Transcript Proteins - HRSBSTAFF Home Page

Proteins
…..a recap
Characteristics of Proteins
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•
•
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Are made up of monomers
These are called amino acids
There are 20 amino acids
And they all have the general molecular
structure:
http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/Danielle%20Arnold/Intoduction.html
Proteins are coded for by DNA (genes),
transcribed (re-written) to mRNA and then
translated into protein molecules at the
ribosome.
http://www.mrothery.co.uk/images/Image46.gif
You’ll learn a little more about this year when
we study cell structure, a lot more next year
when you study the molecular basis of
genetics.
http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/Danielle%20Arnold/Intoduction.html
Polypeptide to Functional Protein
• Refer to your handout “Atoms, Molecules
and Biological Compounds”
• The final shape or “conformation” of a
protein is determined by the sequence of
amino acids it contains.
• How a protein functions is determined by
its three dimensional characteristics.
Levels of Structure of a Protein
http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/Danielle%20Arnold/Intoduction.html
Roughly linear forming strands
or sheets, fibrous proteins
Also check out pg 44-47, Bio-12
One or more polypeptide chains
take on a rounded, globular shape
Campbell Biology
Campbell Biology
A couple of questions for you…..
• What is and what causes sickle cell anemia? (
pg 45, Bio-12)
• What makes spider silk so strong?
• What are some examples of proteins in a
quaternary structure?
• What is denaturation? What is the consequence
of such an event?
• Check out figure 34 c pg 47… learn how a
“perm” works!!
• Read “Directions in Science” from Handout.
Campbell Biology
Campbell Biology
Functions of proteins
• Fibrous:
• Play a structural role such as: collagen found in
cartilage, bones, tendons, and blood vessels
• Globular:
• Regulatory: hormones ( growth, insulin, sex)
• Transport: hemoglobin, in cell membranes
• Protective: antibodies
• Catalytic: Enzymes
A closer look at a special protein…
Enzymes
• Answer the following questions so that you understand
your answers: Ref pg 69-72 (12)
• What is an enzyme?
• What is the substrate?
• In simple, simple terms how does an enzyme work?
• Why can’t living cells rely on high levels of heat to
activate metabolic reactions?
• What does the name “maltase” tell us?
• What things affect enzyme activity?
• Pre-read “Investigating the Effect of Temperature on
Enzyme Activity” page 82 (12)
Overview: What would happen to your cells if they made a
poisonous chemical? You might think that they would die. In
fact, your cells are always making poisonous chemicals. They
do not die because your cells use enzymes to break down
these poisonous chemicals into harmless substances.
In this lab, you will study an enzyme that is found in the
cells of many living tissues. The name of the enzyme is
catalase (KAT-uh-LAYSS); it speeds up a reaction which
breaks down hydrogen peroxide, a toxic chemical, into 2
harmless substances--water and oxygen. The reaction is as
follows:
2H2O2 ----> 2H2O + O2
This reaction is important to cells because hydrogen
peroxide (H2O2) is produced as a byproduct of many
normal cellular reactions. If the cells did not break down the
hydrogen peroxide, they would be poisoned and die.
Many of these autoxidation reactions do
not produce hydrogen peroxide directly, but
rather superoxide (the product of adding
one electron to an oxygen molecule). In
order to get rid of superoxide (which is
more toxic than hydrogen peroxide) the
body also contains lots of superoxide
dismutase, that converts the superoxide
into water and hydrogen peroxide. One of
the most interesting sources of
superoxide in the body is that produced
by white blood cells when they
encounter harmful microorganisms. The
white blood cells produce very large
amounts of superoxide, hydrogen
peroxide, and even hypochlorous acid
(household bleach!) to kill the germs,
just like in the TV ads.