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73 Cards in this Set
- Front
- Back
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Proteins
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large complex molecules composed of amino acids.
-Contain carbon, hydrogen, oxygen, nitrogen -Primary source of nitrogen in our diets -20 different amino acids are used to make proteins |
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Essential amino acids
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-Cannot be produced by our bodies
-Must be obtained from food |
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Nonessential amino acids
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Can be made by our bodies
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How are Proteins Made?
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Proteins are long chains of amino acids.
Amino acids are joined to each other by peptide bonds. The structure of each protein is dictated by the DNA of a gene. |
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Protein Synthesis
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Protein synthesis can be limited by missing amino acids
-if we do not consume adequate amounts of the essential amino acids, or do not consume adequate energy overall |
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Limiting amino acid
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the amino acid that is missing or in the smallest supply
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Incomplete protein:
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does not contain all essential amino acids.
-Not sufficient for growth and health -Considered a “low quality” protein |
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Complete protein
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contains sufficient amounts of all 9 essential amino acids
-Considered a “high quality” protein |
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Mutual supplementation:
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using two incomplete proteins together to make a complete protein.
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Complementary proteins
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two protein sources that together supply all 9 essential amino acids.
ex. beans and rice |
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Digestion of Proteins
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Digestion of proteins begins in the stomach.
-Hydrochloric acid breaks down protein structure -Hydrochloric acid activates pepsin Digestion of proteins continues in the small intestines. -Pancreatic enzymes called proteases complete the digestion of proteins into single amino acids |
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Pepsin
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: an enzyme that breaks down proteins into short polypeptides and amino acids.
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process of digestion of protetins
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Absorption of Proteins
In the LIVER: |
Absorbed amino acids are transported by blood to liver and taken up for conversion into whichever amino acids are needed for body
Excess amino acids can also be converted to fat or glucose and stored in the body, or broken down for energy |
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Absorption of Proteins
In the LARGE INTESTINE: |
proteins from food are not present in large intestine
proteins present in feces come from bacterial cells and from sloughed intestine cells |
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Storage of Proteins
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No storage, unlike that for carbohydrates and lipids
Used to build muscle and organ tissue Contributes to amino acid pool |
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Functions of Proteins
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Cell growth, repair, and maintenance:
Proteins in our bodies are constantly being broken down, repaired and replaced Structures: Important in cell membranes (as lipoproteins); bone and tooth matrix; collagen (skin, bone, muscle filaments, nails, hair) Hormones : act as messengers and regulators in the body Enzymes: a protein which serves to speed up a biochemical reaction Most enzyme names end in –ase, such as lactase |
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Fluid Balance
(func. of pro) |
-Protein works to keep a balance of fluid in the cells, the space surrounding the cells and in the blood.
-If the concentration of protein is too low to draw fluid from the tissues and across the blood vessel walls; it causes fluid to collect in the tissues, causing edema. |
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Electrolyte Balance
(func. of pro) |
-Transport proteins maintain the proper balance of sodium and potassium throughout the body and across cell membranes
-If protein intake is insufficient, this balance may be lost, resulting in changes in the rhythm of the heart |
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Immune function
(func. of Pro) |
Antibodies
-chemicals that attack invading cells or molecules) made up of proteins -If we do not consume enough protein, our resistance to certain diseases is weakened. |
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pH Balance
(func. of pro) |
-Proteins act as buffers by helping to maintain proper acid-base balance
-Proteins attach or release hydrogen ions as the blood acidity changes |
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How Much Protein Should We Eat?
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Recommended Dietary Allowance (RDA)
0.8 grams protein per kg body weight 12-20% of total energy intake should be from protein |
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Can You Eat Too Much Protein?
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High cholesterol and heart disease
Diets high in protein from animal sources are associated with high cholesterol Possible bone loss High protein diets MAY cause excess calcium excretion leading to bone loss -Kidney disease |
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Vegetarianism
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restricting the diet to foods of plant origin.
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Protein-energy malnutrition
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: a disorder caused by inadequate intake of protein and energy.'
two forms: Marasmus Kwashiorkor |
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Marasmus
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disease resulting from severely inadequate intakes of protein, energy, and other nutrients
symptoms: Severe wasting of muscle tissue Stunted physical growth Stunted brain development Anemia |
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Kwashiorkor
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disease resulting from extremely low protein intake.
