Transcript Hello Mighty Achievers

Hello Mighty Collegiate
Stars!!!
Is it Alive?
Characteristics of Living Organisms
1) All living things are composed of cells.
2) All living things perform certain chemical
process such as growth and digestion
3) All living things can reproduce
4) All living things either make their own nutrients
or ingest nutrients from the environment.
5) All living things respond to stimuli such as light
and touch.
Viruses
Virus: is a particle that consists of a
nucleic acid enclosed within a
protein shell that requires a living
cell in order to reproduce.
Note: Most scientist do not consider
viruses to be organisms.
Virus are Nonliving
Viruses lack nearly every
characteristic of life.
They are not composed of cells.
They don’t respond to stimuli.
They don’t use energy for growth
and development.
They cannot reproduce on their
own.
Viruses also cannot make food, take
in food, or produce wastes.
Virus Shapes
Viruses vary widely in shape. Some
viruses are round, while some are
rod-shaped. Other viruses are
shaped like bricks, threads, or
bullets. There are even viruses that
have complex, robot like shapes,
such as the bacteriophage A
Bacteriophage: (bak TEER ee oh fayj)
is a virus that infects bacteria.
Virus Shapes
Structure of Virus
All viruses have two basic
parts: a protein coat
that protects the virus
and an inner core made
of genetic material.
Capsid: the protein shell
that surround a virus
In addition to the capsid,
some viruses also have
protective coating
called an envelope. This
envelope may be
covered with spikes.
Note: A virus uses these
spikes both to
recognize and attach to
the cells they infect.
Structure of Virus
Each virus contains unique surface proteins. The
shape of the surface proteins allows the virus
to attach to certain cells in the host. Like keys,
a virus’s proteins fit only into certain “locks,”.
This is known as the lock and key system.
Viral Nucleic Acid
Viral nucleic acid can either be DNA
or RNA.
DNA is the nucleic acid responsible
for carrying the genetic
information of most organism from
one generation to the next.
RNA is a nucleic acid used by most
organisms for protein synthesis
Prokaryotes
Prokaryotes: is a unicellular organism
that lacks a true nucleus and
membrane-bound organelles.
Remember: Pro-No (Prokaryotes have
no true nucleus and membrane
bound organelles)
Prokaryotes are commonly called
bacteria.
Living Organism
Unlike viruses, bacteria are living
organisms.
Bacteria possess the characteristics
of living organisms.
Bacteria is Alive!!!
Bacteria Shape & Size
Most bacterial cells have one of three
basic shapes: spherical (coccus), rodlike
(bacillus), or spiral (spirillum).
Bacteria Size
Bacterial cells is larger that viruses!!!
Bacteria Structure
Bacterial cells are enclosed by a cell
wall. Within the cell wall is a cell
membrane that contains the
cytoplasm and the hereditary
material of the cell.
Ribosomes are found in the cytoplasm
of the prokaryote cell, but the cell
does not contain other organelles.
Note: Prokaryotes genetic material is
not enclosed in a nucleus.
Bacteria Structure
Bacterial cells don’t have a nucleus!!!
A bacterial cell may also have a flagellum (fluh
JEL um) (plural flagella), a long, whiplike
structure that helps a cell to move.
A flagellum moves the cell by spinning in place like
a propeller.
A bacterial cell can have many flagella, one, or
none. Most bacteria that do not have flagella
cannot move on their own. Instead, they are
carried from place to place by the air, water
currents, objects, or other methods.
Bacteria Structure
Types of Bacteria
Bacteria are classified into two
kingdoms based on differences in
cell structure: Archaebacteria and
Eubacteria.
Archaebacteria: most bacteria in this
group can survive without oxygen.
Eubacteria: this group includes the
most prokaryotes.
Assignment
Students will use the material
provided to create a bacteria and
virus model.
Students must label and describe the
function the following parts:
Virus: capsid, protein coat, genetic
material, spikes
Bacteria: cell membrane, ribosomes,
cytoplasm, flagellum, cell wall,
genetic material, coccus, bacillus,
spirillum.
Welcome Collegiate Stars !!!
Part II
Viruses & Bacteria
Review Virus
 Viruses are nonliving
The two basic parts: protein coat
and inner core that hold the genetic
material.
Some viruses have a protein
envelope that has spikes
Viruses are very specific in their
invasion of their host
Review Bacteria
Bacteria is also known as
prokaryotes
Bacteria is a unicellular organism
Bacteria is a living organism
Bacteria has three shapes: rodlike
(bacillus), spherical (coccus), &
spiral (spirillum).
Flagellum help the bacteria move
How Viruses Multiply
After a virus attaches to a host cell, it
enters the cell. Once inside a cell, a
virus’s genetic material takes over many
of the cell’s functions. It instructs the
cell to produce the virus’s proteins and
genetic material. These proteins and
genetic material then assemble into new
viruses.
Some viruses take over cell functions
immediately. Other viruses wait for a
while.
Active Viruses
After entering a cell, an active virus
immediately goes into action. The
virus’s genetic material takes over
cell functions, and the cell quickly
begins to produce the virus’s
proteins and genetic material. Then
these parts assemble into new
viruses.
When the cell is full of new viruses,
the host cell bursts open, releasing
hundreds of new viruses as it dies.
Active Virus
Lytic Cycle
Hidden Viruses
Other viruses do not immediately become active.
Instead, they “hide” for a while.
When a hidden virus enters a host cell, its genetic
material becomes part of the cell’s genetic
material. The virus does not appear to affect
the cell’s functions and may stay in this inactive
state for years.
Each time the host cell divides, the virus’s genetic
material is copied along with the host’s genetic
material.
Then, under certain conditions, the virus’s genetic
material suddenly becomes active. It takes over
the cell’s functions in much the same way that
active viruses do. Soon, the cell is full of new
viruses and bursts open.
Hidden Virus
Lysogenic Cycle
Lysogenic Cycle
A virus that enters a lysogenic cycle
is an example of a mutagen.
Mutagen: is anything that changes
the DNA of an organism .
In this case the virus is a mutagen
because it inserts its own genes
into the cell’s DNA.
Microbes & Diseases
Disease: is any change that disrupts
the normal function of one or more
body systems.
Some diseases are caused by
exposure to certain chemical in the
environment. Other diseases are
caused by traits that are inherited.
Such diseases are called
noninfectious diseases because
they are not spread from one
organism to another.
Microbes & Diseases
Many diseases in humans and other
organisms are caused by microbes.
Pathogen: any microbe that causes a
diseases.
Infectious disease: any disease that is
caused by a pathogen. An illness that is
passed from one organism to another is
an infectious disease. (ie. Cold)
Contagions: infectious diseases that can be
transmitted or spread from one organism
to another.