BIO 1010 Chapter 5 - Membrane Structure and Transport

A comprehensive set of 100 flashcards covering membrane structure, types of transport (passive, active, bulk), and osmosis/tonicity based on Chapter 5 lecture notes.

What is the main molecule that makes up the plasma membrane?

Phospholipids

Which way does passive transport move molecules relative to the concentration gradient?

High -> low

Does passive transport require $ATP$?

No

Which way does active transport move molecules relative to the concentration gradient?

Low -> high

What is required for active transport to move molecules?

Energy

What is the specific term for the movement of water?

Osmosis

What part of a phospholipid likes water?

A hydrophilic head

What part of a phospholipid avoids water?

Hydrophobic fatty acid tails

How are phospholipids arranged in the plasma membrane?

They form a bilayer

Where do the hydrophilic heads of phospholipids face in the cell membrane?

The watery outside and inside of the cell

Which way do the hydrophobic tails of phospholipids point?

Inward away from water

Besides phospholipids, what is another major key molecule found in the plasma membrane?

Proteins

Identify two other molecules found in the plasma membrane besides phospholipids and proteins.

Cholesterol and carbohydrates

What characterizes a transmembrane protein?

It goes all the way through the membrane

Where is a peripheral protein located in the membrane?

It sits on one side of the membrane surface

What is a glycoprotein?

A protein with a carbohydrate chain attached

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

By a lipid/fatty acid anchor

What is the primary function of cholesterol in the plasma membrane?

It helps stabilize the membrane

How does cholesterol affect membrane fluidity?

It keeps membrane fluidity at the right level

Which model describes the arrangement of molecules in the plasma membrane?

The fluid mosaic model

All molecules must pass through the _________________ to exit or enter the cell.

Plasma membrane

What term describes the plasma membrane's ability to be picky about which molecules pass through?

Selectively permeable

Do molecules in the cell constantly move?

Yes, molecules are constantly moving randomly

What is the definition of a concentration gradient?

A difference in concentration between two areas

In a concentration gradient, molecules move from ________________ concentration to ________________ concentration.

High to low

What is the definition of diffusion?

The movement of molecules from high concentration to low concentration

What state have molecules reached when they are equally distributed?

Equilibrium

How does molecule size affect the rate of diffusion?

Smaller molecules diffuse faster; larger molecules diffuse slower

How does the steepness of a concentration gradient affect the rate of diffusion?

A steeper concentration gradient causes faster diffusion

What effect does a smaller concentration gradient have on the rate of diffusion?

It causes slower diffusion

Name one nonpolar molecule that will easily pass through the plasma membrane.

Oxygen ($O_2$)

Name another nonpolar molecule that will easily pass through the plasma membrane.

Carbon dioxide ($CO_2$)

List any one type of molecule that does not easily pass through the plasma membrane.

Glucose, ions such as $Na^+$, or large polar molecules

On what is a chemical gradient based?

Concentration difference

What two factors are included in an electrochemical gradient?

Concentration difference and electrical charge difference

What is the term used to describe the diffusion of water?

Osmosis

What is the term for anything dissolved in a liquid?

Solute

What are the liquids that molecules dissolve in called?

Solvents

In the context of osmosis, what is the term for a solution with more water?

Hypotonic

In the context of osmosis, what is the term for a solution with less water?

Hypertonic

What is the term for two solutions with equal concentrations of water?

Isotonic

What happens to a cell if it is placed in a hypotonic solution?

It will swell (water will move in)

What happens to a cell if it is placed in a hypertonic solution?

It will shrink (water will exit)

Does a solution with more water have a higher or lower concentration of solutes?

Less solute (lower concentration)

What is the term for shrinking in animal cells?

Crenation

What is the term for swelling or bursting in animal cells?

Lysis

What is the solute and water balance of an outside solution that is hypotonic?

Less solute / more water outside

What is the water movement when a cell is in a hypotonic solution?

