Transcript amino acids

Bio 151-000
Academic Coordinator -- Dr. Alma Ferrier
Office: Room 216 Thomas Hunt Morgan Building
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Syllabus
•Course Description
Bio 151 is the 1st semester of a two semester introductory sequence for
life science majors. The companion lecture course is Bio 150. This
course is designed to prepare students for upper level Biology
courses. Bio 151 is mainly consists of experimentation in the areas of
biochemistry, cell and molecular biology, genetics, and evolution.
Students will perform experiments, analyze results, and submit their
observations in the form of lab reports.
•Attendance:
Attendance is required in the laboratory section to which you are
assigned. Five points will be deducted for each unexcused absence
Syllabus
•Improper care and storage of microscopes and messes in your work
area will result in a Five-point deduction each time
•Plagiarism and Cheating -- Read the section covering this in the
Students Rights and Responsibilities Handbook, University of Kentucky
Syllabus
Homework For Modules:
The homework assignments for modules are a series of worksheets,
which you are required to complete during the course of the semester.
The homework will consist of questions covering material in the
course texts. The assignments may be downloaded from the web site
http://www.biology.uky.edu/bio150labs/
Homework must be submitted before the beginning of the class period
for which they are due (see syllabus for the exceptions) and which
you are officially registered. Late submissions will not be accepted.
Syllabus
1. Required Texts:
1. Biology by Neil Campbell, 5th or 6th edition,Benjamin Cummings
Publishing Company or a Current Introductory Biology Book.
2. Laboratory Manual Bio 151 7th edition by Doris Westerman
Module 1
Chemosynthetic Theory and
Introduction to Simple Amino Acids
Chemosynthetic Theory or “Chemical Evolution":
is the abiotic (non-living) synthesis of organic molecules.
Organic Molecules are by definition molecules that contain
the element carbon. Once thought to come from only living
things, organic compounds range from simple molecules
such as methane CH4 to colossal ones such as proteins with
thousands of atoms.
The elements of life which compose these molecules:
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
Sulfur
Oparin-Haldane hypothesis (1920s):
Primitive Earth’s reducing atmosphere favored chemical
reactions that synthesized organic compounds from inorganic
precursors present in the early atmosphere and seas.
Miller-Urey (1953) tested this hypothesis by:
Simulating primitive Earth’s atmosphere with H2O, H2, CH4,
CH3, CO, CO2, and N2. Then Exposing this atmosphere
to sparks (simulating lightning and providing extreme heat).
Observed the formation of organic molecules, including
amino acids. Thereby allowing the formation of proteins
Figure 26.4 Abiotic synthesis of organic molecules in a model system
Amino Acids and Simple
Peptides
There are 20 common amino acids which are important in protein formation.
The R group(side chain) is different for each amino acid and is what gives
each amino acid is unique characteristic
Of the 20 amino acids, 19 contain asymmetric "-carbons. These 19 amino
acids can form isomers. They isomers have been named L and D.
The L-form is what is naturally occurring in living systems. The only amino
acid that does not have an L and D form is Glycine (It's R-group is a
hydrogen atom).
Amino Acids are joined by an amide bond known as the peptide bond.
When the bond is formed, H2O is liberated
Unnumbered Figure (page 68) Amino acid structure
Figure 5.15a The 20 amino acids of proteins
Figure 5.15b The 20 amino acids of proteins
Figure 5.15c The 20 amino acids of proteins
Two enantiomers possible for
most amino acids
L-form found almost exclusively in naturally occurring proteins
Assigning Amino Acids as either D or L
EXAMPLE:
The amino acid alanine is shown below. Bonded to its alpha
carbon atom are:
a carboxyl group (COO-)
an amino group (NH3+)
a methyl group (CH3)(its R group)
a hydrogen atom
Assigning Amino Acids as either D or L
If you orient the molecule so that you look along it from the
COO- group to the NH3+ group, the methyl (R) group can extend
out to the left, forming L-alanine(shown below on the left) or to
the right, forming D-alanine (on the right).
Polypeptides (proteins)
The importance of proteins is implied by their name, which
comes from the greek word proteios meaning “first place”.
Proteins are the most structurally sophisticated molecules
known. Each type having a unique three-dimensional
shape or conformation.
Polypeptides are formed by the condensation of multiple
amino acids forming a polypeptide chain.
Figure 5.16 Making a polypeptide chain
Formation of a Peptide Activity
(10 minutes)
Per Group of Two Gather the Following Materials
• three of the stick models that are in the form of a tetrahedron.
Each tetrahedron will symbolize one amino acid.
• 3 purple, 3 green, 3 white, and 3 red gumdrops. These will be
placed on the model to symbolize the different parts of the amino
acids.
• white gumdrops will symbolize the free hydrogen on the
alpha carbon of the amino acid
• red gumdrop will symbolize the amino group that is
attached to the alpha carbon
• purple will represent the carboxyl group
• green will represent the R group of the amino acid
Formation of a Peptide Activity
(5 minutes)
•Amino acids combine and displace water to form a peptide bond
between the amino group of one amino acid and the carboxyl group
of another amino acid (Condensation)
•At the cellular level, translation is the process by which
polypeptide chains are formed. The N-terminus of an amino acid is
joined to the C-terminus of the previous amino acid forming a
peptide chain.
•Now, join your three amino acids, one at a time to displace one
molecule of water, forming a peptide bond between each amino
acid.
Now that you have made
polypeptide, what type of
characteristics do these chains
exhibit that produce unique
properties to their structure and
function?
Read Chapters 1-5 in Campbell
and be prepared to discuss this
question next class.
RASMOL
Next class, you will perform some computer
exercises during class.
You may download these exercises from the website
at www.biology.uky.edu/bio150labs . Be sure to
See if you can down load the assignment as it will
be due next week.
Final Slide