Transcript Chapter 14: Feeding the World

Chapter 14: Feeding the World
I.
Human Nutrition: all need a constant supply of
Energy to carry out life processes.
A. Omnivores- eat both plants and animals
1. Macronutrients- provide body with E
E measured in Kcal or calories
1 Kcal= amt of E needed to raise the temp of
1 Kg of water 1 degree C
2. Micronutrients- provide you with chemicals
needed to allow biochemical rxns to occur
Three types of Macronutrients
 Proteins- elements (C,H,O,N)
1. made up of basic units called amino
acids. There are only 20 different a.a.
but they are capable of making millions of
different proteins by their sequence in the
protein chains.
a. Humans can only make 12 of these
20, other 8 from food. These are referred
to as essential amino acids.
Cont.
Types of foods that contain the essential
amino acids are:
1. animals- meats, eggs, and dairy
products contain all 8 of the e.a
2. plants- grains (wheat, rice, corn) and
legumes (peas, beans, and peanuts) do
contain all of the 8 e.a., therefore,
vegetarians must combine both grains
and legumes
Proteins’ Function
 Two types of proteins:
 Structural- provide the basic building blocks
that make up most of the body tissues, including
muscle, blood, and skin. In other words
“proteins make you up!”
 Enzymes- biological catalysts that are
responsible for lowering the need for activation
energy in all biological chemical reactions.
Without them, “Life” as we know it would NOT
occur.
 Proteins, while containing lots of E or Calories,
are not used as a source of ENERGY.
Sample proteins:
Carbohydrates
Elements found in Carbs: C, H, O( 1-2-1)
Example: Glucose: C6H12O6
Three types of Carbs:
Monosaccharides or simple sugars- usually
used for fast energy source
 Disaccharides- sucrose 2 monos attached
 Polysaccharides- many simple sugars
attached to form starches. You need to
break starches down to monos before your
body can use it.
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Cont.
 Function of Carbs: main is providing
Energy( 4Kcal per gram of carbohydrates)
 Foods containing high carbs:
FRUITS, VEGETABLES,BREADS AND
GRAINS
** Proteins also contain 4Kcal per gram, but
as we said earlier they are usually NOT
used as an E source!!**
Lipids
 These are also known as fats, waxes,
oils and steroids
 Basic unit of Lipids are 3 chains of
fatty acids attached to a glycerol
molecule
 Elements- C, H, O and in
phospholipids element P. These lipids
make up, together with carbs and
proteins the cell membrane.
Lipids (Cont.)
 Lipids can provide 9Kcal per gram,
twice the amount of Energy of both
carbs and proteins.
 The major function of Fats, is to
provide us with energy, but it also
serves for structure, protection and
as an insulator
 Two Types: saturated and
unsaturated
Cont.
 Unsaturated fats- contains at least one (=)
Double bond and does not have as many H atoms.
monounsaturated- ?
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an unsaturated fatty acid whose carbon chain has one
double or triple valence bond per molecule; found chiefly
in olive oil and chicken and almonds
polyunsaturated-?
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A fat or oil which have two or more double bonds in each
molecule;
The two main types of polyunsaturated fats are omega-3
fats (salmon, scallops, flex seeds) and omega-6
fats,(corn oil and safflower oil) which are essential fatty
acids, meaning the body cannot manufacture them.***
Most unsaturated fats are liquids and come from plant
materials( oils)
Saturated fats- contain NO double bonds
Cont.
 It has many more H atoms, it is an animal
product, and is solid at room temperature.
( butter, fats on meats, etc.)
 The more solid a fat is the more saturated
that product is ( margarine??)Trans-fat
 Saturated fats causes risks to our health by
adding fat deposits in arteries that can lead
to heart attacks and strokes.
Lipids
Vitamins and Minerals
 These are micronutrients- they do not
provide E directly, but they are needed so
that the biochemical reactions necessary to
obtain E from food can occur. Sources:
plants and animals
 Example: Vitamin C is a co-enzyme, or a
molecule that helps enzymes break down
the macromolecules to their basic building
blocks so that your cells can use them.
With an insufficient amt, of Vitamin C,
reactions cannot occur properly and you
get sick.
