Why types of organism were hypothesized to be inhabiting earth prior to the rise of oxygen

The organism Cyanobacteria was the first organism to inhabit t he Earth prior to the rise oxygen in the atmosphere.

Explanation:

The single-celled Cyanobacteria were known to be the first oxygen-producing organisms even before the rise of oxygen in the atmosphere or the "Great Oxidation Event," way back 3.5 million years ago. They were able to survive the harsh conditions of the Earth by photosynthesis. During this process, the Cyanobacteria would use sunlight, water and organic carbon dioxide  to produce sugar for their energy. As a waste product, oxygen was released to the atmosphere. Accumulation of the oxygen in the atmosphere was increased by the presence of the volcanic gases like hydrogen, reacting with the oxygen. This caused a reduction reaction and made a more viable oxygen-rich atmosphere.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.

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