part 2 the funda mental unit of life - cell

1. THE
FUNDAMENTAL
UNIT OF LIFE
PART -2
BY : MISS RITIMA

2. PLASMA MEMBRANE
 IT IS OUTER MOST COVERING OF ANIMAL CELL.
 IT IS SELECTIVELY PERMEABLE.
 MADE UP OF ORGANIC MOLECULES PROTEINS AND
LIPIDS.
 SUBSTANCES LIKE CARBON DIOXIDE, OXYGEN CAN
MOVE ACROSS THE MEMBRANE BY THE PROCESS
OF DIFUSSION.
DIFUSSION IS THE MOVEMENT OF MOLECULES
FROM HIGHER CONCENTRATION TO LOWER
CONCENTRATION.
 AND THE MOVEMENT OF WATER MOLECULES
TAKES PLACE BY THE PROCESS OF OSMOSIS.
IN OSMOSIS THE MOVEMENT TAKES PLACE FROM
HIGHER TO LOW CONCENTRATION THROUGH
SELECTIVELY PERMEABLE MEMBRANE.

3. ROLE OF DIFUSSION IN GASEOUS BETWEEN
CELL AND ITS EXTERNAL ENVIRONMENT
 IN CELLS EXTERNAL ENVIRONMENT THE
CONCENTRATION OF CARBON-DIOXIDE IS LOW
AS COMPARED TO THAT OF INSIDE THE CELL.
(CARBON DIOXIDE INSIDE CELL- HIGH
CARBON DIOXIDE OUTSIDE CELL – LOW
OXYGEN INSIDE CELL – LOW
OXYGEN OUTSIDE CELL – HIGH )
 BECAUSE OF THIS DIFFERENCE IN
CONCENTRATION THE CARBON DIOXIDE MOVE
OUT OF THE CELL AND OXYGEN MOVES INSIDE
THE CELL BY THE PROCESS OF DIFFUSION.

4. EXCHANGE OF GASES BY THE PROCESS OF
DIFFUSION
HERE THE CONCENTRATION OF OXYGEN INSIDE BLOOD CELLS
IS LOW AND CONCENTRATION OF CARBON DIOXE INSIDE
BLOOD CELLS IS HIGH . WITH THE PROCESS OF DIFUSSION
THE EXCHANGE OF GASES TAKES PLACE.

5. WHAT WILL HAPPEN IF WE PUT ANIMAL CELL
OR PLANT CELL INTO SOLUTION OF SUGAR OR
SALT IN WATER
 IN HYPOTONIC SOLUTION: ENDOSMOSIS
IF THE MEDIUM SURROUNDING THE CELL
HAS HIGHER WATER CONCENTRATION
THAN CELL. THE CELL WILL GAIN
WATER BY THE PROCESS OF OSMOSIS.
AS A RESULT THE CELL SWELL UP. (IT
MAY BURST)

6. ISOTONIC SOLUTION
 IF THE MEDIUM HAS EXACTLY THE SAME
CONCENTRATION AS THE CELL, THERE WILL
BE NO NET MOVEMENT OF WATER ACROSS
THE CELL MEMBRANES.
 WATER CROSSES THE CELL MEMBRANE IN
BOTH DIRECTIONS BUT THE AMOUNT GOING IN
THE CELL IS SAME AS AMOUNT GOING OUT .
SO THERE IS NO NET MOVEMENT . THE SIZE OF
CELL REMAIN SAME.

7. HYPERTONIC SOLUTION - EXOSMOSIS
 THE MEDIUM HAS LOWER
CONCENTRATION OF WATER THAN THE
CELL. THE CELL WILL LOOSE WATER
BY OSMOSIS.
 LOSS OF WATER FROM THE CELL
RESULT IN SHRINKIF AGE OF CELL –
PLASMOLYSIS.

8. MOVEMENT OF WATER WHEN CELL IS PLACED IN
ISOTONIC , HYPOTONIC AND HYPERTONIC
.

9. FUNCTIONS OF PLASMA MEMBRANE
 IT PROVIDE DEFINITE SHAPE TO THE
SEMI FLUID CONTENT OF THE CELL.
 IT FUNCTION AS A MECHANICAL
BARRIER THAT PROTECT THE INTERNAL
CONTENT OF THE CELL.
 IT CONTROLS THE ENTRY AND EXIT OF
MATERIALS IN AND OUT SIDE CELL.

10. DIFFERENCE BETWEEN ENDOSMOSIS AND
EXOSMOSIS

11. IMPORTANT QUESTIONS:
Q1:why plasma membrane called selectively
permeable membrane?
Q2: What is osmosis?
Q3: A person takes concentrated solution of salt.
After some time he starts vomiting. What is the
phenomenon responsible for such situatio?
Explain.
Q4: What will happen if cell is placed in isotonic
solution?
Q5: Differentiate between endosmosis and
exosmosis.
Q6: List two functions of plasma membrane.