Question

Prokaryotes appeared long before Eukaryotes and continue to be the most abundant life form. Prokaryotes are extremely diverse, their diversity is in the result of their metabolic adaptations and their ability to rapidly change their genetic information A) Explain at least 3 metabolic adaptations of prokaryotes, and B) Compare the three ways in which bacteria exchange genetic information. C) Archaea we thought to be ancestral to bacteria. However, now they are closer to eukaryotes, what evidence supports their new placement in the phylogenetic tree?

Answer 1

ANSWER A :-

1. Just like plants, some bacteria are able to produce organic compounds by using light as a source of energy for yielding the high-energy bonds. In the presence of light, carbon dioxide and water is converted to organic compounds which are utilised to produce energy for the prokaryotic cells. Bacteria with this type of Metabolic adaptation are called as Photoautotrophs and example include the Cyanobacteria.
2. Certain prokaryotes are able to produce their own energy through organic or inorganic substrates by means of oxidation of the reducing elements. In the presence of components such as Hydrogen sulfide, ammonia, etc, carbon dioxide is being reduced to produce energy yielding substrates. These prokaryotes are termed as Chemotrophs and include sulfur-oxidizing bacteria, methanobacter, etc.
3. Some prokaryotes utilise the organic compounds produced by the autotrophs in the presence of light energy to prepared the energy yielding molecule (ATP). These are called as photoheterotrophs. All these three shows variations in terms of Metabolic adaptability in order to enhance their survival and sustainance.

ANSWER B :-

1. Lets first discuss about conjugation. It is a process in which DNA transfer occurs between two cells. The cell which transfers the DNA is called as a donor cell and has a protein called as the F-factor which helps in the process of conjugation. In case of transformation, a cell (bacteria) is able to obtain DNA or genetic material present within Its reach in the external environment. If it comes into contact, through specific mechanism, the genetic material gets inserted into the bacterial cell. The last process is transduction in which the bacterial cell requires a virus called as a bacteriophage for transfer of genetic elements. In this case, the newly formed progeny in the host may take up the bacterial genetic elements and when it infects a new host, there are chances that the bacterial elements may get transferred due to which by means of integration, new genes can become available.
2. Conjugation is associated with formation of pilus which is a specialized structure that aids in attachment. Transduction is mediated by a bacteriophage whereas tranformation does not have any mediating agent or contact.
3. Conjugation can lead to change in the strain of bacteria. If the bacteria undergoing the process is able to transfer the genes involved in formation of pilus, the recieving cell would also be able to produce the structure thereby become F+. Such phenomena is absent in other two cases.

ANSWER C :-

1. The archaeal cell resembles a bacterial cell although it has many similarities associated with the Eukaryotes. In case of phylogeny, the Eukarya, Prokarya (Bacteria) and Archaea are considered separate but according to the Archaeal host hypothesis, through genetic examinations and other associated studies, conclusions have been brought up indicating that the primitive Eukaryotes have originates from an Archaeal ancestor which indicates that Eukaryotes have originated from Archaea.
2. There are various Metabolic pathways that share similarities when a comparison is made between Archaea and Eukaryotes. Once such evidence can be given as the findings from research carried out on Lokiarchaeota which shows similarities in terms of the mechanisms that are associated with the remodelling of the membrane structures. This thus helps in connecting both the organisms. It can be considered as an important evidence in highlighting the Archaeal origin.
3. DNA Polymerase that is associated with replication process is also stated to have similarities with respect to the Eukaryotes.

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