Inherited Genetic Variations

Meiosis consists of one DNA replication and two nuclear divisions resulting in 4 daughter cells. The process which provides for genetic variation is crossing over. Crossing over occurs in the early stages when homologous chromosomes move together so that their chromatids form a tetrad. This is called synapsis and allows for the exchange of chromosome sections.

2. a) How does meiosis introduce genetic variation into offspring? Think about how the chromosomes line up.(1 point)

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

Meiotic errors are alterations of a cell's chromosome number or structure. Chromosomal alterations happen in both mitosis and meiosis. But in other ways meiosis provides more opportunities for errors. Do to the three sources of genetic variation in meiosis that can also be opportunities for errors. Crossing over in prophase I independent assortment and in anaphase I and anaphase II are major sources of genetic variation in the sexually

Hypophosphatemia (vitamin D-resistant rickets) is inherited as an sex-linked dominant trait. The relevant gene is found on the X chromosome

* How is it possible for an offspring to exhibit a recessive trait if neither parent exhibited that

exception of identical twins, DNA fingerprinting is a reliable method used to determine the parents of a given baby. DNA fingerprints can be derived from restriction

These mutations are also called germline mutations because they are present in the parent’s egg or sperm

Response Feedback: Meiosis occurs only in replicating gametes or reproducing cells. In phase one, the number of chromosomes is reduced by half but the chromatid pairs remain together. In phase two, the chromatids split apart forming four daughter cells. Non-germ cells such as red blood cells or skin cells undergo mitosis.For more information on this topic, consult:Carol Mattson Porth and Glen Matfin, Pathophysiology, 8th Edition,

This particular type of cell division results in the production of four daughter cells per parent cell with only half the number of chromosomes of the parent cell in each daughter cell. The process of meiosis can be separated into two cycles, the 1st division and the 2nd division. The first division consists of 4 phases. Prophase, Metaphase, Anaphase and Telophase. The Second division consists of prophase II, Metaphase II, Anaphase II and Telophase II. Interphase occurs at the beginning of each phase and Cytokinesis occurs at the end of each phase. Meiosis is used for the production of gametes, or sex cells, in sexually reproducing organisms. These daughter cells have only half the number of chromosomes of a normal body cell. This is important because when two gametes come together, the number of chromosomes in the zygote

Because the hidden genes of one parent may be recessive and may not be present

A genetic make-up is the result of what someone has endured throughout history. Historical events can influence our ancestors in terms of patterns of migration and genetic relationships. The connection between history and genetics is especially important for African Americans due to the impacts of slavery and shortly there after followed by years of discrimination.

Genetic and genomic variations are being taken into consideration when referring to nursing interventions for patients. In the discussion paper, “Individual Genetic and Genomic Variation: A New Opportunity for Personalized Nursing Interventions” by Munro (2014), the author examines the potential for genetic and genomic variations being incorporated into nursing interventions for patients. According to Tremblay and Hamet, “Genomics include interactions among genes, intergenic regions, epigenetic factors and environmental factors” (As cited in Munro, 2014, p. 36). The study of these genomics revealed that genomes are able to respond to environmental influences. Complicated genome-environmental interactions could be presented by cancer, diabetes

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

In meiosis the pairs of chromosomes (that code for possible outcomes of characteristics) temporarily join and exchange information (crossing over) creating different combinations of gene types (alleles). For example; a pair of chromosomes could be a dominant allele (gene type) and a recessive allele which might code for brown hair. After crossing over it might be recessive which could be blond hair.