Uploaded by salsabilaainunnisa777

VIRUSES (Biology material for X grade)

advertisement
VIRUSES
DIFFERENCES BETWEEN VIRUS AND CELL
The Discovery of Viruses: Scientific
Inquiry
• Tobacco mosaic disease stunts
growth of tobacco plants and gives
their leaves a mosaic coloration
• In the late 1800s, researchers
hypothesized that a particle smaller
than bacteria caused the disease
• In 1935, Wendell Stanley confirmed
this hypothesis by crystallizing the
infectious particle, now known as
tobacco mosaic virus (TMV)

TRANSITION BETWEEN LIVING AND NONLIVING THINGS

ACELLULAR (JUST HAVE GENETIC MATERIAL AND CAPSID FROM
PROTEIN)

PARASITE INTRACELLULAR OBLIGATE

REPRODUCE WITHIN HOST CELL

THEY HAVE ONLY RNA / DNA

IN CRYSTAL SHAPED IF OUTSIDE CELL
CHARACTERISTIC OF VIRUS
Structure of Viruses
• Viruses are not cells
RNA
Viral genomes (bringing
genetic code)
DNA
structure
Capsid (protect the
genetic materials)
Capsids are built from
protein subunits called
capsomeres
Envelope
From glycoprotein
become a reseptor
ZXX

SPHERICAL / ISOMETRIC >> HIV, INFLUENZA

ROD-SHAPED/ HELICAL >> TMV

POLYHEDRAL/ ICOSAHEDRON >> ADENOVIRUS

OVAL/CAPSULE SHAPED >> RABIES

T-SHAPED >> BACTERIOPHAGE

FILAMENT >> EBOLA
VIRUS SHAPE
REPLICATIVE CYCLES OF PHAGES

Phages are the best understood of all viruses

Phages have two reproductive mechanisms: the lytic cycle and
the lysogenic cycle
THE LYTIC CYCLE

The lytic cycle is a phage replicative cycle that culminates in the
death of the host cell

The lytic cycle produces new phages and lyses (breaks open) the
host’s cell wall, releasing the progeny viruses

A phage that reproduces only by the lytic cycle is called a
virulent phage

Bacteria have defenses against phages, including restriction
enzymes that recognize and cut up certain phage DNA
FIGURE 19.5-1
1 Attachment
FIGURE 19.5-2
1 Attachment
2 Entry of phage
DNA and
degradation
of host DNA
FIGURE 19.5-3
1 Attachment
2 Entry of phage
DNA and
degradation
of host DNA
3 Synthesis of
viral genomes
and proteins
FIGURE 19.5-4
1 Attachment
2 Entry of phage
DNA and
degradation
of host DNA
Phage assembly
4 Assembly
Head
Tail
Tail
fibers
3 Synthesis of
viral genomes
and proteins
FIGURE 19.5-5
1 Attachment
2 Entry of phage
DNA and
degradation
of host DNA
5 Release
Phage assembly
4 Assembly
Head
Tail
Tail
fibers
3 Synthesis of
viral genomes
and proteins
LYTIC CYCLE
STEPS
DESCRIPTION
1. ATTACHMENT
Virus particle (virion) attaches to a
cell
2. PENETRATION/ INJECTION
Nucleic acid enters or penetrates
the host’s cytoplasm
3. REPLICATION & SYNTHESIS
Virus multiplies itself by controlling or
manipulating the host to produce
viral components, i.e. nucleic acid
and protein for capsid
4. ASSEMBLY
Nucleic acid and capsid are
assembled to become intact viruses
5. RELEASE/ LYSIS
Newly assembled viruses are
released from the host cell by lysis
THE LYSOGENIC CYCLE

The lysogenic cycle replicates the phage genome without
destroying the host

The viral DNA molecule is incorporated into the host cell’s
chromosome

This integrated viral DNA is known as a prophage

Every time the host divides, it copies the phage DNA and passes
the copies to daughter cells
LYSOGENIC CYCLE
STEPS
DESCRIPTION
1. ATTACHMENT
Virus particle (virion) attaches to a
cell
2. PENETRATION/ INJECTION
Nucleic acid enters or penetrates
the host’s cytoplasm
3. INTEGRATION
The virus DNA/RNA is inserted into
host chromosomes becoming a
prophage
4. DIVISION
The modified chromosomes undergo
replication and reproduce normally
creating many new daughter cells
with the infected genetic materials

An environmental signal can trigger the virus genome to exit the
bacterial chromosome and switch to the lytic mode

Phages that use both the lytic and lysogenic cycles are called
temperate phages
BENEFICIAL VIRUSES
HUMAN
DISADVANTAGEOUS BECAUSE CAUSE DISEASES
ANIMAL
PLANT
BACTERIA
HIV caused AIDS
RSV
TMV (tobacco
mosaic virus)
ADENOVIRUS
FOOT AND
MOUTH DISEASE
VIRUS
TUNGRO VIRUS
RABIES
NEWCASTLE
DISEASE VIRUS
CVPD (citrus vein
phloem
degeneration)
POLIO
RABIES
HERPES
EBOLA
INFLUENZA
BACTERIOPHAGE
BENEFICIAL VIRUSES
ADVANTAGEOUS
GENE THERAPY (CURE GENETIC DISORDERS)
Bacteriophage for killing bacteria cause disease
(in human body)
Download
Random flashcards
Rekening Agen Resmi De Nature Indonesia

9 Cards denaturerumahsehat

Nomor Rekening Asli Agen De Nature Indonesia

2 Cards denaturerumahsehat

Card

2 Cards

Create flashcards