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Meiosis as a Process of Division of DNA Into Gametes

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I am researching the structure of DNA, but can not understand how meiosis allows DNA to be divided into gametes.

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Meiosis is a type of cell division that leads to the formation of haploid gametes from diploid cells. During this process, the number of chromosomes present in the gametes gets reduced to half of its original number that is present in normal somatic cells. During meiosis, the homologous chromosomes present in diploid cells get separated. In case of human beings, the sperm and ova contains 23 haploid chromosomes, whereas the somatic cells contain 46 diploid chromosomes. This difference plays a vital role during the process of fertilization. The diploid somatic cell with 46 chromosomes in humans produces haploid sperm or ova with 23 chromosomes during gametogenesis. Fertilization leads to the formation of zygote with 23+23 haploid sets, which results in 46 chromosomes. Mitosis and cell differentiation leads to the formation of a new individual with 46 chromosomes in all the somatic (body) cells.

During interphase, the gametocyte grows and matures until the necessary hormone level is reached to stimulate gamete production. Then DNA replication occurs giving rise to joined chromatids which are prepared to start with the process of meiosis. During Interphase I, the cell will complete the process of replication of genetic material (DNA). The process of Meiosis is ...

Solution Summary

Meiosis is a type of cell division that leads to the formation of haploid gametes from diploid cells. During this process, the number of chromosomes present in the gametes gets reduced to half of its original number that is present in normal somatic cells.

See Also This Related BrainMass Solution

DNA/MRNA Genetics, Traits, Cells Divisions

Lost with this - I have the MRNA I think is 3'UACCUUUAGAGOCACU-5', I'm having a hard time understanding -

Part 1: Genetics - From Genes to Proteins, Mutations
Overview: Genetic information in DNA is transcribed to RNA and then translated into the amino acid sequence of a Protein.
A) Step 1 - Transcription: During the process of transcription, the information in the DNA codons of a gene is transcribed into RNA.
Suppose that gene X has the DNA base sequence 3'-TACCCTTTAGTAGCCACT-5'.
Question: What would be the base sequence of RNA after transcription occurs? Turn this in.
(In this particular example, assume that the RNA product does not require processing to become mRNA. In other words, the transcribed RNA becomes the mRNA sequence.)
B) Step 2 - Translation: During protein synthesis at the ribosome, the base sequence of the mRNA codons is translated to the amino acid sequence of a protein.
Question: Using the mRNA that you transcribed above, use the genetic code table to determine the resulting amino acid sequence? Turn this in.
And, turn in the answer to these questions:
What is the significance of the first and last codons? What meaning do these codons have for protein synthesis?
C) Mutations: A mutation is defined as a change in the base sequence of DNA. This may occur as a "mistake" in DNA replication, for example.
Suppose that during DNA replication, two mutant DNA sequences are produced as shown below.
For the 2 mutated DNA sequences, you will investigate how these changes might affect the sequence of amino acids in a protein.
Question: For each of the two, you will need to first transcribe the mRNA, and then use the genetic code table to determine the amino acid sequence.
Turn these in, and state whether the protein sequence changes for each.
Question: Then, explain why a change in amino acid sequence might affect protein function. Turn in your answer.
Here is the original sequence, followed by two mutated sequences, 1 and 2:
Original sequence 3'- TACCCTTTAGTAGCCACT-5'
Mutated sequence 1) 3'-TACGCTTTAGTAGCCATT-5'
Mutated sequence 2) 3'-TAACCTTTACTAGGCACT-5'.

Part 2: Inheritance of Traits or Genetic Disorders Turn in Punnett Square for Part 2.

Bob and Sally recently married. Upon deciding to plan a family, both Sally and Bob find out that they are both heterozygous for cystic fibrosis, but neither of them has symptoms of the disorder.
Set up and complete a Punnett Square for cystic fibrosis for this couple; turn in the Punnett square.
When doing the Punnett Square, C = normal allele; and c = allele for cystic fibrosis.
Note: You can use the Table function in MS Word to create and fill in a Punnett Square.
Based on the Punnett square, calculate chances (percentages) for having a healthy child (not a carrier), a child that is a carrier for the cystic fibrosis trait, and a child with cystic fibrosis? Turn in these percentages.

Part 3: Cell division, sexual reproduction and genetic variability
Eukaryotic cells can divide by mitosis or meiosis. In humans, mitosis produces new cells for growth and repair; meiosis produces sex cells (gametes) called sperm and eggs.
Although mutations are the ultimate source of genetic variability, both meiosis and sexual reproduction also can contribute to new genetic combinations in offspring.
Question: How do both meiosis and sexual reproduction (fertilization) produce offspring that differ genetically from the parents? Be sure to talk about steps in meiosis that increase variability as well as the process of fertilization.

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