Lipids and Membrane Proteins: CHEM311 Chapter 8

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What is the primary function of lipids in the cell?

Cell signaling
Structural support
DNA replication
Energy storage and release (correct)

Which type of lipid is characterized by a long hydrocarbon tail terminating with a carboxyl group?

Triacyl glycerol
Steroid
Phospholipid
Fatty acid (correct)

What is the main difference between saturated and unsaturated fatty acids?

Number of carbon atoms
Presence of carbon-carbon double bonds (correct)
Length of the hydrocarbon tail
Presence of a carboxyl group

Which of the following types of lipids is NOT mentioned in the chapter?

Glycoproteins (A) Signup and view all the answers

What is the purpose of the polar end of amphipathic membrane lipids?

To interact with water (B) Signup and view all the answers

What is the effect of cis-double bonds on the hydrocarbon chain of fatty acids?

Causes a 'kink' or 'bend' in the structure of the hydrophobic tail, reducing Van der Waal's and hydrophobic interactions (C) Signup and view all the answers

What is the physical state of stearate (C18:0) at 25°C?

Solid (B) Signup and view all the answers

What is the characteristic of fatty acids that are rich in 'trans-fat'?

They are solid at 25°C (C) Signup and view all the answers

What is the difference between saturated and unsaturated fatty acids in terms of their hydrophobic tails?

Saturated fatty acids have a more linear hydrophobic tail (B) Signup and view all the answers

What is the classification of fatty acids based on the presence of double bonds?

Saturated fatty acids have no double bonds, while unsaturated fatty acids have one or more (C) Signup and view all the answers

What is the characteristic of unsaturated fatty acids?

They have one or more double bonds between carbons. (C) Signup and view all the answers

What is the function of phospholipids in cells?

They form plasma membranes of cells. (C) Signup and view all the answers

What is the general structure of triglycerides?

One glycerol molecule linked to three fatty acids. (D) Signup and view all the answers

What is the characteristic of phospholipids in water?

They aggregate to form a lipid bilayer. (B) Signup and view all the answers

What is the difference between cis and trans configurations in unsaturated fatty acids?

Cis has chemical groups on the same side of the double bond. (A) Signup and view all the answers

What happens to the membrane's structure when heat is applied?

The membrane becomes more disordered (D) Signup and view all the answers

What is the characteristic difference between animal and plant membranes?

Plant membranes have a higher percentage of unsaturated fatty acids (C) Signup and view all the answers

What is the primary force driving the formation of lipid bilayers?

Hydrophobic interaction (B) Signup and view all the answers

What is the characteristic of membranes with a higher percentage of unsaturated fatty acids?

They are more fluid (A) Signup and view all the answers

What is the characteristic of prokaryotic membranes?

They are the most fluid (C) Signup and view all the answers

What is the function of kinks in the tails of phospholipids?

To keep the plasma membrane fluid across a range of temperatures (D) Signup and view all the answers

What is a characteristic of waxes?

They are solid at room temperature (B) Signup and view all the answers

What is the structure of steroids?

Four fused carbon rings (C) Signup and view all the answers

What is the function of cholesterol in the cell membrane?

To maintain membrane fluidity and structure (A) Signup and view all the answers

What is a characteristic of triglycerides?

They are amphipathic (C) Signup and view all the answers

What is the function of cholesterol in biological membranes?

To decrease the fluidity of membranes (D) Signup and view all the answers

What is the characteristic of proteins in the fluid mosaic model of biological membranes?

They are embedded in the membrane and can move laterally (D) Signup and view all the answers

What type of proteins are bound to the membrane by electrostatic interactions and can be removed by raising the ionic strength?

Peripheral proteins (A) Signup and view all the answers

What is the term for the structure of biological membranes, composed of a lipid bilayer with proteins, glycolipids, and steroids embedded in it?

Fluid mosaic model (D) Signup and view all the answers

Which of the following is NOT a function of membrane proteins?

Synthesize new membrane lipids (B) Signup and view all the answers

What is the primary function of HDL cholesterol in the body?

To absorb cholesterol in the blood and carry it back to the liver (D) Signup and view all the answers

What is the term given to LDL cholesterol?

Bad cholesterol (A) Signup and view all the answers

What happens to cholesterol when it is carried back to the liver by HDL?

It is flushed from the body (C) Signup and view all the answers

What is the characteristic of lipids that makes them difficult to dissolve in water?

Their low solubility in water (D) Signup and view all the answers

What is the term given to the structures formed by lipids in aqueous environments?

All of the above (D) Signup and view all the answers

What is the purpose of lipid bilayers in biological systems?

To form biological membranes (C) Signup and view all the answers

What is the result of high levels of HDL cholesterol in the body?

A decreased risk of heart disease and stroke (D) Signup and view all the answers

What is the term given to the lipoprotein that carries cholesterol from the liver to the body's tissues?

LDL (C) Signup and view all the answers

What is the effect of high levels of LDL cholesterol in the body?

An increased risk of heart disease and stroke (D) Signup and view all the answers

What is the role of lipids in the body?