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Genetic Disorders
Phenylketonuria (PKU) |
Phenylketonuria:
Inherited disease Individual cannot break down amino acid phenylalanine Phenylalanine builds up in the body and can result in brain damage if untreated Must follow diet that is very low in phenylalanine |
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Genetic Disorders
Sickle Cell Anemia |
Inherited disorder
Causes red blood cells to be sickle- or crescent-shaped Due to a change in an amino acid in hemoglobin Cells rupture easily and become clogged in blood vessels |
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Genetic Disorders
Cystic Fibrosis |
Inherited disease
Affects respiratory system and digestive tract Caused by abnormal protein that prevents the normal passage of chloride into and out of cells |
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Lipids
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diverse class of molecules that are insoluble in water.
Lipids (fats) do not dissolve in water. |
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Three types of lipids
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Triglycerides
Phospholipids Sterols |
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Triglycerides composed of:
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-Three fatty acid molecules
Fatty acids are long chains of carbon atoms surrounded by hydrogen atoms *One glycerol molecule Glycerol is a 3-carbon alcohol that is the backbone of a triglyceride |
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Saturated fatty acids
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have hydrogen atoms surrounding every carbon in the chain.
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Monounsaturated fatty acids
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lack hydrogen atoms in only one region
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Polyunsaturated fatty acids
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lack hydrogen atoms in multiple locations.
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Hydrogenation
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The addition of hydrogen atoms to unsaturated fatty acids.
Coverts liquid fats (oils) into a more solid form Used to create margarine from plant oil Often creates trans fatty acids |
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Phospholipids
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re composed of
Glycerol backbone 2 fatty acids Phosphate Are soluble in water Are manufactured in our bodies so they are not required in our diet |
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Sterols
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Lipids containing multiple rings of carbon atoms.
-Are essential components of cell membranes and many hormones -Are manufactured in our bodies and therefore are not essential components of our diet |
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Digestion of Fats
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Fats are not digested and absorbed easily because they are insoluble in water.
Very little digestion of fats occurs in the watery environments of the mouth or stomach. Digestion of fats primarily begins in the small intestine. |
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Digestion of Fat diagram
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Digestion of Fat in:
Small intestine |
As fat enters the small intestine
Bile is secreted from the gall bladder into the small intestine Bile is produced by the liver and stored in the gall bladder Bile disperses fat into smaller fat droplets Pancreatic enzymes break fat into 2 separate fatty acids and a monoglyceride Single fatty acids and monoglycerides are packaged into micelles, along with bile, and taken to cell walls of small intestine. |
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Chylomicron:
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A lipoprotein produced by cells lining the small intestine.
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Essential fatty acids
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Alpha-linolenic acid (omega-3 fatty acid)
Found in vegetables, fish and fish oils Linoleic acid (omega-6 fatty acid) Found in vegetable and nut oils |
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Fat-soluble vitamins
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Vitamins A, D, E, and K are soluble in fat; fat is required for their transport
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How Much Fat?
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The Acceptable Macronutrient Distribution Range (AMDR) for fat:
20-35% of calories should be from fat |
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The type of fat consumed
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-Saturated fat should be no more than 7% of total calories.
-Trans fatty acids should be reduced to the absolute minimum. -Most fat in our diets should be from monounsaturated fats (eg., olive oil). |
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Health Problems from Fat
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Cardiovascular disease
Dysfunction of the heart or blood vessels Can result in heart attack or stroke |
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Blood lipids include
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Chylomicrons
VLDLs – very low-density lipoproteins LDLs – low-density lipoproteins “bad cholesterol” HDLs – high-density |
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EFFECTS of SATURATION on LIPOPROTEIN LEVELS
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Saturated and trans fatty acids
- Increase LDL and decrease HDL cholesterol output Polyunsaturated fatty acids - Decrease LDL and HDL cholesterol levels Monounsaturated fatty acids -Decrease LDL without lowering HDL cholesterol |
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Vitamins
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13 known vitamins.
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Vitamins – Major Functions
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Anitoxidation: the prevention of unwanted oxidation of compounds in body
production and release of energy regulation of growth and development Hematopoiesis: the production of red blood cells and the hemoglobin contained in them |
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Vitamin K
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Phylloquinone – plant form of vitamin K
Menaquinone – form of vitamin K produced by bacteria in the large intestine Functions of vitamin K Blood coagulation Bone metabolism Recommended intake There is no RDA for vitamin K. AI values are 120 mg/day for men and 90 mg/day for women. Sources of vitamin K Green leafy vegetables, vegetable oils |
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Cancer
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a group of related diseases characterized by cells growing out of control.
