Cells

Question 1

When asked for difference and similarities of scientists in 1935 vs the fluid mosaic model ,what do you write?

Answer 1

Similar:both have hydrophilic head and hydrophobic tail
Differences:no carrier or channel protein present
-glycerol or glycolipid is not present

Question 2

Name and describe five ways substances can move across the
cell-surface membrane into a cell.

Answer 2

Facilitated diffusion:type of diffusion(high to low movement of particles or molecules) using carrier intrinsic protein.

-osmosis:the net movement of water from a dilute to concentrated area(high to low)

-simple diffusion:it is the movement of particles from an area of high to low concentration (passive)

Co-transport:is the coupled move to of particles(facilitated diffusion and active transport is used using carrier protein)

-active transport:movement of particles from a low to high concentration area using ATP.

Question 3

The action of Na-K pump is linked to a membrane-bound ATP hydrolase enzyme,explain the function of ATP hydrolyse.

Answer 3

ATP turn into ADP +Pi releasing energy that energy allows ions be moved against concentration gradient

Question 4

Describe and explain two features you would expect to find in a cell specialised for absorption.

Answer 4

1-Large number of co-transport/carrier/channel proteins for facilitated diffusion
2-Large number of mitochondria so make (more) ATP
3-Folded membrane/microvilli so large surface area.

Question 5

The movement of substances across cell membranes is affected by membrane structure. Describe how.

Answer 5

1-Phospholipid allows movement/diffusion of non-polar,lipid-soluble substances.
2-Phospholipid bilayer prevents movement/diffusion of polar,charged,lipid-insoluble substances
3-Channel/carrier proteins allow facilitated diffusion/co-transport
4-Cholesterol affects fluidity/rigidity/permeability
5-Carrier proteins allow active transport

Question 6

Give 2 similarities of osmosis and diffusion

Answer 6

-passive and it is from a high to low area of concentration.

Question 7

Describe the movement of glucose thru facilitated diffusion.

Answer 7

Facilitated diffusion;
Between A and B

All transport protein are being used up
Between C to D

Question 8

Sodium ions from salt (sodium chloride) are absorbed by cells lining the gut. Some of these cells have membranes with a carrier protein called NHE3

NHE3 actively transports one sodium ion into the cell in exchange for one proton (hydrogen ion) out of the cell.
Use your knowledge of transport across cell membranes to suggest how NHE3 does this.

Answer 8

Co-transport
Hydrolysis of ATP
Sodium ion and proton ion bind to protein changing it tertiary structure
(For the ions to move across the membrane);