PHRM246 Introduction to Biochemistry: Lipids

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Questions and Answers

What characterizes saturated fatty acids?

They are always liquid at room temperature.

They are completely saturated with hydrogen atoms. (correct)

They contain at least one double bond.

They contain an even number of carbon atoms. (correct)

What is the process of saponification primarily used for?

To synthesize complex lipids from simple lipids.

To create fatty acids from triglycerides.

To produce glycerol and soap from triglycerides. (correct)

To hydrolyze fatty acid salts into alcohols.

Which statement is true regarding simple lipids?

They consist of only fatty acids without alcohol.

They are more complex than complex lipids.

They cannot undergo hydrolysis.

They consist of alcohol and one or more fatty acids. (correct)

Which type of fatty acid does not have any double bonds?

Lauric acid Signup and view all the answers

What primarily determines the water solubility of lipids?

The hydrophobic part of the molecule. Signup and view all the answers

Which fatty acid is characterized by having 16 carbon atoms?

Palmitic acid Signup and view all the answers

What does hydrogenation primarily produce when reacting with alkenes?

More saturated fats Signup and view all the answers

What is the primary characteristic of olestra?

It causes loss of fat-soluble vitamins. Signup and view all the answers

What is the role of hydrogen in the process of hydrogenation?

It adds hydrogen atoms to alkenes. Signup and view all the answers

Which of the following describes the structure of phosphoglycerides?

Glycerol, 2 fatty acids, phosphate, and another alcohol Signup and view all the answers

What is a common side effect of olestra consumption?

Loss of fat-soluble vitamins Signup and view all the answers

How does the structure of artificial fats differ from natural fats?

They are produced from synthetic compounds. Signup and view all the answers

Myristyl palmitate is classified as which type of compound?

Waxes Signup and view all the answers

What property does hydrogenation confer to vegetable oils when they are transformed into margarine?

Enhanced stability and texture Signup and view all the answers

What component is shared by both phospho-glycerides and sphingolipids?

Fatty acids Signup and view all the answers

Which of the following alcohols is used in the structure of phosphoglycerides?

Ethanolamine Signup and view all the answers

What is the primary function of dipalmitoyl phosphatidyl choline?

Surfactant in lungs Signup and view all the answers

Sphingomyelin is primarily associated with which type of cells?

Neurons Signup and view all the answers

Which of the following statements about phosphoglycerides is true?

They are esters of glycerol and multiple fatty acids. Signup and view all the answers

What role does phosphatidyl serine play in cellular function?

Participates in apoptosis signaling Signup and view all the answers

Which structural feature differentiates sphingolipids from phosphoglycerides?

Presence of sphingosine Signup and view all the answers

What is true about the polar head group of sphingomyelin?

It contains either phospho-choline or phospho-ethanolamine. Signup and view all the answers

Which of the following best describes phospholipids?

Have a hydrophobic tail and a hydrophilic head. Signup and view all the answers

What is the composition of ceramide?

Sphingosine and fatty acid Signup and view all the answers

What is a major characteristic of sphingomyelins compared to phosphatidyl-cholines?

They have no net charge on their head groups. Signup and view all the answers

What specific role do glycolipids play in cellular function?

They serve as markers for cellular recognition. Signup and view all the answers

What makes up the lipid bilayer of biological membranes?

Non-polar phospholipid tails between polar heads. Signup and view all the answers

Cerebrosides are formed from which components?

Sphingosine, fatty acid, and carbohydrate. Signup and view all the answers

Which of the following statements is true about biological membranes?

Phosphoglycerides make up the majority of lipids. Signup and view all the answers

What is a key distinction of glycolipids compared to other lipids?

They are lipids that have carbohydrates attached. Signup and view all the answers

Study Notes

Overview of Lipids

Biological compounds soluble in non-polar solvents.
Classified into simple (alcohol + fatty acids) and complex lipids (alcohol + fatty acids + additional components).

Lipid Classification and Reactions

Saponification: Reaction of triglycerides with sodium/potassium hydroxide yielding soap and glycerol.
Fatty acids: linear molecules typically containing 10-20 carbon atoms with even numbers and a carboxyl functional group.
Types of fatty acids: saturated (no double bonds) and unsaturated (contain C=C bonds).

Water Solubility and Properties

Lipids are hydrophobic, forming micelles in water, which contributes to their insolubility.

Key Saturated Fatty Acids

Lauric: 12 carbons, 0 C=C
Myristic: 14 carbons, 0 C=C
Palmitic: 16 carbons, 0 C=C
Stearic: 18 carbons, 0 C=C
Saturated fats are solid at room temperature due to no double bonds, fully saturated with hydrogen.

Hydrogenation Process

Involves the reaction of alkenes with hydrogen (H2) in the presence of platinum to increase saturation, often converting plant oils to margarine.

Artificial Fats

Simpless: Micro-particle proteins, smooth texture, not heat stable, low caloric value.
Olestra: A non-digestible polymer of sucrose and fatty acids causing adverse effects like nutrient malabsorption and digestive issues.

Waxes and Phosphoglycerides

Waxes: Combine long-chain fatty acids with long-chain alcohols (e.g., myristyl palmitate).
Phosphoglycerides: Comprise glycerol, 2 fatty acids, and phosphate group; key components of cell membranes.

Alcohols in Phosphoglycerides

Common alcohols: Choline, serine, ethanolamine.
Phosphatidylcholine (Lecithin): Used as an emulsifier, crucial in lung surfactant production.

Sphingolipids

Composed of sphingosine, fatty acids, and additional structures (e.g., choline).
Sphingomyelin: Predominantly found in the myelin sheath around neurons, a significant component of cellular membranes.

Glycolipids

Combinations of lipids and carbohydrates provide energy and cellular recognition markers.
Cerebroside: A type of glycolipid consisting of sphingosine, fatty acid, and carbohydrate.

Biological Membranes

Composed of approximately 60% lipids (mainly phosphoglycerides and cholesterol) and 40% proteins, forming a lipid bilayer structure.

Cholesterol and Lipoproteins

Cholesterol sources include dietary intake and endogenous synthesis in the liver.
Essential for cell membrane integrity, hormone production, and bile synthesis.
High levels are linked to heart disease.
Transported as lipoproteins: HDL, LDL, VLDL, and chylomicrons.

Bile Salts

Formed from cholesterol, act as emulsifying agents for fat digestion, and play a role in cholesterol excretion.
Gallstones may form from concentrated cholesterol.

Hormones Derived from Cholesterol

Adreno-corticoids:
- Glucocorticoids (e.g., cortisol) regulate glucose and inflammation.
- Mineralocorticoids (e.g., aldosterone) maintain sodium and chloride levels.
Sex hormones:
- Testosterone: Involved in male reproductive functions and muscle growth.
- Anabolic steroids: Artificial testosterone with potential negative side effects.
- Estrogens and progesterone: Regulate female reproductive cycles.

Prostaglandins

Function similarly to hormones, influencing processes such as inflammation, fever regulation, and labor induction.
Synthesis can be inhibited by medications like aspirin.

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Description

This quiz explores the essential concepts of lipids in biochemistry, focusing on their classification and chemical properties. You will learn about simple and complex lipids, their composition, and processes like saponification. Prepare to test your knowledge of these vital biological compounds.