Chapter 6- Lipids, Membranes, and the First Cells

Cells

Cells

________ have many different types of pore- like channel proteins in their membranes.

Liposomes

________ provide a three- dimensional model that mimics a membrane- bound cell.

Micelles

________ and phospholipid bilayers form spontaneously in water- no input of energy is required.

Molecules

________ that contain only carbon and hydrogen are known as hydrocarbons.

Vesicles

________ are small bubble- like structures consisting of lipid bilayers surrounding a small amount of aqueous solution.

Gradients

________ are crucial to the function of the cell, in part because they make it possible for cells to engage in secondary active transport- also known as cotransport.

hydrophobic regions

Substances that contain both hydrophilic and ________ are amphipathic.

method

The ________ is called freeze- fracture electron microscopy because the steps involve freezing and fracturing the membrane before examining it with a scanning electron microscope (SEM), which produces images of an objects surface.

Fatty acid

________ is a simple lipid consisting of a hydrocarbon chain bonded to a polar carboxyl functional group.

Phospholipids

________ consist of a glycerol that is linked to a phosphate group and two hydrocarbon chains of either isoprenoids or fatty acids.

Osmosis

________ occurs only when solutions are separated by a membrane that permits water to cross, but holds back some or all of the solutes- that is, a selectively permeable membrane.

outside energy

When substances diffuse across a membrane in the absence of a(n) ________ source, it is known as passive transport.

Singer

________ and Nicolson suggested that membranes are a dynamic and fluid mosaic of phospholipids and different types of proteins.

glycerol

The ________ and fatty acid molecules become joined by what is called an ester linkage.

Fats

________ are nonpolar molecules composed of three fatty acids that are linked to a three- carbon molecule called glycerol.

Spontaneous movement of molecules

________ and ions is known as diffusion.

movement of water

The ________ and K+ are examples of facilitated diffusion through channel proteins, but facilitated diffusion can also occur through specialized membrane proteins called carrier proteins.

particular substance

Gated channels open or close in response to a signal, such as the binding of a(n) ________ or a change in the electrical voltage across the membrane.

solute concentrations

If ________ are equal on both sides of the membrane, the outside is said to be isotonic.

ester linkage

A(n) ________ occurs when two atoms (one of them carrying a double- bonded oxygen, often a carbonyl group) are linked together by an oxygen.

Solutes

________ move randomly in all directions, but when a concentration gradient exists, there is a net movement from regions of high concentration to regions of low concentration.

Hydrocarbon chains

________ that consist of only single bonds between the carbons are called saturated.

Steroids a family of lipids

________ distinguished by the bulky, four- ring structure.

electrical gradients

When considered together, concentration and ________ are called an electrochemical gradient.

Selective permeability

________ means that some substances cross a membrane more easily than other substances do.

active transport

Transport against a gradient is called ________.

membranes permeability

A(n) ________ is closely related to its level of fluidity, which is a measure of molecular mobility.

Micelles

________ tend to form from free fatty acids or other simple amphipathic lipids with single hydrocarbon chains.

The movement of water is a special case of diffusion that is given its own name

osmosis