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Bis 101
Lecture 13
| Question | Answer |
|---|---|
| What is Synteny? | Similarities between chromosomes that can show the large scale mutations |
| What are the types of chromosomal rearrangement? | There are four. They are: Translocation, Deletion, Duplication, and Inversion |
| How does deletion occur in DNA? | Either two sides of a portion of DNA with no centromere break and the DNA floats off, or during crossing over two homologous chromosomes cross and a portion of the DNA is lost. |
| How does translocation occur in DNA? | The both chromosomes are cleaved and they then reanneal with one another so that they bases are at different points in the strands. They can also crossover at different points so that the same outcome occurs. |
| What are deletion loops in Meitotic chromosomes? | When one chromosome is missing a few bases right next to each other, the other chromosome will form a loop with these bases in it and delete them out. |
| How does duplication occur in DNA? | Either a deletion occurs and then either end of the split reanneals with the other chromosome giving one a duplication and one a deletion or crossing over occurs and one chromosome takes bases from the other. |
| How does duplication facilitate evolution? | Either the duplicated bases will be lost over time, or the bases will acquire new uses over the generations. |
| How does inversion occur in DNA? | Either a deletion occurs and the same broken off piece of chromosome reanneals but backwards or during crossing over one of the chromosomes is looped and the other one isnt. When they cross they will trade bases and come back inverted. |
| What is a paracentric inversion heterozygote? | An inversion loop where the centromeres are not within the looped inverted region. This gives a normal product, two deletion products, and one inversion product. Both deletion products are different lengths. |
| What is a pericentric inversion heterozygote? | An inversion loop where the centromeres are in the center of the loop. This results in one normal, one inverted, and two deleted and duplicated products. All are the same length. |
| What are the two main chromosome segregation patterns? | Adjacent-1 and Alternate |
| What is the Adjacent-1 chromosome segregation pattern? | In the final meiotic product: One translocated and one normal chromosome are pulled to a single pole. This arrangement is often inviable. |
| What is the Alternate chromosome segregation pattern? | In the meiotic product: Both the normal chromosomes and both of the translocated chromosomes are pulled to two different poles. This option is often more viable. |
| What is the chromosomal constitution of a Monoploid (n)? Diploid (2n)? | Monoploid (n): A B C Diploid (2n): AA BB CC |
| How does an increased ploidy number affect plants? | It affects the number of chromosomes that a single cell carries. If a plant has a higher ploidy number than it will have larger cells and larger fruit. |
| How does Colchicine affect the ploidy number of cells? | It disintegrates the micro-tubules that separate the chromosomes during Meitosis and increases the number of chromosomes in the cell. This makes a diploid into a tetraploid. |
| How do you make a triploid? Why are triploids useful? | By crossing a tetraploid and a diploid plant. This is useful because triploids cant reproduce so there are no seeds in the plant. |
| Define Aneuploidy. What is Monosomic? Trisomic? | The loss or gain of a single chromosome Monosomic: 2n-1: AA B CC Trisomic: 2n+1: AAA BB CC |
| Define Nondisjunction | When chromosomes do not sort properly during cell division. In Mitosis it can only happen at the only division. During Meiosis the chromosomes may not separate properly at either the first or the second separation. |
| What is an MI Nondisjuction? | When the homologs do not seperate at the first division and both end up in a single cell. Usually results from the homologs failing to complete crossing over. |
| What is an MII Nondisuction? | When the sister chromatids travel to the same pole in the gamete and now one gamete has an extra chromatid and one has one to few. |
| What is a Carcinogen? | An external agent that increases the likelihood of cancer in an individual. This occurs because the carcinogen (cigarettes, UV light, etc.) increase the number of mutations in an individuals somatic cells. |
| What is the Malignant stage of cancer? | When the cell has lost normal growth regulation |
| What is the invasive stage of cancer? | When the cancer cells start invading healthy tissue |
| What is the metastatic stage of cancer? | When the cancer cells start moving to other parts of the body. Occurs when cancer cells enter the blood stream or surrounding body fluids. |
| What is an oncogene? | A mutated Proto-oncogene. Acts as an activator for cancer, when in the mutated state uncontrolled cell growth occurs. |
| What is a Tumor-suppressor gene? | A gene that codes for a protein that prevents cancer. If this gene is mutated then cancer may occur. |
| What is a Proto-oncogene? | A gene that produces cell growth signaling proteins. |
| What are the four mutations that turn Proto-oncogenes into oncogenes? | Missense mutation, Gene amplifications, Chromosomal translocations, and Retro-viral insertions |
| How does a Missense mutations cause cancer? | By changing an amino acid in the Proto-oncogene region, it could change the function of the gene. For example, if mutated the ras gene could be made into an oncogene by putting it in a constant "on" state by preventing the GTP converting to GDP. |
| How does Gene Amplification cause cancer? | It increases the number of Proto-oncogenes so that more proteins that cause cell replication are produced. |
| How does chromosomal translocation cause cancer? | It breaks the proto-oncogene apart and fuses it with another genes. This forms an oncogene that can cause cancer. |
| How does a retroviral insertion cause cancer? | It can happen in two ways. The first is that the viral DNA is inserted into the chromosome right next to the proto-oncogene which then enhances the expression. The second is the viral DNA may have a virus causing oncogene inside of it. |
| In a Tummor-suppressor gene, what is a positive regulator? Negative regulator? | A positive regulator activate cell apoptosis. A negative regulator prevents the cell cycle from occurring. |
| What is a checkpoint protein? Give an example | A protein that scans DNA as it go's through replication. If the DNA is not correct then the cell cant replicate. Ex: P53 |
| How many mutations do Proto-oncogenes need? Tumor suppressor genes? | Oncogenes need just one because they are dominant. Tumor suppressor genes need two though because they are recessive. The one exception to that is an epigenetic change can cause gene silencing will turn off the Tumor suppressor gene without a mutation. |
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24rory
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