Bacteriophage

1. BOT-101:
Diversity
of Plants
Topic:
Virus

2. Tobacco Mosaic Virus
(TMV)
• Plant virus
• Named so because it majorly
infects tobacco plants,
potatoes, tomatoes and other
members of the Solanaceae
family
• The infection creates a mosaic
like pattern, mottling and
discoloration of the leaves.

3. Morphological
notes
• Tobacco mosaic virus (TMV) is a simple rod-
shaped helical virus
• It is 300 nm long with a diameter of 18 nm.
• The genetic material is a single-stranded
RNA molecule.
• RNA is found in a coiled manner. It is
located in center, covered by a protein coat.
• The protein coat is called as capsid. It is
made up of 2130 capsomeres.

4. Infected plant and
Electron micrograph of TMV

5. Adenovirus
• Group of common
viruses
• Infect the lining of
your eyes, airways
and lungs, intestines,
urinary tract, and
nervous system
• Common cause of
fever, coughs, sore
throats, diarrhea, and
pink eye

6. Morphological
notes
• Adenovirus is medium-sized (90-100 nm) non-
enveloped virus.
• The virions are composed of one linear piece of
double-stranded DNA inside an icosahedral capsid.
• Capsid consists of 252 proteins, belonging to 3
major categories: fiber, penton and hexon based
proteins
• 240 hexon based proteins are the structural basis
of Adenovirus and compose most of the viral
capsid.
• Both the fiber and penton based proteins are for
receptor binding and internalization of the
adenovirus into host cells

7. Electron micrograph of
Adenovirus

8. Bacteriophage
• Type of virus that
infects bacteria
• The word
"bacteriophage"
literally means
"bacteria eater"

9. Morphological note
HEAD
• Elongated and hexagonal in shape; made up of capsid and nucleic acid
• Capsid: Produced by identical protein subunits called capsomeres; Stores
and protects the genome
• Genetic material: Can be either DNA or RNA; tightly packed inside head
TAIL
• Neck (collar): Connects head and tail; possesses circular plate-like structure
• Tail tube: Inner non-contractile tube made up of protein; provides passage
for the movement of DNA from head to bacterial cell

10. Morphological note
• Tail sheath: Surround tail tube; Contraction of sheath push tail tube
through outer membrane of bacteria, forming canal for delivery of viral
genome
• Base plate: Hexagonal in shape; present at a distal end; controls sheath
contraction, host recognition, DNA ejection, and attachment
• Tail fibers: Long and thread-like filaments attached to base plate;
generally, 6 in number; used for the attachment of bacteriophage on
surface of bacteria
• Spikes (tail pin): Recognizes receptor sites of host cell; Pierces cell
membrane of bacteria and makes opening for the entrance of tail tube

11. Electron
micrographs
of
Bacteriophage