FSN 110 NUTRITION SCIENCE • STUDY GUIDE • TEXTBOOK: INTRODUCTION TO NUTRITION SCIENCE
Chapter 8: Protein
Name:
Date Due:
Learning Objectives
CRN #:
(Highlight, underline, or mark X by two that most interest you.)
After completing Chapter 8, you should be able to:
1. Describe the basic chemical structure of all amino acids, and understand the difference
between essential and non-essential amino acids.
2. Describe how proteins are formed from amino acids and name the four levels of structural
organization of proteins. Appreciate how the structure of a protein is vital to its function.
3. Describe and give examples of the wide variety of different functions of proteins in the body.
4. Define the guidelines for protein intake, and identify food sources of protein in the diet,
distinguishing between complete and incomplete proteins.
5. Trace the steps of protein digestion and absorption through the gastrointestinal tract, and
discuss how absorbed amino acids are used by the body.
6. Identify the health consequences of too little and too much dietary protein.
7. Discuss the environmental and public health consequences of protein choices, and identify
ways to make more sustainable choices.
Key Terms
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(Notice these as you read the chapter, then use this list to help you review.)
Amino acids
Essential amino acids
Complete protein sources
Peptide bond
Transcription
Translation
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Collagen
Elastin
Enzymes
Hormones
Antibodies
Nitrogen balance
Complementary proteins
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Pepsin
Chymotripsin
Tripsin
Deamination
Marasmus
Kwashiorkor
Antibiotic resistance
Survey Question
Have you eaten any of these plant-based sources of protein during the past month?
Beans, peas, lentils
Peanuts or peanut butter
Nuts such as almonds, walnuts
Sunflower or pumpkin seeds
Chia seeds
Tofu, tempeh, or edamame
Seitan (made from wheat gluten)
Oatmeal
Quinoa, amaranth, spelt or teff
Bread made with sprouted grains
Soy milk (or other milk
alternative made from
almonds, rice, oats, etc.)
Other:
.
Edited by Christine Bisson, MS, RD, at Allan Hancock College, 2021. Contact: cbisson@hancockcollege.edu.
Content adapted from Nutrition: Science and Everyday Application by Alice Callahan, PhD, Heather Leonard, MEd, RDN, and Tamberly Powell, MS, RDN.
Part 1 - Introduction
Protein makes up about ________% of the human body and is present in _______% of cells.
Part 2 - Protein Structure
2a. What is Protein?
1. What are the building blocks of proteins?
2. How many different amino acids are there?
3. What 3 elements do carbohydrate, fat & protein have in common? ____________,
____________, ____________. What element is a key part of protein structure but not of
carbohydrates and fat? ___________________
4. In the space below, draw and label (or use words to describe) the basic structure of an amino
acid. Circle, highlight or underline the side chain—the component that makes each amino acid
different from other amino acids.
5. What are some different ways side chains can differ in their chemical properties? (For this
class, you don’t need to memorize amino acid structures or names, but you should appreciate
the diversity of amino acids and understand that it is the side chain that makes each different.)
2b. Essential and Nonessential Amino Acids
1. Define the following:
a. Nonessential amino acids-
b. Essential amino acids-
c. Conditionally essential amino acids-
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2. What is the difference between complete and incomplete protein sources?
2c. The Many Different Types of Proteins
1. How many different, unique proteins are found in the human body?
2. How are proteins similar to carbohydrates and fats?
3. How are they different?
4. What makes the huge diversity of different types of proteins possible?
2d. Building Proteins with Amino Acids
1. The building of a protein consists of a complex series of chemical reactions that can be
summarized into three basic steps:
a. Transcription - The genetic information in _______ is transcribed or copied into
________.
b. Translation - Based on the specific order of dictated by mRNA, amino acids are linked
together by ____________ bonds to form a polypeptide chain.
c. Protein folding - The polypeptide chain folds into specific _______ _________________________ shapes.
