BM: Lipids Flashcards
Define hydrophobic substances and explain why they do not dissolve in water
Hydrophobic substances “fear” water and do not dissolve in it because they are non-polar and lack a charge. Water is polar, so it cannot attract non-polar molecules. Examples include oils, fats, and lipids.
describe the characteristics of hydrophilic substances
Hydrophilic substances “love” water and dissolve easily because they are polar or ionic, meaning they can form hydrogen bonds with water. Examples include salt, sugar, and ethanol.
explain what amphiphilic molecules are and give an example
Amphiphilic molecules have both hydrophilic and hydrophobic regions, allowing them to interact with water and fats. An example is phospholipids, which form cell membranes.
Identify the three types of lipids and describe their functions
Triglycerides: Store energy and provide insulation.
Phospholipids: Form the cell membrane.
Steroids: Act as hormones (e.g., testosterone) and regulate membrane fluidity (e.g., cholesterol).
explain how triglycerides are structured
Triglycerides consist of one glycerol molecule and three fatty acids. They store energy and are found in fats and oils.
describe the role of phospholipids in the plasma membrane
Phospholipids form a bilayer with hydrophilic heads facing water and hydrophobic tails facing inward. This structure creates a selective barrier for cell membranes.
explain the difference between saturated and unsaturated fats and their impact on health
Saturated fats: Solid at room temperature, raise LDL cholesterol, and increase cardiovascular risk (e.g., butter, lard).
Unsaturated fats: Liquid at room temperature, help lower LDL and raise HDL, supporting heart health (e.g., olive oil, avocados).
Describe how cholesterol regulates membrane fluidity in different temperatures
In warm temperatures, cholesterol decreases membrane fluidity by reducing the movement of fatty acid tails.
In cold temperatures, it prevents tight packing, increasing fluidity and preventing the membrane from becoming rigid.
Explain the difference between LDL and HDL cholesterol and their roles in health
LDL (Low-Density Lipoprotein): “Bad cholesterol,” transports cholesterol to cells, but excess leads to plaque buildup in arteries.
HDL (High-Density Lipoprotein): “Good cholesterol,” removes excess cholesterol from the bloodstream and transports it to the liver for excretion.
State two lifestyle changes that can help manage cholesterol levels
Eating a healthy diet (reducing saturated fats, increasing fiber) and regular exercise can help manage cholesterol levels by raising HDL and lowering LDL.
describe the structure and role of steroids in the body
Steroids have a structure of four fused carbon rings. Cholesterol, a steroid, regulates cell membrane fluidity, and sex hormones like testosterone control bodily functions.
explain the significance of the phospholipid bilayer’s selective permeability
The phospholipid bilayer allows essential molecules like oxygen and nutrients to enter while keeping harmful substances out, maintaining cell homeostasis.
Describe passive and active transport across the plasma membrane
Passive transport: Molecules move from high to low concentration without energy (e.g., diffusion).
Active transport: Molecules move against the concentration gradient, requiring energy (ATP).
Explain how smoking impacts cholesterol and cardiovascular health
Smoking lowers HDL cholesterol and damages arterial walls, increasing the risk of plaque buildup and cardiovascular diseases such as heart attacks and strokes.
Describe the difference between subcutaneous and visceral fat and their health implications
Subcutaneous fat: Located under the skin, acts as an insulator and energy reserve. Excess amounts can lead to obesity-related risks.
Visceral fat: Surrounds vital organs and regulates hormones. Excess visceral fat is linked to cardiovascular diseases and type 2 diabetes.
