unit 3 Flashcards
1
Q
What are the major lipid groups?
A
Triglycerides, sterols, phospholipids
These groups have distinct structures, food sources, and functions.
2
Q
What is the structure of triglycerides?
A
3 fatty acids attached to a glycerol backbone
3
Q
What are common food sources of triglycerides?
A
- Animal fat
- Vegetable fat
- Bakery items
- Snack foods
- Dairy desserts
4
Q
What is the function of triglycerides?
A
- Most common type of lipid in food and body
- Store fat
- Concentrated source of energy
- Insulate and cushion organs
- Help transport nutrients
5
Q
What is the structure of sterols?
A
Carbons are arranged in multi-ringed structures
6
Q
What are food sources of cholesterol?
A
- Meat
- Fish
- Poultry
- Eggs
- Dairy products
7
Q
What is the function of cholesterol?
A
- Makes sex hormones
- Active form of vitamin D
- Adrenal hormones
- Bile
- Cell membranes
8
Q
What is the structure of phospholipids?
A
Similar to triglycerides, but 1 fatty acid is replaced with a phosphate molecule
9
Q
What are food sources of phospholipids?
A
- Egg yolks
- Wheat germ
- Peanuts
10
Q
What is the function of phospholipids in food?
A
Used as an emulsifier
11
Q
How does fatty acid chain length categorize fatty acids?
A
- Small: less than 6
- Medium: 6-12
- Long: 14 or more
12
Q
What characterizes saturated fats?
A
Chains packed tightly, solid at room temperature
13
Q
What characterizes unsaturated fats?
A
Chains packed loosely, liquid at room temperature
14
Q
What is the basic structure of a fatty acid?
A
Long chains of carbon atoms linked together, surrounded by hydrogen atoms
15
Q
What defines a saturated fatty acid?
A
All bonds between the carbons are single, filled with hydrogens
16
Q
What defines a monounsaturated fatty acid?
A
One double bond found in the chain, missing 2 hydrogens
17
Q
What defines a polyunsaturated fatty acid?
A
At least 2 double bonds in the chain, hydrogens missing at these double bonds
18
Q
What are the characteristics of cis fatty acids?
A
- Bent chain
- Hydrogen atoms on the same side of carbon chains
19
Q
What are the characteristics of trans fatty acids?
A
- Straight chain
- Hydrogen atoms attach diagonally on opposite sides of double carbon bond
20
Q
What are essential fatty acids?
A
Fatty acids that must be obtained from food and cannot be synthesized by the body
21
Q
What is the function of DHA?
A
Needed for normal development of vision and the nervous system
22
Q
What is the purpose of hydrogenation in food products?
A
- Makes oils more solid
- Creates trans fatty acids
- Helps resist rancidity
23
Q
What is the energy provided by lipids?
A
9 kcal/g
24
Q
What are the functions of lipids in the human body?
A
- Provide energy
- Compact energy storage
- Insulate and protect the body
- Aid fat-soluble vitamin absorption and transportation
25
What are hidden fats?
Fats not visible in foods, found in items like whole milk and pastries
26
What is the recommended fat intake according to the Institute of Medicine?
20-35% of total calories
27
What are fat replacements?
* Water
* Protein
* Starch derivatives
* Fiber
* Gums
28
How do you calculate the percentage of fat in a food product?
Fats (g) times 9, divide by calories/serving, multiply by 100
29
Where does lipid digestion begin?
In the mouth
30
What enzyme is active in the stomach for lipid digestion?
Gastric lipase
31
Where does the majority of lipid digestion occur?
In the small intestine
32
What is the role of bile in lipid digestion?
Emulsifies fat, breaks it down into micelles
33
How are lipids transported in the bloodstream?
* Chylomicrons
* VLDL
* LDL
* HDL
34
What is a health concern related to high polyunsaturated fat intake?
Can increase cholesterol deposited in arteries
35
What are the effects of excessive omega-3 fatty acid intake?
* Impair immune system
* Allow uncontrolled bleeding
36
What are symptoms of cardiovascular disease related to fat intake?
* High cholesterol
* Obesity
* Inflammation
37
What dietary change occurred with the introduction of grains?
Shift to a diet higher in grains like wheat and rice
38
What are proteins made of?
Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur
39
What are amino acids?
Building blocks for protein synthesis
40
What is the difference between essential and nonessential amino acids?
* Essential: must be obtained from food
* Nonessential: can be synthesized by the body
41
What characterizes high quality (complete) proteins?
Contain all 9 essential amino acids
42
What characterizes low quality (incomplete) proteins?
Do not contain all 9 essential amino acids
43
What is the process of protein synthesis?
Amino acids linked by peptide bonds, determined by gene expression
44
What is denaturation?
Alteration of protein’s 3-dimensional structure, destroying its function
45
What is the sequential order of amino acids in a protein called?
Primary structure
46
What shape does the secondary structure of a protein take?
Spiral-like or pleated sheet shape
47
What determines the overall shape and function of a protein?
