In: Biology
A) Describe the evolutionary relationship between kingdoms and domains within the tree of life. B) Describe similarities and differences in anatomy/structure and physiology between archaea, bacteria and eukaryotes. C) Explain the 3 mechanism for horizontal gene transfer in bacteria. D) Describe the structural and metabolic diversity of prokaryotes
A)ANS.The world of organisms were classified as five kingdom system and well accepted by the scientists all over the world till 1977 when Woese and Wolfe proved that existence of Archaea,a third category of organisms that could live without oxygen besides the two accepted categories called eukaryotes and prokaryotes.thus the world of organisms got divided into three domain systems rather than the 5 kingdom system.
B)ANS.Similarities and differences between archaea,bacteria and eukarytoes.
1) membrane bound nucleus is absent in archaea and bacteria but present in eukaryotes.
2)organelles are absent in archaea and bacteria but present in eukaryotes.
3)peptodoglycon in cellwall is present in archaea but absent in bacteria and eukaryotes.
4)membrane lipids are unbranched in bacteria ,eukarya and branched in archaea.
5)ribosomes are 70S type in bacteria and archaea and 80S type in eukarya.
C)ANS.Horizontal gene transfer may occur in three ways i.e transformation,transduction and conjugation.
Transformation;it involves uptake of small fragments of naked DNA by naturally transferable bacteria.and transformation is a key step in gene clonning.
Tranduction:Transduction involves transfer of DNA from one bacteria to another through the bacteriophages.
Conjugation:it is the process by which one bacterium transfers the genetic material to another through direct contact.during conjugation one bacterium serves as the donor of the genetic material and other serves as the recepient.the donor bacterium carries a DNA sequemce called fertility facteor or F- factor.
D)ANS. Some bacteria are phototrops, getting energy from sunlight.and others are chemotrops ,getting energy from chemical compounds.
2)some prokaryotes are autotrops,fixing carbon from CO2,others are heterotrops getting carbon from organic compounds of other organisms.
3)Prokaryotes can perform either aerobic or anerobic and some can switch between these modes.
4)Some prokaryotes have special enzymes and pathways that let them metabolize the nitrogen and sulfur containing compounds.
5)Prokaryotes play a key role in cycling of nutrients through ecosystem.