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					Chapter 9 - Patterns of Inheritance
AIM: Are we born this way or does the environment make us who we are?


                        TOPIC 2
               Homeostasis in Organisms
Chapter 7 - Photosynthesis: Using light to Make Food
AIM: Describe the process of photosynthesis.

Photosynthesis                                 Fig. 7.5
Occurs in the chloroplasts of
plants, algae and other
protists
Chapter 9 - Patterns of Inheritance
AIM: Are we born this way or does the environment make us who we are?
Summary of Photosynthesis
                   light
 6CO2 + 6H2O                    C6H12O6 + 6O2

   Energy                               From sunlight (solar energy) and put
                                        into glucose (chemical energy)
   Materials used (reactants)           CO2 and H2O
   Materials produced (products)        Glucose and O2
   Time Frame                           When light is available
   Location                             In chloroplasts of producers
                                        (autotrophs): plant cells, algae, and
                                        some single-celled protists
                                        (Some bacteria can also do photosynthesis)
   Importance                           Glucose used as energy source to
                                        make ATP (cell respiration) or used to
                                        make other molecules
Chapter 7 - Photosynthesis: Using light to Make Food
AIM: Describe the process of photosynthesis.
Chapter 9 - Patterns of Inheritance
AIM: Are we born this way or does the environment make us who we are?
Summary of Cellular Respiration

   Energy                             From chemical energy of glucose
                                      and put into ATP to be used by
                                      proteins.
   Materials used (reactants)         Glucose and O2 (made by producers)
   Materials produced (products)      CO2, H2O and ATP
   Time Frame                         24 hours a day in ALL eukaryotes
                                      including plants
   Location                           In ALL living cells…within
                                      mitochondria in eukaryotes.
   Importance                         ATP is needed to fuel proteins so they can
                                      work so you can move, think, maintain
                                      homeostasis, do mitosis/meiosis, etc…
Chapter 9 - Patterns of Inheritance
AIM: Are we born this way or does the environment make us who we are?
Summary
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.




                    Enzymes
Chapter 3 - The Molecules of Cells
AIM: So what are the macromolecules?

Enzymes:
1. Biological catalysts

2. Speed up chemical reactions without being used
up
Example reaction that occurs in small intestines
(digestion):

                 (enzyme)
Sucrose + H2O à              glucose + fructose
   Reactants                    Products
  (substrates)

Reactants are called substrates when involving
enzymes
Active site – spot on enzyme with shape that fits
substrate so that substrate can bind to it and get
turned into products.
Chapter 3 - The Molecules of Cells
AIM: So what are the macromolecules?

Enzymes:
1. Biological catalysts

2. Speed up chemical reactions without being used
up
Remember, proteins are like the people in the cell.
A person doesn’t get used up with they do
something. The reaction might be to tear a piece of
paper in half.

What is the substrate?
What is the product?
Did I get used up?

Enzymes can work at a rate up to 600,000 reactions
per second (try tearing 600,000 pieces of paper per
second)
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.

Model for how enzymes bind their substrates…




              LOCK and KEY MODEL
 The shape of the substrate fits the shape of the enzyme’s
 active site
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.




      Enzymatic Reaction Rate
      What affects the number of reactions an enzyme can perform per second?

   The same thing that affect the shape of the enzyme…

                           Temperature and pH
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.

pH reminder
 A aqueous solutions (solutions with
 water as the solvent) have a pH,
 which is a measure of the
 concentration of protons (H+) in the
 solution.
Chapter 3 - The Molecules of Cells
AIM: So what are the macromolecules?




Proteins are very sensitive to environmental changes, which is
why organisms can only survive in a narrow range of
environmental parameters like pH and temperature and therefore
must maintain homeostasis.
Chapter 3 - The Molecules of Cells
AIM: So what are the macromolecules?




Every protein has a certain temperature and pH that it functions
best at.
Every protein has a certain temperature and pH that it functions best according to where it has
evolved. For example, hydrolytic enzymes in your stomach function best at a pH 2 and temperature
of 98.6F, while those in your blood function best at pH 6.8 and a similar temperature. Bacteria that
lives in ice have proteins that function best near freezing and those that live in hydrothermal vents
have proteins that work best at near boiling temperatures.
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.
You are studying an enzyme in the lab and determine the rate of reaction at
various temperature and pH values. Your data is below. What do you
conclude?




   The enzymes you are studying works best at around 37 degrees C at a pH of
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.




