What's the difference between viruses and bacteria?
Use the following information to make a VEN DIAGRAM describing the differences and similarities
between viruses and bacteria. Once you are done, you should use this information to write a detailed
description of the two in essay format. The introductory paragraph should include a thesis, and the
similarities between bacteria and viruses. The following two paragraphs should detail how the two are
different. You have writers license with this writing prompt, but understand that I am going to be
reading these as someone who knows nothing about viruses and bacteria. Detail is important as well as
flow of the essay. This will count as a test grade and with 3rd quarter ending in a week and a half, some
of you could use an extra good grade. This is due by Monday 3/24/14, which means you will need to
take it home for homework. Do NOT rush through this. I will be grading similar to how Mrs. IkeForeman grades essays so I expect the same quality of work. This essay should be 1-2 pages in length
and you may use outside resources, as long as you cite them. Attach the Ven Diagram to the essay as it
will count for the research portion of this grade.
Bacteria are single-cell organisms that can survive independently.
Bacteria are single-cell organisms that can survive independently. You can kill them by interfering with
their metabolism (internal biological functions), which is basically what antibiotics do.
Most bacteria are neither male nor female and reproduce by simply dividing in to two.
Infections they cause include pneumonia, cystitis and food poisoning bugs like salmonella.
But not all bacteria are bad – some friendly types actually help protect us from disease.
Viruses are not cells, they have no metabolism and they cannot survive alone. A virus is a chain of DNA
(genetic material) and needs a host cell in order to stay alive.
You can, of course, pick them up on door handles and other surfaces. That’s one of the most common
ways of catching colds and flu, but that’s because they’re contained in sweat or skin cells. Once a virus
gets in to cells it persuades the cells to reproduce it! Antibiotics are useless against viruses.
Antiviral drugs either improve the immunity of the cell to the virus or interfere with the virus’s
reproduction.
http://www.mirror.co.uk/lifestyle/sex-relationships/whats-the-difference-between-viruses-and-bacteria270976#ixzz2wQnVqCev
Infections - bacterial and viral
Many human infections are caused by either bacteria or viruses. Bacteria are tiny single-celled organisms,
thought by some researchers to be related to plants. They are among the most successful life forms on the
planet, and range in habitat from ice slopes to deserts. Bacteria can be beneficial – for instance, gut
bacteria help us to digest food – but some are responsible for a range of infections. These disease-causing
varieties are called pathogenic bacteria. Many bacterial infections can be treated successfully with
appropriate antibiotics, although antibiotic-resistant strains are beginning to emerge. Immunization is
available to prevent many important bacterial diseases. A virus is an even smaller micro-organism that
can only reproduce inside a host’s living cell. It is very difficult to kill a virus. That’s why some of the
most serious communicable diseases known to medical science are viral in origin.
How bacteria and viruses enter the body
To cause disease, pathogenic bacteria must gain access into the body. The range of access routes for
bacteria includes:
Cuts
Contaminated food or water
Close contact with an infected person
Contact with the feces of an infected person
Breathing in the exhaled droplets when an infected person coughs or sneezes
Indirectly, by touching contaminated surfaces – such as taps, toilet handles, toys and nappies.
Viruses are spread from one person to another by:
Coughs
Sneezes
Vomits
Bites from infected animals or insects
Exposure to infected bodily fluids through activities such as sexual intercourse or sharing hypodermic
needles
Forgetting to wash your hands after handling pets and animals is another way for germs to be taken in by
mouth.
Bacteria types
Bacteria that cause disease are broadly classified according to their shape. The four main groups include:
Bacilli – shaped like a rod with a length of around 0.03mm. Illnesses such as typhoid and cystitis are
caused by bacilli strains.
Cocci – shaped like a sphere with a diameter of around 0.001mm. Depending on the sort, cocci bacteria
group themselves in a range of ways, such as in pairs, long lines or tight clusters. Examples include
Staphylococci (which cause a host of infections including boils) and Gonococci (which cause the sexually
transmissible infection gonorrhoea).
Spirochaetes – as the name suggests, these bacteria are shaped like tiny spirals. Spirochaetes bacteria are
responsible for a range of diseases, including the sexuallytransmissible infection syphilis.
Vibrio – shaped like a comma. The tropical disease cholera, characterised by severe diarrhoea and
dehydration, is caused by the vibrio bacteria.
Characteristics of the bacterium
Most bacteria, apart from the cocci variety, move around with the aid of small lashing tails (flagella) or by
whipping their bodies from side to side. Under the right conditions, a bacterium reproduces by dividing in
two. Each ‘daughter’ cell then divides in two and so on, so that a single bacterium can bloom into a
population of some 500,000 or more within just eight hours. If the environmental conditions don’t suit
the bacteria, some varieties morph into a dormant state. They develop a tough outer coating and await the
appropriate change of conditions. These hibernating bacteria are called spores. Spores are harder to kill
than active bacteria because of their outer coating.
Curing a bacterial infection
The body reacts to disease-causing bacteria by increasing local blood flow (inflammation) and sending in
cells from the immune system to attack and destroy the bacteria. Antibodies produced by the immune
system attach to the bacteria and help in their destruction. They may also inactivate toxins produced by
particular pathogens, for example tetanus and diphtheria.
Virus types
A virus is a miniscule pocket of protein that contains genetic material. If you placed a virus next to a
bacterium, the virus would be dwarfed. For example, the polio virus is around 50 times smaller than a
Streptococci bacterium, which itself is only 0.003mm long. Viruses can be described as either RNA or
DNA viruses, according to which type of nucleic acid forms their core.
The four main types of virus include:
Icosahedral – the outer shell (capsid) is made from 20 flat sides, which gives a spherical shape. Most
viruses are icosahedral.
Helical – the capsid is shaped like a rod.
