Slides in this set
· Through natural selection, organisms adjust to suit the changing
environmental conditions. This is known as adaptation.
· Adaptation increases the long-term reproductive success of a
species by helping its members to survive long enough to breed.
· Adaptation & selection are major factors in evolution.
· They make a significant contribution to the diversity of organisms.
· One of the most diverse & adaptable group of organisms
· Their adaptation to a changing environment can be seen in their
ability to develop resistance to antibiotics.…read more
How does variation arise in bacteria?
· DNA is the genetic material in Bacteria.
· Diversity in bacteria arises from changes to its DNA.
· These changes occur in two ways:
~ changing the quantity or structure of DNA Mutation
~ recombining the existing DNA of two individuals Conjugation…read more
· Mutations are changes in DNA that result in different characteristics.
· Mutation arise in many ways. For example, one or more bases in a
DNA may be added, deleted or replaced during DNA replication.
· Any differences in the base sequence of a DNA molecule may result
in a different sequence of amino acid being coded for.
· This different amino acid sequence will lead to a different
polypeptide, and hence a different protein, or no protein at all,
· If this protein is an enzyme it is likely to disrupt the metabolic
pathway leading to the production of other substances.
· As proteins are responsible for the characteristics of an organism, it
follows that changes to DNA are likely to alter an organism's
Bacterial conjugation is the transfer of genetic material between
bacterial cells by direct cell-to-cell contact or by a bridge-like
connection between two cells. It takes place as follows:
· One cell produces a thin projection that meets another cell & forms a
thin conjugation tube b/w the two cells.
· Donor cell replicates one of its small circular pieces of DNA
· Circular DNA is broken to make it linear before it passes along tube.
· Replicated plasmid starts to move through conjugation tube and the
linear strand enters recipient cell.
· Linear strand forms a circle (new plasmid).
· Recipient cell acquires new characteristics from the donor cell.
Transfer of DNA in the form of genes from one species to another (by
conjugation) Horizontal gene transfer
· Transfer of genes from one generation to the next generation of the
same species Vertical gene transfer occurs when an organism
receives genetic material from its ancestor…read more