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45 Cards in this Set
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What is Mitosis |
the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei.[1] It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two daughter cells containing roughly equal shares of these cellular components
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What is cytokinesis
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the process whereby the cytoplasm of a single eukaryotic cell is divided to form two daughter cells. It usually initiates during the late stages of mitosis, and sometimes meiosis, splitting a binucleate cell in two, to ensure that chromosome number is maintained from one generation to the next
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What is the cell cycle
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is the series of events that take place in a eukaryotic cell leading to its replication. These events can be divided in two brief periods: interphase—during which the cell grows, accumulating nutrients needed for mitosis and duplicating its DNA—and the mitotic (M) phase, during which the cell splits itself into two distinct cells, often called "daughter cells". The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed.
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What happens during Interphase
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the phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes including preparation for cell division. Interphase is considered to be the 'living' phase of the cell, in which the cell obtains nutrients, grows, copies its DNA, and conducts other "normal" cell functions
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What is the G1 phase
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a period in the cell cycle during interphase, after cytokinesis and before the S phase. For many cells, this phase is the major period of cell growth during its lifespan. During this stage new organelles are being synthesized
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What is the G2 phase
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the third, final, and usually the shortest subphase during interphase within the cell cycle in which the cell undergoes a period of rapid growth to prepare for mitosis. It follows successful completion of DNA synthesis and chromosomal replication during the S phase, and occurs during a period of often four to five hours. This far into interphase the nucleus is well defined, bound by a nuclear envelope and contains at least one nucleolus. Although chromosomes have been replicated they cannot yet be distinguished individually because they are still in the form of loosely packed chromatin fibers
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What is the S phase |
short for synthesis phase, is a period in the cell cycle during interphase, between G1 phase and the G2 phase. Following G1, the cell enters the S stage, when DNA synthesis or replication occurs
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what is a diploid
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have two homologous copies of each chromosome, usually one from the mother and one from the father
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what is a diploid
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have two homologous copies of each chromosome, usually one from the mother and one from the father (2n)
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what is a haploid
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an organism or cell having only one complete set of chromosomes, ordinarily half the normal diploid number (n)
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homologous chromosomes are what
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chromosomes that occur in matched pairs
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what is a sister chromatid |
when chromosomes are made up of two strands during interphase
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what is a centromere
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the centromere region where two chromatids are most closely associated
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what is a kinetochore
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a plate-like protein structure. the kinetochores of the sister chromatids are attached to the kinetochore microtubules coming from opposite poles.
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what is a dyad (bivalent)
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a chromosome composed of two chromatids
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What happens during prophase
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homologous chromosomes come together and synapse (closely apply themselves to each other), pairing along their entire length.
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what is a tetrad
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four chromatids or two dyads
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what is a synaptonemal complex and what does it do
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a ladderlike protein structure that helps to align the tightly paired homologous chromosomes
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what is crossing over
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segments of two non-sister chromatids may be exchanged by breaking and rejoining
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What happens in Metaphase I
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chromosomes have untwined by this time and now can be seen as dyad chromosomes. They now line up in the center of the cell in homologous pairs
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what is a chiasmata
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non-sister chromatids that have crossed over appear to be held together at X-shaped locations
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What happens in Anaphase I
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the homologous chromosomes separate and are pulled to opposite sides of the cell by kinetochore microtubules
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What happens in Telophase I
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Centriole duplication takes place at the end of telophase. A formation of a nuclear membrane and division of the cytoplasm, cytokinesis, often occurs at this time to produce two cells, but this is not always the case.
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What is a chromatian
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the complex of DNA and proteins that makes up a eukaryotic chromosome
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what is a cell plate
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a double membrane across the mid line of a dividing plant cell, between which the new cell wall from during cytokinesis
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what is the cleavage furrow
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a shallow groove in the cell surface near the old metaphase plate
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what is the meristem
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plant tissue that remains embryonic as long as the plat lives, allowing for indeterminate growth
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what is meiosis
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a modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell
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what is a haploid cell
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a cell containing only one set of chromosomes
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what is an allele
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any of the alternate versions of a gene that produce distinguishable phenotypic effects
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what is the synapsis |
the pairing and physical connection of replicated homologous chromosomes during prophase I of meiosis
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what is the synapse
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the junction where one neuron communicates with another neuron in a neural pathway; a narrow gap between a synaptic terminal of an axon and a signal-receiving protein of another neuron or effector cell.
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what is the locus
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a specific place along the length of a chromosome where a given gene is located
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what is the genotype
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the genetic makeup or set of alleles of an organism
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what is a phenotype
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the physical and physiological traits of an organism which are determined by its genetic makeup
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what is a gene
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a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA
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what does heterozygous mean
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having two different alleles for a given trait
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what is a dominant allele
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an allele that is fully expressed in the phenotype of a heterozygote
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what is a recessive allele
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an allele whose phenotypic effect is not observed in a heterozygote
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what is interkinesis
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the name given to meiosis after telophase during interphase II because DNA replication does not occur during interkinesis.
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what does homozygous mean
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the two alleles control alternative expression of the same trait
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name 5 purposes of mitosis
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repair and maintainous, growth, regeneration, cloning, tissue culture, development, asexual reproduction
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what is a zygote
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a fertilized egg
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what are the differences between mitosis and meiosis
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in mitosis there is only 1 division, 2 divisions in meiosis. Mitosis produces a full set of chromosomes while meiosis produces half the number of chromosomes. Mitosis is used for growth and development while meiosis is used for sexual reproduction.
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What are similarities between mitoses and meiosis
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both are methods of reproduction
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