| Question | Answer |
| Tumor-Suppressor Genes | Cells contain genes whose normal products inhibit cell division. Can become oncogene if a mutation decreases the normal activity of a tumor-suppressor protein |
| Proto-Oncogenes | Chromosomes that contain genes that can be converted to oncogenes. Cell can acquire an oncogene either from a virus or mutation. Many code for growth factors. Become oncogenes when genetic change leads to an increase in amount of proto-oncogene's protein product or the rate of activity of each protein molecule. Mutation, multiple copies of a gene, or moved gene to new locus |
| Oncogenes | Genes which can cause cancer when present in a single copy in the cell. Viruses insert oncogenes into cells |
| Adult Stem Cells | Serve to replace non-reproducing specialized cells. Many but not all cell types in the organism |
| Embryonic Stem Cells | Can divide indefinitely. Changes in gene expression that cause differentiation into a variety of cell types |
| Signal Transduction Pathway | Series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell |
| Cell-to-cell Signaling | Key mechanism for coordination of cellular activities. Signal molecule binds to receptor protein in plasma membrane of target cell and initiates a signal transduction pathway. 1. Signal cell secretes signal molecule which binds to a receptor protein embedded in target cell. 2. Triggers series of relay proteins. 3. Last relay molecule in the series activates a transcription factor that transcribes a specific gene and produces a protein |
| Protein Breakdown | Selective breakdown of proteins. Some of the proteins that trigger metabolic changes in cells broken down within a few minutes of hours. Cell can adjust the kinds and amounts of its proteins in response to changes in its environment. |
| Protein Activation | Polypeptides may require alteration to become functional. Cutting of polypeptide to yield smaller final products that is the active protein, able to carry out a specific function |
| Initiation of Translation | Translating an mRNA into a polypeptide. Proteins that control the start of polypeptide synthesis. Inhibitory protein that prevents translation of hemoglobin mRNA unless cell has supply of heme |
| Breakdown of mRNA | Enzymes in the cytoplasm eventually break down mRNA. Timing of breakdown can work to regulate number of proteins produced. The longer an mRNA strand exists, the more proteins it synthesizes. Prokaryotic mRNA very short lifetimes. A reason they can change their proteins very quickly in response to environment. Eukaryotic mRNA longer lifetimes |
| 4 ways Eukaryotic cells regulate gene expression | mRNA breakdown, initiation of translation, protein activation, protein breakdown |
| RNA Interference (RNAi) | Artificially regulating and controlling gene expression |
| microRNA | Complementary sequences on mRNA molecules. Typically about 20 nucleotides long. Associate with large protein complex and bind to any mRNA molecule with complementary sequence. Either degrades target mRNA or blocks its translation. May regulate expression of up to 1/3 of all human genes |
| alternative RNA splicing | Introns removed during RNA splicing. Way of regulating gene expression. Cell can carry out splicing in more than one way. Organism can get more than one type of polypeptide from a single gene. Common in humans |
| silencers | Repressor proteins. May bind to DNA sequences and inhibit the start of transcription |
| enhancers | DNA sequences far away from the gene they regular. Far away from genes they regulate. Activators bind to them, changing the shape of the DNA molecule |
| transcription factors | Eukaryotic RNA polymerase requires their assistance. Includes activator proteins |
| eukaryotic control mechanisms | Involve proteins that bind to specific segments of DNA. More regulatory proteins and more control sequences. Each gene usually has its own promoter and other control sequences. More activators usually. Genes usually switched off. Transcription factors, enhancers, Large assembly of proteins facilitates correct attachment of RNA polymerase to the promoter, silencers, genes coding for enzymes of metabolic pathway often scattered over different chromosomes |
| Barr body | Inactive X |
| x chromosome inactivation | One X chromosome in each somatic cell exists in a highly compacted an almost entirely inactive form. One of the two X chromosomes is inactivated at random |
| DNA packing | Tightly coiled DNA. How DNA fits into such a small nucleus. During Mitosis. Prevents transcription proteins from contacting the DNA. Uses higher levels of packing for long-term inactivation of genes |
| nucleosome | Each 'bead' of DNA. DNA wound around a protein core of 8 histones. Short stretches of DNA, called linkers, join nucleosomes |
| histones | Small proteins that associate with DNA to help its structure in DNA packing |
| differentiation | When individual cells become specialized in structure and function. Results from selective gene expression, the turning on and off of specific genes. Particular genes that are active in each type of differentiated cell are the source of its particular function and structure |
| activator | Proteins that turn operons on by binding to DNA. Make it easier for RNA polymerase to bind to promotor. Some activators in E coli and other prokaryotes |
| The trp operon | Repressor inactive alone, and active with tryptophan present |
| regulatory gene | Located outside the operon, codes for the repressor. Expressed continually |
| repressor | Turns 'switch' either on or off. Protein that functions by binding to the operator and physically blocking the attachment of RNA polymerase to the promoter. Binding changes repressor's shape. When not attached to operon, RNA polymerase can transcribe enzymes |
| operon | Cluster of genes with related functions, along with a promoter and an operator. Exists only in prokaryotes. The on/off switch |
| operator | Control sequence. Acts as a switch. Determines whether RNA polymerase can attach to the promoter and start transcribing genes |
| promoter | Control sequence. Site where transcription enzyme, RNA polymerase, attaches and initiates transcription |
| control sequences | Short sections of DNA that help control the enzyme genes. 2 in a bacteria |
| the lac operon | E coli makes enzymes to absorb sugar lactose and use it as an energy source. When lactose is not plentiful, E coli does not waste energy producing these enzymes. 3 enzymes that digest lactose, Therefore, three genes code for it. Turned on when repressor deactivated. Lactose binds to repressor and operon is active. Repressor active when alone, and inactive when bound to lactose |
| gene expression | The overall process by which genetic information flows from genes to proteins |
| Gene regulation | Helps organisms respond to environmental changes. Gene turned on being transcribed into RNA. Control of a gene expression makes it possible for cells to produce specific kinds of proteins |
36 cards - created dec 9, 10:07pm