Week 4 & 5 Study Guide

1. Which disaccharide is found in table sugar? 2. This disaccharide is formed from which two monosaccharides?

1. Sucrose 2. Glucose and Fructose

Triglycerides (triacylglycerols) are broken down to ____ and ____ before absorption.

Free fatty acids Monoglycerides

Explain how carbohydrates are processed by the liver after absorption.

. The liver either stores glucose as glycogen or exports it back to the blood. Galactose and fructose may be converted to glucose or used in similar metabolic pathways. How much glucose the liver exports to the blood is under hormonal control.

1. Explain why the hydrophobic nature of fats poses a challenge to digestion. 2. Explain how bile overcomes this challenge.

1. Because most digestive enzymes are water-based. As stomach contents enter the small intestine, the digestive system sets out to combine the separated fats with its own watery fluids. 2. Bile contains bile salts, lecithin, and substances derived from cholesterol so it acts as an emulsifier. It attracts and holds on to fat while it is simultaneously attracted to and held on to by water. Emulsification increases the surface area of lipids over a thousand-fold, making them more accessible to the digestive enzymes.

Sterols: Functions in the Body Describe Structure

1. Cholesterol is an important component of the cell membrane and is required for the synthesis of sex hormones, vitamin D, and bile salts. 2. Most sterols do not contain any fatty acids. They are complex molecules that contain interlinking rings of carbon atoms, with side chains of carbon, hydrogen, and oxygen attached.

Triglycerides (Triacylglycerols): Functions in the Body Describe Structure

1. Control the body's internal climate, maintaining constant temperature. Also help the body produce and regulate hormones. Omega-3 and omega-6 essential fatty acids help regulate cholesterol and blood clotting and control inflammation in the joints, tissues, and bloodstream. Fats also play important functional roles in sustaining nerve impulse transmission, memory storage, and tissue structure. More specifically in the brain, lipids are critical to brain structure and function. They help form nerve cell membranes, insulate neurons, and facilitate the signaling of electrical impulses throughout the brain. 2. To form a triacylglycerol, a glycerol molecule is joined by three fatty acid chains. Triacylglycerols contain varying mixtures of fatty acids.

Phospholipids: Functions in the Body Describe Structure

1. Crucial for building the protective barrier, or membrane, around your body's cells. In fact, phospholipids are synthesized in the body to form cell and organelle membranes. In blood and body fluids, phospholipids form structures in which fat is enclosed and transported throughout the bloodstream. 2. Like triacylglycerols, phospholipids have a glycerol backbone. But unlike triacylglycerols, phospholipids are diglycerides (two fatty-acid molecules attached to the glycerol backbone) while their third fatty-acid chain has a phosphate group coupled with a nitrogen-containing group.

1. Name the three monosaccharides. 2. Which monosaccharide circulates in the blood as a fuel source for your cells?

1. Glucose, Fructose, Galactose 2. Glucose

1. _______ is the polysaccharide that our liver and muscle cells make to store glucose. 2. _______ is the polysaccharide that plants use to store glucose.

1. Glycogen 2. Amylose or Amylopectin

1. [HDL/LDL] is your "good blood cholesterol". [HDL/LDL] is your "bad blood cholesterol". 2. Explain the effects these two types of lipoproteins have on heart disease.

1. HDL is your "good cholesterol" / LDL is your "bad" cholesterol. 2. LDLs carry cholesterol into cells for normal usage, but LDLs can also deposit cholesterol into the walls of blood vessels, which can lead to harmful disease. HDLs scavenge excess cholesterol from the cells, tissues, and blood vessels and deliver these back to the liver, where these are either reused or excreted. LDLs carry lipids that are proinflammatory and may contribute to heart disease. HDLs transport lipids that are anti-inflammatory and may reduce the occurrence of heart disease.

The pancreas releases two hormones that together regulate blood sugar levels: 1. _______________ is released when blood sugar levels are high and stimulates cells of the body to take up glucose from the blood. 2. ________________ is released when blood sugar levels are low and stimulates the liver to break down glycogen and release glucose into the blood.

