Bio 4 & 5 & 8

______are involved in many different cellular functions, including cell compartmentalization and the selective uptake of ions and molecules.

Biological membranes

The double bonds in unsaturated lipids create ______ in the nonpolar tails, making it more difficult for neighboring lipids to interact.

kinks

One layer, or half of a phospholipid bilayer, is termed a(n

leaflet

Antiporter

moves two substances in opposite directions

When a double bond is present in the nonpolar tail of a phospholipid, the lipid is said to be

unsaturated.

A lipid bilayer is composed of ______ leaflet(s).

2

What is an aquaporin?

A channel protein for water

Lipid-anchored protein

A lipid molecule is covalently attached to an amino acid side chain of the membrane protein.

Transmembrane protein

A segment of amino acids is inserted into the phospholipid bilayer.

Uniporter

A single solute moves in one direction.

To move a substance through a membrane against a concentration gradient you need

A transport protein A source of energy

Cholesterol in a membrane has which of the following effects?

At a high temperature, it makes the membrane less fluid; at a low temperature, it makes the membrane more fluid.

How is a lipid-anchored protein attached to the membrane?

Covalently bound to an amino acid side chain within the protein

true statements comparing simple and facilitated diffusion.

Facilitated diffusion, but not simple diffusion, requires a transport protein. Both simple and facilitated diffusion require concentration gradients.

What property of biological membranes describes the ability of individual molecules to move within the membrane?

Fluidity

Which of the following can readily diffuse across the cell membrane?

Gases Small, uncharged molecules

What is the significance of being able to gate a channel protein?

Gating a channel protein allows the cell to regulate the movement of solutes.

Which of the following statements is correct about a biological membrane that is fluid?

Individual molecules can move within the membrane.

When the concentrations of dissolved particles (solutes) on both sides of the plasma membrane are equal, the two solutions are said to be

Isotonic

How does cholesterol affect the plasma membrane at low temperatures?

It makes the membrane more fluid and prevents freezing.

Proteins that associate with a membrane because they have a lipid molecule that is covalently attached to a side chain with the protein are called

Lipid-anchored proteins

Which of the following statements are consistent with the fluid-mosaic model?

Many membrane proteins move within the plane of the membrane. Membranes are mainly composed of proteins and phospholipids. Phospholipids can move within the plane of the membrane.

Diffusion

Movement of a substance from a region where its concentration is high to a region where its concentration is low

Facilitated diffusion

Movement of a substance from a region where its concentration is high to a region where its concentration is low through a passageway provided by a transport protein

Active transport

Movement of a substance from a region where its concentration is low to a region where its concentration is high with the aid of a transport protein and a source of energy

Peripheral membrane protein

Noncovalent associations form with phospholipids or other membrane proteins

What are likely binding sites for peripheral membrane proteins?

Polar head groups of phospholipids Hydrophilic regions of integral membrane proteins

active transport involves a pump that uses energy from ATP to transport solutes against a gradient.

Primary or Direct

The three main types of macromolecules that comprise the plasma membrane are

Proteins, carbohydrates, and phospholipids.

What type of transport uses a pre-existing gradient to drive the transport of another molecule?

Secondary active transport

What separates the internal contents of a cell from the extracellular environment?

The plasma membrane

The plasma membrane of a cell is considered to be

The plasma membrane of a cell is considered to be

How do transporters differ from channel proteins?

Transporters must change conformation to allow solutes to cross the membrane. Need help? Review these concept resources. Feedback Next QuestionReading

Lipid-anchored proteins typically associate with:

a membrane

What is the basic structure of the plasma membrane?

a phospholipid bilayer

A phospholipid molecule consists of:

a polar head and two nonpolar tails

The transport of a substance that requires an input of energy is called transport.

active

Which type of transport requires a source of energy and a transport protein?

active transport

What types of transport require a transport protein?

active transport and facilitated diffusion

In multicellular organisms, intercellular channels such as gap junctions in animals and plasmodesmata in plants

allow the movement of substances between adjacent cells.

Phospholipids have both hydrophobic and hydrophilic components. As such, they are said to be

amphipathic

Cellular membranes play a role in which of the following cell functions?

anchoring the cytoskeleton cell and nuclear division protein sorting cell signaling

A(n) ______ is a special channel protein that allows the facilitated diffusion of water.

aquaporin

signaling, a cell can respond to its own signal.

autocrine

A key component of anchoring junctions are proteins called CAMs, which stands for

cell adhesion molecules

The anchoring junction proteins that form the connections between cells are called:

cell adhesion molecules

At what level does a receptor interpret signals?

cellular

Unlike transporters, proteins provide an open passageway all the way across the plasma membrane.

channels

Proteins that assist in the movement of substances across membranes can be classified into two types based on how they move solutes across a membrane: and Listen to the complete question Need help? Review these concept resources.

channels and transporters

What is the short, rigid molecule produced by animal cells that is involved in membrane fluidity?

cholesterol

A key similarity between simple and facilitated diffusion is that both require

concentration gradients.

