the Galapagos
While visiting the Galapagos in 1835, British naturalist Charles Darwin observed local plants and animals.
Cyanobacteria, also known as blue-green algae, are found in vast quantities in fresh and salt water. Cyanobacteria are able to conduct photosynthesis. By utilising energy from the sun, they produce carbohydrates from water and carbon dioxide. As a byproduct, they produce oxygen. So cyanobacteria provided oxygen to the atmosphere that allowed other lifeforms to develop.
Explanation:
1) The enzyme helicase catalyses the unwinding of the two DNA strands by disrupting the hydrogen bonds between complementary base pairs.
2) Single-stranded binding proteins attach to the DNA strands to stabilise them and prevent them from joining back together.
3) The enzyme primase catalyses the addition of a short primer consisting of RNA nulceotides to the DNA strand. This serves as an 'anchor' DNA polymerase to initiate replication.
4) The enzyme DNA polymerase synthesizes a new DNA strand by incorporating DNA nucleotides complementary to the existing strand. DNA polymerase activity only occurs in the 5' ---> 3' direction.
5) The enzyme ligase catalyses the formation of hydrogen bonds between the two new pairs of DNA strands, and seals any breakages in the sugar-phosphate backbone.