Lecture notes in Microbiology

Difference between Flagella and Fimbriae of Bacteria- A Comparison Table


Difference between Fimbriae and Flagella

Fimbriae vs Flagella
(Similarities and Differences between Fimbriae and Flagella of Bacteria)

Both Fimbria (plural Fimbriae) and Flagellum (plural flagella) are the filamentous proteinaceous structures found on the surface of some bacterial cells. 

Fimbriae definition: Fimbriae are bristle like short fibres occurs on the surface of some Gram positive and Gram negative bacteria. Fimbriae enable the bacterial cell to stick to the surface of host cells. They also help in the formation of pellicles or biofilms. (Pellicle: thin sheet of cells on the surface of a liquid).

Flagella definition: Bacterial flagella are long whip like filamentous structures present in some bacteria. The most important function of flagella is to assist in locomotion. Flagella can also act as a sensory organ to detect temperature and the presence of certain chemicals in the external environment of the cell. Even though the flagella are present in prokaryotes and eukaryotes, both are entirely different in their structure and formation and mechanism of propulsion.

The present post describes the Similarities and Differences between Fimbriae and Flagella of bacteria with a Comparison Table.

Similarities between Fimbriae and Flagella

Ø  Both fimbriae and flagella are filamentous structures.

Ø  Both are present in Gram positive and Gram negative bacteria.

Ø  Both are cell surface appendages, present on the cell surface of bacteria.

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Lecture notes in Microbiology

Difference between Pili and Fimbriae of Bacteria- A Comparison Table


Difference between Pili and Fimbriae

Fimbriae vs Pili
(Similarities and Differences between Fimbriae and Pili of Bacteria)

Both Fimbria (plural Fimbriae) and Pilus (plural Pili) are the filamentous proteinaceous structures found on the surface of some bacterial cells. They extend from the surface of the bacterial cell wall and can have many functions such as attachment, adhesion and assisting in genetic exchange.

Fimbriae definition: Fimbriae are bristle like short fibres occurs on the surface of some Gram positive and Gram negative bacteria. Fimbriae enable the bacterial cell to stick to the surface of host cells. They also help in the formation of pellicles or biofilms. (Pellicle: thin sheet of cells on the surface of a liquid).

Pili definition:  Pili are long hair like tubular micro-fibres like structures present on the surface of some Gram negative bacteria. They are comparatively longer filamentous structures and their number per cell is very limited. There are many classes of pili based on their structure and function. Most of the pili can act as the receptors of some viruses.

The term Pili and Fimbriae are used inter-changeably by many authors in many microbiology text books. However, modern studies have clearly shown that they are two different entities in the bacteria distinguished by their development, structure and functions.

The present post describes the Similarities and Differences between Fimbriae and Pili with a Comparison Table

Similarities between Fimbriae and Pili

Ø  Both fimbriae and pili are filamentous structures.

Ø  Both are cell surface appendages, present on the cell surface of bacteria.

Ø  Both are the attachment or adhesion organs in bacteria.

Ø  Both are made up of proteins.

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Lecture notes in Microbiology

Difference between Murein and Pseudomurein- A Comparison Table


difference murein and pseudomurein

Murein vs Pseudomurein – A Comparison Table
(Similarities and Difference between Peptidoglycan and Pseudopeptidoglycan)

The majority of Bacteria and Archaebacteria have a rigid cell wall around its plasma membrane. The peptidoglycan (also called murein) cell wall, which is considered as the biomarker of bacteria, is absent in the cell wall of Archaea. However, the members of Archaea show great diversity in their cell wall composition. The cell wall in Archaea may contain polysaccharides, proteins or glycoproteins. Some methanogenic Archaebacteria possess a cell wall molecule that is remarkably similar to that of the peptidoglycan molecules in the cell wall of bacteria. These cell wall molecules are called Pseudopeptidoglycan or Pseudomurein. The peptidoglycan and pseudopeptidoglycan shows many structural and functional similarities and differences. The present post describes the Similarities and Differences between the Peptidoglycan (Murein) and Pseudopeptidoglycan (Pseudomurein) with a comparison table.

Similarities between Peptidoglycan (Murein) and Pseudopeptidoglycan (Pseudomurein)

Ø. Both Peptidoglycan and Pseudopeptidoglycan are glycoconjugates.

Ø. Both are polymers of monomer units joined by specific glycosidic bonds.

Ø. Both are hetero-polysaccharides (consists of more than one type of monomer units).

Ø. Both contain long un-branched carbohydrate chains inter-connected by short peptide segments.

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Free Net Life Science Study Materials

CSRI JRF NET Life Sciences June 2017 Model Question Paper Set- 4


biological significance of hydrogen bonds in water

CSIR JRF/NET Life Science Exam June 2017 (I)
Model Question Paper 4/5
(CSIR MCQ011: Practice Questions with Answer Key)

1.  Penicillin-resistant bacteria produce β-lactamase which inactivates penicillin by:

a.       Esterifying the carboxyl group
b.      Oxidizing S atom
c.       Hydrolyzing the side chain
d.      Hydrolyzing the C-N bond

Ans. (d)

β-lactamases or penicillinase are a class of enzymes produced by some bacteria which degrade penicillin antibiotic and thereby impart resistance against penicillin. All penicillin antibiotics contain a β-lactum ring structure which is essential for the antibiotic activity. The β-lactamase enzyme will degrade the β-lactum ring and thus inhibit the antibiotic properties.

2. Pseudo-murein is present in cell wall of:

a.       Streptococci
b.      Staphylococci
c.       Methanococci
d.      Micrococci

Ans. (c). Methanococci

Methanococci is an Archaebacteria.

Pseudo-murein or pseudo-peptidoglycan is a major cell wall component of some Archaebacteria. It is structurally different from the peptidoglycan of the true bacteria. However, it is functionally similar to the peptidoglycan wall of bacteria. Pseudo-murein is a hetero-polysaccharide of N-acetylglucosamine and N-acetyltalosaminuronic acid connected by β-1,3-glycosidic bonds. Lysozyme enzyme is unable to degrade the pseudo-murein cell wall.

Learn more: Comparison table of Bacteria, Archaea and Eukarya

3. Bacteria that can penetrate intact corneal epithelium is:

a.      Pseudomonas aeruginosa
b.      Staphylococus aureus
c.       Listeria monocytogenes
d.      Yersinia pestis

Ans. (b). Staphylococus aureus

4. Which of the following bacterial toxins does not have ADP-ribosyl transferase activity:

a.       Cholera toxin
b.      Diphtheria toxin
c.       Exotoxin A
d.      S aureus α toxin

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questions and answers Biology

HSA Natural Sciences Kerala PSC Previous Year Question Paper (2007)


Biology HSA Kerala PSC Question Paper

H.S.A. Natural Sciences Previous Question Papers
Kerala Public Service Commission (K-PSC)
(HSA Natural Science Exam 2006)

Original question paper of Kerala PSC HSA (High School Assistant) in Natural Sciences (Biology, Life Science, Botany and Zoology) examination conducted by Kerala PSC (Kerala Public Service Commission) for the appointment of High School Teachers (High School Assistants) in Government High Schools of Kerala under the Directorate of Public Instructions (DPI), Trivandrum, Kerala, India. Questions are in MCQ (Multiple Choice Questions) format.

HSA Natural Science Question Paper Code 223/2007

To download the question paper, please click on the link below…

To download the question paper, please click on the link below…

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