BT102 Merged PPT Handouts Lectures 1-104

BT-102 Microbiology

Topic-001 Microbes and Microbiology

What are Microbes?

➢ Also called germs or microorganisms ➢ Too small to be seen with the unaided eye ➢ A microscope is needed to see them ➢ Studying microbes is microbiology ➢ Microbes are simple. ➢ Diverse ➢ Classification has been a challenge. ➢ Procaryotes (no nuclear membrane) and eucaryotes (distinct nucleus)

Topic-002 Why do we Classify Organisms?

➢ Studying them becomes convenient ➢ Easy Identification ➢ Easy to establish relationship between organisms ➢ Evolutionary relationships can be established

Bases of Classification

Similarities among them

➢ Morphology used to be the main feature prior to the advent of molecular biology ➢ Biochemical similarities ➢ Genetic similarities ➢ Evolutionary relationships

Five Kingdom Classification of Organisms

➢ Monera: Bacteria and Archea ➢ Protista ➢ Fungi ➢ Plantae ➢ Animalia ➢ Microbes placed in the first 3 kingdoms

Reasons for Changes in the Classification

➢ Electron microscope ➢ Biochemical and physiological characteristics ➢ Nucleic acid and protein sequencing o Ribosomal RNA (rRNA) ➢ Bacteria and Archea two different groups

Three Domain Classification (1977)

➢ Bacteria: True or eubacteria ➢ Archea: ➢ Eucarya

• Protists (slime molds, protozoa, algae)
• Fungi
• Plants
• Animals

Domains & Kingdoms

➢ Domain: Bacteria, Kingdom Bacteria ➢ Domain: Archea, Kingdom Archea ➢ Domain: Eucarya Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia

Bacteria

➢ Procaryotes ➢ Usually single-celled organisms ➢ Cell wall made up of peptidoglycan

Archea

➢ Procaryotes ➢ Cell wall has no peptidoglycan, but has special lipids. ➢ Vary in rRNA sequencing ➢ Live in extreme conditions – Thermophiles

o Halophiles

Eucarya

1. Protists
2. Fungi
3. Animals
4. plants

Carl · Linnaeus, · Protists

➢ Algae: Cellulose cell wall, Photosynthetic Produce (O2) ➢ Protozoa: motile, unicellular organims ➢ Slime mold: Protozoa like at one stage and fungus like in another

Fungi

➢ Unicellular form is called yeast. ➢ Multicellular is known as mold or mushroom

Other Microbes

➢ Viruses: Acellular organisms o Proteins and nucleic acids ➢ Viroids: composed only of circular ssRNA (potato spindle tuber viroid) ➢ Virusoids: Contain circular ssRNA, need helper viruses for replication and encapsidation; also called satellite viruses ➢ Prions: Infectious proteins

Naming Organisms: Binomial Nomenclature

➢ Linnaeus (in 1735) established the system of scientific nomenclature ➢ Each organism has two names: the genus and specific epithet (descriptive word)

• Escherichia coli

Scientific Names

➢ Are italicized or underlined. The genus is capitalized, and the specific epithet is lowercase. ➢ Are ―Latinized‖ and used worldwide. ➢ May be descriptive or honor a scientist.

Escherichia coli

➢ Honors the discoverer, Theodor Escherich ➢ Describes the bacterium‘s habitat—the large intestine, or colon

Staphylococcus aureus

➢ Describes the clustered (staphylo-) spherical (cocci) cells ➢ Describes the gold-colored (aureus) colonies

Scientific Names

➢ After the first use, scientific names may be abbreviated with the first letter of the genus and the specific epithet:

• Escherichia coli and Staphylococcus aureus are found in the human body. E. coli is found in the large intestine, and S. aureus is on skin.

Bacterium Vs Bacteria

E.coli as a species is a bacterium. One E.c0li cell is a bacterium. Many E.coli cells are bacteria.