Signals passing through a cell junction from the cytosol of one cell to an adjacent cell is a description of

direct intracellular signaling,

An unsaturated lipid contains

double bonds

the signaling molecule can affect cells at a distance from the cell that secreted the signal.

endocrine

Vesicular movement of large molecules into cells is called , and vesicular movement of large molecules out of cells is called .

endocytosis, exocytosis

According to the ______ model, membrane proteins and lipids are able to move relative to one another within the plasma membrane.

fluid-mosaic

In animals, junctions form channels between cells that allow cells to communicate with one another.

gap

When channel proteins are transporters____, it means they can open and close to regulate the movement of ions and molecules across the cell membrane.

gated

Membrane fluidity is increased when membrane lipids

have shorter nonpolar tails.

Movements that keep the phospholipid nonpolar tail within the region of the bilayer are energetically favorable.

hydrophobic

Movements that keep the phospholipid nonpolar tail within the region of the bilayer are energetically favorable.

hydrophobic.

Which of the following changes in lipid composition would be expected to increase the fluidity of a phospholipid bilayer?

incorporating more cholesterol at low temperatures Incorporating more unsaturated fatty acids

A membrane protein that has a portion integrated into the hydrophobic region of the membrane is called a(n) ______ membrane protein.

integral

While individual cells have many types of transport proteins in their membranes, the cells of multicellular organisms also may have ______ that allow the movement of substances between adjacent cells.

intercellular channels

The presence of a double bond in a phospholipid tail makes the membrane more fluid because

it prevents phospholipids from packing tightly.

At a high temperature, cholesterol makes a membrane ______ fluid.

less

A membrane protein with a lipid covalently bound to an amino acid side chain within the protein is known as a(n)

lipid-anchored protein.

Which of the following proteins are integral membrane proteins?

lipid-anchored proteins transmembrane proteins

In osmosis, water moves from areas of

low solute concentration to areas of high solute concentration.

What are functions of the selectively permeable plasma membrane?

maintain a proper balance of ions within the cell remove waste products from within the cell maintain a proper supply of essential molecules such as glucose and amino acids

Shorter nonpolar tails make the membrane ______ fluid.

more

Because the plasma membrane contains lipids, proteins, and carbohydrates, it is often described as a(n)

mosaic.

Symporter

moves two substances in the same direction

The fatty acid tails of phospholipids are ______ and are found in the ______ of the phospholipid bilayer.

nonpolar; interior.

a secreted signaling molecule affects nearby target cells but not the cell that secreted the signal

paracrine

Small, uncharged molecules pass through the membrane via

passive diffusion.

Proteins that associate with the plasma membrane through non-covalent interactions with phospholipids or transmembrane proteins are called

peripheral membrane proteins.

The selective___of the plasma membrane allows the cell to maintain a favorable internal environment.

permeability

The plasma membrane consists of a(n)

phospholipid bilayer

The internal and external environments of a cell are separated by a structure known as

plasma membrane

What type of cell junctions form channels between adjacent plant cells?

plasmodesmata

What is the result of placing a plant cell into a hypertonic solution?

plasmolysis

When a plant cell is placed into a hypertonic extracellular solution, water leaves the cell, and the plasma membrane pulls away from the cell wall in a process called

plasmolysis

Phospholipids have a ______ head region that will interact with aqueous environments.

polar or hydrophilic

Which of the following types of transport involves pumping ions against a gradient using ATP as a source of energy?

primary active transport

What are the three molecular components of cellular membranes?

proteins phospholipids carbohydrates

The cell membrane is referred to as a mosaic because it is a mixture of what types of molecules?

proteins, carbohydrates, lipids.

Communication at the cellular level involves receiving and sending signals as well as their interpretation. For this to occur, a signal must be recognized by a cellular protein called a

receptor protein

Which of the following movements of a phospholipid are energetically favorable within the bilayer?

rotational movements lateral movements

In animals, junctions form channels between cells that allow cells to communicate with one another.

secondary

All cells are surrounded by a permeable plasma membrane, meaning that the membrane allows the passage of some molecules and ions but not others.

selectively

The fluidity of the plasma membrane can be increased by incorporating fatty acids with ______ tails or by incorporating ______ lipids.

shorter ; unsaturated

An agent that influences the properties of cells is called a(n)

signal

The process through which cells detect, interpret and respond to signals in their environment is called cell

signaling

Transporters are classified by the number of___ they bind, as well as the____ of transport.

solutes , direction

In a solution, the ions and molecules that are dissolved are called the molecules, and the liquid in which they are dissolved is called the .

solutes , solvents

Water is considered to be a ______ that dissolves ______ molecules.

solvent; solute

Transmembrane proteins are able to span the hydrophobic portion of the bilayer because they have

stretches of nonpolar amino acids.

Transporter proteins are classified by which of the following? Select all that apply. Multiple select question. the number of solutes they bind the rate of transport the type of solutes they bind

the number of solutes they bind the direction of transport

Membrane proteins that span both leaflets of the lipid bilayer are called

transmembrane proteins.