Trabsport In And Out Of Cells

Question 1

Improvements for osmosis experiment

Answer 1

Use intermediate conc of sucrose solution to obtain more accurate value that gives no change in mass

Carry our repeats to allow mean to be calculated

Use same cork borer to get same diameter

Blot directly to remove excess liquid

Use same type of sample as water potential may differ

Question 2

Risks in osmosis experiment

Answer 2

Cork borer - cut away from you or downwards onto tile

Broken glass- keep test tubes away from edge of desk

Question 3

Why is % change calculated

Answer 3

To allow comparison despite diff starting masses

Question 4

Why is sample kept in solution for 24 hours

Answer 4

The mass will of sample become constant

Question 5

Why each test tube covered with bung

Answer 5

To prevent evaporation of water from sucrose solution
Will result in decreasing water potential

Question 6

How to find equilibrium of osmosis

Answer 6

Graphs % change on y axis against sucrose conc x axis
Find sucrose conc where there is 0 mass chbange
Find out water potential

Question 7

Why’s plasma membrane important

Answer 7

Forms a boundary between cytoplasm and environment
Controls movement of substances in and out of cell
Allows different conditions to be established

Question 8

Structure of plasma membrane

Answer 8

Glycolipid =embedded in
Cholesterol = completely in
Integral protein
Extrinsic protein
Carbohydrate above

Question 9

Phospholipids

Answer 9

Hydrophilic head with phossphoester bond
Glycerol
Hydrophobic fail with fatty acid and ester bond

Question 10

Why do phospholipids form a bilayer

Answer 10

One layer layer with Hydrophilic heads pointing inwards interacting w aqueous cytoplasm
One layer has its hydrophilic head pointing outwards interesting w aqueous cells
Hydrophobic tails both point to the Centre protected

Question 11

What can pass through bilateral

Answer 11

Small
Non polar
Lipids soluble

Question 12

Function of proteins in membrane

Answer 12

To allow certain substances to move in and out of the structure
Provides structural support
Provides channels for passive transport
Allow AT
Form recognition sites
Act as hormone binding site

Question 13

Intrinsic protein

Answer 13

Completely span bilayer
Act as carries to transport water soluble
Can act as enzymes

Question 14

Extrinsic proteins

Answer 14

Bound to surface partially embedded
Give mechanical support
Work with glycolipids as cell receptors

Question 15

Cholesterol function

Answer 15

Restrict movement of other molecules
Adds strength

Question 16

Fluid mosaic

Answer 16

Fluid : phospholipids can move so membrane is flexible
Mosaic : proteins embedded vary in shape and size

Question 17

Define diffusion

Answer 17

Passive net movement of particles from area of high conc to area or low conc down a conc gradient

Question 18

Factors affecting rate of diffusion

Answer 18

SA : larger sA = faster
Conc gradient : bigger the diff the faster
Thickness of exchange surface : thinner

Temp
Size of molecule
Nature of molecules : fat soluble faster

Question 19

Facilitated diffusion

Answer 19

Involves proteins that recognize a specific molecule and help it move across membrane passively
Uses channel (allow one type) and carrier (rotate) proteins

Question 20

Define osmosis

Answer 20

Passive net movement of water molecules for high WP to low WP across partially permeable membrane

Question 21

Define water potential

Answer 21

Pressure created by water molecules
Always moves towards more negative wp
KPa

Question 22

Hypertonic

Answer 22

Higher solute conc inside than outside

Question 23

Hypotonic

Answer 23

Less solute conc inside than outside

Question 24

Osmosis in RBC

Answer 24

Shrivels if higher WP inside
Bursts if lower WP inside

Question 25

Osmosis in plant cells

Answer 25

Plasmolyzed = hypertonic Isotonic = flaccid Turgid = hypotonic

Question 26

Define active transport

Answer 26

Movement of molecules from area of low concentration to area of height conc against conc gradient using energy from ATP and using carrier proteins

Question 27

How does AT use ATP

Answer 27

Used directly by carrier proteins By using conc gradient that’s already been set up

Question 28

Process of AT

Answer 28

Molecule or ion attaches to receptor on carrier protein ATP binds to carrier protein ATP undergoes hydrolysis forming ADP and phosphate The phosphate attaches to carrier protein causing it to change shape Shape change causes carrier protein to transport molecule to other side of membrane where it’s released Phosphate now leave carrier protein ADP and phosphate will later form ATP during respiration

Question 29

How ATP is used by AT

Answer 29

Directly by carrier proteins to move molecules Using conc gradient that has already been set up by direct active transport (co-transport)

Question 30

How ATP acts as source of energy

Answer 30

Bonds between phosphate is weak so low Ea Easy to break and release lots of energy ATP synthase sysnthesizes ADP back into ATP

Question 31

What’s ATP used for

Answer 31

Metabolic processes = joining amino acids/ peptide bond formation Movement = energy for muscle contraction Active transport = changes shape of carrier proteins to move against conc gradient Secretion = forms lysosomes which are needed for secretion of all products Activation of molecules