Recap: Organisms have evolved to occupy very different environments
and therefore enzymes occupy different environments. Most of out
enzymes function at 98.6F (37C) and a pH of around 7.2. The enzymes
in our lysosomes, however, function at a pH of 4 to 5. The enzymes in
our stomach like pepsin function at a pH of 2. Different enzymes have
evolved to function in different conditions and therefore enzymes have
different optimal conditions. If one moves away from those optimal
conditions the enzyme will likely lose activity.
Chapter 5 - Energy and the Cell
AIM: Describe the structure/function of Enzymes.

You discover a new bacterium in a hot spring at
Yellowstone National Park. The temperature of the
spring is 78 degrees Celcius (172F) and a pH of 5.
Hypothesize the optimal temperature and pH of this
organism’s enzymes assuming the cytosol of the
organism is similar to the spring.
    They would likely work best at pH 5 and a temp of 78…
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?



 Inhibiting (turning off) enzyme
             (This is NOT denaturing)
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

   Inhibitors tend to have SIMILAR SHAPE as the
   substrates and compete against the substrates for the
   active site.




  Many of our medicines are inhibitors of bacterial or viral
  enzymes
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?




  Positive and negative feedba
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

 Cells use enzyme inhibition to maintain specific
 levels (homeostasis) of substances in the cell…

       For example, the level of ATP must be maintained in
       the cell. Making too much ATP would be wasteful.
       Making too little ATP would also be a problem as the
       cell could not power reactions like moving vesicles
       around, active transport, etc…

Let’s see how inhibition is used to maintain specific levels of solutes (maintain
homeostasis)…
Using inhibition to maintain specific solute concentrations:


                 1          2




                                4          5         6
                 3


  In this example, a series of enzymes will convert substrate A into end
  product G using six reactions (six enzymes). Remember, this is like a
  factory line where each worker (enzyme) makes a small change to the
  substrate to get the end product.
The cell must regulate the concentration of G (let’s say it is an amino acid like
glycine). Right now there is too little G. Therefore, what will these enzymes
do?                                              They will be active and make
Using inhibition to maintain specific solute concentrations:


             1       2                   This slide will not make sense
                                         unless you use it in powerpoint
                                         and watch the substrate get
                                         converted to final product.




                         4       5       6
             3




                             TOO MANY!!!!!!
                             STOOOOPPPP!
Using inhibition to maintain specific solute concentrations:


                1          2




                               4         5         6
                3




When the concentration of the product “G” gets too high,
it will bind to enzyme 3 and shut it off. “G” will no longer
be made. It shut itself off…negative feedback. What will
                         “G” decrease?
happen when levels of“G” will fall off enzyme 3 and production will resume.
Using inhibition to maintain specific solute concentrations:


                   1           2




                                    4           5          6
                   3




This is how you regulate the concentration of G. If G is too
high, it will shut its own production off, if it stop inhibiting and
be made again…therefore, the levels of G are constantly
       what?
doing They are constantly fluctuating up and down over a narrow range.
Using inhibition to maintain specific solute concentrations:


               1          2




                              4        5        6
               3




This method of inhibition where the product shuts itself is
called:                   NEGATIVE FEEDBACK
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

Negative Feedback
  Define negative feedback:

     When the output of a system goes back (feeds back)
     and inhibits or turns down (in the negative direction) its
     own production when it gets too high thereby
     maintaining a specific concentration.
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?


Negative Feedback
       When the output of a system inhibits its own
       production thereby only allowing it to ever reach a
       certain level the thermostat in your house that controls heating. If
       Ex. Think about
       there is too much heat, the heat turn the thermostat off. The house
       will cool and when there is too little heat, the thermostat kicks on
       again until the heat turns it off again.
       Ex. The product of an enzyme or series of enzymes when
       reaching a certain concentration inhibits one of the
       enzymes thereby shutting its own production off until the
       concentration falls during which the product will no longer
       inhibit the enzyme and it will be made again (homeostatic
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?


Negative Feedback
Ex. Glucose/insulin example – glucose levels
are high in the blood (you drank grape juice).
Insulin (hormone) is secreted into blood and
binds to insulin receptors on liver and muscle
cells causing them to take up glucose. Low
glucose then shuts off insulin production.
Output: insulin, shut itself off.
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?


Positive Feedback
       Opposite of negative feedback.
       When the output of a system goes back (feeds back)
       and further enhances its own production (in the
       positive direction) leading to more output and in turn
       more enhancement and even more output, etc…


        Such a condition is considered unstable…
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?


