y12 biology cell membrane transport

What is a triglyceride molecule made from

Glycerol + 3 fatty acids

Are triglyceride molecules polar or non polar

Non polar

Are triglyceride molecules soluble in water and why

No because they have 3 fatty acids which are hydrophobic non polar molecules

What are phospholipids molecules made from

Two fatty acid molecules, a phosphate group and a glycerol molecule

What is diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration

How does rate of concentration gradient affect diffusion

The greater the concentration the higher the rate of diffusion

Can charged particles diffuse through the membrane

No except water because it’s small

How does size affect rate of diffusion

Bigger particles typically diffuse faster than smaller ones

How does temperature affect rate of diffusion

Higher temperature means higher rate of fission due to higher kinetic energy more frequent successful collision

How does surface area affect rate of diffusion

Faster in a larger surface area

How does distance affect rate of diffusion

Longer distance means slower rate of diffusion

How do carrier proteins work

They have a specific binding site for a specific chemical, when binder the tertiary structure of the carrier protein changes bringing the chemical across the membrane where it is now released

How do protein channels work

A central pore from the protein channel is lined up with hydrophilic amino acids and contains water. Allowing hydrophilic substances to pass through the membrane

Do protein channels let every chemical pass through

I they are selective for which chemicals that can pass

are all protein channels always open

No some only open in response to a stimulus

What are the two proteins of facilitated diffusion

Carrier proteins

Channel proteins

What is the definition of active transport

Active transport transports different molecules into and out of the cell against the concentration gradient (from a net area of low concentration to a net area of high concentration)

How does the process allow the substances to move

• Molecule binds to a specific receptor site on the carrier protein.

• ATP → ADP + inorganic phosphate; inorganic phosphate attaches to the carrier protein.

• Inorganic phosphate causes a change in tertiary structure, moving the molecule against its concentration gradient.

• Molecule is released; inorganic phosphate detaches, returning the protein to its original shape.

• ADP + inorganic phosphate → ATP during respiration

Is active transport passive?

No it uses a lot of atp

Why is the sodium potassium pump needed

• Initially, Na⁺ concentration is higher in the ileum lumen than inside the epithelial cell.

• The sodium pump uses ATP to pump Na⁺ out of the epithelial cell, maintaining this gradient.

• Na⁺ diffuses into the cell through the co-transporter, so the gradient is gradually lost as Na⁺ enters.

• The gradient must be maintained so Na⁺ can continue diffusing into the cell and provide energy for glucose co-transport.

• The sodium pump continually pumps Na⁺ out, restoring the gradient and allowing co-transport to continue.

How does cotransport occur involving the sodium pump

• 3 Na⁺ are pumped out of the epithelial cell and 2 K⁺ are pumped in using ATP.

• This creates a high Na⁺ concentration in the ileum lumen compared with inside the epithelial cell.

• Na⁺ diffuses from the lumen into the epithelial cell down its concentration gradient through a co-transporter protein.

• The energy from Na⁺ moving in transports glucose into the epithelial cell against its concentration gradient.

• Glucose then diffuses from the epithelial cell into the blood through a carrier protein.

How is the atp needed for the sodium potassium pump funded?

The epithelial cells contain a lot of mitochondria

What do the membrane of the epithelial cells folded into to increase surface area

Microvilli

What does this surface area allow

More space for membrane proteins needed for facilitated diffusion and active transport

Why is there a steep concentration gradient between the epithelial cells and the blood

The glucose molecules that are absorbed are rapidly carried away by the bloodstream

Why is the diffusion of glucose into blood rapid?

Because of the steep concentration gradient

Define osmosis

The net movement of water molecules from a a region of high water potential to a region of lower of water potential through a semi permeable membrane

What is water potential

The tendency of water molecules to move from one region to another

What is the water potential of pure water

0 kilopascals (kPa)

What is the highest water potential possible

0 kPa

How does concentration affect water potential

Higher concentration of solution means lower water potential

When does plasmolysis occur

When the water potential inside the cell is greater then outside so water flows out via osmosis cussing the protoplasm to pull away

What is turgor pressure

The pressure applied on the cell wall when water flows in via osmosis causing the protoplast to push outwards against the cell wall