1: Cels and Genomes egun to characterize a sae of Jupi oceans on to your surpris

Question

1: Cels and Genomes egun to characterize a sae of Jupi oceans on to your surprise, the sample ws well in a rich broth. Your prei that it is cellular and contains DNA you show your results to a col. that your sample was om Earth. What approaches might sh between based on DNA, RNA, and protein? ult to imagine what it means to es that living things produce. That But what does it mean to "feed on do? Or even stranger, to "feed orn Where is the "food." for example msect s from a hydrothermal vent? Clam The e different trees (branching pat- wn to display the evolution of aryotes assuming that they all mal RNA are highly conserved anges) in all organisms on of species (Problem 1-11). The kegumes are highlighted in green. The engths of lines that connect the present-day species represent the evolutionary distances that separate them. Figure 01-2 Prhylogenetic tree for hemoglobin genes from a varlety wery slowly over time. Were perfect? n informational processes tion, and translation are 1-11 When plant hemoglobin genes were first discoy nuch less often than are ered in legumes, it was so surprising to find a gene typi- he basis for this inequality cal of animal blood that it was hypothesized that the plant ggestion is that it relates gene arose by horizontal transfer from an animal. Many he two types of processes. more hemoglobin genes have now been sequenced, and involve large aggregates a phylogenetic tree based on some of these sequences is eas metabolic reactions shown in Figure Q1-2 s composed of a single A. Does this tree support or refute the hypothesis that y of the underlying pro the plant hemoglobins arose by horizontal gene transfer? have any effect on the B. Supposing that the plant hemoglobin genes were Rinke originally derived from a parasitic nematode, for example, what would you expect the phylogenetic tree to look like? Wat 1-12 Rates of evolution appear to vary in different lin- re eages. For example, the rate of evolution in the rat lineage oth. Fungal cells a The Blatt l walls but lack chlo- is significantly higher than in the human lineage. These rate differences are apparent whether one looks at changes rplant cells that lost in nucleotide sequences that encode proteins and are sub- resented a difficult ject to selective pressure or at changes in noncoding nucle- ht to assign evolu otide sequences, which are not under obvious selection ell characteristics pressure. Can you offer one or more possible explanations that this question for the slower rate of evolutionary change in the human be animal cells that Bo Ca lineage versus the rat lineage?

Explanation / Answer

Ans-1-11(A)

This phylogenetic tree refutes the hypothesis that plant hemoglobin genes were acquired by horizontal transfer.If we look at the tree we see that the hemoglobins of vertebrates have approximately the same phylogenetic relationships as do the species themselves. Plant hemoglobins also form a distinct group that displays accepted evolutionary relationships with barley a monocot diverging before bean, alfalfa and lotus which are all dicots and are also legumes. The basic hemoglobin gene therefore was in place long ago in evolution. The phylogenetic tree indicates that the hemoglobin genes in modern plant and animal species were inherited from a common ancestor.

Ans-1-11(B)

If the plant hemoglobin genes arose by horizontal transfer from a nematode, then the plant sequences would have clustered with the nematode sequences in the phylogenetic tree.

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