AP BIO: Membranes and cellular transport, PT 1/Quiz

4 functions of the plasma membrane

1. Barrier: containment and separation of the cell interior

2. Material exchange: selectively permeable

3. Information detection and signal transduction (relay)

4. Movement: Proteins pull or pinch the membrane for the cell to move

• Pseudopods: cytoplasmic extensions for movement/ingeston in white blood cells

• Microfilaments of the cytoskeleton attach to the inside surface of the membrane

(4 functions of the plasma membrane)

What is the function for relay

Information detection and signal transduction

(4 functions of the plasma membrane)

What is the function for material exchange

selectively permeable

(4 functions of the plasma membrane)

what is the function for barrier

containment and seperation of the cell interior

(4 functions of the plasma membrane)

What is the function of movement

proteins pull or pinch the membrane for the cell to move

(4 functions of the plasma membrane) (movement)

Pseudopods

cytoplasmic extensions for movement/ingestion in white blood cells

Main components of the structure of a biological membrane

• Phospholipids

• Proteins

• Glycolipids

• Glycoproteins

In the phospholipids how is the hydrophilic phosophate portion of the phospholipid oriented?

Towards the aqueous external or internal environment

OUTSIDE/EXTERNAL

In a phosopholipid what is the outer surface and what is the inner surface?

Outer Surface: hydrophilic

Inner Surface: hydrophobic

In the phospholipids how is the hydrophobic phosophate portion of the phospholipid oriented?

hydrophobic fatty acid portions face each other within the interior of the membrane itself

INSIDE

In the phospholipids, what is the permeability of the hydrophilic phosphate portion of the phospholipid?

Semipermible barrier

In the phospholipids, what is the permeability of the hydrophobic phosophate portion of the phospholipid?

Permeability is determined by the fatty acid tails packing loosley, resulting in small spaces between the phospholipids to allow small, non-polar molecules to slip through

(Structure of the Biological membrane)

What do phospholipids do?

• Forms a semipermeable barrier

• The outer surface is hydrophilic (attracted to water)

• The hydrophilic phosphate portions of the phospholipids are oriented towards the aqueous external or internal environments

• OUTSIDE

• Inner component is hydrophobic (repels water)

• Hydrophobic fatty acid portions face each other within the interior of the membrane itself

• Permeability is determined by the fatty acid tails packing loosely, resulting in small spaces between the phospholipids to allow small, non-polar molecules to slip through

• INSIDE

(Structure of the Biological membrane)

What do Proteins do

• Peripheral: surface layer proteins

Function as receptors or attachment sites

• Integral: Proteins that extend across the entire width of the membrane

Function as transport proteins or motor proteins, and as attachment sites for cilia and flagella

• Embedded proteins can be hydrophilic and can have charged polar side groups OR can be hydrophobic with Non-polar side groups

(proteins)

Integral

Proteins that extend across the entire width of the membrane

Function as transport proteins or motor proteins

cites of attachment for cilia and flagella

(proteins)

Peripheral

Surface layer proteins

Function as receptors or attachment sites

(Structure of the Biological membrane)

Glycolipids

Sugar + Lipid'

cell recognition sites and provide energy

(Structure of the Biological membrane)

Glycoprotein

Sugar + protein’

Cell recognition and regulate cell transport as “gateways”

for the fatty acid tails of a membrane on a phospholipid, which side is saturated and which side is unsaturated?

Saturated = Straight, not bent side

Unsaturated = bent side

Function of the unsaturated fatty acid tail (bent side)

• Maintains membrane flexibility

• Opens tiny spaces where small things can diffuse through the membrane

is the head of a fatty acid hydropohobic or hydrophilic?

Hydrophilic

Polar

is the tail of the fatty acid hydrophobic of hydrophilic?

hydrophobic

What is selective permibility a direct consequence of?

Membrane structure

Phospholipid fatty acid tails determine spacing: what can get acroos the membrane/lipid bilayer

Substance that can freely cross the lipid bilayer

SMALL & NON-POLAR

• Small, uncharged, polar molecules (Urea) ← slow process

• Small, non-polar molecules (Ex. N_2, O₂ ← not slow, normal process

Substances that require a embedded channel proteins to pass through the membrane

• Hydrophilic substances, large polar molecules, proteins, and ions (Ex., H⁺, Na⁺, OH^-)

• These channel proteins act as a doorway to allow things that can’t diffuse regularly an alternate route so they can get through the membrane

• Ions attrach waterv and become hydrated and large

• aquaporins: channel proteins for water so it can move across the membrane

aquaporins

Channel proteins for water so it can diffuse across the membrane

What are the types of membrane transport proteins?

Channel Proteins

Carrier proteins

what are the functions of Channel proteins?

Forms a channel or pore to permit transport of substances based upon SIZE and CHARGE

• Creates a hole/doorway in the membrane to draw the ions towards opposite charge to attract the Ions so they can pass through the membrane

• EX. Aquaporins, H⁺ ion channels, K⁺ Ion channel, Na⁺ Ion channels

what are the functions of Carrier Proteins

Bind to molecules and change the shape to transport across the membrane

Ligand-gated / Ligand molecule

Channel and carrier proteins are ligand-gated

Compound that binds to the protein to open the protein up tomlet Ions and things go through and get transported

- Molecule that binds to a protein

Ex. Neurotransmitters

Different types of transports across the membrane

• Passive transport

-Diffusion

-Facilitated Diffusion

-Osmosis

• Active transport

(Types of passive transport )

Diffusion

• No energy

• High concentration to Low concentration needs a concentration gradient

• Nonpolar

• No charge

• Super small because they can diffuse through the hydrophobic fatty acid tail

(Types of passive transport )

Osomosis

• No energy

• Diffusion of WATER from High concentration to low concentration;

