Exam 2- Ch 6
What substance converts the inactive pepsinogen to its active form, pepsin?
hydrochloric acid
Urea is the body's principal vehicle for excreting unused ________ .
nitrogen
The part of the chemical structure that differentiates one amino acid from another is its _____
side group
What is the protein RDA per kilogram of healthy body weight?
0.8g
How many grams of protein are in fruits?
0g
How many grams of protein are in dairy products?
1 cup = 8g of protein
How many grams of protein are in Protein foods?
1 oz = 7g of protein • meats, seafood, plants, eggs
How many grams of protein are in grains?
2-3g
How many grams of protein are in vegetables?
2-3g
The USDA Food Patterns sorts protein foods into three subgroups. The total recommended intake of seafood should be about _______%.
20%
The average life span of a skin cell is about ________ .
30 days
The protein RDA for adults is 0.8 grams per kilogram of healthy body weight per day. A woman weighs 60 kg and her weight falls within the normal range for her height. How much protein (in grams) should she consume in one day? Grams of protein:
48g
Assuming a healthy weight for Erin is 141 pounds, what is her recommended daily protein requirement?
51g
The protein RDA for a healthy adult who weighs 180 pounds is:
65 g/day
On average, an ounce of a protein food delivers how many grams of protein?
7g
An ounce of most protein foods delivers about ________ .
7g of protein
Which part of its chemical structure differentiates one amino acid from another?
its side group
Protein Synthesis
DNA -> RNA by transcription RNA -> Protein by translation
T or F? Eating predigested proteins can help keep your digestive system from being overworked.
False
T or F? Most athletes in training need supplemental protein in their diets to maintain muscle mass.
False
T or F? Sickle-cell anemia is caused by low amounts of iron in the blood.
False
T or F? Unlike some other nutrients, overconsumption of protein has little or no adverse health effects.
False
T or F? Plant proteins are always considered low-quality proteins.
False; Animal and Plant proteins (soy protein) are high-quality proteins
T or F? Nonessential amino acids are those that are not made in the body and thereby unnecessary.
False; Essential amino acids must be supplied by the diet
T or F? In transforming DNA into proteins, the DNA is translated into RNA, and then RNA is transcripted into a protein.
False; In transforming DNA into proteins, the DNA is transcribed into RNA, and then RNA is translated into a protein.
T or F? Proteins contain only nitrogen, carbon, and oxygen atoms.
False; proteins contain carbon, hydrogen, oxygen, and nitrogen
Non-essential amino acids are
alanine arginine asparagine aspartic acid cysteine glutamic acid glutamine glycine proline serine tyrosine
If an essential amino acid that is needed to make a protein is unavailable, the cells must:
break down proteins to obtain it
Proteins that maintain the acid-base balance of the blood and body fluids by accepting and releasing hydrogen ions are:
buffers
High-quality proteins
contains needed essential amino acids -Animal proteins -Plant proteins (soy protein) •some better than others
Erin loves whole grains. Suppose she makes herself a snack from one serving of grains and one cup yogurt topped with a serving of fresh strawberries. How much protein is in her snack?
dairy: 1 cup= 8g grains: 2-3g =10 to 11 grams
The action of hydrochloric acid in the stomach on protein results in ________ .
denaturation
In the stomach, hydrochloric acid:
denatures proteins and activates pepsin
Protein turnover describes the amount of protein:
synthesized and degraded; Within each cell, proteins are continually being made and broken down, a process is known as protein turnover
Essential amino acids are those that ________ .
the body does not make in sufficient amounts, so they must be included in the diet
The process of messenger RNA being made from a template of DNA is known as ________ .
transcription
Functions of proteins in the body
•Building blocks for most body structures •Replacement of dead or damaged cells •Act as enzymes •Regulators of fluid balance •Acid-base regulators •Transporters (hemoglobin) •Maintain a strong immune system •Source of energy and glucose
denaturation of proteins in food
•Disruption of stability and shape •Uncoil and lose shape Examples: •Cooking an egg (heat) •Curdling of milk (acid) •Stiffening of egg whites (whipping)
the enzymes needed to digest proteins in the small intestine
•Enteropeptidase •Trypsin •Chymotrypsin •Carboxypeptidases •Elastase and collagenase •Intestinal tripeptidases •Intestinal dipeptidases •Intestinal aminopeptidases
the enzymes needed to digest proteins in the stomach
•Hydrochloric acid (HCl) •Pepsin
positive nitrogen balance
•If the body synthesizes more than it degrades: - intake > excretion -Protein is added (Growing infants, children, and others)
Amino acid characteristics
•The building blocks of proteins are amino acids •20 amino acids •Proteins made of amino acids contain: -Carbon, hydrogen, oxygen, nitrogen
The digestibility of most animal proteins is ________ .
90-99%
What is an example of foods for complementary proteins?
- Legumes and Grains - Black beans and rice
Erin is a 28-year-old professional woman who is 5 feet 8 inches tall and vigilantly maintains her weight at 118 pounds by following a lacto-ovo (non-fat milk and egg whites only) vegetarian diet that supplies approximately 1200 calories a day. With her understanding that protein should provide between 10 and 35 percent of her daily calories, she reasons that her daily intake of 40 grams of protein from milk, eggs, legumes, and nuts is adequate for her needs. She is concerned, however, that she has been sick more than usual and has experienced two stress fractures in her leg over the past three years while exercising.
