True or False. Explain your reason for each statement. 1. Histone proteins are n

Question

True or False. Explain your reason for each statement.

1. Histone proteins are necessary for packaging of DNA into euchromatin and heterochromatin. Additional histone proteins are recruited to the chromosomes during cell division to facilitate the condensation of the sister chromatids.

2. Homologous recombination that occurs during Prophase I serves to scramble the alleles between chromosomes, but can also introduce new alleles into a chromosome.

3. Mitochondria and chloroplast DNA inheritance is independent of the nuclear chromosomes. To ensure that each daughter cell receives some of these DNA molecules, the microtubules also assist in segregating the mtDNA and cpDNA genomes into the daughter cells.

Explanation / Answer

1. True.

Histone proteins are necessary for packaging of DNA by forming nucleosomes into euchromatin, the "beads on a string" structure and by 30 nm fibre consisting of nucleosome arrays in their most compact form known as heterochromatin. Additional histone proteins are recruited to the chromosomes during cell division to facilitate the condensation of the sister chromosome. Higher-level DNA packaging of the 30 nm fibre by additional histone proteins are recruited to the chromosomes during cell division into the metaphase chromosome.

2. True.

During the zygotene stage of prophase I, the homologous chromosomes pair up with each other, serves to scramble the alleles known as recombinant chromosomes. And also introduce new alleles into a chromosome.

3. True.

Mitochondria and chloroplast DNA inheritance are known as Extranuclear inheritance or cytoplasmic inheritance, therefore they are independent of the nuclear chromosomes. To ensure that each daughter cell receives some of these DNA molecules, the microtubules also assist in segregating the mtDNA and cpDNA genomes into the daughter cells.

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