u had a supply of nucleotides made with atoms that were twice as heavy as normal
ID: 196190 • Letter: U
Question
u had a supply of nucleotides made with atoms that were twice as heavy as normal, and you allowed some cells to replicate their DNA once, using only the heavy nucleotides. What would be 1. Suppose yo the weight of the double-stranded DNA molecules in the resulting G2 cells if replication is semiconservative? Why? What would be their weight if replication is conservative? Why? For background information goto h tp en wikpedia.org/wk/EteDNArtalicationtodes.pns 93Stahi oxperimen a. All will have normal weight. b. All will weight twice normal c. Half will have normal weight, and half will weight twice normal. d. All will weight 1.5 times normal. e. The weight cannot be predicted, because we do not know the total number of base pairs in the genome. 2. DNA content was estimated in several individual cells from a culture of diploid cellsExplanation / Answer
1) Option d will be the correct answer.
All will weight 1.5 times normal. As given in the question, DNA replication is semiconservative which means that in replicated DNA that is present in the cells at G2 phase, one strand of the double helical structure is derived from original DNA and the other strand is derived from the nucleotides supplied by us which contained atoms twice as heavy as normal atoms. Thus, after a single cycle of semi-conservative DNA replication, all the DNA will have one original strand and one strand of heavy nucleotides, thus all DNA will weigh 1.5 times the normal weight.
2) Gametes are always haploid in nature, i.e., chromosome pairing is not present in gametes. There is only a single copy of the chromosomes which is derived from either male parent or a female parent. The terms homozygous and heterozygous are used in case where chromosomes are present in pairs. Since, gametes don't have such pairing, they can neither be considered homozygous nor heterozygous.
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