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What phase are the chromosomes lined up on the equatorial plate?
The chromosomes are lined up at the equatorial plate during metaphase of mitosis and metaphase II of meiosis. This alignment ensures that each chromosome is properly attached to the spindle fibers before they separate and move to opposite poles.
What happens in the cell and to the tetrads in each phase?
During prophase I, homologous chromosomes pair up to form tetrads, which allows for crossing over to occur. In metaphase I, tetrads line up at the metaphase plate and independent assortment takes place. Anaphase I sees homologous chromosomes separate and move to opposite poles of the cell. Telophase I concludes with the formation of two haploid daughter cells, each containing a mix of maternal and paternal chromosomes.
How does sexual reproduction creates variety?
Crossing overIndependent assortmentRandom fertilizationMutation1. Crossing overCrossing over is the exchange of corresponding segments of non-sister chromatids of homologous chromosomes. During prophase I (of meisosis I), homologous chromosomes synapse to form aggregates called either bivalents (bi = 2, and there are two homologous chromosomes in the aggregate) or tetrads (tetra = 4, and there are 4 chromatids in the aggregate). While the chromosomes are synapsed in prophase I, crossing over occurs. As a result, a chromatid that originally consisted of 100% maternal alleles and a chromatid that originally consisted of 100% paternal alleles become chromatids with a mixture of both maternal and paternal alleles. This shuffles genetic information and increases variation.2. Independent assortmentIn metaphase I (of meiosis I), the tetrads (bivalents) line up at the center of the cell. Which pole the maternal and paternal chromosomes face is a matter of chance; and the direction the maternal and paternal chromosomes face in one tetrad has no bearing on which way the maternal and paternal chromosomes of another tetrad face. Thus, when the homologous chromosomes separate and move to opposite poles, each pole will receive a mix of maternal and paternal chromosomes. This shuffles genetic information and increases variation.3. Random fertilizationBecause of the above processes, male animals can potentially produce millions or hundreds of millions of genetically unique sperm. And, male animals typically release millions of sperm during sex. Which one of the millions of genetically unique sperm happens to end up fertilizing the egg is largely a matter of chance. Thus, except foridentical twins, siblings never have exactly the same genetic information.4 Mutation takes place during replication of DNA which result in new varieties .
What metaphase does nondisjunction occur in Metaphase 1 or metaphase 2?
Non-disjunction is the failure of a pair of chromosomes or chromatids to separate. Since this happens in both metaphase I and II, non-disjunction can occur in either stage.In metaphase I it is the failure of the two homologous chromosomes in the pair to separate. In this case all of the gametes will be affected.In metaphase II it is the failure of the two sister chromatids to separate. In this case only half of the gametes are affected.Non-disjunction is the cause of a number of genetic conditions eg Down syndrome, Triple-X syndrome.See http://en.wikipedia.org/wiki/Nondisjunction
How animal cells separate?
Mitosis: Prophase, Metaphase, Anaphase, and Telephase (in that order)
What is the difference between sister and non sister chromatids?
Sister chromatids are those replicated from the same chromosome whereas non-sister chromatids may be found in meiosis (particularly metaphase II) where paternal and maternal chromatids line up and eventually separate at the metaphase plate.
What phase are the chromosomes lined up on the equatorial plate?
The chromosomes are lined up at the equatorial plate during metaphase of mitosis and metaphase II of meiosis. This alignment ensures that each chromosome is properly attached to the spindle fibers before they separate and move to opposite poles.
What is the random separation of maternal and paternal chromosomes during anaphase 1?
During anaphase I of meiosis, homologous chromosomes separate and move to opposite ends of the cell. This random separation ensures genetic diversity in the resulting gametes, as each gamete receives a unique combination of maternal and paternal chromosomes.
How can a genetic disorders as Turner syndrome occur?