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2e. Protein Organization
1. Define and draw (or describe) the different levels of protein structure in the table:
Level of protein
structure
Definition
Quick sketch or
description
a. Primary
This is the 1-D polypeptide chain of
amino acids held together by
___________ bonds.
b. Secondary
The polypeptide chain folds into
simple ________ (also called helices)
and sheets, determined by the
_______________ interactions
between amino acids.
c. Tertiary
This is the unique 3-D shape of a
protein, formed as the different
_________ chains of amino acids
chemically interact, either repelling or
attracting each other. (The sequence
of amino acids in a protein directs the
protein to _______ into a specific,
organized shape.)
d. Quaternary
In some proteins, multiple folded
polypeptides called _____________
combine to make one larger
functional protein.
2. What is denaturation?
3. What causes denaturation?
4. Give an example of denaturation:
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2f. Shape Determines Function
1. The __________ ___________ sequence determines SHAPE of a protein, and SHAPE
determines ___________________.
2. Give an example of how the wrong amino acid sequence can influence shape and function.
Part 3 - Protein Functions
3a. Complete the table below to describe the many and diverse protein functions.
Protein Types and Functions
Type
Examples
Functions
Give ____________ (bone, tendons,
Structure
ligaments, cartilage, skin, muscles)
_____________ and _____________.
Digest _______________ into smaller
Enzymes
monomers that can be ______________;
performs steps in metabolic pathways to
allow for nutrient utilization.
Chemical ___________________ that
Hormones
travel in ______________ and coordinate
processes around the body
Maintains appropriate balance of
Fluid and acidbase balance
________ and ________ in different body
___________________.
Carry substances around the body in the
Transport
_________ or ____________; help
molecules cross cell ________________.
Protect the body from foreign
Defense
________________________.
3b. Energy Production
1. Can amino acids be used as an energy source?
2. Are they a major energy source? What percent of dietary proteins are broken down to use for
energy?
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3. What is the downside of using amino acids for energy?
4. Can amino acids be transformed into glucose? What is this process called?
5. Can amino acids be transformed into fat? When would this happen?
6. Carbohydrates (glucose) can be stored as glycogen and fat can be stored as adipose tissue.
Does protein have a similar storage system?
Part 4 - Protein in Foods and Dietary Recommendations
4a. How Much Dietary Protein Does a Person Need?
1. The Recommended Dietary Allowance (RDA) for a sedentary adult is ______ g per kg body
weight per day.
2. The Acceptable Macronutrient Distribution Range (AMDR) for protein for adults is _____% to
_____% of total energy intake.
3. The following populations have higher protein needs (on a per body weight basis):
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4. What is the recommended amount of protein per day for athletes?
4b. Nitrogen Balance to Determine Protein Needs
1. Fill in the table below to describe different states of nitrogen balance. (The first line is
completed for you.)
State
Define
Examples
(Neutral) Nitrogen
Balance
Nitrogen consumption =
nitrogen excretion
Most healthy adults
Negative Nitrogen
Balance
Positive Nitrogen
Balance
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2. What happens if a healthy adult in nitrogen balance consumes more protein than their body
needs? Where does extra the nitrogen go?
4c. Dietary Sources of Protein
1. Examples of animal sources of protein:
2. Examples of plant sources of protein:
3. Whole foods contain ___________ protein than refined foods. Very refined foods like
________ and __________ contain NO protein.
4d. Protein Quality
1. Give examples of complete protein food sources (contains all 9 essential amino acids) -
2. Give examples of incomplete protein food sources (does not contain all 9 essential amino
acids) -
3. Definition of mutual supplementation-
4. Examples of complementary proteins-
5. In general, what types of protein are more digestible, animal-based or plant-based?
6. If plant-based proteins are considered incomplete sources of protein and are less digestible,
does this make them poor choices? Can you think of some nutrition advantages of choosing
plant-based proteins compared with animal-based proteins?
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Part 5 - Protein Digestion and Absorption
5a. Protein digestion: Fill in the details of how each organ contributes to protein digestion in the
space provided.
