Students can go through AP Inter 2nd Year Botany Notes 7th Lesson Bacteria will help students in revising the entire concepts quickly.
AP Inter 2nd Year Botany Notes 7th Lesson Bacteria
→ Bacteria were discovered by Anton van Leeuwenhoek and he is regarded as the Father | of Microbiology.
→ The term Bacteria was coined by Ehrenberg (1829).
→ Bacteria are chemical factories capable of bringing about significant changes in nature
– Louis Pasteur.
→ The study of Bacteria is called Bacteriology.
→ According to WH. Whittakaer’s five kingdom classification Bacteria along with Blue green algae are included in the kingdom Monera.
→ Bacteria are found in soil, water, air and on or inside living organisms. They also occur on food stuffs, they can withstand extreme cold, heat and drought conditions.
→ Some are deadly parasites of plants, animals and human beings.
→ Escherichia coli is a common inhabitant of human intestines.
→ Majority of the Bacteria are in the range of 2.0 to 5.0 pm in length and 0.5 to 1.0 pm in breadth.
→ Bacterial cells may be spherical (cocci), as elongated rods (bacilli), helical rods (spirillum) or comma-shaped (vibrios).
→ Some are pleomorphic.
Eg : Acetobacter.
→ Some spirillum type are flexible and are referred to as spirochaetes.
→ Some are in the form of a thread of filament.
Eg : Beggiotoa
→ Cell wall of Bacteria is made up of two to several layers of peptidoglycan. Teichoic acid is present in the cell wall of Gram Positive Bacteria.
→ External to the cell wall, flagella, pilli, sex pilus and glycocalyx are present.
→ Sex pilus help in Bacterial conjugation in binding the two conjugants.
→ Genophore consists of single circular, double stranded DNA molecule.
→ In addition, to genophore,’Certain Bacteria possess a self replicating circular, naked, double stranded DNA molecule is called plasmid.
→ Depending on the source of availability of carbon artd energy, Bacteria are classified into photoautotrophs, chemoautotrophs, photoheterotrophs and chemoheterotrophs.
→ Bacteria reproduces commonly by Binary fission.
→ Sexual reproduction is absent in Bacteria but the exchange of genetic material takes place by three ways. They are (a) Conjugation
→ Many Bacteria are directly or indirectly beneficial to humans. Hence they are considered both as ‘Friends and foes of man’.
→ DNA components from Bacteria are used as Biosensors that can detect biologically active toxic pollutants.