Term
density-dependent inhibition
is an example of what?
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Definition
external signals...crowded cells stop dividing when this occurs. A reduction in cell division.
When a cell population reaches a certain density, the amount of required growth factors and nutrients available to each cell becomes insufficient to allow continued cell growth.
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Term
| What is anchorage dependence? |
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Definition
| most animal cells exhibit this. it means they must be attached to a solid surface in order to divide (for example the solid glass or plastic surface of a culture dish) |
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Term
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Definition
| normal benign type of programmed cell death in which a cell shrinks, fragments its DNA, and alters its surface so as to activate the cell's phagocytosis by macrophages |
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Term
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Definition
| the process by which particulate material is engulfed ("eaten") by a cell. Prominent in predatory cells, such as Amoeba proteus and in cells of the vertebrate immune system such as macrophages |
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Term
| What happens when cells ignore apoptosis? |
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Definition
they continue to grow and divide despite external signals
cancer can occur
and failure in cell communication occurs |
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Term
| Define cancer and what does it affect |
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Definition
"a group of diseases characterized by uncontrolled growth and spread of abnormal cells"
if affects cell cycle control |
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Term
| What is the process by which a cell is converted to a cancerous cell? |
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Definition
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Term
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Definition
masses of abnormal cells within otherwise normal tissue
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Term
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Definition
| when abnormal cells remain at the original site |
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Term
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Definition
| invade surrounding tissues and metastasize (export cancer cells to other parts of the body where they may form secondary tumors) |
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Term
| Do cancer cells need growth factors to grow and divide? |
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Definition
not always.
-they may make their own growth factors
-they may convey a growth factor's signal without the presence of the growth factor
-they may have an abnormal cell cycle control system |
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Term
| Cancer cells often have abnormal chromosomes. What is a gene translocation? |
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Definition
A translocation means that a piece of one chromosome has broken off and stuck on a different chromosome. Chromosome translocations cannot be repaired. If a translocation has not resulted in any genetic material being lost, it is known as a balanced translocation.
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Term
| The gene regulation systems that go wrong during cancer are the same systems that play important roles in_____ ______. They also regulate ____ ____ and ____. |
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Definition
embryonic development
regulate cell growth and division
also codes for growth factors, their receptors and intracellular molecules of signalling pathways |
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Term
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Definition
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Term
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Definition
| normal cellular genes that code for proteins that stimulate normal cell growth and division |
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Term
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Definition
| encode proteins that inhibit abnormal cell division |
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Term
| What happens when a DNA change occurs making a proto-oncogene excessively active? |
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Definition
| it converts it to an oncogene, which may promote excessive cell division and cancer |
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Term
| Name the three different ways proto-oncogenes can be converted to oncogenes |
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Definition
- Point mutations (causing an increase in gene expression)
- Amplification - multiple copies of a section of a chromosome being reproduced
- Movement of DNA to a promoter (increasing transcription) |
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Term
When a proto-oncogene is converted to an oncogene what can result from the following
a. mutation in coding sequence
b. gene amplification
c. chromosome rearrangement |
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Definition
a. hyperactive protein made in normal amounts
b. normal protein greatly overproduced
c. nearby regulatory DNA sequence causes normal protein to be overproduced, or fusion to actively transcribed gene produces hyperactive fusion protein |
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Term
| What type of protein is the Ras protein? |
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Definition
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Term
| What is the role of the Ras protein? |
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Definition
| it relays a signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases |
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Term
| What does the p53 gene do? |
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Definition
it encodes a tumor-suppressor protein
it is also a specific transcription factor
it promotes the synthesis of cell cycle-inhibiting proteins for example when DNA is damaged |
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Term
| what do mutations in p53 prevent? |
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Definition
| suppression of the cell cycle |
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Term
| Mutations that knock out the p53 gene can lead to what? |
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Definition
| excessive cell growth and cancer |
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Term
| Explain the development of colorectal cancer. |
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Definition
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Term
| Mutations in ras cause .... |
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Definition
| production of hyperactive ras protein and increased cell division |
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Term
| Incidence of cancer increases with age. Why? |
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Definition
| multiple mutations are generally needed for full fledged cancer |
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Term
A cancerous cell is usually characterized by
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Definition
at least one active oncogene
the mutation of several tumor-suppressor genes |
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Term
| Mutations in what genes are found in 50% of all breast cancers? |
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Definition
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