Lecture 5 Flashcards
1
Q
Key Chemical Properties of Fatty Acids:
A
- Fatty acids are important lipids primarily used as fuel. They vary in chain length and saturation, which affects their physical properties:
o Saturated fatty acids: Have no double bonds, are linear, solid at room temperature, and have a high melting point (e.g., in pork, beef, butter).
o Unsaturated fatty acids: Have one or more double bonds, are liquid at room temperature, and can be further classified as monounsaturated or polyunsaturated.
2
Q
Major Lipids and Their Biochemical Functions:
A
- Free Fatty Acids: Used primarily as fuel and components of membrane lipids.
- Triacylglycerols: The storage form of fatty acids.
- Phospholipids: Key components of cell membranes, consisting of a polar head and nonpolar tails.
- Glycolipids: Important membrane components that are bound to carbohydrates.
- Steroids: Function as hormones (e.g., estrogen, testosterone), and cholesterol, a key membrane components.
3
Q
Role of the Liver, Gallbladder, and Pancreas in Lipid Metabolism:
A
- Liver: Produces bile (about 1L/day) that helps emulsify fats, making them more accessible for digestion.
- Gallbladder: Stores and concentrates bile, releasing it into the duodenum to aid in lipid digestion.
- Pancreas: Secretes pancreatic lipases into the small intestine, which break down triglycerides into fatty acids and monoglycerides.
4
Q
Chylomicron Formation:
A
- Chylomicrons are large lipoprotein particles formed in intestinal cells. They consist of reassembled triglycerides, cholesterol, and fat-soluble vitamins, surrounded by phospholipids and proteins (apolipoproteins), making them water-soluble. Chylomicrons transport dietary lipids from the intestines into the lymphatic system and eventually into the bloodstream.
5
Q
Lipid Metabolism in a Fed and Fasted State:
A
- Fed State: Excess dietary fats and glucose are stored as triglycerides in adipose tissue through a process called lipogenesis when energy intake exceeds demands.
- Fasted State: Stored triglycerides are broken down into glycerol and fatty acids through lipolysis during periods of fasting (e.g., between meals, during exercise).
6
Q
Lipid Digestion in Infants:
A
- Infants digest lipids efficiently due to several adaptations:
o They have high levels of lingual and gastric lipases, which are more crucial in infants than adults.
o Breast milk contains lipases that are activated in the baby’s small intestine to assist in fat digestion.
o Despite low bile and pancreatic enzyme secretion, these adaptations help infants digest fats, which are crucial for growth and brain development.
7
Q
What are the Monomers of Lipids?
A
- The basic building blocks or monomers of lipids are fatty acids and glycerol. Lipids, such as triglycerides, are made of fatty acids attached to a glycerol backbone.
8
Q
Differences Between Monoglyceride, Diglyceride, and Triglyceride:
A
- Monoglyceride: A lipid molecule consisting of one fatty acid attached to a glycerol molecule.
- Diglyceride: A lipid molecule consisting of two fatty acids attached to a glycerol molecule.
- Triglyceride: A lipid molecule consisting of three fatty acids attached to a glycerol molecule, and it is the most common form of fat storage in the body.
9
Q
The Five Classes of Lipids:
A
- Free Fatty Acids: Used as fuel and membrane components.
- Triacylglycerols (Triglycerides): The storage form of fatty acids.
- Phospholipids: Major components of cell membranes with polar heads and nonpolar tails.
- Glycolipids: Membrane lipids that are bound to carbohydrates.
- Steroids: Include hormones like estrogen and testosterone, and cholesterol, which is vital for cell membranes.
10
Q
Meaning of Saturated Fatty Acids and Unsaturated Fatty Acids:
A
- Saturated Fatty Acids: Fatty acids that have no double bonds between carbon atoms, resulting in straight chains. They are solid at room temperature and found in animal fats like butter and meat.
- Unsaturated Fatty Acids: Fatty acids that have one or more double bonds in the carbon chain, causing bends. These are typically liquid at room temperature and found in plant oils. They can be monounsaturated (one double bond) or polyunsaturated (multiple double bonds).
11
Q
Enzymes Involved in Lipid Digestion:
A
- Lingual Lipase: Secreted in the mouth and initiates the breakdown of triglycerides.
- Gastric Lipase: Produced in the stomach and continues triglyceride digestion.
- Pancreatic Lipase: Secreted by the pancreas and plays a major role in breaking down triglycerides into fatty acids and monoglycerides in the small intestine.
12
Q
The Role of the Gallbladder:
A
- The gallbladder stores and concentrates bile produced by the liver and releases it into the small intestine to aid in lipid digestion by emulsifying fats, making them more accessible to digestive enzymes.
13
Q
Meaning of Micelles and Chylomicrons:
A
- Micelles: Structures formed by bile salts surrounding the products of fat digestion (fatty acids and monoglycerides). Micelles help transport these products to the intestinal cells for absorption.
- Chylomicrons: Lipoprotein particles formed in the intestinal cells that carry reassembled triglycerides, cholesterol, and fat-soluble vitamins through the lymphatic system and into the bloodstream. They are essential for transporting dietary lipids throughout the body.
14
Q
Lipid Digestion in Infants:
A
- Infants rely on lingual and gastric lipases more than adults for fat digestion. Additionally, breast milk contains lipase enzymes that are activated in the infant’s small intestine. These adaptations allow infants to efficiently digest fats, which are critical for growth and brain development.
15
Q
In order to form the various lipids which keep us alive, we must first digest the lipids we take in in our diet. What is the name for the group of enzymes responsible for this?
a. Proteases
b. Amylases
c. Lipases
d. Lactases
A
C
