Term
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Definition
-A heritable change in the genetic material
-Essential to the continuity of life (source of variation for natural selection)
-New mutations more likely to be harmful than beneficial (may cause death and not be passed on)
-DNA repair system reverse DNA damage (attempt to fix mutation before it becomes permanent) |
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Definition
-Affects only a single base pair
1. change base sequence (substitution)
2. add or remove nucleotide(s) |
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Definition
| -Does not alter the amino acid sequence (even with substitution the same amino acid is coded for) |
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Definition
-Changes a single amino acid in a polypeptide
-May not alter function if new amino acid is similar to original (Galamate to Asparate) |
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Definition
-The result of a single amino acid substitution
-(BETA)-globin gene
-Change in amino acid sequence causes blood cells to become sickle shaped(Glu to Val) |
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Definition
-Change from a normal codon to a stop or a termination codon (UAA, UGA, UAG)
-Produces truncated polypeptide (results in reduced or no function) |
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Definition
-Addition of deletion of nucleotides that are not multiples of 3
-protein function likely to be completely inhibited
-Results in completely different amino acid sequence downstream |
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Definition
| A cell that fuses with another cell during fertilization. |
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Definition
-Mutation in a gamete
-Because all other cells rise from these cells, a mutation this early on will cause all other cells to be affected. |
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Term
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Definition
| Can occur at any time and often lead to 'patches' of affected cells. (referred to as mosaic) |
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Term
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Definition
| Spontaneous mutations result from abnormalities in biological processes -Rates vary from species to species and from gene to gene |
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| Expected rate of mutation? |
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Definition
| 1 mutation for every 1 million genes |
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Term
| Induced mutations are brought on by environmental agents |
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Definition
-Mutation rate higher than spontaneous mutation
-Mutagens are chemical or physical agents (can alter DNA in various ways)
-Disrupt pairing by:
-Modifying nucleotide structure
-Nitrous acid deaminates bases so that modified bases to not pair with proper nucleotide
-Using base analogue similar to particular bases
-Akylating bases
-Interfering with replication - inserts between bases and distorts helix |
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Term
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Definition
-Has high energy and can penetrate deeply into biological materials to create free radicals
-X-rays and gamma rays
-Cause base deletions or breaks in one or both DNA strands |
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Term
| UV rays can cause formation of... |
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Definition
-A thymine dimer causing gaps or incorporation of
incorrect bases (two adjacent thymine bases become covalently bonded) |
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Term
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Definition
| A test to determine the mutagenic activity of chemicals by observing whether they cause mutations in sample bacteria. |
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Term
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Definition
-All organisms must have the ability to repair changes that occur in DNA to minimize mutation
-Requires: DNA damage to be detected and Repair or DNA damage
1. Direct Repair
2. Altered DNA strand removed and replaced
3. Nucleotide Excision Repair (NER) |
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Term
| Types of DNA repair - 3. Nucleotide Excision Repair (NER) |
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Definition
-Region encompassing several nucleotides in the damage strand is removed from DNA
-Intact, undamaged strand is used as a template for re-synthesis of a normal complimentary strand
-Found in all Eukaryotes and Prokaryotes
-Four Key proteins: UvrA, UvrB, UvrC, UvrD
-involved in ultraviolet repair |
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Term
| NER and human genetic disease |
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Definition
-NER system was discovered in humans by the analysis of genetic diseases that affect DNA repair
-Xeroderma pipmentosum (XP)
-Cockayne’s syndrome (CS)
-PIBIDS
-Photosensitivity is a common characteristic in all three syndromes because of an inability to repair UV-induced lesions |
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Term
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Definition
-Disease of multicellular organisms that is characterized by uncontrolled cell devision.
-1.5 million americans diagnosed each year
-In about 10% of cancers, a higher predisposition to develop the disease is an inherent trait
-Most cancers (90%) do no involve genetic changes that are passed down from parent to child
-Most cancers are caused by mutagens
-A few viruses are known to cause cancer (Rous sarcoma virus (RSV)) |
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Term
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Definition
-About 80% of all human cancers are related to exposure to carcinogens
-Agents that increase the likelihood of developing cancer
-Most carcinogens, such as UV light and certain chemicals in cigarette smoke, are mutagens that promote genetic changes in somatic cells.
