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Nutrition exam 2
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NUTRITION EXAM 2 STUDY GUIDENUTR 200
Exam 2 Review
This review is designed to help you cover key concepts and guide you through the textbook and your
lecture notes. How much detail you cover under each topic is up to you.
Chapter 6
Know the basic structure and function of triglycerides, phospholipids and sterols.
How are triglycerides (specifically the fatty acid part) classified?
What are SFAs, MUFAs and PUFAs?
What are fats?
A type of lipid
Lipids: diverse class of molecules that are insoluble in water
3 types of lipids
1. Triglycerides
2. Phospholipids
3. Sterols
Triglycerides
- Composed of 3 fatty acid molecules
- Fatty acids: long chains of carbon atoms surrounded by hydrogen atoms
- Glycerol molecule: 3 carbon alcohol, backbone of a triglyceride
Classified by
- Length of their carbon chain → Short, medium, or long
- Level of saturation → how many hydrogen atoms surround each carbon
→ saturated fatty acids (SFA): hydrogen atoms surrounding every carbon in the chain and no
double bonds (saturated with hydrogen)
, → monounsaturated fatty acids (MUFA): lack hydrogen atoms in one region and have one
double bond
→ polyunsaturated fatty acids (PUFA): lack hydrogen atoms in multiple locations and have
two or more double bonds
- Shape → determined by how the fat is chemically processed
- Short and medium chain fatty acids are digested and absorbed more quickly than long-chain fatty
acids
Phospholipids
Composed of
- Glycerol backbone
- 2 fatty acids (FA)
- phosphate
Phospholipids are manufactured in our bodies and are not required in our diet
- They are important components of cell membranes
- Amphipathic
Sterols
Sterols are lipids containing multiple rings of carbon atoms
- Essential components of cell membranes
- Help maintain structural integrity
- Many hormones
- Manufactured in our bodies and are not essential components of our diet
- Cholesterol is the major sterol found in the body
Shape of saturation
The hydrogen atoms at the unsaturated region can be arranged in different positions
Cis: the same side of the carbon chain
Trans: opposite sides of the chain
What is hydrogenation?
Hydrogenation: the addition of hydrogen atoms to unsaturated FAs
- Converts liquid fats (oils) into a semisolid (spreadable) or solid form
- Used to create margarine from plant oil
- Often creates trans fatty acids (these increase risk for cardiovascular disease)
- Must be listed on food labels as partially hydrogenated oil
What are the 2 essential fatty acids? Where do we find them in foods? What do they do in the
human body?
Essential fatty acids
- 2 fatty acids can not be synthesized in the body and must be obtained in the diet
- Linoleic and alpha-linolenic acid
- Converted into important regulatory compounds in the body
, - Precursors to eicosanoids
- Regulate cell function → GI motility, blood clotting, blood pressure, vessel permeability,
inflammation
Linoleic acid
- Omega-6 fatty acid
- Found in vegetable and nut oils
- Converted in body to arachidonic acid
- Involved in blood clotting and blood pressure
Alpha-linolenic acid
Omega-3 fatty acid
- Found in dark green leafy vegetables, fish and fish oils and flax and flaxseed oil
- Converted to EPA and DHA
- Important regulators of inflammation, blood clotting and blood pressure
What are the functions of fats?
Why do we need fats?
→ they provide energy
- Fat is very dense, providing 9 kcal/gram
- 30-70% of the energy used at rest comes from fat
- Fatty acids are used for energy during low to moderate intensity physical activity exercise
- Fat is also used for energy storage in adipose tissue
→ they transport some vitamins
- Vitamins A, D, E, and K are soluble in fat, and fat is required for absorption across intestinal wall
- Vitamin A: essential for vision
- Vitamin D: maintain bone health (we produce when UV lights hit our skin)
- Vitamin E: protects cell membranes from by-products of metabolism
- Vitamin K: important for blood clotting (produced by bacteria in large intestine)
→ help maintain cell function –
- Phospholipids, cholesterol and fatty acids help maintain cell membrane integrity, permeability of
cell and regulate binding of substances to the cell
- Fats help maintain membrane fluidity and flexibility
- Enable red blood cells to move through small capillaries
- White blood cells move out of capillaries and fats help them squish to do this
- PUFAs are important for healthy brain and spinal cord tissue
→ provides protection
- Adipose tissue pads our body and protects organs
- No living person can have 0% body fat
- Fat acts as insulation to retain body heat
- Where we store fat does have a relation to health
→ contribute to flavor, texture and satiety of food
- Fat provides flavor and texture of foods example: creamy, crisp, moist, tender
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