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Renin Angiotensin Mechanism.

Introduction to Prokaryotes and Eukaryotes

Introduction to Prokaryotes and Eukaryotes 

Introduction: 

  • The organisms are mainly divided by the type of cell they are having as “Prokaryotic” and “Eukaryotic”.

Prokaryotic Organisms:

  • The name is derived from Greek for “primitive nucleus”.

  • Organisms made up of cell(s) that lack a well developed cell nucleus or any membrane-enclosed organelles.

  • e.g. Bacteria, Archaea, and Bluegreen algae.

  • Developed around 3.5 billion years ago.

  • Approximate size is around 0.5-3.0 μm.

  • Usually unicellular (some cyanobacteria may be multicellular).

  • Nucleus is primitive and free in the cytoplasm, attached to mesosomes, and lacks nuclear membrane and nucleolus.

  • It contains DNA as a haploid genome.

  • Membrane-bound organelles are absent.

  • Ribosomes are smaller, 70S (50S + 30S).

  • Chloroplasts are absent; chlorophyll scattered in the cytoplasm.

  • Cell wall has a complex structure containing protein, lipids, and peptidoglycans.

  • For movement some organisms have flagella which has a simple structure.

  • They reproduce by asexual reproduction.

Eukaryotic Organisms:

  • The name is derived from Greek for “true nucleus”.

  • Organisms are made up of cell(s) that contain a well developed cell nucleus covered with nuclear membrane, and membrane bound cell organelles.

  • e.g. Algae, fungi, protozoa, plants, animals.

  • Developed around 2 billion years ago.

  • Approximate size is above 5 μm.

  • Usually multicellular.

  • Nucleus is well developed and is enclosed in a nuclear membrane, nucleolus is present in the nucleus. Different well developed cell organelles are present

  • It contains DNA as a diploid genome.

  • Ribosomes are bigger, 80S (60S + 40S).

  • Chlorophyll is present in chloroplast in plants.

  • Cell wall is present in plant cells and fungi, in animal cells it is absent.

  • For movement some organisms contain flagella which are complex in nature.

  • They reproduce by Sexual and asexual/ Mitotic division.

Questions:

  1. Differentiate between Prokaryotic and Eukaryotic cells / organisms.
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