Lab 2Nutrition and the Cell

BY 102Zach Nolen

Why is nutrition important?

Why is nutrition important? It is important to know about nutrition, so that

we can understand how the food that we eat helps to keep our bodies functioning.

The Science of Nutrition is the relationship between food (nutrients) and the health of the body.

Fortunately, in America, we do not have to worry about planning our meals to ensure that we get all of our required nutrients.

However, generally our eating habits are not the best when choosing what is best for us to eat.

Types of Nutrients

Six types of nutrients: Protein Carbohydrates Lipids Vitamins Minerals Water

Proteins

Proteins are composed of amino acids, which are linked together by peptide bonds and are called polypeptides.

Proteins play a role in proper muscle development, regulation of body fluids, development of hormones, and the production of enzymes.

Antibodies are a type of protein

Proteins

There are 20 different amino acids found in animal and plant proteins.

Of these, 9 are “essential” which means that they can not be made by the body and must be obtained through diet.

About 20% of our total body weight is proteins

50% of the body’s protein is muscle, while the other 50% is divided between bone, skin, enzymes, blood cartilage, etc.

Differences between plant and animal protein.

Animal protein is referred to as “complete” protein because all essential amino acids can be found in a single source.

Plant sources are referred to as “incomplete” because they do not contain all essential amino acids.

A complete source of protein can be obtained from plants by eating a combination of grains and beans.

Carbohydrates

Carbohydrates function as a major source of energy for the body.

A single macromolecule is called a monosaccharide (glucose), two sugar molecules are called a disaccharide (sucrose).

Long chains of sugar molecules are called a polysaccharide (starch).

It is recommended that 55-60% of daily caloric intake be made up of carbohydrates.

If there is not enough energy from carbohydrates, the body will begin to break down proteins to create energy.

Carbohydrates

Plants are the main source of carbohydrates. What is the only non-plant source of

carbohydrates? Lactose in milk

Carbohydrates are broken up into three groups: simple sugar, starch, and dietary fiber.

Nearly 70% of daily carbohydrate intake is supplied by simple sugars, which has increased from 33% at the beginning of the 20th century.

Lipids

Lipids are commonly known as fat, which our bodies need.

In healthy men and women, what percent of body weight is fat? Men: 15-18%; Women: 18-23%

There are several terms used to describe dietary fat: Saturated – solid at room temp (animal fat) Unsaturated – liquid at room temp (vegetable oils) Trans-fatty acid – hydrogen enriched vegetable

fats (margarine and shortenings); very unhealthy

Lipids

Excess fat consumption leads to weight gain, which can lead to fat in the blood which causes heart problems.

Recommended fat consumption should be 30% of our caloric intake.

Excess fat consumption can lead to high cholesterol which can cause heart problems.

Vitamins and Minerals

Vitamins are organic substances required in very small amounts that perform specific metabolic functions in the body.

There are 13 vitamins that are required for good health.

Generally, if you have a balanced diet, then you should receive adequate amounts of vitamins.

If you do not have a balanced diet, you may wish to take vitamin supplements to improve general health.

Minerals are basic elements (iron), not some complex molecules.

We will not be testing for vitamins and minerals in this lab.

Testing for different nutrients

To test for proteins, we will be using Biuret’s reagent.

To test for carbohydrates, we will be using Benedict’s solution to test for simple sugars and Lugol’s solution to test for starch.

To test for lipids, we will be using Sudan IV (which I will add).

Results

Biuret’s Test

+-

Lugol’s Test

+-

Benedict’s Test

- +

Sudan IV Test

-+

Review Questions

1. What are the 6 types of nutrients?2. What solution do we use to test for:

Protein? Starch?

3. How many vitamins are essential for good health?

4. In healthy individuals, which gender has a higher percentage of fat?

Before you leave lab!

Clean up! Take tape off of test tubes Make sure you clean used test tubes

and place in the bin next to the sink Wipe down your work station Let me check your station before you

leave

Before next lab!

Review topics covered in lab today Read the next lab (Lab 4) Do the online prelab Complete questions 1-15 on page

18-19 (omit #12)