Positive Feedback
         Examples:
     1. Hypothetical – if your house thermostat worked
     based on positive feedback, the output (heat) would
     further activate the thermostat, which would instruct
     the release of more heat, which would even further
     activate thermostat, etc…
      2. Child Birth contractions – the hormone oxytocin
      stimulates contration of the uterus. This will cause the
      baby to press up against the uterus, which causes
      more oxytocin release, more contractions, more
      pushing of the baby, more oxytocin, even harder
      contractions, etc… until baby and placenta are out and
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?


Positive Feedback
        Examples:
     3. Sneezing
        - You initially have to somewhat sneeze, which causes
        you to feel more like you have to sneeze, and then
        more, and more, and aaaaaaahhhhhhh
        choooooooooooooo!
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

Disease
   - Body fails to maintain homeostasis
   - causes:
        1. Pathogens – disease causing organisms like certain
        viruses, fungi, bacteria and other parasites (tapeworm,
        etc…)
                  Treat bacteria with ANTIBIOTICS
                  Treat fungi with fungicides
                  Infection by certain pathogens can be
                  prevented using vaccines (more in a moment)
        2. Inherited Disorders – sickle cell anemia, cystic
        fibrosis, Down syndrome (all genetic)
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

Disease
   - Body fails to maintain homeostasis
   - causes:
        3. Exposure to toxins – lead poisoning, radiation
        poisoningMalfunction – heart attack, diabetes
        4. Organ
        5. Poor Nutrition – scurvy (vitamin C deficiency), goiter
        (iodine deficiency)
        6. High Risk Behaviors – lung cancer due to smoking
Chapter 5 - Energy and the Cell
AIM: How are enzymes regulated (controlled)?

Disease
   - Body fails to maintain homeostasis
   - causes:
        7. Cancer
            - When one of your cells goes rogue and starts undergoing
            mitosis uncontrollably and moves around the body
            (metastasizes). The result is clumps of cells in organs called
            tumors.
Chapter 24: The Immune System
NEW AIM: How does the body defend itself against MO’s?




      ix. Vaccines



   a. First vaccine - small pox - 1797
      1. Edward Jenner
      2. Two related diseases: cow pox and small pox
      3. Took pus from cowpox pustule and inserted it into an incision on a boy
      4. Boy could not get small pox (he was immune)
Chapter 24: The Immune System
NEW AIM: How does the body defend itself against MO’s?




     ix. Vaccines
        b. Inject a harmless variant of the disease causing microbe
           1. Body (WBC’s) responds to antigens by making antibodies
           2. Some of these WBC’s remain after the “war”
           3. Immune system is now primed for the “real thing”
           4. That’s easy…so where is the HIV vaccine?
                 HIV is a retrovirus. Viral particles that use reverse transcriptase and prone to
                 making more errors in their DNA that a virus using DNA polymerase. This results
                 in a quickly changing virus…the antigens change quicker than out immune
                 systems can keep up with. It is like a criminal that can shape-shift (change what
                 they look like…become anyone).
Chapter 10 - Molecular Biology of the Gene
NEW: Viruses: Packaged Genes…
Viruses
 -Small molecular machines with their own
 nucleic acid that need a host cell to make
 more of itself.
 - They bind cell surface receptors to get
 into the cell and hijack it, using the cell’s
 machinery to make more of itself.
Chapter 10 - Molecular Biology of the Gene
NEW: Viruses: Packaged Genes…

HIV
   How is HIV transmitted?

The virus is transmitted through
contact of a bodily fluid
containing HIV like blood, semen,
vaginal fluid, and breast milk with
a mucous membrane or the
bloodstream.

A. ~33 million people are HIV positive in the world.
B. Estimated 1.1 million people are HIV positive in the
US.
C. ~2.2 million people, 330,000 of which were children, died as a result of the virus
last year – 75% of deaths occurred in Sub-Saharan Africa.
D. HIV invades and destroys white blood cells (WBC’s) leaving the person without an immune
Chapter 10 - Molecular Biology of the Gene
NEW: Viruses: Packaged Genes…

Retroviruses                                                     Fig 10.21A


HIV
  What disease does HIV cause?
   - AIDS – Acquired Immune Deficiency Syndrome

        Immune system gradually declines leaving the individual
        susceptible to opportunistic infections like tuberculosis (5 –
        10% of Americans test positive for the bacterium that causes
        tuberculosis, but the immune system keeps it in check and the
        person is fine)and tumors (many cells that would have caused
        cancer are destroyed by the immune system).

  Therefore, HIV/AIDS does not kill anyone directly, it is the
  opportunistic infection or cancer that kills the person.

				
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