Exam 3 Study Guide
Chapter 6
1. Amino acids- structure and classification. How many total? How many essential?
a.
... [Show More] Basic structure: amino group (N containing), Acid group, and R-side Chain
b. 20 total amino acids
c. 9 essential amino acids: histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, threonine, tryptophan, and valine
Amino Acids:
• 3 branched chain amino acids are essential
• Leucine, isoleucine, valine
• Can be used for muscle during activity
- When amino acids bond, proteins are formed
- The bond between amino acids is called a peptide bond (acids, enzymes, and
other agents can break these bonds during digestion)
2. What is a limiting amino acid?
Limiting Amino Acids:
• The amino acid that is in the shortest supply in the diet in relation to the
body needs
• Meat contain all amino acids
• Plants are very low or miss certain amino acids (ex: vegetarians or vegans
will miss amino acids)
3. Protein synthesis. Understand the process! Draw it for practice.
a. DNA contains coded instructions for protein synthesis within the nucleus of
the cell
b. Occurs in the cytoplasm of the cell
c. mRNA
i. A transcribed segment of DNA that is then transferred to the
cytoplasm
ii. Process from DNA to mRNA = TRANSCRIPTION
iii. Amino acids added one at a time
iv. Protein synthesis requires energy
d. Once in the cytoplasm of the cell translation takes place
e. RNA (specifically tRNA) takes codes to ribosomes
f. Ribosomes read the code and translate into a protein
4. Protein organization. What determines the shape of a protein?
Order of amino acids in a protein determines its ultimate shape
a. Proteins final shape determines its function in the bod
i. If the amino acid sequence is mutated, then the final shape is
disrupted, which causes disease
5. What causes sickle cell anemia?
i. hemoglobin contains 4 subunits ii. in sickle cell anemia one amino acid is changes (glutamic acid –
valine)
iii. this change occurs on two of the subuints – change I protein
organization – disease state
iv. symptoms: decease in oxygen to cells, severe pain in joints/ bones,
headaches, abdominal pain, convulsions, paralysis
v. What happens when the the protien synthsis is messed up
6. What is denaturation? How do we do it?
Denaturation: alteration of protein’s three-dimensional structure, usually caused by:
heat, enzymes, acid or alkaline solutions, or agitation.
a. Results in:
i. Alteration in function
ii. Often destroys normal physiological functions
iii. Useful for some body processes (digestion)
Example of denaturation: frying an egg
7. Food sources of protein. Which protein sources are complete (“high quality”)?
Protein Food Sources:
- 70% of protein in the American diet is from animal sources
- plan sources contribute: magnesium, fiber, other micronutrients and
phytochemicals
High quality (Complete Protein):
a. Provide all essential amino acids
b. Support body growth
Lower Quality (Incomplete Protein):
a. Dietary proteins that are low or lack one or more essential amino acid
b. Plant protein (except soy and quinoa)
c. Have limiting amino acids
Top 5 Contributors of Protein in the U.S. Diet: beef, poultry, milk, white bread,
cheese
8. How do you complement proteins?
Complementary Proteins:
a. 2 or more incomplete proteins may be combined to make a complete protein
(ex: rice and beans)
b. Complementing is important throughout the day, not just one meal
c. If not complemented, incomplete proteins= used for energy needs or
converted to CHO or fat
9. UNDERSTAND DIGESTION, ABSORPTION, TRANSPORT, AND EXCRETION OF
PROTEINS. If you are not 100% confident on the anatomy of the digestive system,
review that first. Practice drawing it!
a. Pancreatic enzymes:
i. Trypsin, amont others, into the duodenum. Peptides = amino acids
ii. Small peptides and amino acids , ready for absorption b. Protein absorption
i. Microvilli surface and within absorptive cells
ii. Many different amino acid transport mechanisms
iii. Active absorption
iv. Amino acids are sent to the liver via portal vein
c. Digestion of protein in the stomach:
i. Denatured : by cooking and acid in the stomach
ii. Gastrin: stimulates the release of acid pepsin
iii. Pepsin: breaks down proteins
10. List the functions of proteins
• Regulate and maintain body functions
• Provide essential form of nitrogen (in the form of amino acids).
• Maintains fluid functions
-Blood proteins exert pressure which attracts fluid into blood; fluid levels
decrease during protein deficiency which leads to EDEMA.
Edema= Swollen tissue; Happens when pregnant or protein malnourished.
• Proteins assist to acid-base balance
-Assists in keeping blood slightly alkaline
-act as buffers-maintaining PH within a narrow range.
• Forming hormones and enzymes
-Hormones=internal body messengers with important regulatory functions.
-Enzymes=Speed up chemical reactions that are crucial to cell function.
• Contribute to immune function
-Antibodies: Proteins that our body makes to recognize viruses, diseases.
• Forming glucose
-Brain needs 130 grams of glucose. Breakdown proteins to get glucose.
-With inadequate glucose is available-glucose
-Glucose is necessary for the brain, RBC, and nervous tissue function.
-With starvation, muscle wasting and edema result from protein breakdown.
• Energy
-Using amino acids for energy is very inefficient only with calorie restriction
prolonged exercise.
• Satiety
-proteins provide the highest feeling of satisfaction after eating
-May contribute to calorie during weight loss.
11. How much protein do we need? What happens if we eat too much or too little?
-Sufficient dietary amount is needed to balance output with intake.
-Requirements determined by Nitrogen intake.
-0.8 grams of protein per day
-Most of us eat more than what the RDA says
Positive Protein Balance= “More than enough”; consuming more protein than
recommended.
- Required to build new tissues-It is when protein intake >losses
-Resistance exercise increases protein needs
-Insulin, growth hormone, and testosterone
-Need when pregnant or recovering after an illness
Negative Protein Balance= “not enough”
-Intake Output. (Weight Gain)
-Required during pregnancy, infancy, and childhood.
Negative Energy Balance= Output>Input (Weight Loss)
Reduction of lean and adipose mass
4. How do we measure the calorie content of food?
We measure the calorie content of food with the Bomb Calorimeter.
-It measures calorie content by igniting and burning a dried portion of food.
-The burning food raises the temperature of the water surrounding the chamber
holding the food.
5. What is basal metabolism? What factors affect it?
Basal Metabolism: minimum energy expended to keep a resting, awake body active;
keep blood pumping, breathing
Amount of energy needed for basal metabolism varies between individuals, why?
- Everyone is a different height and weight [Show Less]