Enveloped – the capsid is encased in a baggy membrane, which can change shape but often appears
spherical.
Complex – the genetic material is coated, but without a capsid.
The body’s response to viral infection
Viruses pose a considerable challenge to the body’s immune system because they hide inside cells. This
makes it difficult for antibodies to reach them. Some special immune system cells, called T-lymphocytes,
can recognise and kill cells containing viruses, since the surface of infected cells is changed when the
virus begins to multiply. Many viruses, when released from infected cells, will be effectively knocked out
by antibodies that have been produced in response to infection or previous immunisation.
Curing a viral infection
Antibiotics are useless against viral infections. This is because viruses are so simple that they use their
host cells to perform their activities for them. Antiviral drugs work differently than antibiotics by
interfering with the viral enzymes. Antiviral drugs are currently only effective against a few viral
diseases, such as influenza, herpes, hepatitis B and C and HIV – but research is ongoing. A naturally
occurring protein, called interferon (which the body produces to help fight viral infections), can now be
produced in the laboratory and is used to treat hepatitis C infections.
Immunization against viral infection is not always possible
It is possible to vaccinate against many serious viral infections such as measles, mumps, hepatitis A and
hepatitis B. An aggressive worldwide vaccination campaign, headed by the World Health Organization
(WHO), managed to wipe out smallpox. However, some viruses – such as those that cause the common
cold – are capable of mutating from one person to the next. This is how an infection with essentially the
same virus can keep dodging the immune system. Vaccination for these kinds of viruses is difficult,
because the viruses have already changed their format by the time vaccines are developed.
Where to get help
Your doctor
Your pharmacist
Things to remember
Many human illnesses are caused by infection with either bacteria or viruses.
Most bacterial diseases can be treated with antibiotics, although antibiotic-resistant strains are starting to
emerge.
Viruses pose a challenge to the body’s immune system because they hide inside cells.
It is possible to be vaccinated against some of the major disease-causing viruses (such as measles and
polio), as well as bacterial diseases such as Hemophilus influenza Type B (Hib), tetanus and whooping
cough.
Bacteria (singular: bacterium) are unicellular microorganisms. They are
typically a few micrometers long and have many shapes including curved
rods, spheres, rods, and spirals.
A virus (from the Latin noun virus, meaning toxin or poison) is a submicroscopic particle (ranging in size from 20–300 nm) that can infect the
cells of a biological organism.
Ribosomes
Bacteria
Viruses
Present
Absent
Living organism
Opinions differ on whether
viruses are a form of life or
Living attributes
organic structures that interact
with living organisms.
Number of cells
Structures
Unicellular; one cell
No cells; not living
DNA and RNA floating freely in
cytoplasm. Has cell wall and cell
DNA or RNA enclosed inside a
coat of protein.
membrane.
Cell wall
Peptidoglycan/Lipopolysacchar
ide
No cell wall.Protein coat present
instead.
Antibiotics
Vaccines prevent the spread and
antiviral medications help to slow
Treatment
reproduction but can not stop it
completely.
Enzymes
Yes
Yes, in some
Nucleus
No
No
Virulence
Yes
Yes
Localized
Systemic
Some bacteria are beneficial
(e.g. certain bacteria are
Viruses are not beneficial.
However, a particular virus may
be able to destroy brain tumors
(see references). Viruses can be
Infection
Benefits
required in the gut)
useful in genetic engineering.
Fission- a form of asexual
Reproduction
reproduction
Invades a host cell and takes over
the cell causing it to make copies
of the viral DNA/RNA. Destroys
the host cell releasing new viruses.
Size
Larger (1000nm)
Smaller (20 - 400nm)
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Viruses are the smallest and simplest life form known. They are 10 to 100 times
smaller than bacteria.
The biggest difference between viruses and bacteria is that viruses must have a
living host - like a plant or animal - to multiply, while most bacteria can grow on
non-living surfaces.
Bacteria are intercellular organisms (i.e. they live in-between cells); whereas viruses
are intracellular organisms (they infiltrate the host cell and live inside the cell).
They change the host cell's genetic material from its normal function to producing
the virus itself.
There are some useful bacteria but all viruses are harmful.
Antibiotics can kill bacteria but not viruses.
An example of a disease caused by bacteria is strep throat and an example of an
affliction caused by a virus is the flu.
Differences in reproduction
Bacteria carry all the "machinery" (cell organelles) needed for their growth and
multiplication. Bacteria usually reproduce asexually. In case of sexual reproduction,
certain plasmids genetic material can be passed between bacteria. On the other
hand, viruses mainly carry information - for example, DNA or RNA, packaged in a
protein and/or membranous coat. Viruses harness the host cell's machinery to
reproduce. Their legs attach onto the surface of the cell, then the genetic material
contained inside the head of the virus is injected into the cell. This genetic material
can either use the cell's machinery to produce its own proteins and/or virus bits, or
it can be integrated into the cell's DNA/RNA and then translated later. When
enough "baby" viruses are produced the cell bursts, releasing the new viral particles.
In a sense, viruses are not truly "living", but are essentially information
(DNA or RNA) that float around until they encounter a suitable living host.
Transmission electron microscope (TEM) image of a recreated 1918 influenza virus
Living vs. Non-living
Bacteria are living organisms but opinions vary on whether viruses are. A virus is an
organic structures that interacts with living organisms. It does show characteristics
of life such as having genes, evolving by natural selection and reproducing by
creating multiple copies of themselves through self-assembly. But viruses don't have
a cellular structure or their own metabolism; they need a host cell to reproduce. It
should be noted that bacterial species such as rickettsia and chlamydia are
considered living organisms despite the same limitation of not being able to
reproduce without a host cell. See also: Virus - Life Properties (Wikipedia)