This lesson will increase your knowledge of concepts covered in the following TEKS for biology

1
This lesson will increase your knowledge of
concepts covered in the following TEKS for
biology
3.f Research and describe the history of
biology and contribution of scientists. 4.a
Identify the parts of a cell 4.b Investigate
and identify cellular processes including
homeostasis, permeability, energy production,
transportation of molecules, disposal of wastes,
function of cellular parts, and synthesis of new
molecule 4.c Compare the structures and
functions of viruses to cells and describe the
role of viruses in causing disease 4.d Identify
and describe the role of bacteria in causing
disease 5.b Identify cell differentiation in
the development of organisms.
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10.a Interpret the functions of systems in
organisms 11.a Identify and describe the
relationships between internal feedback
mechanisms in the maintenance of homeostasis 11.b
Investigate and identify how organisms,
including humans, respond to external stimuli
11.d Summarize the role of microorganisms in
maintaining and disrupting equilibrium including
diseases in plants and animals and decay in an
ecosystem
3
Previous Lesson Parasites and Disease
4
Question When you travel to areas of the world
where malaria is considered a problem, what can
you do to protect yourself against getting
malaria and what is the problem with this
approach?
Basded on U.S. News World Report, January 20,
1997
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People can take drugs like chloroquine to protect
against infection by Plasmodium. But in some
area of the world, Plasmodium is resistant to
chloroquine.
From Science
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Question Mosquitoes breed in water bodies
without fish (ponds that dry up or old tires).
Why are such waters now considered dangerous in
Texas?
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West Nile virus appeared in Texas in 2002

• West Nile virus is
• spread by mosquitoes
• Mosquitoes breed in
• standing water
• West Nile virus can
• cause flu-like symptoms
• to fatal brain swelling

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Question Which stage of the tick life cycle
causes problems for humans?
Photo courtesy of Texas Parks and Wildlife
Department
9
The nymph stage of the deer tick feeds on humans
and passes the Lyme disease bacteria to them
Based on Harvard Health Letter, 1991
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Todays Lesson Immune System, Viruses and
Bacteria
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Overview of Lesson

• Immune system
• Viral infections
• Bacterial infections
• E. coli outbreaks

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Cells of the Immune System

• Macrophages
• Helper T cells
• B cells
• Killer T cells
• Memory cells

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Microbe with protein coat enters body and starts
to reproduce
Immune System Response to a Microbial Infection
(viruses bacteria)
Macrophages circulate thru body and ingest some
of the microbes, alerting Helper T cells by
presenting protein coat
Helper T cells recognize protein coat of microbe
and alert T and B cells by making cytokines
B cells make antibodies that neutralize microbes
Killer T cells kill microbe or human cells
infected with microbes
Memory B cells remain to provide immunity
Memory T cells remain to provide immunity
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The Miracle of the Immune System
From birth, humans have the ability for an immune
system response to any microbial infection but
the response is only initiated when the infection
occurs
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After we become sick, why are we ill for about a
week?
After the infection starts, it takes about one
week to make the T cells and B cells necessary to
defeat the microbe
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Overview of Lesson

• Immune system
• Viral infections
• Bacterial infections
• E. coli outbreaks

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Viruses

• Viruses do not have
• ribosomes and
• cannot make their
• own protein
• After the virus
• attaches to the host
• cells membrane, it
• injects its genetic
• material which directs
• synthesis of viral
• proteins

Based on Harvard Medical School Family Health
Guide
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Viral Infection

• Viruses penetrate epithelial surfaces and take
  over cells to produce more viruses
• The host cell then ruptures and releases the
  newly produced viruses
• Although the immune system can defeat most viral
  infections, some viruses can hide from the immune
  system and remain in the body

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Shingles is caused by the chickenpox virus that
has hidden in the body

• After having
• chickenpox, some of
• viruses lie dormant in
• nerve cells near spinal
• cord
• Years later, the virus
• reactivates and travels
• along nerve fibers to
• skin
• As the virus moves, it
• causes pain
• When it reaches the skin,
• it causes a rash and
• blisters

Based on Mayo Clinic Health Letter
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Why do we keep getting the common cold?
There are over 200 viruses that cause cold
symptoms Cold viruses can mutate and change
their health-related effects
Based on Starr, C. Biology Concepts and
Applications, Brooks/Cole
21
Severe Acute Respiratory Syndrome (SARS)
More than 8000 people became sick worldwide 774
people died
From Fort Worth Star Telegram, March 26, 2003
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A New Strain of Lethal Cold Virus?

• Previous virus strains could only survive in the
  throat and nasal passages because the temperature
  was too high deep in the chest

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Overview of Lesson

• Immune system
• Viral infections
• Bacterial infections
• E. coli outbreaks

24
Bacteria have DNA and ribosomes and can make
their own protein
Based on Mader, S., Inquiry Into Life,
McGraw-Hill
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Binary Fission
1 bacterium can become 1/2 million in 6-7 hours
Based on Harvard Medical School Family Health
Guide
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Bacterial Infection

• Bacteria penetrate epithelial cells and undergo
  rapid division. One bacterium can become 1/2
  million bacteria in 6-7 hours
• Bacteria can produce protein toxins that kill
  cells and interfere with nerve and muscle
  function
• The immune system cannot respond rapidly enough
  to protect the body against the most dangerous
  bacteria

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Discovery of Penicillin First Antibiotic
From Time, March 31, 2003

• Fleming happened to observe that petri dishes
  with
• molds had killed bacteria in rings around the
  mold
• He postulated that the mold juice had killed
  the
• bacteria
• The mold was Penicillium notatum and the juice
  was named Penicillin

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Antibiotics

• Antibiotics like penicillin kill bacteria by
  blocking cell wall formation
• Antibiotics like penicillin do not kill human
  cells because they have no cell walls
• Antibiotics like penicillin do not work against
  viruses because viruses lack cell walls

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Overview of Lesson

• Immune system
• Viral infections
• Bacterial infections
• E. coli outbreaks

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In slide show mode, use the hot link below to
download a copy of the cover of Time Magazine on
E. coli
TIME Magazine Cover E. Coli - Aug. 3, 1998
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E. coli Outbreaks
From Time, Aug. 3, 1998
Cabbage Patch
Dirty Toys
Bad Cheese
Swimming Pool
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From Time, Aug. 3, 1998
What makes this E. coli strain so bad?

• One strain of E. coli has extra genes that allow
  it to stick to the walls of the intestine and
  produce a potent toxin
• The toxin injures the cells of the intestinal
  wall, leading to bleeding
• The toxin travels in the bloodstream to the
  kidneys, leading to kidney failure

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Why is kidney failure life threatening?
Answer
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(No Transcript)
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Next LessonVaccines and Disease Prevention
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Because kidneys are responsible for removal of
nitrogenous waste (urea) and water balance.
Back
Based on Mader, S., Inquiry Into Life,
McGraw-Hill