2.3 Carbohydrates and lipids Flashcards
Definition of Monosaccharides
The simplest types of carbohydrates that cannot be hydrolyzed to simpler carbohydrates. Examples include glucose, fructose, and galactose.
Condensation Reactions
Two monosaccharide monomers join together, releasing a water molecule and forming a disaccharide plus water. This reaction forms glycosidic bonds.
Polysaccharides’ Structure and Function
Cellulose: structural component in plant cell walls. Starch: energy storage in plants. Glycogen: energy storage in animals.
Amylose vs. Amylopectin
Amylose is a linear form of starch, while amylopectin is branched. Amylopectin makes up about 70-80% of starch granules.
Saturated vs. Unsaturated Fatty Acids
Saturated fatty acids have no double bonds between carbon atoms, making them solid at room temperature. Unsaturated fatty acids have one or more double bonds, making them liquid at room temperature.
Cis vs. Trans Fatty Acids
In cis fatty acids, hydrogen atoms are on the same side of the carbon–carbon double bond, making them healthier. Trans fatty acids have hydrogen atoms on opposite sides, posing health risks.
Energy Content of Lipids vs. Carbohydrates
Lipids provide about twice as much energy per gram as carbohydrates (37 kJ/g for fats vs. 17 kJ/g for carbohydrates) and are stored without water, making them more efficient for energy storage.
Health Risks of Trans Fats and Saturated Fatty Acids
Both are linked to increased risk of coronary heart disease (CHD) due to their contribution to the formation of atherosclerotic plaques in arteries.
Calculating BMI
BMI = weight (kg) / (height (m))^2. It’s a measure of body fat based on height and weight.
Health Risks by BMI Category
Underweight (<18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), Obese Class I (30.0–34.9), Obese Class II (35.0–39.9), and Obese Class III (≥40.0).
Monounsaturated vs. Polyunsaturated Fatty Acids
Monounsaturated fatty acids contain one double bond in their hydrocarbon chain, making them liquid at room temperature. Polyunsaturated fatty acids contain more than one double bond, offering greater fluidity and health benefits compared to saturated fats.
Cis and Trans Isomers of Unsaturated Fatty Acids
Unsaturated fatty acids can exist as cis or trans isomers, which differ by the arrangement of hydrogen atoms around the double bond. Cis isomers have hydrogen atoms on the same side, while trans isomers have them on opposite sides. Cis fats are generally healthier than trans fats.
Formation of Triglycerides
Triglycerides are formed by a condensation reaction involving three fatty acids and one glycerol molecule. This reaction results in the formation of three ester bonds and the release of water, creating a triglyceride, a type of lipid used for long-term energy storage.
Evaluating Evidence on Lipids’ Health Effects
To evaluate health claims about lipids, consider the correlation between lipid intake and health outcomes, the statistical significance of data, sample size, control of variables, dietary levels of lipids used in studies, and whether the study reflects a broad population. Look for peer-reviewed studies and meta-analyses for reliable information.
Using a Nomogram to Determine BMI
A nomogram for BMI allows individuals to find their BMI by drawing a line between their height and weight on a scaled chart. The point where the line intersects the BMI scale provides an immediate visual representation of the individual’s BMI category, offering an alternative to calculation.