1. Insulin 2. Glucagon

1. Which disaccharide is found in milk? 2. This disaccharide is formed from which two monosaccharides?

1. Lactose 2. One glucose + One galactose

1. The essential fatty acids are _______________ and ________________. 2. Name the symptoms associated with deficiency of these fatty acids.

1. Linolenic acid (Omega-3) Linoleic acid (Omega-6) 2. Too little Omega-3 or an out of balance Omega-3/Omega-6 may elevate the risks for allergies, arthritis, asthma, coronary heart disease, diabetes, and many types of cancer, autoimmunity, and neurodegenerative diseases, all of which are believed to originate from some form of inflammation in the body. Without Omega-6, the body would not be able to heal wounds, fight infections, or fight off illness each time a foreign germ presented itself. Eicosanoids work together with the body's immune and inflammation processes to play a major role in several important body functions, such as circulation, respiration, and muscle movement.

Explain three ways blood glucose may be used by cells in the body.

1. Providing energy for cells through cellular respiration. When the body breaks the chemical bonds in glucose, that releases energy the body can use. 2. Energy storage. When the body has enough energy to support its functions, it stores glucose as glycogen. Stored in muscles and liver. 3. Building macromolecules. Some glucose is converted to ribose and deoxyribose which are essential building blocks for RNA, DNA, and ATP. Also used to make the molecule NADPH. 4. Spare protein and fat for other purposes.

Proteins are broken down to ____________ before absorption.

Amino acids

Explain the relationship between proteins and amino acids.

Amino acids are the building blocks for proteins. Proteins are macromolecules composed of amino acids.

Amino acids are more frequently used to make new proteins rather than for energy. Identify the many (many!) things proteins do in our body.

Amino acids are used not only to build proteins, but also to build other biological molecules containing nitrogen, such as DNA and RNA, and to some extent to produce energy. Structure & motion of the body Enzymes Hormones Fluid and Acid-Base balance Transport molecules in/out of cells Protection (immune system) Wound healing/tissue regeneration Energy production

Animal fats are usually [saturated/unsaturated]. Plant-based fats are usually [saturated/unsaturated].

Animal fats are usually saturated. Plant-based fats are usually unsaturated.

Describe how the arteries are affected in cardiovascular disease.

Arteries start to narrow and harden when fats accumulate along their inner walls and form plaques. Plaque formation causes arteries to narrow and harden, which elevates blood pressure because the vessels can't expand effectively to accommodate blood pulses. Higher blood pressure strains the heart and causes more damage. Arterial walls can become so weakened due to high blood pressure that they balloon and form what is known as an aneurysm. If the aneurysm bursts, it becomes a life-threatening event. The plaques themselves can also rupture due to a spike in blood pressure or a tremor along an arterial wall, and the body responds to this perceived injury by forming blood clots. These clots are serious health threats, whether they are stationary (a thrombus) or moving (an embolus).

Explain the role of micelles in lipid absorption.

Bile salts envelop the fatty acids and monoglycerides to form micelles. Micelles have a fatty acid core with a water-soluble exterior. This allows efficient transportation to the intestinal microvilli. Here, the fat components are released and disseminated into the cells of the digestive tract lining.

Explain the potential health effects of consuming too many unhealthy fats.

Cardiovascular disease, heart attack, ischemic stroke, congestive heart failure, heart valve problems, obesity, arrhythmia

Explain why dietary fiber can help control blood cholesterol levels.

Cholesterol absorption is aided by an increase in dietary fat components and is hindered by high fiber content. This is the reason that a high intake of fiber is recommended to decrease blood cholesterol. Foods high in fiber such as fresh fruits, vegetables, and oats can bind bile salts and cholesterol, preventing their absorption and carrying them out of the colon.

Discuss the health benefits of eating whole grains.

Decreased the risk for obesity, Type 2 diabetes, and cardiovascular disease. Lower blood cholesterol levels, and potentially decreased risk for colon cancer and diverticulitis.

Loss of protein structure is called ___________________.

Denaturation

Explain the role of dietary fat in the absorption of fat-soluble vitamins.

Dietary fats carry fat-soluble vitamins through the digestive process, improving intestinal absorption of these valuable nutrients. This improved absorption is also known as increased bioavailability.

