Form 4 Chapter 3 Biology - Movement of Substances Across The Plasma Membrane

what is the plasma membrane?

semi-permeable lipid bilayer found in all cells

what does plama membrane do?

controls water and certain substances in and out of the cell

function of plasma membrane?

• protects the cell.

• separate the intracellular components from the extracellular environment.

• controls what enters and exits the cell

necessities for the movement of substances across the plasma membrane?

• to transport nutrients into the cell.

• for gases exchange

• to excrete metabolic waste

substances leaving the cell through membrane

secretion, oxygen, carbon dioxide, excess water and nitrogenous waste

substances entering the cell through membrane?

nutrients, oxygen, carbon dioxide, water and ionic salts

structure of the plasma membrane?

fluid mosaic model

phospholipid

• bilayer ( double layer )

• polar head (hydrophilic) [ love

  H2O

• non-polar tail ( hydrophobic ) [hate H20]

Protein

-Pore protein : protein with pore 有洞的protein -Carrier protein : protein carry substance in&out -Glycoprotein: protein attached with carbohydrates [ receptors to hormones ]exp:insulin, stabilise membrane by forming hydrogen bonds with water & act as antigens for cell identification

Function of pore protein & carrier protein

1.Pore protein

-allow movement [ small water - soluble substances & ions ] 可以让小水进

2.Carrier protein 太大进不到？

carrier protein 会带你 -sites to bind specific molecule ( exp : glucose)

Cholesterol

make phospholipid bilayer

1. stronger

2. more flexible

3. less permeable to water-soluble substances

whats the 3 characteristics to determine

the permeability of the phospholipid

bilayer？（3个特征 plasma membrane)

• the molecular size

• the ionic charge

• the polarity of the substances pass through it

CHARACTERIS

TICS OF MOVEMENT OF SUBSTANCES

ACROSS A PLASMA MEMBRANE她的允许进出条规

-lipid soluble molecules permeable

-non-polar molecule (02 & CO2 )permeable

-hydrophobic tail prevent polar substances 尾巴避免+-的

BUT H2O is so small, can slide through pores between the phospholipid layer

what is passive transport?

movement of substances across the cell membrane without / does

not involve the use of energy

# simple diffusion

# osmosis

# facilitated diffusion

what happens during passive transport?

substances move down their concentration gradient

what are the 3 different channels passive

transports can happen through?

• lipid bilayer

• pore protein

• carrier protein

Simple diffusion meaning

- the [movement of substance] from an area of (high concentration) to an area of (low concentration) until an equilibrium is achieved

what is the particles that move through the plasma membrane

through diffusion?

-substances soluble in fat (vitamins

A,D,E, K)

- neutral particles (water, oxygen,carbon dioxide)

example of diffusion?

between alveoli and blood capillaries in the lung during gases exchange

what is Osmosis ?

[ movement of water molecules ] from an area of (high water potential) to an area of (low water potential) through a semi-permeable membrane until equilibrium achieved

what is the

direction of movement for osmosis?

high to low concentration

Facilitated diffusion

-dos not require energy (down a concent gradient)

Process of : Lipid-insoluble molecules (ions) [ channel protein ] , large molecule (amino acids & glucose ) [ carrier protein ] unable to pass through the phospholipid bilayer. [ across by transport protein ]

The process of the movement of glucose molecules

across a plasma membrane

occurs through a facilitated

diffusion

1) molecule move toward the binding sites of carrier proteins 往前去黏

2)molecule binds to a specific sit

on carrier protein 黏住他

3) the carrier protein changes its shape, allow molecule to pass

through 改自己形状，让他进

4) carrier protein return its original shape

what is active transport?

- movement of molecules across the plasma membrane (against the concentration gradient)

what is the

energy required used in active

transport?

energy (ATP) adenosine triphosphate

what is the simillarity between passive transport and active transport?

1. Moving a substance across a membrane 2. Occurs through a selectively permeable membrane

what is the direction of movement for passive transport & active transport

following concentration gradient lI against the concentration gradient

type of

molecules involve in

passive transport & active

water Il glucose & mineral salt

what is the

energy requirement for

passive transport &active

transport?

absent, not required II required

Movement

Movement of substance in everyday life

1) Hypotonic solution 里面cell的水

少，外面的水多，所以要进去cell

-solution with a [lower solute concentration ] than solute concentration within the cell

2) Hypertonic solution 里面cell的

水多过外面的水所以里面cell的水

会出来

-solution with [higher solute concentration] than solute concentration within the cell

3) Isotonic solution

-solution with [equal solute concentration with the cytoplasmic fluid ]

Effect of hypotonic, hypertonic and isotonic solutions on

ANIMAL CELLS

1) direction 2) cell shape

3)process name

Hypotonic solution

1. Water diffuse [into] cell by osmosis

2. Cell become [turgid & burst] 水

太多所以爆开，cuz plasma

membrane too thin to contain water

Hypertonic solution

1. Water diffuse [out] cell by osmosis

2. Cell become [ shrink / shrivel] 没水扁

3. Crenation

Isotonic solution

1. Water diffuse [in & out] at the same rate

2. Maintain normal shape

Effect of hypotonic, hypertonic and isotonic solutions on

PLANT CELLS

1) direction 2)

cell shape

3)process name

Hypotonic solution

1. Water diffuse [into] cell by osmosis

2. Cell become [turgid ]

3. Cell [does not burst ]cuz [cell wall is rigid & strong ]

4. [Cell turgidity ] cause guard cell swell to allow stomata open for [photosynthesis]

Hypertonic solution

1. Water diffuse [out] cell by osmosis

2. Cell become [shrink &flaccid ]ix

7K cuz plasma membrane pulled away from the cell wall - called [Plasmolysis ]

3. Deplasmolysis 让水进回去变回

size

Isotonic solution

1. Water diffuse [in & out] at the same rate

2. Cell become [ flaccid ]

Effect on STEM

OF NON-WOODY PLANT

Put DISTILLED WATER (hypotonic solution)水多solute少

- Strip become longer, turgid, curved outwards

17%SUCROSE SOLUTION (isotonic solution)

-the length, shape of strip remain the same

30%SUCROSE SOLUTION (hypertonic solution ) 水少solute多
-strip become shorter , softer , curved inwards (flaccid )

Effect & application of

osmosis

1. WILITING IN PLANTS 枯了

-excessive fertilisers, dissolve soil water, hypertonic to cell sap of root, water diffuse out, flaccid【肥料太多，solute高水少，导致

root give water, root flaccid, 缺水，枯了（wilt）】

2. FOOD PERSERVATION

-salt/sugar solution hypertonic to cell, cell lose water, prevent microorganisms growth [solute&

水少，cell will give water，没水，干了，细菌不会生长】

glycolipid , glycoprotein

Channel protein

Cholesterol