Cell Surface Memebrane

Question 1

Why don’t molecules freely diffuse across cell surface membrane

Answer 1

Not soluble in lipids therefore cannot pass through the bilateral
Too large to pass through channels in the membrane
Of the same charge as protein channel and so even if they are small enough they are repealed
ElectricLly charged therefore difficulty passing through non polar sections such as hydrophobic tails

Question 2

Why is membrane called fluid

Answer 2

Because individual molecules can move relative to one another this gives membrane the flexible structure so constantly changing shape

Question 3

Why is membrane mosaic

Answer 3

Protiens embededd in the phospholipid bilateral vary in shape size and pattern in the same way as a mosaic

Question 4

What is diffusion

Answer 4

The net movement of molecules or ions from region where they are more highly concentrated to one where concentration is lower until evenly spread out

Question 5

Where does energy come from in diffusion

Answer 5

From natural inbuilt motion of the particle

Question 6

What are the three things to understand how atp doesn’t provide energy

Answer 6

All particles are constantly moving in motion due to kinetic energy that the possess
The motion is random and in all directions no set pattern
Particles are constantly bouncing off each other as well as other objects

Question 7

What is facilitated diffusion

Answer 7

It’s a passive process relies on only the inbuilt motion of the diffusing molecules it occurs down a concentration gradient but with the use of protein channels or carrier protiens

Question 8

What are protein channels

Answer 8

Water filled hydrophilic tubes which allow water soluble substances to pass through

They are selective and open in prescribed of particular ion which binds to the protein causin f it to change shape and release the ion to other side

Question 9

What is a carrier protein

Answer 9

Protiens which span across the membrane

When molecule specific to the protein is present it binds to the protein causing it to change shape so molecules is released inside of the membrane

Question 10

What is osomosis

Answer 10

The passage of water from a region of high water potential to low water potential through selectively permeable mebrane

Question 11

What is selectively permeable

Answer 11

They are permeable to water molecules and other small molecules but not large molecules

Question 12

What is waterpotential

Answer 12

Measured in units of pressure the water potential is the pressure created by the water molecules 25.c is 100kpa

Question 13

What are some of the principle of water potential

Answer 13

The addition of dilute to pure water will lower its water potential

Water potential of a solution must always be less than zero
More solute addedthe more concentrated so more negative

Water will move by osomsois from an area of high concentration to low concentration

Question 14

What will happen to animal cells in high water potential and why

Answer 14

It will absorb water by osomosis as it has lower water potential cell surface membrane are very thin and cannot stretch a lot so cell membrane will therefore break lysis

Question 15

What is the protoplasm

Answer 15

The outer surface membrane the nucleas the cytoplasm and the inner vacuole mebrane

Question 16

What is active transport

Answer 16

The movement of molecules from an area of low concentration to high concentration against concentration gradient and using atp and carrier protein

Question 17

What is atp used directly for

Answer 17

Directly move molecules

Individually move molecules using a concentration that has already been set up co transport

Question 18

How is at different to diffusion’s

Answer 18

Metabolic energy in form of atp is needed
Substances moved against a concentration

Carrier protiens act as a pump

Process is very selective

Question 19

Describe active transport

Answer 19

Carrier protein span the plasma membrane and bind to molecule or ion being transported

The molecules bind to the carrier protien

Once inside the atp binds to protien and it’s hydrolysed to form adp and phosphate as a result the carrier protien changes shape in presence of phosphate molecule and release the ion

The phosphate molecule is then released which Male protien revert to original shape and recombine with adp to form atp during respiration

Question 20

How is Vikki adapted

Answer 20

Has microcilli which increase surface area which allows more carrier protiens so diffusion and active transport can take place

Question 21

How are things absorbed in the ileum

Answer 21

Carbs are being digested there are higher levels of glucose and amino acid in ileum than the blood

So glucos then moves by facilitated diffusion into the blood

The blood is continuously moving so helps maintain concentration gradient

Question 22

How does co transport word

Answer 22

Sodium ions are actively transported out of epithelial cells into the blood using a carrier protien
This increase the concentration gradient between the cavity and the epithelial cells as there is less sodium in the epithelium cells so sodium ions diffuse down this gradient through carrier protien carrying an amino acid or glucose with them

The glucos then pass into the blood through facilitated diffusion

Question 23

What is special about the corralspott

Answer 23

Sodium moves into the cell through diffusion whereas glucose and amino acid move into the cell against concentration gradient using active transport the movement of ions is powered by the movement of sodium ions tea their than atp it powers the molecules to move