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Dental Biochemistry 2012 Lecture 1

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Dental Biochemistry 2014
Lecture 1
Dr. Kumar, MSB E-639, x-4750
E-mail:kumarsu@umdnj.edu
Web site:
http://njms2.umdnj.edu/biochweb/education/bioweb/
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Dental Biochemistry
Examinations:
• There will be three unit examinations and a final
comprehensive examination. Students must sign in and
sign out before leaving the examination room. Grading
policy is described in the handout.
• Any student who is late by more than 30 min will not be
given the examination.
• If a student can not take a unit examination due to
unavoidable circumstances, the student may be reexamined.
• A student discovered cheating on the examinations is
subject to disciplinary action by the dental school.
• The course director will try to get tutorial help for
students in academic difficulty following first unit exam.
Please see the course director if you need assistance.
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• An all class session is held to review each examination at which time
student concerns about individual questions are addressed.
• Individual students may challenge one or more questions through
the class representative.
PBL:
There are three problem based learning sessions of two hours each.
Attendance at these sessions is mandatory.
Textbook:
Lippincott’s Illustrated Reviews in Biochemistry, Lippincott Williams and
Wilkins; 6th North American Edition. ISBN-13: 978-1451175622
RECOMMENDED TEXT(s):
Medical Biochemistry by Gerhard Meisenberg and William Simmons,
Elsevier Publishers, 3rd Edition
Students may consult other books for content and/or explanations
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GRADING POLICY
Grades in the course will be based on three unit examinations and a
final comprehensive examination. Each unit exam will constitute 21%
of the grade. The final exam will constitute 32% of the grade.
Final grades will be adjusted to give a class mean average of not less
than 79.
There will be four PBL sessions of 2 hours each. Five percent of the
overall grade will be given to a student based on his/her performance
in PBL sessions as assessed by the instructor. Attendance at PBL
sessions is compulsory. Students will lose additional 1.0% of the grade
for every missed PBL session. PBL session grades will be disclosed after
all the PBL sessions are completed.
Requests for correction or re-evaluation of graded examinations must
be presented to Dr. Kumar, the Course Director, within three (3)
working days after the examination key has been posted. All requests
must be typed.
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Final Grades
• Letter grades will be assigned on the following basis:
•
•
89.5 and above
A
•
84.5 -- 89.49
B+
•
79.5 – 84.49
B
•
74.5 – 79.49
C+
•
69.5 – 74.49
C
•
65-69.49
D
•
<65
F
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The components of an idealized eukaryotic cell. A cell such as this
probably does not exist, but the diagram shows the relative sizes and
locations of the cell parts
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Anabolism and Catabolism
• Anabolism is the phase of intermediary metabolism that
encompasses the biosynthetic and energy requiring
reactions.
• The cellular synthesis of complex substances and
macromolecules from low molecular weight precursors.
• In general, the reactions of anabolic pathways are
reductive and consume reducing potential (energy) (ATP)
Catabolic reactions are energy producing, are oxidative and
produce reducing cofactors.
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Regulation of the degradation and synthesis depends on
the energy state of the cell (ATP)
High [NADH] is indirectly equivalent to high[ATP].
This means that the cell is high in “energy”.
High [NAD+] or [ADP or AMP] means that the cell is
low in “energy”.
ATP + ВЅ ADP
Energy Charge=
ATP + ADP +AMP
The energy charge can have a value of 0 (all AMP)
to 1 (all ATP).
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Synthetic and degradative pathways are distinct.
If [ATP] is low, degradative pathways are stimulated.
If [ATP] is high, degradative pathways are inhibited and
synthetic pathways are stimulated
Degradation
Synthesis
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Energy Charge Fluctuations
• The energy charge can have a value ranging from 0 (all AMP)
to 1(all ATP). It has been shown that ATP-generating
(catabolic) pathways are inhibited by a high energy charge.
In plots of the reaction rates of such pathways versus the
energy charge, the curves are steep near an energy charge of
0.9, where they usually intersect. It is evident that control of
these pathways has evolved to maintain the energy charge
within rather narrow limits. In other words the energy
charge like the pH of a cell is buffered. The energy charge of
most cells range from 0.8 to 0.95."
• A high Energy Charge signals the slow down of metabolism.
A low Energy Charge signals up regulation of metabolism
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A few reaction types are repeatedly observed in
biochemistry
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Oxidation-reduction
Succinate DH
Malate DH
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Ligation
Formation of carbon-carbon
bond.
Pyruvate
carboxylase
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Isomerization
Aconitase
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Group transfer
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Hexokinase
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Hydrolytic reactions
Peptidases
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Lyases
The addition of functional groups to double bonds or the
removal of groups to form double bonds
Aldolase
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Dehydration
Enolase
Removal of H2O (group) to form a double bond
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Learning objectives lecture 1
• Know general structure of eukaryotic cell and general
functions of various structures.
• Know about the energy charge of a cell and conditions under
which it will go up or down. Does the energy charge always
stay constant?
• Understand general type of reactions observed in
biochemistry.
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