Explain the relationship between monosaccharides, disaccharides, and polysaccharides

Disaccharides are two monosaccharides joined together. They always contain one glucose molecule. Polysaccharides are long chains of monosaccharides joined together. They may be branched or not branched.

Distinguish between: Essential amino acids Nonessential amino acids Conditionally essential amino acids.

Essential: The body can not synthesize them either at all or in sufficient amounts. Nonessential: The body can synthesize them naturally. Conditionally essential: When during infancy or in a diseased state, a body cannot synthesize enough of an essential amino acid, so it needs to be supplemented through diet.

True/False: Eating more protein makes you build bigger muscles, regardless of exercise.

False

Distinguish between incomplete protein sources and complete (high-quality) protein sources.

High-quality protein contains all the essential amino acids in the proportions needed by the human body. The amino acid profile of different foods is therefore one component of protein quality. Foods that contain some of the essential amino acids are called incomplete protein sources, while those that contain all nine essential amino acids are called complete protein sources, or high-quality protein sources. Foods that are complete protein sources include animal foods such as milk, cheese, eggs, fish, poultry, and meat, and a few plant foods, such as soy and quinoa.

Identify the essential amino acids.

Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine

Give examples of low glycemic index and high glycemic index foods.

Low Glycemic index: non-starchy vegetables, whole grain foods, legumes, lentils High Glycemic index: Refined grains (white bread and pasta), high fructose corn syrup, soda and candy, instant oatmeal, saltine crackers

Explain what hydrogenated fats and trans fats are and how they may affect your health.

In a trans fatty acid, the hydrogen atoms are attached on opposite sides of the carbon chain. Hydrogenation is the process of adding hydrogen to the carbon double bonds, thus making the fatty acid saturated (or less unsaturated, in the case of partial hydrogenation). According to the ongoing Harvard Nurses Health Study, trans fatty acids have been associated with increased risk for coronary heart disease because of the way they negatively impact blood cholesterol levels.

What is hyperlipidemia?

Inclusive of several conditions but more commonly refers to high cholesterol and triacylglycerol levels. When blood lipid levels are high, any number of adverse health problems may ensue. (Cardiovascular disease, heart attack, ischemic stroke, congestive heart failure, heart valve problems, obesity, arrhythmia)

Discuss the health effects of too little dietary protein.

Kwashiorkor is characterized by swelling (edema) of the feet and abdomen, poor skin health, growth retardation, low muscle mass, and liver malfunction. Marasmus is characterized by an extreme emaciated appearance, poor skin health, and growth retardation. The symptoms are acute fatigue, hunger, and diarrhea.

Lactose intolerance may be caused by a lack of the enzyme _______________. Explain how lack of this enzyme leads to the symptoms of lactose intolerance (bloating, diarrhea, cramps).

Lactase When people do not have enough of the enzyme lactase, lactose is not sufficiently broken down resulting in a condition called lactose intolerance. The undigested lactose moves to the large intestine where bacteria are able to digest it. The bacterial digestion of lactose produces gases leading to symptoms of diarrhea, bloating, and abdominal cramps.

Explain how carbohydrate intake affects blood sugar (glucose) levels.

Large amounts of carbohydrate intake results in more glucose stores in the body.

Name the enzymes involved in lipid digestion.

Lingual lipase Gastric lipase Pancreatic lipase

Explain how eating low glycemic index foods can help regulate blood sugar levels.

Low glycemic-index foods prevent rapid spikes in blood-glucose levels.

Name the three disaccharides.

Maltose Lactose Sucrose

Why is it particularly important for vegetarians to get their protein from a variety of sources?

Most plant-based foods are deficient in at least one essential amino acid and therefore are incomplete protein sources. Because grains and legumes are not deficient in the same amino acids they can complement each other in a diet. Incomplete protein foods are called complementary foods because when consumed in tandem they contain all nine essential amino acids at adequate levels.

Name the two digestive organs where carbohydrates are broken down.

Mouth Small intestine

Name the organs where lipids are digested.

Mouth Stomach (small amt) Small intestine

[Positive/negative/neutral] nitrogen balance may indicate starvation, disease, or protein deficiency.