1. Mouth:
2. Stomach:
3. Small Intestine:
1. In which organ do proteins usually lose their function? What is this process called?
2. In which two organs does enzymatic digestion of proteins occur? Where does MOST
enzymatic digestion occur?
3. What is the final product of protein digestion?
5b. What Happens to Absorbed Amino Acids?
Assuming the body has enough glucose and other sources of energy, absorbed amino acids will be
used in one of the following ways:
● Protein _____________ in cells around the body
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● Making ______________amino acids needed for protein synthesis
● Making other ______________-containing compounds
● Rearranged and stored as _____________ (there’s no storage form of protein)
If there is not enough glucose or energy available, amino acids can also be used in one of these
ways:
● Rearranged into ___________ for fuel for the brain and red blood cells
● Metabolized as fuel, for an immediate source of _________.
In order to use amino acids to make ATP, glucose, or fat, the ______________ first has to be
removed in a process called ______________, which occurs in the liver and kidneys.
Part 6 - Health Consequences of Too Little and Too Much Dietary Protein
6a. Health Consequences of Protein Deficiency
1. Kwashiorkor is a deficiency of ____________. It is characterized by:
2. Marasmus is a deficiency of both __________ and ____________. It is characterized by:
3. Marasmic kwashiorkor (a combined syndrome) where the main cause of death is due to
_____________.
4. Is severe protein deficiency common in the U.S.?
5. In the U.S., which populations are at risk of low protein intake?
6b. Health Consequences of Too Much Protein in the Diet
1. Why might a diet containing lots of steak, bacon, and sausage be problematic?
2. Studies show that when protein comes from _________ meat and __________ sources, risk of
chronic diseases may be reduced.
3. Are osteoporosis and kidney function a concern for healthy individuals with a high protein diet?
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Part 7 - Protein Food Choices and Sustainability
7a. Animal Agriculture and Resource Use
1. Comparing greenhouse gas emissions per gram of protein, do the lowest impact sources of
protein come from plant or animal sources?
2. Which are the most resource-intensive sources of protein?
3. What are some important roles of animal agriculture?
4. Moderate shifts to reduce meat consumption can be good for the planet and our
______________.
7b. Animal Agriculture and Antibiotic Resistance
1. What is antibiotic resistance? (A common misconception is that people can become resistant
to antibiotics, but this isn’t the case. In your answer, be sure to specify what has become
resistant to the effects of antibiotics?)
2. What has contributed to the growth of antibiotic-resistant bacteria?
3. SKETCH or describe how antibiotics given to food animals can lead to the development of
antibiotic-resistant bacteria and 4 ways in which those bacteria can spread:
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4. What can you do to prevent yourself and your family from getting sick with antibiotic-resistant
infections?
a. Take antibiotics ___________________________.
b. Follow simple Food Safety Tips:
■ C_______. Use a food thermometer to ensure that foods are cooked to a safe
internal temperature: 145°F for whole beef, pork, lamb, and veal (allowing the
meat to rest for 3 minutes before carving or consuming), 160°F for ground meats,
and 165°F for all poultry, including ground chicken and turkey.
■ C________. Wash your hands after touching raw meat, poultry, and seafood.
Also wash your work surfaces, cutting boards, utensils, and grill before and after
cooking.
■ C________. Keep your refrigerator below 40°F and refrigerate foods within 2
hours of cooking (1 hour during the summer heat).
■ S____________. Germs from raw meat, poultry, seafood, and eggs can spread
to produce and ready-to-eat foods unless you keep them separate. Use different
cutting boards to prepare raw meats and any food that will be eaten without
cooking.
c. Wash your hands after contact with __________, ______________, or
_________________ ________________________.
d. Report suspected outbreaks of illness from food to your local health department.
e. Review CDC's Traveler's Health recommendations when preparing to travel to a foreign
country.
5. How can our purchasing habits help with antibiotic resistance?
7c. Issues of Fish Sustainability
1. How can your purchasing habits encourage sustainable fish production?
2. Which types of fish have the highest levels of mercury and should be avoided by pregnant
women and growing children?
3. What are some examples of fish with low levels of mercury?
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