Nutrition Exam 2

Lipids are fats and oils, categorized into triglycerides, phospholipids, and sterols.

A fatty acid consists of a hydrocarbon chain with a carboxyl group (-COOH) at one end and a methyl group (-CH3) at the other.

Saturated fats have no double bonds, while unsaturated fats contain one (monounsaturated) or more (polyunsaturated) double bonds.

Saturated fats are found in animal products like butter, meat, and dairy, as well as tropical oils like coconut and palm oil.

Trans fats are artificially created through hydrogenation, converting liquid oils into more solid fats, and are found in margarine and processed foods.

Triglycerides store energy, insulate and protect organs, and transport fat-soluble vitamins.

Phospholipids are key components of cell membranes and help emulsify fats in the body for digestion.

Sterols, including cholesterol, are a type of lipid involved in producing hormones, vitamin D, and bile acids.

Bile emulsifies fats in the small intestine, breaking them into smaller droplets for easier digestion by lipases.

Fats are absorbed into the intestinal cells, packaged into chylomicrons, and transported via the lymphatic system to the bloodstream.

Essential fatty acids (omega-3 and omega-6) must be obtained from the diet because the body cannot synthesize them. They are crucial for inflammation regulation and cell membrane function.

Omega-3s are found in fatty fish (like salmon), flaxseeds, walnuts, and chia seeds.

Omega-6s, found in vegetable oils, help with growth, reproduction, and inflammatory responses.

Saturated fats can raise LDL ("bad") cholesterol, increasing the risk of atherosclerosis and heart disease.

HDL ("good") cholesterol helps transport cholesterol from the arteries to the liver for excretion, reducing the risk of heart disease.

Trans fats raise LDL cholesterol and lower HDL cholesterol, significantly increasing the risk of heart disease.

Monounsaturated fats (found in olive oil, avocados) improve heart health by lowering LDL cholesterol and reducing inflammation.

Fat provides energy, supports cell membranes, insulates organs, and aids in the absorption of fat-soluble vitamins (A, D, E, K).

The recommended fat intake is 20-35% of total daily calories, with emphasis on unsaturated fats over saturated and trans fats.

Omega-3s reduce inflammation, lower blood pressure, improve heart health, and support brain function.

Proteins are made of amino acids, which contain a central carbon, an amino group, a carboxyl group, and a unique side chain.

There are 20 amino acids, 9 of which are essential, meaning they must be obtained from the diet.

A peptide bond is a chemical bond formed between the amino group of one amino acid and the carboxyl group of another.

Denaturation is the unfolding of a protein's structure due to heat, acid, or mechanical force, which alters its function (e.g., cooking an egg).

Proteins are digested by enzymes like pepsin in the stomach and proteases in the small intestine, breaking them into amino acids for absorption.

Amino acids are absorbed into the bloodstream and transported to the liver, where they are used for protein synthesis, energy, or conversion into glucose or fat.

Proteins perform various roles, including building muscle, enzymes, hormones, antibodies, and transport proteins (e.g., hemoglobin).

Nitrogen balance compares nitrogen intake to excretion. Positive balance indicates growth or muscle building, while negative balance suggests muscle breakdown or malnutrition.

High-quality proteins contain all essential amino acids (e.g., meat, eggs), while low-quality proteins lack one or more essential amino acids (e.g., legumes, grains).

Complementary proteins are combinations of plant-based proteins (e.g., rice and beans) that together provide all essential amino acids.

The RDA for protein is 0.8 grams per kilogram of body weight for adults, higher for athletes and pregnant women.

Protein turnover refers to the continuous process of breaking down and synthesizing proteins in the body.

Proteins form antibodies, which help the body identify and neutralize foreign invaders like bacteria and viruses.

PEM occurs when there is inadequate protein and energy intake, leading to conditions like marasmus and kwashiorkor.

The body synthesizes proteins through transcription (DNA to mRNA) and translation (mRNA to amino acids).

Protein deficiency can lead to muscle wasting, weakened immune function, stunted growth, and poor wound healing.

Excess protein is deaminated, with the nitrogen excreted as urea, and the remaining carbon skeleton converted into glucose or fat.

Plant-based proteins are rich in fiber, vitamins, and antioxidants, and they are lower in saturated fat, making them beneficial for heart health.

A complete protein contains all nine essential amino acids, found in foods like eggs, meat, dairy, and soy.

Proteins like albumin help maintain fluid balance by regulating osmotic pressure between blood and tissues.

Metabolism refers to all the chemical reactions in the body that convert food into energy or build and repair tissues.

ATP (adenosine triphosphate) is the body's main energy currency, storing and transferring energy for cellular processes.

Glycolysis is the anaerobic process of breaking down glucose into pyruvate, producing 2 ATP molecules.

In the presence of oxygen, pyruvate is converted into acetyl-CoA, which enters the citric acid cycle for further energy production.

In the absence of oxygen, pyruvate is converted into lactate through anaerobic glycolysis, which allows glycolysis to continue temporarily.

The citric acid cycle is a series of chemical reactions in the mitochondria that break down acetyl-CoA to produce ATP, NADH, FADH2, and CO2.

NADH and FADH2 carry high-energy electrons to the electron transport chain, where their energy is used to produce ATP.

Oxidative phosphorylation is the process in the mitochondria where ATP is produced using the energy from electrons transferred through the electron transport chain.

Fats are broken down into glycerol and fatty acids. Fatty acids undergo beta-oxidation to produce acetyl-CoA, which enters the citric acid cycle.

Beta-oxidation is the process of breaking down fatty acids into two-carbon units that form acetyl-CoA, which can then enter the citric acid cycle for ATP production.

Amino acids are deaminated (removal of the amino group), and their carbon skeletons are converted into intermediates that enter the citric acid cycle or are used to make glucose or ketones.

The electron transport chain is a series of protein complexes in the inner mitochondrial membrane where electrons from NADH and FADH2 are passed along to generate ATP.

Ketosis occurs when the body breaks down fat for energy, producing ketone bodies. It happens during prolonged fasting, low-carb diets, or uncontrolled diabetes.

Alcohol is metabolized primarily in the liver by enzymes like alcohol dehydrogenase, converting it into acetaldehyde, then into acetate, and finally into water and carbon dioxide.

Excess carbohydrates are stored as glycogen, but when glycogen stores are full, they are converted to fat. Excess fats and proteins are also stored as body fat.

Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources, such as amino acids and glycerol, especially during fasting or starvation.

Catabolism is the breakdown of molecules to release energy, while anabolism is the building of complex molecules from simpler ones, which requires energy.

Insufficient caloric intake slows metabolism, increases the breakdown of glycogen and fat for energy, and eventually leads to the breakdown of muscle proteins.

Excess energy is stored as glycogen in the liver and muscles, and when glycogen stores are full, the remaining energy is stored as fat in adipose tissue.

Insulin promotes glucose uptake and storage after meals, while glucagon stimulates the breakdown of glycogen and the release of glucose during fasting.