Negative nitrogen balance. The body is breaking down more protein in order to meet its demands, causing a wasted appearance.

Identify at least 6 different sources of healthy fats.

Nuts Nut products Avocados Fish (salmon, tuna, mackerel, trout, cod liver oil) Plant-based foods and oils Green leafy vegetables Eggs, poultry, wheat germ oil, whole grains

Discuss health consequences of added sugars.

Obesity, Type 2 diabetes, cardiovascular disease, arthritis, depression, and some cancers.

Discuss the health effects of too much dietary protein.

Observational studies conducted in the general population suggest that diets high in animal protein, specifically those in which the primary protein source is red meat, are linked to a higher risk for kidney stones, kidney disease, liver malfunction, colorectal cancer, and osteoporosis. High-protein diets can restrict other essential nutrients.

Explain what omega-3 and omega-6 fats are and how they may affect your health.

Omega-3 and omega-6 fatty acids are precursors to important compounds called eicosanoids. Eicosanoids are powerful hormones that control many other hormones and important body functions, such as the central nervous system and the immune system. Eicosanoids derived from omega-6 fatty acids are known to increase blood pressure, immune response, and inflammation. In contrast, eicosanoids derived from omega-3 fatty acids are known to have heart-healthy effects.

What are some of the problems that can arise if blood glucose levels are not controlled?

People with diabetes are between two and four times more likely to die from cardiovascular disease. Diabetes is the number one cause of new cases of blindness, lower-limb amputations, and kidney failure. Many people with diabetes develop peripheral neuropathy, characterized by muscle weakness, loss of feeling and pain in the lower extremities. More recently, there is scientific evidence to suggest people with diabetes are also at increased risk for Alzheimer's disease. Hypoglycemia and hyperglycemia.

Name the enzymes involved in protein digestion.

Pepsin Chymotrypsin Trypsin

Explain how cardiovascular disease can lead to a heart attack or stroke.

Plaque formation causes arteries to narrow and harden, which elevates blood pressure because the vessels can't expand effectively to accommodate blood pulses. Higher blood pressure strains the heart and causes more damage.

Growing children and pregnant women are in a [positive/negative/neutral] nitrogen balance. (Note: Positive nitrogen balance is when Nitrogen in is greater than nitrogen out. Negative nitrogen balance is the opposite.)

Positive nitrogen balance. They are taking in more nitrogen than they are excreting because the body is using more protein to build new tissues.

Describe each of the four levels of protein structure.

Primary: Sequence of an amino acid chain. One-dimensional. Secondary: Amino acid strand acquired a spring-like shape as they repeal and attract each other. Two-dimensional. Tertiary: Coiled strand of amino acids folds and loops over on itself to take on a fuctional shape. Three-dimensional. Quaternary: Protein that consists of one or more amino acid strands. Once coiled and folded the protein can function as it is or it may join to other proteins, or add carbohydrates, vitamins, or minerals.

Describe the types of foods that increase the risk of developing coronary heart disease.

Refined starches, added sugar, saturated fats, diets low in Omega-3 fatty acids, alcohol, high-fat dairy products.

Name the enzymes involved in carbohydrate digestion.

Salivary amylase Pancreatic amylase Disacchridases (sucrase, maltase, lactase)

Consumption of [saturated/unsaturated] fats has been linked to an increased risk of cardiovascular (heart) disease.

Saturated

[Saturated/Unsaturated] fatty acids have only single bonds between their carbons.

Saturated

[Saturated/Unsaturated] fats are usually solid at room temperature and [saturated/unsaturated] fats are usually liquid (oils) at room temperature.

Saturated fats are usually solid at room temperature Unsaturated fats are usually liquid (oils) at room temperature.

Explain the role of lacteals in lipid absorption.

Short- and medium-fatty chains can be absorbed directly into the bloodstream from the intestinal microvillus because they are water-soluble.

Dietary fiber can be classified as either water-soluble or insoluble. Which kind of fiber is broken down by gut bacteria?

Soluble fibers

Identify at least two sources of each type of fiber.

