UNF General Biology 1 Exam 2 Active and passive transport

What is passive transport?

Natural movement of substances across the plasma membrane;

does not require any energy

What determines the direction of passive transport?

Passive transport always moves

from areas of high concentration

to areas of low concentration

What is this called?

The image shown is a Concentration gradient

What is diffusion?

Movement of substances from areas of higher concentration to

areas of lower concentration without assistance. It continues until the concentration gradient is equal across a space and not there anymore

What is dynamic equilibrium?

Occurs when concentrations of a substance are equal and there

is no longer a concentration gradient and no net movement

What does it

mean to have no

net movement?

Molecules will still

move back and

forth across the

membrane, but

concentrations will

remain equal

What 7 factors affect how fast diffusion will happen:

1. Extent of the concentration gradient

2. Mass of the molecules diffusing

3. Temperature

4. Solvent density

5. Solubility

6. Surface area and plasma membrane thickness

7. Distance traveled

What is facilitated transport?

Movement of substances from areas of higher concentration to

areas of lower concentration with assistance from membrane

proteins

What kind of substances are primarily passed by facilitated transport?

Polar substances

Why are polar substances primarily passed by facilitated transport?

Polar substances can’t get through the hydrophobic portion of

the phospholipid bilayer

What else is required for facilitated transport?

Concentration gradient

What are the two types of proteins used in facilitated transport?

1. Channel proteins

2. Carrier proteins

What type of proteins are channel and carrier proteins?

transmembrane proteins

How does a channel protein

function?

Has hydrophilic channel

that allows polar

compound passage

How does a carrier protein function?

Binds with the

substance and

then changes

shape to move

the bound

molecule from

one side of the

membrane to

the other

What is osmosis?

The movement of water across the plasma membrane

Describe the directionality

of osmosis:

Water moves towards

areas with high solute

concentration and low

water concentration

What is tonicity?

Water balance across the plasma membrane

What are the 3 categories of tonicity:

Hypotonic, Isotonic, Hypertonic

What is hypotonic?

solute concentration is lower outside the cell (water is higher outside), so water enters the cell

What is isotonic?

equal solute and water concentration inside and outside of the cell

What is hypertonic?

Solute concentration is higher outside of the cell (water is lower outside), so water leaves the cell

What are the 2 key differences between active and passive

transport?

1. Active transport requires energy; passive does not

2. Active transport moves against the concentration gradient; passive moves with the concentration gradient

What is a concentration

gradient?

Movement from areas

of high concentration

to areas of low

concentration

What 2 things are required to form an electrochemical gradient?

Electrical gradient + chemical gradient

What is an electrical gradient?

difference in charge across the plasma membrane

Which is more electrically negative:

the interior or exterior of the cell?

Interior

Why is the interior of the cell more negatively charged?

Negatively charged proteins

stay on the interior

What is a chemical gradient?

difference in concentration across the plasma

membrane. also called a concentration gradient

What are the 3 types of transporter proteins used for active

transport?

uniporter, symporter, antiporter

What is a uniporter?

carries one specific ion or molecule

What is a symporter?

Carries two different ions or molecules, both in the

same direction

What is an antiporter?

Carries two different ions or molecules, but in

different directions

What is an example of an antiporter?

Sodium potassium pump

What is primary active transport?

Uses ATP and creates an electrochemical

gradient

What is secondary active transport?

Moves non-target molecules across the

membrane using the electrochemical gradient

created by primary active transport

What type of transporter is a sodium potassium pump considered?

Primary active transport

In a sodium potassium pump, which one is moved out of the cell?

Na+

In a sodium potassium pump, which is moved inside the cell

K+

what does the initial moving of Na+ outside the cell membrane and K+ inside the membrane create?

It creates the chemical/concentration gradient part

What is the ratio of Na+:K+ being moved via the pump?

3:2 ; 3 Na+ move out of the cell and 2 K+ move inside.

How is the electrical gradient part created in the sodium potassium pump?

The 3:2 Na+:K+ ratio moves more positive ions out of

the cell than into the cell, maintaining

the negatively charged cell interior

What is the first step of the sodium potassium pump?

3 Na+ ions from the interior enter

the pump

What is the second step of the sodium potassium pump?

ATP binds with the pump and

activates the release of the Na+

ions into the extracellular space

What is the third step of the sodium potassium pump?

2 K+ ions enter the

pump from the

extracellular fluid and

a phosphate

molecule binds to the

pump

What is the fourth step of the sodium potassium pump?

K+ ions and phosphate ion are

released into the cell’s interior

What is secondary active transport?

Movement of non-target molecules using the electrochemical

gradient created during primary active transport

In a sodium potassium pump, which is the target molecule and which is the non-target molecule?

Na+, Glucose

Which molecule is moving against the concentration gradient in the secondary active transport part of a sodium potassium pump

glucose is

What is the first step of the secondary active transport of the sodium potassium pump?

Na+ ions and glucose

molecules enter the

transporter

What is the second step of the secondary active transport of the sodium potassium pump?

Energy from the

electrochemical

gradient stimulates

the transporter to

move Na+ and

glucose into the cell’s

interior

What is bulk transport?

transportation of large substances across the plasma membrane

What are the two types of bulk transport>?

Endocytosis and exocytosis

What is endocytosis?

Moves large

particles into

the cell

What is exocytosis?

Moves large

particles out of

the cell

What are the three variations of endocytosis?

1. Phagocytosis

2. Pinocytosis

3. Receptor-mediated

What is Phagocytosis?

Process by which a

cell takes in large

particles

What is Pinocytosis?

Process by which a cell takes

in water and other fluids

What is Receptor-mediated endocytosis?

Receptor proteins bind

specific substances

What happens in exocytosis?

Waste material is enveloped in a

vesicle, fuses with the plasma

membrane and is then expelled

What is a glycoprotein?

protein with an attached carb

What is a glycolipid?

lipid with an attached carb

Glycolipid + Glycoprotein

Glycocalyx

What does the glycocalyx do?

Form specialized sites with unique patterns on the cell's surface that allow cells to recognize each other

What is the defining trait of glycocalyx?

collective terms for glycoproteins and glycolipids. Highly hydrophilic and attracts large amounts of water to the cell's surface.

What is a fluid mosaic model?

Describes the structure and function of the plasma membrane

The plasma membrane is a mosaic of components including

Phospholipids, cholesterol, Proteins, carbohydrates

What is cholesterol?

Type of lipid. Made of four fused carbon rings. Specifically in plasma membranes of animals.

Where does cholesterol fit?

Between the phospholipids

What are peripheral proteins?

proteins that are either on the membrane's exterior or interior surface (aka don't span the entire membrane

What do peripheral proteins do?

serve as enzymes, structural attachments from the cytoskeleton's fibers, and part of the cell's recognition sites (how tissues form from similar cells.)

What are integral proteins?

proteins that integrate completely into the membrane structure and span the entire membrane

What must integral proteins have in order to span the plasma membrane?

hydrophobic and hydrophilic parts

How does the extent of the gradient affect diffusion?

bigger difference in concentration = faster diffusion which slows down as it approaches dynamic equilibrium

How does the mass of a molecule affect diffusion?

heavier molecules move slower

How does temperature affect diffusion?

higher temp = faster movement

How does solubility affect diffusion?

nonpolar or lipid-soluble materials pass through easier than polar materials

How does Surface area and plasma membrane thickness affect diffusion?

increased surface area= increased diffusion rate; thicker membrane=slower diffusion

How does distance traveled affect diffusion?

the greater the distance need to travel, the slower the diffusion rate