Nutritional Deficiencies
 Typical Adult- 2000-2800 Kcal per day
 People that receive less than 90% of their
energy needs are considered undernourished.
 People that receive less than 80% of their
energy needs are seriously undernourished.
 Children that are seriously undernourished
suffer from stunted growth and mental
development.
 Statistics: 800 millions world wide suffer from
malnutrition,500 million chronically hungry, 13
million die of starvation each year, this averages
I person dying of hunger every 2.5 seconds
Malnutrition
 Individuals can obtain enough E but lack one or more of
the other nutrients.
 These Individuals are defined as being malnourished.
Malnutrition is the lack of a specific type of nutrient in
the diet, and/or
 Inability to absorb or process a nutrient
 Vitamin deficiency is a type of malnutrition
 Ex: scurvy(Vitamin C), beri beri(B1 Thiamine),rickets(
Vitamin D)
 Kwashiorkor- too little proteins in a otherwise adequate
diet- children would have a “flag” of red hair, bloated
belly, become unresponsive, and catch infectious
diseases easily.
Scurvy
World Food Supply
 If food supply has increased at a
tremendous rate in the past 40
years…Why then are there still
starving people?
 Two main reasons:
 Much of the food increase has been
accomplished through advancements in
agriculture
 Food is traded as a commodity whose
price is driven by economic factors
The Green Revolution
 It began in the mid 60’s with the
development of new strains of wheat and
rice, 2 main foods in the world
 It responds better to fertilizers and
pesticides, grow faster under many
conditions of climates
 Crop yield can be increased 4X the normal
yield
 New farming techniques and machinery
The Green Revolution:
Why is the Green revolution NOT
working for the poorer nations?
 While the green revolution is supposed to
produce huge crops, the poor farmers
cannot afford all that is needed to achieve
it.
 Therefore, Farmers in developed nations
take full advantage of the above, these
large crops increase world’s food supply of
grains which drives down the price of grains
on the market
 Poor farmers find the price they receive for
their crops is even lower than it used to be
Cash Crops
 In developing nations, cash crop is a crop
grown for the purpose of sale. In other
words landowners prefer to grow crops to
sell on the world market to further their
political ambitions than to feed their poor
people.
 Although the hunger in the world is caused
by natural causes(drought and
overpopulation), the role of governments
and profit driven land management plays a
big role.
Food From Water
 Land grown food provides a large portion of the
world’s food supply
 Fish and other aquatic animals provide much of the
animal protein
 40% of the animal proteins supply in developing
nations come from fish
 Over harvesting of our oceans is putting many fish
species in jeopardy
 Alternatives: Aquaculture, where fish are grown in a
controlled, maintained environment.(ponds, swamps)
 Most of our clams and oysters in the US are produced
by this method
Modern Farming Techniques
 Industrialized agricultureLarge pieces of farm equipment
powered by fossil fuel replaced
human powered tools.
 This tripled the amount of crops
produced
 1850 each farmer could feed 5 people
 Modern day farmer can feed 78people
Harmful side effects of
Industrialized Farming
 Large input of Energy
 Large input of Pesticides-altered
ecosystem; created resistant pests
and insects (white flies in 1992 in
California)
 Large input of fertilizers
 Monoculture- only one crop is grown,
no rotation of crops-soil depletion
Cont.
 Newer grains not too good for all
environments; re-look as some of the basic
grains such as quinoa, an ancient grain
dating back to the Incas
 Large industrialized farms are owned by
business conglomerates called agribusiness,
in addition to controlling food production
they control packaging and transport
Sustainable Agriculture
 Also called regenerative farming, is
based on crop rotation, reduces soil
erosion, integrates pest management,
and a minimal use of soil additives.
 Change type of crops in an area in
regular cycles
 Alternate legumes with other crops to
restore N in the soil
 N-fixing plants also used as a cover crop.
To restore N in soil and stop soil erosion
Reducing Erosion
 Soil erosion- a natural process by which soil
is formed, transported and sometimes lost
to a particular ecosystem. Water and wind
are causes
 Preventive methods- proper irrigation
techniques, tilling when done with proper
criterion
 Pest Management-a biological approach
called IPM or integrated pest management,
can be used to control pests without the
use of too many pesticides. Ladybugs,
wasps and spiders are natural predators