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Biology chapter 9 meiosis
Biology chapter 9 meiosis
Biology chapter meiosis
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Recommended: Biology chapter 9 meiosis
Meiosis is the process of cell division with reduction. Meiosis occurs in 9 stages. These stages include: meiosis I and meiosis II. These stages allow the original haploid cell to split into four daughter cells. Through Gregor Mendel’s two experiments with monohybrid and dihybrid crosses and Thomas Hunt Morgan’s experiment on recombination, there is a much closer look at meiosis and how it is affected by different circumstances and characteristics.
Meiosis does not add new variation, also known as alleles. Instead, it rearranges the allele combinations between genes. Only 23 chromosomes are required for meiosis to occur which is a haploid cell. A haploid cell is one complete copy of the genome. In meiosis I, the stages are: interphase, prophase
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When interphase occurs, DNA in the cell is copied. In prophase I, the chromosomes that have been copied condense and pair to begin separating each set from each other. Metaphase I occurs when the different sets of chromosomes line up in the middle of the cell and the spindle fibers begin to attach to each chromosome. In anaphase I, the fibers then pull the copied chromosomes towards opposite ends of the cell. Once the cells have reached the opposite sides of the cell, the cell then begins to pinch in the middle; this is called telophase I. Once cytokinesis has occurred the cells will have completely separated into two haploid daughter cells. The process of meiosis II occurs the same as meiosis I except now within the two daughter cells that were a result of meiosis I. Meiosis II begins with prophase II and then progresses through each of the following stages until cytokinesis and the result is four daughter …show more content…
These traits included the flower color, seed color, seed texture, pod color, pod shape, flower position and plant height. He began with a homozygous parent of both the recessive and dominant traits. He then crossed the filial one generation to create the filial two generation. He found that the results of each traits were always similar to the predicted ratio of 3:1. Once seeing the traits passed on from the F2 generation he concluded that the ratio was not 3:1, but instead 1:2:1. This lead to his principle of segregation. This principle stated that the traits did not have a combined form of each trait, but instead represented either the dominant one or recessive distinctly. His ratio of 3:1 was then known as the Mendelian
This meant that we had to reject our hypothesis for the dihybrid cross which stated that there would be no difference in the observed and expected values. This showed that the F2 generations did not follow Mendelian genetics because it did not express a 9:3:3:1 phenotypic ratio. In both our F1 and F2 generations, we had to reject our hypotheses because they did not follow the Mendelian genetic inheritance pattern show by our results above. Because both the F1 and F2 generations of Brassica rapa failed to follow the Mendelian genetics inheritance pattern, there could have been some biological errors that cause this to happen. An example of this is that maybe not every single plant got the exact same amount of water or same amount of sunlight, causing the plants to grow differently and therefore deviate from the Mendelian’s law of inheritance. To prevent this from happening in the future, what could have been done was measure out the amount of water each plant got rather than just watering each plant casually. Also, for the amount of sunlight, steps could have been taken to ensure that each plant would get the exact same amount of light and not get different amounts just because of where they were
Meiosis, also called reduction division, is a distinct type of cell division that is essential for sexual reproduction to occur. It is one in which two successive divisions of diploid cell occur thereby producing four genetically different haploid daughter cells, also called gametes, each with half the number of chromosomes and thus, half the total amount of genetic material as compared to the amount before meiosis began. Interphase precedes meiosis and thus, paves the way for meiosis to eventuate as the cell’s DNA replicates in the S phase yielding corresponding, identical chromosomes. Interphase sparks the marvelous process of meiosis that allows variation to transpire within the organisms it occurs, hence, giving rise to millions of organisms with unique aspects unlike any other on Earth. Because meiosis is a form of sexual reproduction itself, it is the means through which gametes are produced, each with a reduced number of chromosomes, so that when two gametes fuse during fertilization, not only do they form a diploid zygote with 46 chromosomes, but also have manifested differing features due to the rearrangement (crossing-over) of chromosomes.
The major topic of this experiment was to examine two different crosses between Drosophila fruit flies and to determine how many flies of each phenotype were produced. Phenotype refers to an individual’s appearance, where as genotype refers to an individual’s genes. The basic law of genetics that was examined in this lab was formulated by a man often times called the “father of genetics,” Gregor Mendel. He determined that individuals have two alternate forms of a gene, referred to as two alleles. An individual can me homozygous dominant (two dominant alleles, AA), homozygous recessive, (two recessive alleles, aa), or heterozygous (one dominant and one recessive allele, Aa). There were tow particular crosses that took place in this experiment. The first cross-performed was Ebony Bodies versus Vestigle Wings, where Long wings are dominant over short wings and normal bodies are dominant over black bodies. The other cross that was performed was White versus Wild where red eyes in fruit flies are dominant over white eyes.
