Temperature Transition in Lipid Bilayers and Membrane Fluidity

What is the role of kinks in the tails of phospholipids in the plasma membrane?

They increase the permeability of the membrane to ions
They provide a barrier to the entry of water
They keep the plasma membrane fluid across a range of temperatures (correct)
They help to regulate the movement of proteins within the membrane

What is the characteristic feature of steroids?

They contain four fused carbon rings (correct)
They are composed of a single carbon ring
They have a long chain of fatty acids attached to a glycerol backbone
They have a polar head and a nonpolar tail

What is the function of cholesterol in the cell membrane?

It is a precursor molecule for the synthesis of other steroids
It provides a barrier to the entry of water
It helps to regulate the movement of proteins within the membrane
It is a component of the cell membrane, providing structural support and regulating fluidity (correct)

What is the characteristic of the functional groups attached to the carbon skeleton of steroids?

They can be polar or nonpolar (A) Signup and view all the answers

What is the relationship between testosterone and estrogen?

They differ only in the functional groups attached to the same carbon skeleton (B) Signup and view all the answers

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

The presence or absence of carbon-carbon double bonds (A) Signup and view all the answers

What is the characteristic of most membrane lipids?

They are amphipathic, having a non-polar end and a polar end (A) Signup and view all the answers

What is the primary function of lipids in cell membranes?

To provide structural support and fluidity (B) Signup and view all the answers

Which type of lipid is commonly found in biological membranes?

Phospholipids (C) Signup and view all the answers

What is the main characteristic of fatty acids in terms of their carbon atom number?

They usually have an even number of carbon atoms (A) Signup and view all the answers

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

Hydrophobic interaction (A) Signup and view all the answers

Which type of fatty acids are more likely to make a membrane more fluid?

Unsaturated fatty acids (C) Signup and view all the answers

What is a characteristic of animal membranes that is not typical of plant membranes?

Presence of cholesterol (D) Signup and view all the answers

What is the term used to describe the difference in lipid composition between the inner and outer layers of a lipid bilayer?

Lipid bilayer asymmetry (D) Signup and view all the answers

Which type of cell membranes are the most fluid?

Prokaryotic cell membranes (C) Signup and view all the answers

What is the primary function of cholesterol in biological membranes?

To affect the fluidity of the membrane (C) Signup and view all the answers

Which type of membrane protein is associated with one side of the membrane and bound by electrostatic interactions?

Peripheral protein (B) Signup and view all the answers

What is the characteristic of the lipid bilayer structure in the fluid mosaic model of biological membranes?

A double layer of lipids with proteins and cholesterol embedded in it (D) Signup and view all the answers

What is the difference between integral and peripheral membrane proteins in terms of their binding to the membrane?

Integral proteins are bound tightly to the interior of the membrane, while peripheral proteins are bound by electrostatic interactions (A) Signup and view all the answers

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

There is lateral motion of components in the membrane, with proteins and lipids moving along the plane of the membrane (C) Signup and view all the answers

Which type of protein is rhodopsin?

Integral protein (D) Signup and view all the answers

What is the primary source of energy for primary active transport?

Hydrolysis of ATP (A) Signup and view all the answers

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

Number of double bonds between carbon atoms (C) Signup and view all the answers

In which type of transport is a molecule or ion carried across the membrane by a carrier/channel protein?

Facilitated diffusion (B) Signup and view all the answers

What is the arrangement of phospholipids in a lipid bilayer?

Polar phosphate heads oriented towards the water, nonpolar fatty acid tails oriented away from water (C) Signup and view all the answers

What is the role of the modified phosphate group in a phospholipid?

Acts as a polar and hydrophilic head (B) Signup and view all the answers

What is the driving force behind secondary active transport?

Electrochemical gradient (B) Signup and view all the answers

What is the result of the binding of Na+ ions to the enzyme in the Na+/K+ ATPase mechanism?

Phosphorylation and release of ADP (D) Signup and view all the answers

What is the function of phospholipids in cells?

Forming the plasma membranes of cells (C) Signup and view all the answers

What is a characteristic of triglycerides?

They are composed of a glycerol molecule linked to three fatty acids (C) Signup and view all the answers

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

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

What is the consequence of high levels of LDL cholesterol in the bloodstream?

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

What is the primary characteristic of lipids in an aqueous environment?

Low solubility in water, forming structures such as monolayers and bilayers (B) Signup and view all the answers

What is the relationship between lipid bilayers and biological membranes?

Lipid bilayers are a component of biological membranes (B) Signup and view all the answers

What is the role of the liver in HDL cholesterol function?

To flush HDL cholesterol from the body (C) Signup and view all the answers

What is the effect of high levels of HDL cholesterol on the risk of heart disease and stroke?

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

What is the primary function of lipoproteins in the bloodstream?

To transport cholesterol throughout the body (B) Signup and view all the answers

What is the consequence of high levels of LDL cholesterol in the arteries?

Increased risk of heart disease and stroke (B) Signup and view all the answers

What is the relationship between lipoproteins and cholesterol in the bloodstream?

Lipoproteins carry cholesterol throughout the body (A) Signup and view all the answers

What is the primary characteristic of HDL cholesterol?

HDL cholesterol absorbs cholesterol in the blood and carries it back to the liver (A) Signup and view all the answers