Soluble: Peas, beans, oats, barley, rye Insoluble: Whole-grain foods, cauliflower, avocados, flax

Some types of polysaccharides are classified as dietary fiber. Explain why cellulose is a dietary fiber but starch is not.

Starch is a crystalline structure whereas cellulose is a highly branched and cross-linked

Name the two organs in which proteins are digested.

Stomach Small intestine

Explain how the acidity of the stomach aids in protein digestion.

The acidity of the stomach facilitates the unfolding of the proteins that still retain part of their three-dimensional structure after cooking and helps break down the protein aggregates formed during cooking.

Explain the role of chylomicrons in lipid absorption.

Triacylglycerols, cholesterol, and phospholipids form lipoproteins when joined with a protein carrier. Lipoproteins have an inner core that is primarily made up of triacylglycerols and cholesterol esters (a cholesterol ester is a cholesterol linked to a fatty acid). The outer envelope is made of phospholipids interspersed with proteins and cholesterol. Together they form a chylomicron, which is a large lipoprotein that now enters the lymphatic system and will soon be released into the bloodstream via the jugular vein in the neck. Chylomicrons transport food fats perfectly through the body's water-based environment to specific destinations such as the liver and other body tissues.

What are lipoproteins?

Triacylglycerols, cholesterol, and phospholipids form lipoproteins when joined with a protein carrier. Lipoproteins have an inner core that is primarily made up of triacylglycerols and cholesterol esters (a cholesterol ester is a cholesterol linked to a fatty acid). The outer envelope is made of phospholipids interspersed with proteins and cholesterol.

What are the symptoms of diabetes mellitus?

Type 1: Hunger, excessive thirst and urination, rapid weight loss, blurred vision, thrust/genital itching, slow-healing wounds, exhaustion. Type 2: Increased thirst and urination, unexplained weight loss, and hunger. The first stage of Type 2 diabetes is characterized by high glucose and high insulin levels. This is because the insulin-secreting cells in the pancreas attempt to compensate for insulin resistance by making more insulin. In the second stage of Type 2 diabetes, the insulin-secreting cells in the pancreas become exhausted and die.

Identify the two types of diabetes and explain how each arises.

Type 1: Insulin-secreting cells in the pancreas are killed by an abnormal response of the immune system, causing a lack of insulin in the body. Its onset typically occurs before the age of thirty. Type 2: A metabolic disease of insulin insufficiency, but it is also caused by muscle, liver, and fat cells no longer responding to the insulin in the body. In brief, cells in the body have become resistant to insulin and no longer receive the full physiological message of insulin to take up glucose from the blood.

Identify risk factors for coronary heart disease (and cardiovascular disease in general).

Unmodifiable: Age, Sex, Family History Modifiable: Cigarette smoking, obesity, diabetes, physical inactivity, cholesterol levels

[Saturated/Unsaturated] fatty acids have one or more double bonds between their carbons.

Unsaturated

Describe the differences in chemical structure between: Unsaturated fatty acids Monounsaturated fatty acids Polyunsaturated fatty acids

Unsaturated: When one or more bonds between carbon atoms are a double bond (C=C). It has one or more points of unsaturation. Monounsaturated: Any fatty acid that has only one double bond is a monounsaturated fatty acid, an example of which is olive oil (75 percent of its fat is monounsaturated). Polyunsaturated: A polyunsaturated fatty acid is a fatty acid with two or more double bonds or two or more points of unsaturation.

Explain the effect loss of structure has on the functioning of proteins.

When a protein denatures, its complicated folded structure unravels, and it becomes just a long strand of amino acids again. Weak chemical forces that hold tertiary and secondary protein structures together are broken when a protein is exposed to unnatural conditions. Because proteins' function is dependent on their shape, denatured proteins are no longer functional.

Explain what the body's nitrogen balance is.

When proteins are broken down, nitrogen is released when the amino acids are catabolized. Some of it is used by the body while most of it is converted to urea and excreted through urine, feces, sweat, and through hair/nail growth. A nitrogen balance is when the amount of nitrogen that is taken in by a person (through protein consumption) is equal to the amount of nitrogen that is excreted.

Dietary carbohydrates are digested into ______________ before absorption.

single sugar units (monosaccharides)