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Chapter 2

BIOL 1320 Chapter Notes - Chapter 2: Food, Glorious Food, Manual Testing, Lab Partners


Department
Biology
Course Code
BIOL 1320
Professor
Lowell
Chapter
2

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Biology 13A Lab Manual
5Lab #13 Nutrition and Digestion
102
Biology 13A Lab #13: Nutrition and Digestion
Lab #13 Table of Contents:
Expected Learning Outcomes . . . . 102
Introduction . . . . . . 103
Food Chemistry & Nutrition . . . . 104
Activity 1: Testing for the Presence of Nutrients . 104
Activity 2: The Digestive System and Digestion . 111
Expected Learning
Outcomes
At the end of this lab, you
will be able to
list the essential
nutrients found in
food;
describe the basic
chemical composition
of carbohydrates,
proteins, fats, and
vitamins;
identify nutrient
content in foods and
test for nutrients in
unknown samples;
learn the parts of the
digestive system;
explain functions of
major nutrients in the
body.
Figure 13.1 Digestive System

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Biology 13A Lab Manual
5Lab #13 Nutrition and Digestion
103
Introduction
Food, glorious food! Movement,
processing information and
responding to the environment,
and maintenance of homeostasis
all require energy. Ultimately,
energy is derived from food. In
addition, food provides building
material for cells and tissues.
The job of the digestive
system is to break down food
and absorb nutrients:
carbohydrates, proteins, and
lipids and smaller quantities of
vitamins and minerals. Most of
the water we need also comes
from food. Few foods combine all
six nutrients. As primates, we are
omnivores, adapted to eat a wide
variety of foods to obtain a full
complement of necessary
nutrients. Our digestive system
anatomy and physiology reflects
the eclectic diet for which we are
adapted.
Releasing nutrients from food
requires mechanical digestion
where large pieces are crushed
and ground primarily by teeth,
with the aid of tongue and saliva.
This increases the surface area
for chemical digestion in which
digestive enzymes break down
complex large molecules such as
proteins and carbohydrates to
their basic components (e.g.
amino acids and simple sugars).
Chemical digestion is
performed by many organs: for
example, salivary glands produce
amylase, an enzyme that breaks
down starches (polysaccharides)
to disaccharides; the pancreas
and small intestine produce
numerous enzymes that complete
the breakdown of proteins, lipids,
and carbohydrates to forms
usable by cells. The nutrients are
absorbed through the lining of
the small intestine and are then
transported throughout the body.
Today we will examine
nutrients in food and review the
structures of the digestive
system.
Testing Your Comprehension: Answer the following questions based on
your reading of the introduction.
1. List the five nutrients found in food.
2. What is an omnivore? How does the fact that humans are omnivores
influence our anatomy and behavior?
3. Where and how does mechanical digestion occur?
4. What molecules are necessary for chemical digestion? Give examples
of organs that perform chemical digestion.

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Biology 13A Lab Manual
5Lab #13 Nutrition and Digestion
104
Food Chemistry & Nutrition
Carbohydrates, proteins, lipids,
and vitamins and minerals are
the nutrients in food.
Carbohydrates are either simple
sugars (monosaccharides)
consisting of a single sugar
molecule such as glucose, or
disaccharides, two
monosaccharides joined together
(e.g. sucrose, or table sugar), or
polysaccharides (complex
carbohydrates), large chains of
monosaccharides. Starch and
glycogen are polysaccharides.
They are major sources of energy
for cellular work. Common
sources of carbohydrates in the
diet are breads, cereals, fruits
and vegetables.
Proteins have numerous
functions. They are the basis for
tissue and organ structure; some
are capable of movement (so-
called “motor proteins”) while
others act as enzymes. All
proteins are chains of amino
acids. Twenty amino acids
combine to form thousands of
different proteins. Twelve amino
acids can be assembled in the
body but eight must be obtained
directly from the diet. Dietary
sources of proteins include fish,
soybeans, meat, and dairy
products.
Lipids are hydrophobic
(insoluble in water). They include
fats, oils, waxes, phospholipids,
and steroids. Concentrated
sources of energy, each gram of
lipid has more calories than a
gram of protein or carbohydrate.
of plasma membranes and
provide support for joints,
tendons, and internal organs.
Dietary sources of lipids include
nuts, meat, butter and cheese,
and vegetable oils.
Although only minute
quantities of vitamins and
minerals are required, a
deficiency can have devastating
effects. Vitamins help control
chemical reactions, often
facilitating the actions of
enzymes. They are necessary for
normal growth and metabolism.
Thirteen vitamins are essential
for health—four of those are fat
soluble and are stored for
months at a time in adipose
tissue; nine are water soluble
and must be regularly replaced.
Minerals such as calcium and
phosphorus are also derived from
the diet and perform vital
functions.
Vitamins are obtained from a
wide variety of foods. For
example, vitamin C is obtained
from citrus fruits and tomatoes
whereas vitamin B is found in
nuts, whole grains, and beans.
Vitamin pills may supplement
the diet. Each vitamin has
specific functions in the body,
leading to particular symptoms if
there is a lack. The first symptom
of vitamin C deficiency is fatigue,
followed by anemia, back and
joint pain, bleeding of the gums,
and poor wound healing. With
time, death ensues, as was the
fate of numerous sailors who
succumbed to “scurvy.”
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