Transport Across Membranes

Question 1

Fluid mosaic model

Answer 1

Fluid= phospholipid molecules from a bilayer constantly moving
Mosaic = different protein structure that unevenly distributed throughout the membrane

Question 2

Phospholipid biyaler

Answer 2

polar phosphate head can attract other polar molecules. The hydrophobic fatty tails oriented in words towards the middle and point away from the water whereas the hydrophilic heads are orientated towards the outside and point towards the water. The hydrophilic had makes contact with water cytoplasm, and extra cellular fluid. Allows Lipid soluble nonpolar and small molecules passed through

Question 3

Cholesterol

Answer 3

decreases permeability and increases the stability of the membrane. More cholesterol means less fluidity of the membrane. Different types of cells have different proportions of cholesterol.

Question 4

Channel proteins

Answer 4

have a specific trust structure so allow specific molecules that are complementary to the shape to past through via facilitated diffusion. They only allow charged small molecules to pass through.

Question 5

Carrier proteins

Answer 5

they aid the transport of polar and large molecules to enter facilitated diffusion and active transport

Question 6

Receptor proteins

Answer 6

specific tertiary tructure to allow specific molecules combined to specific receptor proteins

Question 7

Enzymes

Answer 7

embedded in the cell membrane shape of the enzymes active site is specific and complementary to a substrate, allowing them to bind and for enzyme substrate complexes

Question 8

Glycoproteins

Answer 8

they are composed of carbohydrates and proteins are on the outer surface membrane which are important for our recognition of an acting and antigens

Question 9

Aquaporins

Answer 9

they are specific type of channel proteins specific to water and allow water molecules to pass through via osmosis

Question 10

Ficks law

Answer 10

surface area times concentration gradient/ diffusion distance

Question 11

Simple diffusion

Answer 11

it’s a passive process as it doesn’t require ATP from respiration. This only allows movement of nonpolar small and liable molecules. Diffusion is the net movement of molecules from the area of higher concentration to an area of lower concentration across a partially permeable membrane.

Question 12

Factors affecting rate of diffusion

Answer 12

Temperature= increase connect energy there for faster rate of diffusion
Surface area= larger surface area provides more space for molecules to pass through therefore faster
Concentration gradient= as the concentration difference increases the rate of diffusion increase
Diffusion pathway= the shorter the diffusion distance the faster molecules will travel from one area to the next

Question 13

Facilitated diffusion

Answer 13

allows water soluble charged or large proteins that cannot pass through phospholipid bilayer passed through the specific proteins. It’s also a passive process using carrier or channel proteins

Question 14

Osmosis

Answer 14

net movement of water molecules from an area of higher water potential to an area of lower water potential to a selectively partially permeable membrane
Higher water potential= 0kpa = no dissolved molecules
Lower water potential= more solute dissolved in water eg -10kpa
Hypotominc = lower osmotic pressure
Hypertomibc = higher osmotic pressure

Question 15

Active transport

Answer 15

net movement of large charged molecules to go from a lower concentration to a higher concentration against the concentration gradient using only carrier proteins using ATP.

The molecule of transport by the binding side of the specific carrier protein
The hydrolysis of ATP into ADP plus PI phosphate the carrier protein this causes the protein to change shape
The change in protein shape allows the molecule to transport across the membrane into everywhere there is a higher concentration