Tag: bacteria - introduction, shape and structure

Membrane bound organelles are absent in prokaryotes. As compared to a eukaryotic cell, the only comparable organelles present in prokaryotes are ribosomes which are naked nucleoprotein particles. Plasmodium is a unicellular eukaryotic organism which belongs to Kingdom Protista. Saccharomyces is also a unicellular eukaryotic organism which belongs to Kingdom Mycota or Fungi. Streptococcus is a unicellular prokaryotic organism which belongs to Kingdom Monera. Chlamydomonas is a unicellular eukaryotic organism, previously classified under Kingdom Plantae as Chlorophyceae but has now been moved to Kingdom Protista. Of the given options only Streptococcus is a prokaryotic organism. Hence, membrane bound cell organelles are missing in Streptococcus.

An Amoeba is a type of organism belongs to kingdom Protista. They have the ability to alter its shape, primarily by extending and retracting pseudopods. Amoeba has contractile vacuole which expels excess water from the cell. The various processes which are involved in the nutrition of Amoeba are:
Ingestion, digestion, absorption, assimilation and egestion. Amoeba has not excretory organs. The undigested food collects inside the Amoeba is thrown out of the body by the cell membrane. Thus, the correct answer is option A.

  E. coli , a gram negative rod shaped bacteria has since the time of discovery have been commonly used for biological lab experiment and research. The simple cell structured E. coli has one circular chromosome and a ds circular DNA molecule with 4.6 million base pairs in length and 4288 protein coding genes.

The cell walls of bacteria are composed of a macromolecule peptidoglycan which is a repeating framework of long glycan chains having alternate N-acetyl glucosamine and N-acetyl muramic acid; these glycan chains are cross-linked by short peptide fragments to provide a strong but flexible support framework. This makes option A correct. The green algal cell wall is composed mainly of cellulose which makes option B incorrect. Chitin is common constituent of cell walls of all type of fungi; option C is incorrect. The yeast cell wall itself is mainly composed of glucans ($\beta$$-glucans), mannoproteins and chitin; option D is incorrect. Thus, the correct answer is option A.

Amoeba is a protozoan belonging to the kingdom Protista. They are unicellular eukaryotic organisms and thus, made up of single cell.

Cocci that remain in pains after dividing are called diplococci. Cocci that remain in chains after dividing are called streptococci.

Microorganisms are the organisms that we cannot see by our naked eyes. It can be prokaryotic unicellular like bacteria, eukaryotic unicellular like protozoa, eukaryotic multicellular like fungi and algae and even acellular like viruses.

Thus, the correct answer is option C.

Unicellular organisms are made up of a single cell and perform all the life processes for survival and independent existence.  Hence, the cell is called as the fundamental structural and functional unit of life.