Question

What lines of reasoning support the hypothesis that the first self-replicating systems were based on RNA molecules?

What kinds of evidence support the three-domain concept of life?

What evidence supports the idea that the mitochondrion and chloroplast were once free-living members of the domain Bacteria?

Answer 1

Ans. -

* The Miller-Urey experiment provided the first evidence that organic molecules needed for life could be formed from inorganic components. Some scientists support the RNA world hypothesis, which suggests that the first life was self replicating RNA. The RNA world hypothesis suggests that life on Earth began with a simple RNA molecule that could copy itself.

RNA is capable of both storing genetic information and catalyzing chemical reactions. RNA molecule that could copy itself without help from other molecules. DNA, RNA , and proteins are central to life on Earth.

* Organisms can be classified into one of three domain based on differences in the sequences of nucleotides in the cell's ribosomal RNAs, the cell's membrane lipid structure, and its sensitivity to antibiotics.

3 types of evidence are:

Differences in the sequences of nucleotides in the cell's robosomal RNAs

The cells's membrane lipid structure

Its sensitivity to antibiotics

The three domain -

Archaea - oldest known domain, ancient forms of bacteria.

Bacteria - all other bacteria that are not included in the Archaea domain.

Eukarya - all the organisms that are eukaryotic or contain membrane-bound organelles and nuclei.

* The first piece of evidence that needed to be found to  the end support osymbiotic hypothesis was whether or not mitochondria and chloroplasts have their own DNA and if this DNA is similar to bacterial DNA. This was later proven to be true for DNA, RNA, ribosomes, chlorophyll, and protein synthesis. Chloroplasts green factories within plant cells that help convert energy from sunlight into sugars, and they have many similarities to mitochondria . The evidence suggests that these  organelles chloroplast were also once free-living bacteria . They replicate independently of the cell they are in. They have circular pieces of DNA.