Cytogenetics
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2011-12-09 22:13
Section
| Question | Answer |
|---|---|
| What is DNA composed of? | 5-carbon sugar (deoxyribose), phosphate group, and a nitrogen containing base (purine or pyrimadine) |
| How are DNA strands held together? | Through hydrogen bond interactions between nitrogenous bases |
| How are nucleotides linked together? | NOTE: Nucleotides are not nitrogenous bases. Nitrogenous bases are the two-strand-linkers; Nucleotides are a base unit, composed of a phosphate group, a sugar and a nitogenous base. they are linked covalently by phsophodiester bonds through the 3' hydroxyl group to the 5' phosphate group. This twisted bonding creates a doubled helical structure. |
| Appx how many nucleotides does a human genome contain? (in each cell) | 10^9 nucleotides. |
| What is the functional difference between major and minor grooves in DNA? | Major grooves expose hydrogen-bound base pairs--attracting protein moelecules and allowing regulation of DNA to occur. Minor groove allows similar interactions but at smaller scale. |
| What two organelles contain DNA? | nucleus; mitochondria |
| How is mitochondrial DNA similar to bacterial DNA? | has circular vs. linear double helix; has no unexpressed sequences; exists as multiple copies within a single organelle |
| What three phases compose interphase? | G1, S, G2 |
| Describe the 8 histone proteins that DNA wraps around, and what is created once DNA does so. | 2 H2A, 2 H2B, 2 H3, and 2 H4. creates chromatin. |
| What does each histone complex contain that controls chromatin structure? How can it be controlled? | long N-terminal amino acid tail; Histone acetylase (addition of acetyl group creates separation in chromatin structure and increases accessibility to DNA); Histone deacetylase removes the acetyl group and makes the region less acessible to transicription factors. Controls gene expression. |
| What does wrapped segment of DNA, histone octamer and length of DNA to the next bundle form? | nucleosome |
| Term for extended chromatin vs. term for condensed chromatin | Extended and under current gene expression: euchromatin; silent, condensed: heterochromatin. |
| What is the cell cycle governed by? | activated protein kinases interacting with protein binders called cyclins (cyclin-dependent kinases (Cdks)); |
| What is the first sign that a cell is about to enter M phase? | condensation of the DNA at the end of g2 phase |
| What are identical copies of chromosomes (sister chromatids) bound by? | cohesins |
| What triggers accumulation of condensins at M phase initiation? | M-phase Cdk |
| What do microtubules grow out from? | the centrosome outside of the nucleus; forms poles of mitotic spindle |
| What does each centrosome contain that initiates microtubule growth? | gamma tubulin |
| What subunits are microtubules made of? | alpha and beta tubulin |
| What protein controls microtubule synthesis? What reduces the ability of these proteins to stabilize microtubules? | MAPs (microtubule-associated proteins); M-Cdk reduces ability of MAPs to stabilize microtubules |
| What happens in prometaphase? | Nuclear envelope breaks down, allowing microtubules to reach inside cell and contact chromosomes at kinetochores. |
| What gene sequence is manipulated in cancer and causes normal function of the kinetochore? | APC gene (familial adenomatous polyposis) |
| What acronym is used to describe the symptoms of a disease that causes development of antibodies to the centromere/kinetochore complex | CREST: calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasia |
| What is the name of an autoimmune disorder that causes antibodies to attack components of protein machinery such as centromere/kinetochore complex, DNA topoisomerase I, RNA polymerase I? | Systemic sclerosis |
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