animals - movement of the cells and tissues transform the embryo into the 3D form of the organism.
In plants - morphogenesis and growth in overall size is not limited to embryonic and juvenille periods, this occurs throughout the life span.
