Chemical Compounds in Cells
and in Our Food
pp 52-55 & pp 505-517
Review of basic chemistry
• Element – any substance that cannot be broken
down into a simpler substance
– Ex – carbon, nitrogen, oxygen, hydrogen
• Atom – smallest unit of an element
• Compound – two or more elements chemically
combined
– Ex – water, sugar, starch
• Molecule – smallest unit of most compounds
– Ex – H2O, C6H12O6, O2, CO2
Inorganic Compounds
• Don’t contain Carbon, Hydrogen, and Oxygen
– Ex – water (H2O), salt (Sodium chloride), CO2
Organic Compounds
• Contain Carbon, Hydrogen and Oxygen
– Includes:
Carbohydrates
Proteins
Lipids
Nucleic Acids
Proteins
• Contain C, H, O, N and sometimes Sulfur
• Found in many foods
• In the cell, used as: part of cell membranes
structures of organelles
muscles in the body
Structure of Proteins
• Made of amino acids
– There are 20 different amino acids in living
things
• These aa’s link together to form a large molecule of
50-3000 aa’s in one protein.
• Change one aa, changes whole protein
Protein
Enzymes
• Special kinds of proteins
• Chemicals that speed up chemical reactions in the body
without being used up themselves.
• Here the enzyme helps break a large molecule into 2
smaller ones. Some enzymes join two small molecules to
make one larger one.
Carbohydrates
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•
•
•
Energy rich
C, H, and O
Simple sugars - glucose
Complex carbohydrates – made up of many
simple sugars attached to each other
– Starch
– Cellulose – make up plant cell walls
Found in cell membranes, other cell parts, and
store energy
Lipids
• Fats, oils, waxes
• Store energy
• Made of C, H, and O
• Contain more energy
than carbs
Nucleic Acids
• DNA = deoxyribonucleic acid
• RNA – ribonucleic acid
• Made of C, H, O, N, and Phosphorus
• Contain instructions for cells to carry
out all their functions.
Water
• Makes up about two thirds of your body.
• Most chemical reactions occur in water.
• Essential for all life.
Food and Digestionpp 504-530
• Why do we need food?
– Material for growth, repair
– Energy
– Allows body to maintain homeostasis
Nutrients – substances in food that
provides body with raw materials and
energy to carry out essential processes
•
•
•
•
•
•
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Water
Energy
• Carbs, fats and proteins provide body with
energy
• Amount of energy in food measured in
calories
– One calorie is the amount of energy to raise the
temperature of 1 gram of water 1 degree
Celsius
Calorie or calorie?
• Calorie – used to measure energy in foods.
• 1 Calorie = 1000 calories
– Ex – 1 apple contains 50 Calories or 50,000
calories.
– The more calories a food has, the more energy
it contains.
Amount of Calories needed?
• Depends on physical needs and age of the
person
– Very active people need more
– Infants and small children need more
– Older people need fewer
Carbohydrates
• 1 gram carbohydrates provides 4 Calories of
energy
• Provide raw materials to make cell parts
• Two groups:
– Simple carbohydrates
– Complex carbohydrates
Simple Carbohydrates = Sugars
• Found in fruits, vegetables, milk
• Glucose (C6H12O6) – major source of
energy for your cells.
• Another simple sugar = fructose in fruits
Complex Carbohydrates
• Made of many simple sugars connected
• Starch – found in potatoes, wheat, rice, corn
• Fiber (Cellulose) – found in plants, but
cannot be digested and passes through your
digestive system - helps keep things
moving along.
How much carbohydrates do you
need?
• 50-60% of Calories should come from carbs.
• Complex carbs are better to eat than simple carbs –
sugars give a quick burst of energy, but starches are a
longer, more even energy source.
• Foods high in complex carbs usually have other
useful nutrients
• Foods with lots of sugar usually have fewer other
useful nutrients
FATS
• Contain more than 2x
the energy of carbohydrates
• Store energy
• Parts of cells
• Protect internal organs
• Insulate the body
Types of Fats
• Unsaturated Fats
– Liquid at room temprerature
– Oils
– Considered good for you
• Saturated Fats
– Solid at room temperature
– From animals; a few plants –
coconut palm
– Bad for you
Cholesterol
• Saturated fat found in meat, eggs, cheese,
etc
• Necessary for cell membranes in animals
• Not needed in diet; liver makes all that is
needed.
• Can clog arteries and lead to heart attack
How much fat do we need?
• Should have no more than 30% of Calories
in diet from fat
• Should particularly limit intake of saturated
fats and cholesterol
• Read labels – look for palm or coconut oil,
hydrogenated or partially hydrogenated oils
– these are bad for you and you should
avoid them if you can
Proteins in the diet
•
•
•
•
For tissue growth and repair
Enzymes speed up chemical reactions
Can be used for energy, but not usually
About 12% of your daily Calorie intake
should be protein
Amino Acids
• The body makes about half the amino acids it
needs
• Rest come from food
• Complete proteins -contain all
of the essential amino acids
– Meat and eggs
• Incomplete proteins – missing
one or more essential amino acid
– Beans, grains, and nuts
Vitamins
• Act as helper molecules for a variety of
chemical reactions in the body.
• The body makes some – K is made by
bacteria in intestine
• The rest come from foods – eating a wide
variety of foods provides all the vitamins
needed.
Types of vitamins – chart p 511
• Fat soluble vitamins
– Dissolve in fatty tissue and are stored there.
– Includes vitamins A, D, E and K
• Water soluble vitamins
– Dissolve in water and not stored in body
– Needed in diet every day.
– Includes vitamins B and C
Minerals
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•
•
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Nutrients not made by living things
In soil and absorbed by plants
Includes calcium and iron
See chart - 512
Water
• People die within days of not having water
• Makes up about 65% of your body weight
• The body’s most important functions take place in
water
• Makes up most of the body’s fluids
• Nutrients are dissolved in water in blood and
transported around the body
• Perspiration
• Need about 2 liter s of water per day
– Need more if weather is hot or your are exercising
Food Guide Pyramid
• Classifies food into
6 groups and indicates
how many servings
from each group
should be eaten per day
Food Labels
• Allow you to evaluate a single food as well
as compare the nutritional value of two
foods.
• Tells:
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–
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Serving size
Calories from fat
% daily value of one serving
ingredients
THE END