Question

Answer all three prompts.

1. Explain the roles of each structure in bacteria cells.

2. Explain how bacteria cells make energy for cellular processes.

3. How are plant cells, animal cells, and bacteria cells different?

Answer 1

1. The outermost covering of a bacterial cell is it cell wall in case of Gram positive bacteria which is made up of peptidoglycan. It protects the cell from heat and desiccation and provides shape to the cell point but in Gram Negative bacteria the outermost covering is an outer membrane made up of lipopolysaccharide which imparts virulence to the bacteria.

The plasma membrane is present in a two cell wall and is made up of phospholipids. It is is selectively permeable in nature and regulate the entry and exit of molecules across cell surface.

The cytoplasm is a watery fluid into which all the cell molecules and components are suspended. The nucleoid is a membrane less region in the cytoplasm which contains DNA. DNA is not associated with histone proteins and like eukaryotes.

Plasmids are extrachromosomal DNA molecule. They are present in multiple copies and are circular and double stranded in shape. They impart unique characteristics feature to bacteria like antibiotic resistance, ability to degrade pollutants etc.

Ribosomes are 70S type and are associated with synthesis of protein.

Flagella is present on the surface of cell and is meant for locomotion and movement.

2. Bacteria undertake aerobic and anaerobic respiration and fermentation to obtain energy.

If there is enough supply of oxygen in the medium, then it undertake aerobic respiration and if there is a deficiency of oxygen then it undertakes fermentation. If oxygen is completely absent, than anaerobic respiration is carried.

During aerobic respiration, glycolysis convert 1 molecule of glucose into two molecules of pyruvic acid. Pyruvic acid is then oxidised into acetyl coenzyme a which then enters citric acid cycle. Citric acid cycle produces maximum number of electron Carriers. All the electron Carriers finally enter electron transport chain and participate in the production of ATP. ATP is the energy currency of the cell which is used by the bacteria to carry out its metabolic activities. The overall process of aerobic respiration produces around 38 molecules of ATP. Anaerobic respiration is little less efficient than aerobic respiration and produces around 30 to 32 molecules of ATP.

Fermentation is energetically very less efficient process. It undertakes glycolysis followed by fermentation. It generates only 4 molecules of ATP.

3. Plant cells and animal cells are Eukaryotic whereas Bacteria is prokaryotic. Plant cells and animal cells have nucleus and membrane-bound organelles but all of them are absent in bacteria.

Chloroplast are present in plant cells and few bacterial cells but not in animal cells.

Vacuoles are present in plant cells and some of the bacterial cells but not in animal cells.

Centrioles are present in only animal cells but not in plant cells and bacteria.

Animal and plant cells have 80s type ribosomes and bacteria have 70s type ribosomes.

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