• The water molecules move down the osmotic potential gradient

• Water potential is expressed as a negative value

• Lower Potential (more negative) = more concentrated

• Water flows from a high potential to a lower potential

(Types of passive transport )

Facilitated diffusion

• No energy

• Diffusion of charged and polar molecules through the membrane

• Moves from High concentration to low concentration; Moving down the concentration gradient

• Channel Proteins: allow things to move based on size and charge

• Carrier protein: changes the shape of molecules to allow them to fit through the membrane and pass through

Types of passive transport

• Osomosis

• Diffusion

• Facilitated Diffusion

(transport across the membrane)

Passive Transport

• No energy

• Does not require the input of metabolic energy; net movement of molecules is from a high concentration to a low concentration

• Plays a primary role in the import of resources and the export of waste

• Types of passive transport include: osmosis, Facilitated diffusion, diffusion

Cholesetrol

makes membrane more stable and reduces fluidity and movability so only small, non-polar things cvan get through

Active Transport

• USES energy (ATP)

• Goes against the gradient: “low concentration to high concentration”

• Uses free energy (ATP) iand s embedded in the membrane to move molecules and ions across the membrane and/or Ions to establish and maintain a concentration gradient

• Membrane proteins are necessary for active transport

• Sodium Potassium Pump (Na⁺/K⁺)

What is the function of proteins within the cell membrane?

• Receive - (receptors) info glycolipid and glycoproteins

• Transport- allows cells to connect so they can attach to each other

• Movement- cilia and Flagella allow the cells to move

During the Sodium Potassium Pump (Na⁺/K⁺) waht does the energy from the ATP (with the phosphorus) do?

The energy from the ATP changes the shape of the transport proteins to move the ions across the membrane

During the Sodium Potassium Pump (Na⁺/K⁺), what binds to the proteins to allow the pumping to happen and things to more across?

3 phosphorus ATP

The energy from the ATP changes the shape of the transport proteins to more the ions across the membrane

Sodium Potassium Pump (Na⁺/K⁺)

• Pumps 3 sodium ions out of the membrane and 2 potassium ions into the membrane (so there’s more sodium on the outside than potassium)

• This created a gradient where there is more of one of the other things (Na⁺/K⁺) on the oustdie of the cell

Glucose transport

(created the charge difference)

To let the sodium back in after it’s being pumped out and continuously bring in glucose (sugar) with the sodium at the same time

Sodium + glucose go back in at the same time - cotransport

in the sodium-potassium pump (Na⁺/K⁺), what is getting pumped out and what is getting pumped in (and amount of each)

3 sodium ions are getting pumped out

2 potassium ions are getting pumped in

Creates the standing charge difference where theres more sodium than potassium on the outside to move other molecules across the membrane

What is the point of the Soidum potassoum pump (Na⁺/K⁺)

Because we need a charge difference to move other molecules across the membrane

Ex. glucose transport

Isotonic solution

equal solute concentrations between two solutions

equal movement of water in and out of the cells

Hypertonic solution

higher solute concentration

(ex. Water movement OUT of the cells)

plasmdysis

Hypotonic solution

Lower solute concentration

(water movement INTO the cells)

turgid pressure

Cotransport Symport

membrane protein that moves two different substances in the same direction across the cell membrane at the same time.

How is cotransport symport shown in the Ka⁺ / N⁺ Pump?

As Na⁺ is going out of the membrane

Glucose wants to come in

The glucose binds to the transport protein (Na⁺) and gets taken into the cell with Na and Glucose together at the same time

The energy to move the glucose into the cell membrane is derived from the Na⁺ gradient moving out generated by then Ka⁺ / N⁺ pump

During the cotransport symport of glucose in the Ka⁺ / N⁺ Pump, where is the energy derived from?

the Na⁺ gradient moving out generated by then Ka⁺ / N⁺ pump

Types of Bulk transports of materials

• Endocytosis (moving materials into the cell)

-Pinocytosis (intake of small/dissolved particlesl)

-Phagocytosis (intake of large/solid particles or cells)

- Receptor-mediated endocytosis (Food/nutrients bind to receptors)

Endocytosis

Movement of materials into the cell

3 Forms include:

• Pinocytosis (small)

• Phagocytosis (large)

• Receptor - mediated Endocytosis (bind or receptors)

What are the three forms of Endocytosis

• Pinocytosis (small)

• Phagocytosis (large)

• Receptor - mediated Endocytosis (bind or receptors)

(Endocytosis)

Pinocytosis

Intake of small/dissolved particles and liquid

ex. Amino acds, sugars, nucleotides

(Endocytosis)

Phagocytosis

Intake of large, solid food particles or cells

• Used pseudopods to enguld large quantities of food

(Endocytosis)

receptor-mediated endocytosis

Food/nutrient molecules bind specifically to receptors

• Direct contact between the transport molecules and the receptors

• LDL cholesterol is absorbed into the cell membrane through this process

Process of Pinocytosis (small)

1. A dimple forms oin the plasma membrane

2. The dimple deepens and surrounds the extracellular fluid

3. The membrane encloses the extracellular fluid, forming a vesicle

Process of Phagocytosis (big)

1. The plasma membrane extends pseudopods towards an extracellular particle (ex., food)

2. The ends of the Pseudopods fuse, encircling the particle

3. A vesicle called a food vacuole is formed, containing the engulfed particle

(ex. White blood cell, Amoeba)

Process of receptor-mediated endocytosis

1. Receptor proteins for specific molecules or complexes of molecules are localized at coated pit sites

2. A vesicle (“coated Vesicle”) containing the bound molecules is released into the cytosol

3. The coated pit region of the membrane encloses the receptor-bound molecules.

4. The receptors bind the molecules, and the membrane dimples inward