-DNA alterations can lead to effects on gene expression that ultimately affect cell division and thereby lead to cancer. |
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Term
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Definition
-Tumor may begin a benign or pre-cancerous (do not invade or spread)
-Malignant stage
-Lost normal cell growth regulation
-Invasive - can invade healthy tissues
-Metastatic - can migrate to other parts of the body
-Left untreated, will cause death of the organism |
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Term
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Definition
-Cell division regulated by hormones called grown factors
-Bind to cell surface and initiate cascade leading to cell division which includes activating specific genes
-Mutations in genes producing cell growth signaling proteins can change them into oncogenes producing abnormally high level of activity in some proteins
-An oncogene may promote cancer by keeping the cell division signaling pathway in a permanent ‘on’ position
-In some cancers the amount of gene product is abnormally high
-In others, the gene produces a functionally hyperactive protein |
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Term
| Ras - intracellular signaling protein (relate to oncogenes) |
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Definition
-GTPase that hydrolyzes GTP to GDP -When GTP is bound, Ras promotes cell division
-Oncogenic mutations may decrease ability of Ras to hydrolyze GTP or exchange GDP for GTP factor (both keep signaling pathway on). |
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Term
| Proto-oncogene (also see table 14.7) |
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Definition
-Normal gene that, if mutated, can become an oncogene
-4 common genetic changes |
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Term
| Proto-oncogene 1 - Missense Mutation |
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Definition
| -Chemical mutations have been shown to cause missense mutations leading to cancer |
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Term
| Proto-oncogene 2 - Gene Amplifications |
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Definition
-Abnormal increase in copy number results in too much of the encoded protein
-Many human cancers are associated with the amplification of some proto-oncogenes |
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Term
| Proto-oncogene 3 - Chromosomal translations |
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Definition
-Two different chromosomes break, and the ends of the chromosomes fuse incorrectly
-Very specific types of chromosomal translocations have been identified in certain tumors
-Chimeric genes are composed of two genes fragments fused together |
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Term
| Proto-oncogene 4 - Retroviral Insertions |
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Definition
-Viral DNA may insert into a host chromosome in such a way that a viral promoter and response elements are next to a proto-oncogene. (may result in the over-expression of the proto-oncogene, thereby promoting cancer)
-Alternatively, a virus may cause cancer if it carries an oncogene in the viral genome |
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Term
| Tumor-supressor gene functions (2) |
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Definition
1. Proteins that maintain the integrity of the genome by monitoring and/or repairing alterations in the genome. (Checkpoint proteins check the integrity of the genome and prevent a cell from progressing past a certain point in the cell cycle).
2. Proteins that are negative regulators or inhibitors of cell division. (Function is necessary to properly halt cell division otherwise cell division in abnormally accelerated). |
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Term
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Definition
| Proteins called cyclins and cyclin-dependent protein kinases (sdks) are responsible for advancing a cell through the four phases of the cell cycle. |
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Term
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Definition
| Responsible for monitoring the integrity of the genome and preventing it's progression throught the cell cycle if abnormalities are detected. |
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Term
| Cancer is a series of changes (3) |
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Definition
-Cancer usually requires multiple genetic changes to the same cell
-Begin with a benign genetic alteration that over time, with additional mutations lead to malignancy
-Malignancy can continue to accumulate genetic changes that make it even more difficult to treat |
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Term
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Definition
-Diagnosed in approximately 170,000 men and women each year in the US
-1.2 million cases diagnosed worldwide
-Nearly 90% of these cases are caused by smoking and are preventable
-Unlike other cancers for which early diagnosis is possible, lung cancer is usually detected only after it has become advanced and is difficult, if impossible to cure.
-The five-years survival rate of a lung cancer patient is 15% |
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Term
| Leukemia can be caused by... |
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Definition
| gene amplification of a proto-oncogene |
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