How To Write A G2 Unit 2 Biology

Chromosome pairs line up across the equator of the spindle at metaphase I (5). In anaphase I the chromosomes separate and travel to opposite ends of the spindle. The chromosomes migrate to the equators of two new spindles for metaphase 2 (7). Next the chromatids are pulled apart in anaphase 2 to form four clusters of chromosomes in telophase 2. The nuclear envelopes reform around four haploid nuclei that will give rise gamete

Later on a male and female haploid cell will join to form a diploid cell with the right number of chromosomes.

Mitosis: This is the process by which a cell duplicates the chromosomes in its cell nucleus in order to generate two identical daughter nuclei.

A) Meiosis consists of two cell divisions and is broken up into Meiosis I and Meiosis II. At the beginning of the Cell Cycle, in this case there are four chromatids each from the homologous pairs being A, a, B, b. This is the Diploid number (4) meaning it is 2 times the haploid number that will be seen at the end of meiosis II. During the S phase of interphase, the chromatids replicate and reach the end of G2 phase. Now starting meiosis, during the first stage of prophase I the chromosomes condense and pair up through synapsis with their sister chromatids creating AA, aa, BB, bb. After they pair up they go through a process called crossing over, where the homologous chromosomes share a piece of their genetic material with each other. Crossing over allows for the genetic diversity of chromosomes. Now there are four homologous chromosomes Aa, Aa, Bb, Bb, each containing heterozygous alleles because the sister chromatids exchanged genetic information with their homologous pair. During late prophase I, spindle fibers being to form where they will later attach to a homologous chromosomes centromere. The next stage is Metaphase I. During metaphase I, the homologous pairs line up at the metaphase plate, also known to be the center of the cell. The homologous pairs form a tetrad which is considered a group of four homologous chromosomes. These homologous chromosomes orient themselves randomly, which is know as the process of independent

The two sets of chromosome become arranged on the metaphase plate in this phase of meiosis. Centrioles at opposite poles of the cell produce spindle fibers that latch on to each set of chromosomes.

Error 2: In the video, they state that in anaphase “Each CHROMATID transforms into a CHROMOSOME in its own right…And SPINDLE FIBERS drag them to the POLES.” This is incorrect; the chromatids don’t “transform” into chromosomes. They chromatids pair up to make paired

During Cell Division, three chromosomes evolve rather than the usual two (Cobb). Cell division is referred to as nondisjunction, or the failure of all chromosomes to separately properly resulting in retention of one of the chromosomes in one of the two new daughter cells. This reults in the condition called Trisomy 21, and about ninety-five percet of Down Syndrome patents have.

Uniparental disomy is when both members of a chromosome pair comes from one parent, while the chromosome from the other parent is lost. During anaphase in meiosis II, the chromosomes fail to split properly, which will cause two abnormal daughter cells. This is termed the anaphase lag where a gamete will end up with 47 chromosomes instead of 46 (Shaffer et al. 2001). Usually what will happen during meiosis is that one diploid cell will form two haploid daughter cells, and then those two daughter cells will form two more haploid daughter cells. This makes four haploid daughter cells at the end of meiosis. Sometimes a mutation will occur where a daughter cell produced in meiosis will have either three copies or one single copy of a chromosome

Meiosis I had 6 steps: Interphase, Prophase I, Metaphase I, Anaphase I, Telophase, and Cytokinesis. In Interphase, the cell grows, repairs, performs its usual functions, and replicates DNA. During Prophase I, each replicated chromosome pairs with its corresponding homologous chromosome forming a tetrad. During tetrad formation, sections of chromosomes can be exchanged between chromatids, a process called crossing over. In Metaphase I, paired homologous chromosomes line up across the middle of the cell. During Anaphase I, Spindle fibers pull each homologous pair toward opposite ends of the cell. In Telophase I, a nuclear membrane forms around each cluster of chromosomes. Cytoplasm then occurs resulting in two new daughter cells. The daughter cells contain chromosome sets that are different from each other and the parent

In order for this to happen, the original cell must copy it's genetic material so both daughter cells have a

During anaphase I, the paired homologous chromosomes separate, or disjoin, and move toward opposite poles. Each pole collects a random combination of maternal and protective chromosomes, but only one member of each homologous pair is present at each pole. The sister chromatids remain united at their centromere regions. Again, this differs from mitotic anaphase, in which the relative chromatids separate and move to opposite poles.

Within prophase, various structures begin to be broken down by the cell while others are instead built up. This prepares the chromatin to be split into two rod-like structures known as chromosomes, each one the sister of the other. For example, the nucleolus entirely disappears. A structure comprised of microtubules, known as the mitotic spindle, begins to form with its primary function being to arrange the chromosomes. The mitotic spindle proceeds to compact the chromosomes into a very tight package-like structure. The nuclear envelope soon dissipates, allowing for the release of the chromosomes. In the metaphase, the chromosomes have been brought into the middle of the cell (a concept referred to as the “metaphase plate”) in preparation for division. Structures that are in charge of pulling sister chromatin apart known as kinetochores will attach to microtubules from the mitotic spindle so as to insure correct division. Anaphase is the phase in which the chromatin are officially separated from one another and in turn tugged to opposite ends of the cell. In order for this to happen, the cell breaks down a protein that behaves as an adhesive. This allows for the chromatin to become two separate chromosomes, each pair yielding to the opposite side. Telophase allows

In Anaphase I, the homologous chromosomes will shift and migrate towards opposite sides of the cell in a segregation process. Mendel’s Law of Segregation states that two copies of an allele will segregate during the process of creating gametes. The law if evident during meiosis I when the segregation of alleles occurs within Anaphase I. Within Telophase I, the cell will display two independent nuclei formed, however, it is still considered one cell because it has not completely separated yet. Through cytokinesis, the cell will pinch off into two cells, each containing half of the original number of chromosomes. The chromosomes each still have two sister chromatids at this point. Moving on to Meiosis II, sister chromatids will be separated through this cycle. Prophase II will display chromosomes condensing. Metaphase II will show independent assortment as the sister chromatids line up at the equatorial plate once again. As stated in Mendel’s second law, alleles of different genes will assort independently from each other during gamete formation. The law is clearly supported during Metaphase II. However, Mendel’s law does not always apply to genes that are closely linked as they are more

As cells divide and reproduce in two ways, this is known as Mitosis and Meiosis. Mitosis is the process of asexual reproduction, which means the cell divides into two producing another, with an equal numbers of chromosomes resulting in a diploid cell. Meiosis is a type of cellular reproduction where the numbers of chromosomes are reduced by half, because of the separation of homologous chromosomes, which results in the production of two haploid cells.

Mitosis is the nuclear division that produces two nuclei containing chromosomes identical to the parental nucleus. Mitosis is divided into five stages; prophase, prometaphase, metaphase, anaphase, and telophase.