Tertiary structure
48
What is the quaternary structure of a protein?
2 or more separate polypeptides interacting
49
What is denaturation in the context of proteins?
Alteration of protein’s 3-dimensional structure
50
List three causes of protein denaturation.
* Exposure to acid or alkaline solutions
* Enzymes
* Heat
* Agitation
51
What is protein turnover?
Constant state of breakdown, rebuilding, and repair of body proteins
52
What is the typical percentage of proteins from animal sources in a North American diet?
70%
53
What percentage of protein comes from animal sources in a typical worldwide diet?
35%
54
List four benefits of plant proteins.
* Do not contain cholesterol
* Have little saturated fat
* May help decrease risk of cardiovascular disease
* May help decrease risk of certain cancers, obesity, and diabetes
55
What method is used to determine protein needs?
Nitrogen balance
56
What is maintained when protein intake equals losses?
Protein balance (equilibrium)
57
What occurs when protein intake is less than losses?
Negative protein (nitrogen) balance
58
During which conditions can an individual be in positive protein (nitrogen) balance?
* Growth
* Recovery from trauma, injury, illness
59
What is the Recommended Dietary Allowance (RDA) for protein for adults?
0.8 g/kg of body weight
60
What is the Acceptable Macronutrient Distribution Range (AMDR) for protein?
10-35%
61
What enzyme starts protein digestion in the stomach?
Pepsin
62
What triggers the release of secretin and cholecystokinin (CCK) in the small intestine?
Chyme entering the small intestine
63
What are the main products of protein digestion in the small intestine?
Short peptides and amino acids
64
What is the role of antibodies in the immune system?
Bind to foreign antigens and help prevent disease
65
What can excessive protein consumption lead to?
* Dehydration
* Increased urinary calcium loss
* Kidney disease
* Elevated blood cholesterol
66
What characterizes marasmus?
Severe deficiency of energy, protein, and micronutrients
67
What is kwashiorkor?
Rapid occurrence of severe protein deficiency, often with underlying infection or disease
68
What is phenylketonuria (PKU)?
Inherited disease that prevents breakdown of amino acid phenylalanine
69
What type of vegetarianism includes dairy products?
Lacto-vegetarians
70
What are the dietary sources of Vitamin B-12 for vegetarians?
* Fortified foods
* Supplements
71
What is the primary function of lipids in the human body?
* Provide energy
* Build cell membranes
* Protect organs
* Absorb fat-soluble vitamins
* Regulate body temperature
* Make hormones
72
What is the effect of saturated fats on LDL cholesterol?
Can raise LDL (bad) cholesterol
73
What is the recommended percentage of daily calories from fat according to health professionals?
20-35%
74
How does fat digestion begin in the digestive tract?
Starts in the mouth and continues in the stomach
75
What are the four major lipoproteins and their roles?
* Chylomicrons: Carry fat from food through the lymph system
* VLDL: Transport fat through the blood
* LDL: Delivers cholesterol to cells
* HDL: Picks up excess cholesterol and returns it to the liver
76
Which population group is at increased risk of PEM?
c. older adults
77
True or False: Many children with kwashiorkor maintain some muscle and subcutaneous fat.
a. true
78
Which of the following is not a usual characteristic of marasmus?
a. edema
79
Which of the following is associated with excessive protein intakes?
a. dehydration
80
Which food is a common cause of food allergies?
d. all of the above
81
Which nutrient would most likely be low in a vegan diet?
c. vitamin B-12
82
Why is it important for essential amino acids lost from the body to be replaced by the diet?
Essential amino acids cannot be made by the body and are needed to build new proteins and maintain body functions.
83
Explain the process for synthesizing nonessential amino acids.
The body makes nonessential amino acids using transamination, transferring a nitrogen group from one amino acid to a different molecule.
84
What is a limiting amino acid?
A limiting amino acid is the essential amino acid found in the lowest amount in a food, limiting protein synthesis.
85
Why is the concept of limiting amino acids a concern in a vegetarian diet?
Many plant proteins don’t contain all essential amino acids in the right amounts, making it harder to build complete proteins.
86
Describe factors that determine whether a person is in nitrogen equilibrium.
Nitrogen equilibrium occurs when nitrogen consumed equals nitrogen excreted, typical in healthy adults with stable body weight.
87
Describe the process of protein digestion from ingestion to excretion.
Protein digestion starts in the stomach with pepsin, continues in the small intestine where proteins are broken into amino acids, which are absorbed into the blood.
88
Describe the functions of protein.
Proteins build and repair body tissues, make enzymes, hormones, antibodies, transport nutrients, and can be used for energy.
89
Outline the major differences between kwashiorkor and marasmus.
Kwashiorkor is caused by a lack of protein and shows swelling (edema); marasmus results from severe lack of calories and protein, leading to extreme thinness.
90
What is a food allergy?
A food allergy is an immune reaction to a specific protein in food, causing symptoms like hives, swelling, or trouble breathing.