Going down to the cellular level, it occurs in meiosis when chromosomes fail to separate (nondisjuction). We get a set of chromosomes from our paternal side and the other set from out maternal side. For example, one of the gamete that may have came from our maternal side contains no chromosomes , O, when it should contain that chromosome x while from our paternal side we get a gamete containing the x chromosomes. This results in a XO, a sterile female when the normal sex chromosomes are XX or XY. -or- nondisjunction
What happens in the cell and to the tetrads in each phase?
During prophase I, homologous chromosomes pair up to form tetrads, which allows for crossing over to occur. In metaphase I, tetrads line up at the metaphase plate and independent assortment takes place. Anaphase I sees homologous chromosomes separate and move to opposite poles of the cell. Telophase I concludes with the formation of two haploid daughter cells, each containing a mix of maternal and paternal chromosomes.
Which event occurs during metaphase?
During metaphase, the chromosomes align at the metaphase plate in the center of the cell. The spindle fibers attach to the centromeres of the sister chromatids, preparing to separate them during anaphase. Metaphase is a critical step in mitosis in ensuring accurate chromosome segregation.
What causes the abnormality in chromosome numbers in people with down syndrome?
It is most commonly caused by increased maternal age.Add: It is the result of nondisjunction of the 21st chromosome pair, in which the pair fails to separate, so that one cell gets an extra copy of chromosome 21.
What is the Swedish word for great grandfather?
This aspect of the Swedish language is surprisingly confusing. Swedish has four words for great-grandfather, all referring to separate people. These are: - farfars far (paternal grandfather's father) - dad's dad's dad - farmors far (paternal grandmother's father) - dad's mom's dad - morsfars far (maternal grandfather's father) - mom's dad's dad - morsmors far (maternal grandmother's father) - mom's mom's dad
How does sexual reproduction creates variety?
Crossing overIndependent assortmentRandom fertilizationMutation1. Crossing overCrossing over is the exchange of corresponding segments of non-sister chromatids of homologous chromosomes. During prophase I (of meisosis I), homologous chromosomes synapse to form aggregates called either bivalents (bi = 2, and there are two homologous chromosomes in the aggregate) or tetrads (tetra = 4, and there are 4 chromatids in the aggregate). While the chromosomes are synapsed in prophase I, crossing over occurs. As a result, a chromatid that originally consisted of 100% maternal alleles and a chromatid that originally consisted of 100% paternal alleles become chromatids with a mixture of both maternal and paternal alleles. This shuffles genetic information and increases variation.2. Independent assortmentIn metaphase I (of meiosis I), the tetrads (bivalents) line up at the center of the cell. Which pole the maternal and paternal chromosomes face is a matter of chance; and the direction the maternal and paternal chromosomes face in one tetrad has no bearing on which way the maternal and paternal chromosomes of another tetrad face. Thus, when the homologous chromosomes separate and move to opposite poles, each pole will receive a mix of maternal and paternal chromosomes. This shuffles genetic information and increases variation.3. Random fertilizationBecause of the above processes, male animals can potentially produce millions or hundreds of millions of genetically unique sperm. And, male animals typically release millions of sperm during sex. Which one of the millions of genetically unique sperm happens to end up fertilizing the egg is largely a matter of chance. Thus, except foridentical twins, siblings never have exactly the same genetic information.4 Mutation takes place during replication of DNA which result in new varieties .
Anaphase follows what phase in mitosis?
Anaphase follows metaphase in mitosis. In metaphase, the chromosomes align along the metaphase plate, while in anaphase, the sister chromatids separate and begin moving towards opposite poles of the cell.
What happens in metaphase 2?
During metaphase of meiosis 2, or metaphase II, there are 3 major points. 1st is the chromosomes are positioned on the metaphase plate as in mitosis. 2nd is, because of the crossing over in meiosis I, the two sister chromatids of each chromosome are not genetically identical. 3rd is the kinetochores of sister chromatids are attached to microtubules extending from opposite poles.
Phase of mitosis in which the duplicated chromosomes separate from one another?
metaphase
