Transcript Lab 2B Introduction

Energy, Nutrition, Calories
& Lab 2B
“Focus On” – p. 54
Food and Nutrition

Why do we need food?


Energy (catabolism)
Building new molecules (anabolism)



Proteins
Cell membrane
DNA/RNA

Nutrition is the study of food and its effects on the
body

Essential Nutrients

Water, Vitamins, Minerals, Fats (lipids), Proteins, Carbohydrates
Water
Every cell in the body needs water to
complete many of the body’s processes and
chemical reactions
 Water loss causes problems in all the body
systems

Fats (Lipids)
Manufacture cell membranes, produce
hormones and store energy
 Saturated- contains only single bonds (all
possible hydrogens) eg. butter
 Unsaturated- contains one or more double or
triple bonds eg. olive oil
 Trans-fats

Protein




Provide body with material for
growth
Make up parts of muscles,
skin and internal organs
Enzymes
Body can naturally produce
12 of 20 amino acids


The other 8 must be obtained
from food
Called essential amino acids
Vitamins
Organic molecules that are needed by the
body to help perform important chemical
reactions
 14 essential vitamins


2 types:
 fat-soluble
(A,D,E,K)- stored in fatty tissues of the
body
 water-soluble (C,B)- cannot be stored
Minerals
Inorganic nutrients that the body needs
 Found in periodic table
 Examples: Ca (bones), Fe (needed for
hemoglobin), Mg (normal function of nerves
and muscles)
 Lost in sweat, urine and other waste
products

Carbohydrates
Major source of energy
 Two forms:

 Simple
sugars
 Complex starches

Broken down into simple sugar in digestive system
 Cellulose=
fiber (cannot be broken down, helps
process food more efficiently)
Food and Energy
Food contains- Carbs, Fat, Protein and
Nulceic Acids Which is our main source for
energy? Back up source?
 Carbs are broken down by the digestive
system to the simple sugar, GLUCOSE
 Our cells like to use glucose for cell
respiration. As a back up fatty acids and
even amino acids can be used if necessary

How Much Energy is in the Food We
Eat?

CALORIE
Measures the amount of energy that is in food
 Amount of heat energy needed to raise the temp.
of 1 mL of water by 1 degree Celsius
 On our food labels we see Calories (kilocalorie)
 1 Calorie = 1000 calories


1 jelly bean = 3 Calories = 3000 calories!
(That’s a lot of energy!)
Food Labels
What are calories? Calories?
calorie = amount of energy required to raise
temp of 1 g of water 1ºC (15º-16º)
 Calorie = 1 kilocalorie

Calories are used
on food labels
 Why do we use C
rather than calories?

How do we determine caloric
content of foods?

Calorimeter
Completely combust
food  heats up water
 Measure temperature
change of water
 Good ones are highly
insulated so all heat
goes to water rather
than surroundings

Our setup . . .
Calorimetric Calculations

Q = m c ΔT





Q = heat in calories
m = grams of water in calorimeter (same as mL)
c = specific heat of water  1 cal/gºC
ΔT = change in temp of water
EX: burning a 0.2 g peanut raises the temp of 10
mL water in the calorimeter from 20º to 37ºC.
cal
 17C  170 cal  1000 cal  0.170 kcal (Calories)
g C
0.170 kcal  0.2g peanut  0.85 kcal/g  85 Calories per 100g
Q  10g  1
Foods We Will Test



Potato chips
Beef Jerky
Marshmallows

Each is primarily one type of food (lipid, protein, carb)
 Which is which?

“Rule of Thumb” for caloric content:
 1g of fat = 9 Calories (9000 cal)
 1 g of carb/protein = 4 Calories (4000 cal)
Lab Prep

Create a hypothesis
Think: What will the results of the lab be?
 What samples am I using?
 Therefore, of the 3 samples, what do I think…


Copy the data table from your book(p703)
using the food items provided


Leave samples blank for now
Draw flow chart of the experiment
Additional Analysis Questions
A1. One of the foods had a high fat content (chip),
high protein content (beef jerky), and high carb
content (marshmallow). From your results, what
can you conclude about the relative energy content
of carbs, proteins, and fats?
A2. What advice would you give to a sports team
about their diets?
A3. What’s the difference between “Power Bars” and
“Protein Bars”? For what type of physical activity
would you recommend eating each type?