Difference between revisions of "Robbins and Cotran 9th Edition Questions"

{{hidden|What do we think that the rest of the genome does?|[[80% of the genome binds proteins, implying that it is involved in regulating gene expression, related to the regulation of gene expression, often in a cell-type specific fashion.]]}}

{{hidden|List the major classes of functional non-protein-coding sequences found in the human genome.|[[1. Promoter & enhancer, 2. Chromatin binding site structures, 3. non-coding regulatory RNAs, 4. Mobile genetic elements (transposons), 5. telomeres, 6. centromers. ]]}}

{{hidden|What are the two most common forms of DNA variation in the human genome?|[[1) Single nucleotide polymorphisms (SNPs), 2) copy number variations (CNVs)]]}}

{{hidden|What are the possible implications of SNPs.|[[1) regulatory = alters gene expression, 2) Correlation with disease states when in close proximity with altered genes, 3) association used to define linkage disequilibrium,?]]}}

{{hidden|Define epigenetics.|[[Heritable changes in gene expression which are not caused by alterations in DNA sequence.]]}}

{{hidden|List the 6 types of epigenetic changes.|[[1) Histone & histone modifying factors (Histones organize chromatin into heterochromatin and euchromatin, 2) histone methylation, 3) histone acteylation, 4)histone phosphorylation, 5) DNA methylation, 6) Chromatin organizing factors.]]}}

{{hidden|What is the function of micro-RNA (mi-RNA)?|[[It does not encode protein, instead they function primarily to modulate the translation of target mRNAs into their corresponding proteins, and are responsible for post-transcriptional silencing of gene expression.]]}}

{{hidden|What is knockdown technology?|[[The use of synthetic  si-RNA (short RNA sequences) introduced into cells that serve as substrates for Dicer and interact with the RISC complex in a manner analogous to endogenous miRNAs, and are used to study gene function, and are being developed as therapeutic agents to silence pathogenic genes, e.g. oncogenic in neoplasms.]]}}

{{hidden|What is long non coding RNA?|[[ Lnc-RNA modulate gene expression by binding to regions of chromatin, restricting RNA polymerase access to coding genes within the region, and may exceed the number of mRNA's by 10-20 fold.]]}}

{{hidden|What is XIST?|[[XIST is a lnc-RNA which is transcribed from the X-chromosome and plays an essential role in physiologic X chromosome inactivation, though not inactivated itself, it forms a repressive cloak on the X chromosome from which it is transcribed resulting in gene silencing.]]}}

{{hidden|What are the cellular housekeeping functions?|[[ 1) protection from the environment, 2) nutrient acquisition, 3) communication, 4) movement, 5) renewal of senescent molecules, 6) molecular catabolism, 7) energy generation.]]}}

{{hidden|List the cellular compartments and the role in the cell.|[[1) cytosol = metabolism, transport, protein translation, 2) Mitochondria = energy generation, apoptosis, 3) Rough ER = synthesis of membrane and secreted proteins, 4) Smooth ER / Golgi = protein modification, sorting, catabolism, 5)Nucleus = cell regulation, proliferation, DNA transcription, 6) Endosomes = intracellular transport and export, ingestion of extracellular substances, 7) Lysosomes = cellular catabolism, 8) peroxisomes = very long-chain fatty acid metabolism]]}}

{{hidden|Describe the basic structure and functions of the cell membrane.|[[ The plasma membrane is composed of a lipid bilayer of phospholipids studded with a variety of proteins and glycoproteins involved in ion and metabolite transport, fluid phase and receptor-mediated uptake of macromolecules, cell-ligand/cell matrix/cell-cell interactions.]]}}

{{hidden|What are aquaporins?|[[Special integral membrane proteins which augment passive water transport in tissues where water is transported in large volumes.]]}}

{{hidden|What is the "multidrug resistance (MDR) protein"?|[[A type of transporter ATPases which pumps polar compounds (e.g. chemo drugs) out of cells which may render cancer cells resistant to treatment.]]}}

{{hidden|What are the two fundamental mechanisms of fluid or macromolecules by the cell (endocytosis)?|[[1)Caveolae -invaginations of the plasma membrane, 2) Pinocytosis/receptor mediated endocytosis - macromolecules bind to receptor  and membranes invaginate around it.]]}}

{{hidden|What is exocytosis?|[[It is the opposite process of pinocytosis, where the receptor bound macromolecule is move to the cell surface and released.]]}}

{{hidden|Describe the difference between phagocytosis and transcytosis.|[[In phagocytosis microbes are ingested forming phagosomes, which fuse with lysosomes and become phagylosomes, releasing undigested residual material when fusing again with the external membrane, in contrast transcytosis the materials are carried across the cell membrane unaltered.]]}}

{{hidden|List the three major classes of 3 cytoskeleton proteins.|[[1) Actin, 2)Intermediate filaments, 3)Microtubules]]}}

