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38 Cards in this Set
- Front
- Back
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Define kinetochore
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a complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach. |
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Define centrosome
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an organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division. |
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Define centromere
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the region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division. |
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What are the mitotic spindle fibers made of?
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clusters of microtubules. |
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What are the three types of spindle fibers?
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kinetochore microtubules, polar microtubules, and aster microtubules. |
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Describe the role of motor proteins in mediating separation of sister chromatids AND separation of centrosomes during anaphase
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Compare and contrast cytokinesis in plants and animals.
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In animal cells, the first sign of cytokinesis is the appearance of an indentation around the middle of the cell. The ring contracts like the pulling of a drawstring and pinches the parent cell in two. Because the two new nuclei are forming at the ends of the cell, cytokinesis results in two new cells.In cytokinesis a cell plate forms inside the cell and grows outward. Eventually this new piece of cell wall divides the cell in two. The result is two daughter cells, each bounded by its own continuous membrane and its own cell wall.
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What is a cleavage furrow
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the indentation of the cell's surface that begins the progression of cleavage, by which animal and some algal cells undergo cytokinesis, the final splitting of the membrane, in the process of cell division.
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What is a contractile ring?
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the constricting force to separate one cell into two cells.
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What is the contractile ring made of?
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composed of filamentous actin (F-actin) and the motor protein myosin-2, along with additional structural and regulatory proteins.
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Know the three main checkpoints in the cell cycle and know what influences whether the cell proceeds through each checkpoint.
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The integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint.
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What are cyclins and cdks and how do they control movement through the cell cycle?
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Cyclins: any of a number of proteins associated with the cycle of cell division that are thought to initiate certain processes of mitosis.
Cdks: are a family of protein kinases first discovered for their role in regulating the cell cycle. |
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How are cdks activated?
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CDK activation depends on phosphorylation by a CDK-activating kinase (CAK).
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What are the main cellular targets of mitotic cdks and how does each contribute to movement through mitosis?
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Describe how the anaphase-promoting complex is activated and also describe how it works once activated,
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prometaphase– metaphase transition where it will induce cyclin A and Nek2 degradation.
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What is the role of cohesion
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Cohesion means the water molecules cooperate with each other.
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What is the role of securin
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Securin has 5 known phosphorylation sites that are targets of Cdk1; 2 sites at the N-terminal in the Ken-Box and D-box region are known to affect APC recognition and ubiquitination (Figure 2).[2] To initiate the onset of anaphase, securin is dephosphorylated by Cdc14 and other phosphatases. Dephosphorylated securin is recognized by the Anaphase-Promoting Complex (APC) bound primarily to Cdc20 (Cdh1 is also an activating substrate of APC). The APCCdc20 complex ubiquitinates securin and targets it for degradation. This results in free separase that is able to destroy cohesin and initiate chromosome separation.
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What is the role of separase
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is a cysteine protease responsible for triggering anaphase by hydrolysing cohesin, which is the protein responsible for binding sister chromatids during the early stage of anaphase. In humans, separin is encoded by the ESPL1 gene.
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Explain the role of the Rb protein and E2F transcription factor in regulating the G1-S transition
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to prevent excessive cell growth by inhibiting cell
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Explain the role of Mad and Bub proteins in regulating the cell cycle
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Mad and Bub proteins accumulate atunattached kinetochores .
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What is p53?
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also known as TP53 or tumor protein (EC :2.7.1.37) is a gene that codes for a protein that regulates the cell cycle and hence functions as a tumor suppression.
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What signals activate p53?
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in response to ionising radiation..
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What is apoptosis?
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the death of cells that occurs as a normal and controlled part of an organism's growth or development.
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How does apoptosis differ from necrosis?
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Apoptosis, or programmed cell death, is a form of cell death that is generally triggered by normal, healthy processes in the body. Necrosis is the premature death of cells and living tissue. Caused by factors external to the cell or tissue, such as infection, toxins, or trauma..
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Describe the signaling pathways needed to trigger apoptosis in cells infected by viruses
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immune and inflammatory responses.
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Define diploid
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. containing two complete sets of chromosomes, one from each parent.
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Define haploid
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.a haploid organism or cell.
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Define homologous chromosome
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are chromosome pairs (one from each parent) that are similar in length, gene position, and centromere location..
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Define sister chromatid
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may also be said to be 'one-half' of the duplicated chromosome..
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Define synapsis
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the fusion of chromosome pairs at the start of meiosis..
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Define chiasma
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a point at which paired chromosomes remain in contact during the first metaphase of meiosis, and at which crossing over and exchange of genetic material occur between the strands..
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What is homologous recombination?
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a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA.
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When does homologous recombination occur?
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It is most widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks.
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How does homologous recombination occur?
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After a double-strand break occurs, sections of DNA around the 5' ends of the break are cut away in a process called resection. In the strand invasion step that follows, an overhanging 3' end of the broken DNA molecule then "invades" a similar or identical DNA molecule that is not broken. After strand invasion, the further sequence of events may follow either of two main pathways discussed below (see Models); the DSBR (double-strand break repair) pathway or the SDSA (synthesis-dependent strand annealing) pathway.
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How does homologous recombination contribute to genetic variation?
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Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution.
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Compare and contrast the stages of meiosis and mitosis
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The main difference between meiosis and mitosis is the type of cells that undergo the process. Mitosis occurs in all eukaryote cells, while meiosis is a special type of mitosis that only occurs in gamete, or sex, cells.
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Describe how the gametes (sperm and egg) are formed
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Both the male and female gametes are formed during a process of cellular reproduction called meiosis. During meiosis, the DNA is only replicated or copied one time.
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Explain the process of oocyte maturation.
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This growth culminates just prior to ovulation, when oocyte maturation occurs. Oocyte maturationrefers to a release of meiotic arrest that allows oocytes to advance from prophase I to metaphase II of meiosis.
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