In the 19th century Gregor Mendel accomplished pioneered the first laws of genetics after crossing peas. He conducted an experiment with pea plants. He would use a paintbrush to transfer the genetic coding from one pea plant to another, so he could know exactly who the parents were. With the end of this experiment Mendel came up with two laws; Mendel 's law of segregation, and Mendel 's law of independent assortment. Mendel crossed over purple pea flowers with white pea flowers, which gave him purple pea flowers for the first generation also called F1. Since the offspring were all purple flowers Mendel understood that the purple gene was the dominant gene. Mendel decided to cross the F1 generation with themselves. Which resulted in three purple pea flowers and one white pea flower. By using basic Punnett square, and identify the genotype as PP and the phenotype as pp. This gave Mendel the following ratio of 3:1, three purple pea flowers and one
Using the principles expounded by Galton and through Mendel's research in laws of recessive and dominant traits discovered in plant breeding, American researchers entered this new scientific field.
Trisomy 13 or Patau Syndrome” Trisomy 13 is a genetic disorder found in babies. It is also called Patau syndrome in honor of the physician who first described it, Krause Palau. Trisomy 13 is a genetic disorder in which there is three copies of chromosomes on Chromosome 13. Patau first described the syndrome and its involvement with trisomy in 1960. It is sometimes called Bartholin-Patau syndrome, named in part for Thomas Bartholin, a French physician who described an infant with the syndrome in 1656.
Mendel’s law of segregation states that offspring receive only one of two alleles of a gene from the parent (Brooker et al. 2014). This means that utilizing a monohybrid cross where each parent has both a dominant allele of a gene and a recessive allele, that by producing offspring of these plants, a predictable outcome of trait inheritance should be observed (Brooker et al. 2014). This experiment investigated the inheritance of anthocyanin in Brassica rapa.
Each cell contains the same genetic code as the parent cell, it is able to do this because it has copied it’s own chromosomes prior to cell death. division. The. Meiosis consists of two divisions whilst mitosis is followed. in one division; both these processes involve the stages of interphase, prophase, metaphase, anaphase, and telophase.
The process of mitosis can take place in either a haploid (23 chromosomes) or a diploid (46 chromosomes) cell. Before a cell can be ready for a mitotic division it must primarily undergo its interphase stage. Following the interphase stage several other stages come into play. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. During each specific stage certain sequences of events take place that assist to the completion of the division.
Sexual reproduction is that the union of male and feminine gametes to create a fertilised egg or zygote. The ensuing offspring inherit one-half their traits from every parent. Consequently, they 're not genetically similar to either parent or siblings, except within the case of identical twins. As theorised by Mendel, adults are diploid, meaning as 2N, having 2 alleles offered to code for one attribute. The gametes should be haploid, signified by N, containing just one allele in order that once 2 haploid gametes mix, they manufacture a traditional diploid individual. The method where haploid sex cells are created from diploid parents is known as meiosis, and it happens solely within the reproductive organs.
In Meiosis 1, chromosomes in a diploid cell resegregate, producing four haploid daughter cells. It is this step in Meiosis that generates genetic diversity.Meiosis 2 is similar to mitosis. However, there is no "S" phase. The chromatids of each chromosome are no longer identical because of recombination. Meiosis II separates the chromatids producing two daughter cells each with 23 chromosomes (haploid), and each chromosome has only one chromatid.
The differences between the two phases of meiosis are that in meiosis I, while the cell undergoes the phases, prophase I, metaphase I, anaphase I, and telophase I, it causes the cell to divide into two with each of the cells having a double stranded chromosome. But in meiosis II, it is just the division of the the cells from meiosis I. The ending result being that four haploid daughter
To start this off, conception is the action of conceiving a child, and pregnancy is the period from conception to birth. They both share the same meaning: the process of getting pregnant. Conception happens when a sperm penetrates on one of the female’s eggs. Then, at around day 14 of a 28 day cycle, the egg leaves the ovary, and it is surrounded by a protective layer of cells. The fallopian tube is lined with cilia, which helps move the egg towards the womb. This is called ovulation. In the next 12-24 hours, the egg waits to be fertilized by a single sperm. The sperm then swims through the womb to meet the egg in the fallopian tube. And the sperm secretes enzymes to help penetrate the outer layer of the egg. Once the
Once the sperm fuses with the ovum both chromosomes will pair up and begin the first stages of cell division.
There are certain things that must happen first before the cell can actually split. There is a six step process required during Mitosis. The first five steps of mitosis are called prophase, prometaphase, metaphase, anaphase, and telophase. This is where all the training and preparation is done for cell division. The sixth step is Cytokinesis, and that is when the cell literally splits into two. Like I said, there are certain things in order to happen before it can enter the M phase. first, it must meet the requirements of the certain size and environment. Since in the S phase the cell duplicated it’s amount of chromosomes it be represented as 2N, where N equals the number of chromosomes in the cell. Cells about to enter M phase, which have passed through S phase and replicated their DNA, have 4N chromosomes. Because of this they are now allowed to enter within the M phase to prophase. Here is where the cell thickens up its chromosomes and begin to sprout microtubules from clone centrosomes. Microtubules tub-like are protein filaments and where the chromosomes migrate but are still within the nuclear envelope in the nucleus. There are centromeres, that are inside the chromosomes and during the later process of this phase, specialized microtubules called kinetochores, assemble on the centromere then later attach to these sites. They act like magnets and go