{{hidden|Describe actin.|[[Actin - 5 to 9nm diam fibrils, G-actin polymerized into F-actin, the form double strands helices, which interact with myosin (filamentous protein).]]}}

{{hidden|List the various intermediate filaments, which are 10nm in diameter.|[[1) Lamin A, B, and C (nuclear lamins of all cells, 2) Vimentin (mesenchymal), 3)Desmin (scaffold for actin/myosin), 4) Neurofilaments (axons of neurons), 5) Glial filament protein (glial cells), 6)Cytokeratins (acid and basic and vary based on cell type). ]]}}

{{hidden|Describe microtubules.|[[ Microtubules are 25nm diam fibrils of dimers of a and b tubulin, with a negative end embedded in the centrosome near the nucleus, the + end grows or shrinks as needed. There are kinesins and dyneins motors that move stuff around the cell, also found in cilia and flagella.]]}}

{{hidden|What is clatharin?|[[A molecule found in the cell membrane that when the cell membrane invaginates forming a basket like structure.]]}}

{{hidden|List and describe the 3 main classifications of cell junctions.|[[1) Tight /occluding junctions - form a high resistance barrier to solute movement, and allows the cell to maintain polarity, 2) anchoring junctions / desmosomes - mechanically attach the cell and their cytoskeleton to other cells and the ECM (hemidesmosome), 3)communicating/gap junctions - mediate the passage of chemical or electrical signals from one cell to another.]]}}

{{hidden|What cell organelle has a reactive hyperplasia with repeated exposure to phenobarbitol catabolism in the cytocrhome p450 system?|[[Smooth endoplasmic reticulum.]]}}

{{hidden|List three main functions of mitochondria.|[[1) Energy generation, 2) intermediate metabolism (instead of ATP make intemediate that can be used to make lipids, nucleic acids, and proteins), 3) Cell death ( necrosis & apoptosis)]]}}

{{hidden|List and describe the four extracellular cell-cell signaling pathways based on the distance the signal travels.|[[1)Paracrine (immediate vicinity), 2) Autocrine (cell affecting itself), 3) Synaptic (neurons sending neurotransmitters at synapse), 4) endocrine (signals released elsewhere into bloodstream).]]}}

{{hidden|What are the two characterizing features of stem cells?|[[Self renewal and asymmetric division (one daughter cell stays a stem cell)]]}}

{{hidden|What are the two types of stem cells?|[[embryonic stem cells (inner cell mass of the blastocyst, totipotent), and tissue/adult stem cells (found in stem cell niches associated with specialized tissues, limited repetoire of differentiation = multipotent)]]}}

{{hidden|What is the Warburg effect?|[[Increased cellular uptake of glucose and glutamine, increased glycolysis, and decreased oxidative phosphorylation by the cell.]]}}

{{hidden|Which CDKI's have selective effects on CDK4 and CDK6?|[[p15,p16,p17,and p19]]}}

{{hidden|List some examples of signal transduction pathways.|[[1) Receptor tyrosine kinases (RTKs), 2) Nonreceptor tyrosine kinase, 3) G-protein coupled receptors, 4) nuclear receptors, 5)Notch family receptors, 6) Wnt protein ligands (Frizzled family receptors).]]}}

{{hidden|Why does nuclear beta catenin occur in some neoplasms?|[[When Wnt ligand bins to frizzled it recruits Disheveled, this leads to the disruption of the wnt-ubiquitin complex, this stabilized pool of b-catening is then translocated to the nucleus forming a transcriptional complex]]}}

{{hidden|What are the functions of the extracellular matrix?|[[Mechanical support, control of cell proliferation, scaffolding for tissue renewal, establishment of tissue microenvironments]]}}

{{hidden|What are the two basic forms of the ECM?|[[interstitial matrix (fibrillar and non fibrillar collagen, fibronectin, elastin, proteoglycans, hyloronate, and other stuff), basement membrane (type IV collagen and laminin) ]]}}

{{hidden|What are the three proteins groups in the ECM?|[[1) fibrous structural proteins (collagen, elastins), 2) water hydrated gels (proteoglycans and hyaluronan), 3) adhesive glycoproteins (connect ECM to each other and other cells)]]}}

{{hidden|Describe the structure of a protein that is dependent on vitamin C.|[[Collagen is composed of 3 seprate polypeptide chains braided into a rope like triple helix, lateral cross linking of the triple helices by lysyl oxidase (requires vitamin C) give it it's tensile strength. ]]}}

{{hidden|List three non-fibrillar collagens.|[[Type IV -basement membrane, Type IX  - Fibrillar associated collagen with interrupted triple helices (FACIT), Type VII (provides anchoring fibrils to basement membrane beneath skin)]]}}

{{hidden|Which structural protein is associated with Marfan syndrom?|[[Fibrillin synthetic defects, which wrap the elastin core. ]]}}