No Lecture Be able to identify dependent and independent variables in both observational tests and experiments Know how to cite a scientific paper in the text of something you write and then how to write out the citation at the end Independent Variable Dependent Varaible o The variable being manipulated or changed by the experimenter o X axis o the variable that is effected by the independent variable and is measured o Y axis Citation Lecture 2 Know that cells grow synthesize DNA and divide in a cycle with distinct phases Understand that the cell cycle is controlled by molecules present in the cytoplasm that regulate movement of the cycle past checkpoints In a cell there are two phases Interphase and Mitotic Phase Interphase most of the cells life is spent in interphase about 90 cell grows throughout this phase has three parts G1 S and G2 the DNA is replicated o Synthesis S Phase Mitotic Phase M Mitosis and cytokinesis make up the division phase in cell cycle o Mitosis the division of genetic material in the nucleus 1 Prophase 2 Prometaphase chromatin fibers become more tightly coiled nucleoli disappears each duplicated chromosome appears as 2 identical sister chromatids mitotic spindle begins to form nuclear envelope disappears each of 2 chromatids now has a kinetochore specialized protein structure attached at the centromere are lined up at metaphase plate ends of the cell have complete collections of chromosomes less condensed any spindle microtubules disappear centromere are now at opposite poles chromosomes 2 sister chromatids part by the end of anaphase the two two daughter nuclei form in cell chromosomes become 4 Anaphase 5 Telophase 3 Metaphase o Cytokinesis the division of cytoplasm in animal cells cleavage is the division of the cell s cytoplasm by pinching it in two end result is two daughter cells in plant cells a cell plate forms this is the plants way of dividing the two cells Cell Cycle Control System cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle Checkpoints a control point where stop or go ahead signals can regulate the cycle o G1 Checkpoint if a cell receives go ahead signal at this checkpoint the cell will most likely finish the complete cycle If cell does not receive go ahead signal the cell will enter the G0 phase G0 Phase non dividing state Many nerve and muscle cells never divide o G2 Checkpoint o M Checkpoint o Particular protein kinases give the go ahead signal at G1 and G2 checkpoints To be active the kinases must be attached to cyclin a protein Cyclin dependent kinases Cdks activity of CDK rises and falls with changes in concentration of its cyclin partner MPF cyclin CDK complex Triggers cell s passage past G2 and into M phase The MPF initiates a process which breaks down its own cyclin Lecture 3 Understand that meristems are sites of cell division and that development occurs after cell division Meristems undifferentiated tissue that divide when conditions permit lead to new cells Apical meristems Lateral meristems tissue and in cork cambium replaces epidermis located at tips of roots and shoots new cell growth in vascular cambium adds layers of vascular Lecture 4 Control of transcription occurs through the binding of activators or repressors to special sites on the DNA Know that gene expression in eukaryotes can be controlled at multiple stages during transcription and translation Know that modification of histone structure can affect transcription Know that enhancers and transcription factors can affect transcription Cells control metabolism by regulating enzyme activity or expression of genes that code for enzymes Operator on off switch that controls segment of DNA Positioned within the promoter o Promoter RNA polymerase binds starts transcription of DNA to RNA Operon switched on by the operator Example is the trp operon Repressor operon can be switched off by the repressor The repressor binds to the operator and blocks attachment of RNA polymerase to the promoter o Corepressor small molecule that cooperates with a repressor protein to switch an operon off All Organisms must regulate which genes are expressed at any given time Differentual Gene Expression expression of different genes by cells with the same genome o Transcription factors of a cell must locate right genes at the right time Histone Acetylation this loosens chromatin structures enhancing transcription DNA methylation binding of methyl groups to DNA generally reduces transcription Specific transcription factors called activators bind to enhancer DNA sequences which in turn bind them to transcription factors initiating transcription Lecture 5 Cell differentiation occurs during early development because of different concentrations of cytoplasmic determinants Cytoplasmic Determinants in the unfertilized egg regulate the expression of genes in the zygote that affect the developmental fate of embryonic cells Induction signaling molecules that cause transcriptional changes in nearby target cells Positional information molecular cues that control pattern formation tells a cell its location relative to body s axes and other cells Example in the Drosophila fly the protein bicoid determines the anterior posterior axis When this protein was injected into the fly larva at both ends the result was a fly with two anterior ends Lecture 6 Understand that polyspermy is blocked by 2 mechanisms in sea urchins and why blocking multiple fertilizations is important Know that cleavage has different patterns in different organisms and what those patterns are In Sea urchins polyspermy entry of multiple sperm is blocked by the arcosomal reaction and the cortical reaction Arcosomal Reaction happens when the sperm contacts the jelly coat of the egg o Is the discharge of hydrolytic enzyme This enzyme acts as a lock and key recognition allowing the fusion of the sperm and egg plasma membranes o Sodium ions then defuse into the egg and cause depolarization acts as a fast block to polyspermy which prevents additional sperm from fusing with membrane Cortical Reaction o longer lasting block to polyspermy is established by vesicles that lie just beneath membrane of egg called cortex o cortical granules fuse with the membrane and develop the fertilization envelope requires high amounts of calcium ions Ca2 Cleavage rapid series of mitotic cell divisions that occur in the absence of cell growth Sea Urchin Cleavage proceeds to a morula solid ball of cells
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