--
Factors of protein quality
1. Digestibility -amt. of aa absorbed from the protein •Animal (90-99%) vs. plant proteins (70-90%) 2. Amino acid composition •The liver synthesizes non-essential if needed •Limiting amino acid- too little of an EAA available for protein synthesis to proceed then protein can't be made or body must break down its own stores
Levels of protein structure
1. Primary- amino acid sequence 2. Secondary- local folding of the polypeptide chain into helices or sheets 3. Tertiary- a 3D folding pattern of a protein due to side-chain interactions 4. Quaternary- protein consisting of more than one amino acid chain
Name the protein for each function given: 1. Provides strength and shape to skin 2. Inactivates foreign invaders 3. Facilitates chemical reactions
1. Provides strength and shape to skin- structural protein 2. Inactivates foreign invaders- antibody 3. Facilitates chemical reactions- enzyme
calculating protein recommendations for people
1. Take the person's weight (lbs) and divide it by 2.2 in order to get the weight in kilograms 2. Multiply kg to get 0.8 to get the RDA in grams of protein/day
The value of a protein in a diet is determined by which four factors? What is the exception?
1. amino acid composition 2. comparison with a reference protein 3. quality 4. digestibility - amount of food
Are these amino acids essential or non-essential? 1. lysine 2. valine 3. cysteine 4. methionine
1. lysine- essential 2. valine- essential 3. cysteine- non-essential 4. methionine- essential
For each food, state whether it is high or low quality: 1. seafood 2. poultry 3. gelatin 4. corn 5. soy
1. seafood- high 2. poultry- high 3. gelatin- low 4. corn- low 5. soy- high
What percentage of total energy intake should come from protein?
10-35%
What percentage of total food energy should protein provide?
10-35%
Remembering that protein provides 4 kcalories per gram, what percentage of Erin's current total energy intake comes from protein?
13.3%
What is the simplest amino acid?
Glycine
negative nitrogen balance
If the body degrades more than it synthesizes: - excretion > intake - State of starvation or severe stress; breaks down muscle for energy
denaturation of proteins in the body
In the stomach, Hydrochloric acid (HCl) denatures protein structure by uncoiling protein strands •Stomach acid can cause protein denaturation
Complementary proteins
Low-quality proteins combined within meal to provide adequate levels of essential amino acids •Not necessary
non-essential amino acids
More than half of the amino acids are nonessential, meaning that the body can synthesize them for itself. Proteins in foods usually deliver these amino acids, but it is not essential that they do so.
______ are protein making machines and are composed of RNA and protein.
Ribosomes
conditionally essential
Sometimes a nonessential amino acid becomes essential under special circumstances. For example, the body normally uses the essential amino acid phenylalanine to make tyrosine (a nonessential amino acid). But if the diet fails to supply enough phenylalanine, or if the body cannot make the conversion for some reason then tyrosine becomes a conditionally essential amino acid
T or F? After leaving the mouth, proteins are denatured in the stomach by hydrochloric acid.
T
T or F? Animal proteins are more digestible than are plant proteins.
T
T or F? Enzymes facilitate both catabolic and anabolic reactions.
T
T or F? Hemoglobin is the protein in red blood cells that transports oxygen from the lungs to tissues throughout the body.
T
T or F? Pepsin inhibits pepsinogen synthesis.
T
T or F? Proteins form the building blocks of muscle, blood, and skin.
T
T or F? The Recommended Daily Allowance of protein for adults is 0.8 grams per kilogram of healthy body weight per day.
T
essential amino acids
There are nine amino acids that the human body either cannot make at all or cannot make in sufficient quantity to meet its needs. These nine amino acids must be supplied by the diet; they are essential.
What can be said about Erin's protein intake? a. She is actually getting more protein than recommended, and this may cause her to excrete calcium, increasing her risk of bone fracture. b. Although it falls within the recommended range in terms of the percentage of total energy intake, it is less than recommended in terms of the absolute amount. c. Erin's reliance on legumes and other non-meat sources of protein may increase her risk of certain cancers, such as colon cancer. d. Given her Lacto-ovo vegetarian diet, she is probably consuming too much methionine and tryptophan. e. Given that she is a Lacto-ovo vegetarian, it is virtually impossible for her to get adequate, balanced protein.
b. Although it falls within the recommended range in terms of the percentage of total energy intake, it is less than recommended in terms of the absolute amount.
Most proteins are broken down into their amino acids (before/after) absorption in the small intestine.
before
Whey protein is a waste product from the manufacturing of ________ .
cheese
A person who regularly eats a high-protein diet needs to make sure they ________ .
drink plenty of water
Which of the following foods provides the highest quality protein?
egg
Isoleucine, leucine, and lysine are:
essential amino acids
Essential amino acids are
histidine isoleucine leucine lysine methionine phenylalanine threonine tryptophan valine
Translation
mRNA at the ribosome gives sequence of amino acids to be placed -> protein strand made
Transcription
mRNA made complementary to DNA sequence
Like carbohydrates and lipids, proteins are composed of carbon, hydrogen and oxygen. However, they also contain _____ atoms.
nitrogen
zero nitrogen balance
nitrogen intake = nitrogen output • input: food • output: sweat, urine, feces
Transcription occurs in the ______ and translation occurs in the ______.
nucleus; cytoplasm
Which of these foods has the least protein per 1/2 cup? rice broccoli pinto beans orange juice
orange juice
In the stomach, hydrochloric acid denatures proteins and activates ______.
pepsin
The condition that occurs when the diet provides too little protein is known as ______
protein-energy malnutrition
Evidence suggests cancer of the colon, pancreas, and ovaries is connected with high consumption of ________ .
red meat and processed meats