the digestive system, thermodynamics, enzymes, and transport across membranes april 28, 2003...
TRANSCRIPT
The digestive system, thermodynamics, enzymes, and transport across membranes
April 28, 2003 Learning objectives-
Understand the major organs involved in the digestive system Understand the molecular difference between sugars and lipids Understand how enzymes break down complex molecules to derive energy ATP is the energy currency of the cell Understand how complex molecules are built up and know that this is an energy-requiring process
Workshop-Work in groups to report on some aspect of digestion Homework-see last slide
Grading Quizzes (15%), Homework (10%),
Midterm (25%), Writing assignment (15%), Final Exam (35%)
6 Quizzes (each 10 points) = 60 points1 Midterm = 100 points1 paper = 60 points1 final = 140 points6 homeworks (ea. 6.67) = 40 points Total = 400 points
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56
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(ATP) (warmth)
First Law of Thermodynamics-Energy cannot be createdor destroyed but it can change form.
Second Law of Thermodynamics-Systems change in a way that increases disorder of the system and its surroundings
6CO2 + 6H2O + ATP
+ heat energy
+ 6O2 + ADP + Pi
•Enzyme action video 1•Enzyme action video 2•Enzyme action video 3
Characteristics of enzymes Globular proteins that function as biological catalysts
to mediate specific biochemical chemical reactions Enzymes are not changed by the reactions they
mediate Functional units of metabolism - responsible for all
biochemical reactions May require cofactors/coenzymes for reaction to
occur metal ions - e.g., Mn2+, Zn2+, Fe3+
coenzymes (NAD+, TPP, THF, etc.)
Characteristics of enzymes (cont.)
Apoenzyme - enzyme lacking essential cofactor
Holoenzyme - intact & functional enzyme containing all cofactors/coenzymes
Substrate (S) - molecules that enzymes react with
Product (P) - molecules formed by enzyme-mediated reactions
Obesity in America
What is a calorie? The calorie (symbolized cal) is the unit of heat
Heat is a form of kinetic energy transfer from one medium or object to another. An energy transfer of 1 cal will raise the temperature of one gram (1 g) of pure liquid water by one degree Celsius (1 oC)
In nutrition, a unit called the diet calorie is sometimes mentioned; this unit is equivalent to 1000 cal, or one kilocalorie (1 kcal).
Calorie content is measured with a bomb colorimeter
H
Workshop
Site 1
Websites on human digestive system
Site 2
Work in assigned groups of two to give a 6 minute presentation to the class on a molecular aspect of human digestion prepare a 3 question quiz for the class
Starch hydrolysis Protein digestion Fat emulsification
Types of transport
1. Passive-requires no energy2. Facilitated-requires no energy
(put needs a protein transporter)3. Active transport-requires energy
Video on transport systems
Endocytosis vs. exocytosis
Do the following exercises
Homework Due May 5 Answer Reviewing Ideas on p. 74,
problems 1, 2, 5-9, 11; Using Concepts on p. 75, problems 2, 3, 6, 8, 10
Answer Check and Challenge questions on p. 85
Reading for next week: 226-229; and familiarize yourself with the following website: http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowSection&rid=gnd