Water moves into the cell

What is the result for an animal cell in a hypotonic solution?

Cell swells; may lyse

What is the memory pattern for a hypotonic solution result?

HypO = cell Opens / swells

What is the solute and water balance of an outside solution that is hypertonic?

More solute / less water outside

What is the water movement when a cell is in a hypertonic solution?

Water moves out of cell

What is the result for an animal cell in a hypertonic solution?

Cell shrinks; crenates

What is the memory pattern for a hypertonic solution result?

Hyper = water exits

What is the solute and water balance for an isotonic solution?

Equal solute and water

What is the water movement when a cell is in an isotonic solution?

Water moves equally both ways

What is the result for an animal cell in an isotonic solution?

Cell stays normal

What is the memory pattern for an isotonic solution?

Iso = equal

What type of molecules located in the plasma membrane help large or charged molecules pass through?

Transport proteins / membrane proteins

Which way do molecules move in facilitated diffusion?

High concentration to low concentration

Does facilitated diffusion require energy?

No

Facilitated diffusion is considered a form of ________________ transport.

Passive

What is the function of a channel protein in facilitated diffusion?

It forms a tunnel or pore for molecules to move through

How does a transporter protein move molecules across the membrane?

It changes shape to move a molecule

In active transport, molecules move from ________________ to _________________ concentration.

Low to high

Does active transport require energy?

Yes

What are two energy sources used for active transport?

Usually $ATP$ or energy from another gradient

What is the difference between primary active and secondary active transport regarding $ATP$?

Primary active transport directly uses $ATP$, while secondary active transport uses energy from another gradient

What is the direction of movement in simple diffusion?

High -> low

Does simple diffusion require a protein?

No

Does simple diffusion require $ATP$?

No

What are examples of molecules that move via simple diffusion?

Small nonpolar molecules like $O_2$ and $CO_2$

What is the direction of movement in facilitated diffusion?

High -> low

Does facilitated diffusion require a protein?

Yes

Does facilitated diffusion require $ATP$?

No

What is the direction of movement in active transport?

Low -> high

Does active transport require a protein?

Yes

What is the source of energy for active transport mentioned in the transport type table?

Yes ($ATP$ or stored gradient)

Describe the pattern of movement for active transport.

Pumps molecules against the gradient

What does a cell use to transport many molecules or a very large molecule?

A vesicle

What is the definition of endocytosis?

Bringing material into the cell using vesicles

What is the definition of exocytosis?

Moving material out of the cell using vesicles

What must happen to a vesicle during exocytosis for output to occur?

It must fuse with the plasma membrane

What is phagocytosis?

Endocytosis that takes in food or solids

What is pinocytosis?

Endocytosis that takes in liquids

Which process is utilized if the cell needs to be selective in taking in molecules?

Receptor-mediated endocytosis

What occurs during receptor-mediated endocytosis before molecules enter the cell?

Specific molecules bind receptors

What is the memory trick for endocytosis?

ENDO = enters

What is the memory trick for exocytosis?

EXO = exits

What is the memory trick for phagocytosis?

Phago = food (cell eating)

What is the memory trick for pinocytosis?

Pino = drinking (cell drinking)

What is the memory trick for receptor-mediated endocytosis?

Selective endocytosis

According to the Final Quick Study Box, what is the main membrane molecule?

Phospholipid

According to the Final Quick Study Box, how do heads and tails relate to water?

Heads love water; tails fear water

What is the direction of passive transport (Final Quick Study Box)?

High -> low

What is the direction of active transport (Final Quick Study Box)?

Low -> high

In which direction does water move during osmosis?

Toward more solute

What is the result for a cell in a hypotonic solution (Final Quick Study Box)?

Swells / may burst

What is the result for a cell in a hypertonic solution (Final Quick Study Box)?

Shrinks / crenates

What is the result for a cell in an isotonic solution (Final Quick Study Box)?

Normal