Composed of three steps: Initiation Promotion Progression |
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Antioxidants may work by
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Antioxidants may contribute to reducing the risk of cancer.
Enhancing the immune system Inhibiting growth of cancer cells Preventing oxidation damage to cells |
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Cardiovascular disease (CVD)
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The leading cause of death
Includes heart disease, hypertension, atherosclerosis Can lead to heart attack or stroke Risk factors include smoking, obesity, hypertension, high LDL levels, low HDL levels, inactivity, diabetes |
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4 major functions if Vitamins:
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-Serving as antioxidants to prevent unwanted oxidation of other compounds
-Regulation of growth and development -Hematopoiesis (production of red blood cells) -Production or release of energy from other substances such as lipids, carbohydrates, and proteins (vitamins do NOT supply energy themselves) |
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Vitamins Fat soluable
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A, D, E, K
regulate and promote growth and development; antioxidant |
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Water soluble vitamins
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B, C
energy production, hematopoiesis, antioxidant, regulate metabolism |
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Provitamin
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can be converted to active vitamin in the body
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Where does most absorption of vitamins take place?
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Small intestine – almost all absorption takes place here
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Vitamin E
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Primary role is as an antioxidant
Protects poly-unsaturated fatty acids (PUFAs) Protects low-density lipoproteins (LDLs) Recommended Intake 15mg alpha-tocopherol per day Upper limit (UL) is 1,000 mg per day Sources of Vitamin E Vegetable oils, nuts, seeds, wheat germ, soybeans |
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Vitamin C
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Vitamin C is a water-soluble vitamin that must be consumed in the human diet.
Functions of Vitamin C Antioxidant Synthesis of collagen Prevents the disease scurvy Enhances the immune system Recommended intake 90 mg/day for men; 75 mg/day for women Smokers need an extra 35 mg/day Sources of vitamin C Fresh fruits and vegetables (Cooking destroys the vitamin C) |
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Beta-carotene
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provitamin
Functions of beta-carotene A weak antioxidant Effective against oxidation in cell membranes and LDLs Carotenoids in general are known to Enhance the immune system Protect skin from damage by UV light Protect eyes from damage |
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Vitamin A
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Excess vitamin A is stored in the liver, adipose tissue, kidneys, and lungs.
There are 3 active forms of Vitamin A: Retinol Retinal Retinoic acid Functions of vitamin A Essential to proper vision Antioxidant, protecting LDL cholesterol Cell differentiation – the process by which cells mature and specialize Sperm production and fertilization Bone growth Recommended intake RDA is 900 mg/day for men; 700 mg/day for women Sources of vitamin A Obtained from animal sources (liver, eggs) and plant sources (dark green, orange, and deep yellow fruits and vegetables) -highly toxic |
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Antioxidation
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is the prevention of “unwanted” oxidation of compounds in the body
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B-complex vitamins
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are especially important for energy metabolism
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Beriberi
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deficiency of thiamin resulting
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Riboflavin
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Is part of coenzymes involved in oxidation-reduction reactions
Is part of the antioxidant enzyme glutathione peroxidase Milk is a good source of riboflavin Ariboflavinosis – riboflavin deficiency; sore throat, swollen mucous membranes |
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Niacin
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Coenzyme assisting with metabolism of carbohydrates and fatty acids
Good sources: meat, fish, poultry, enriched bread products Toxicity can result from supplements Pellagra – severe niacin deficiency |
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Folate
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Involved in DNA synthesis, amino acid metabolism
Critical for cell division of very early embryos Good sources: ready-to-eat cereals, enriched bread products Toxicity can mask vitamin B12 deficiency |
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Pantothenic acid
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Component of coenzymes for fatty acid metabolism
Required for building new fatty acids Good sources: chicken, beef, egg yolk, potatoes, oat cereals, tomato products No toxicity from excess pantothenic acid Deficiencies are very rare |
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Vitamin D
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Excess is stored in liver and fat tissue
Can be synthesized by the body by exposure to UV light from the sun Is a hormone since it is synthesized in one location and acts in another location Functions of vitamin D Required for calcium and phosphorus absorption Regulates blood calcium levels Stimulates osteoclasts Necessary for bone calcification The RDA for vitamin D ranges from 400 – 600 IU a day depending on age and gender. |
