Cell Membrane

Question 1

What are the other names of cell membrane

Answer 1

Plasma membrane

Biomembrane

Plasmalemma

Question 2

What type of permeability does cell membrane has?

Answer 2

Selectively permeable

Question 3

When was the detailed study of cell membrane done?

Answer 3

After the invention of electron microscope in mid 1950s

Question 4

What is the cell membrane composed of?

Answer 4

Lipids, proteins and carbohydrates

Question 5

Is the ratio of protein and lipid constant in all types of cell?

Answer 5

No…ratio of protein and lipid vary on the basis of type of cell

Question 6

What is the ratio of protein and lipid in human RBC (ncert)

Answer 6

Protein : Lipid

52% : 40%

Question 7

Average composition of lipid and the types of lipids found in cell membrane

Answer 7

40%….phospholipid, phosphoglyceride, cholesterol and glycolipid

Question 8

Average composition of protein and the types of protein found in cell membrane

Answer 8

58% - 59%….arginine and lysine rich protein

Question 9

Average composition of carbohydrates in cell membrane

Answer 9

1% - 2%

Question 10

Does the structure and function of cell membrane change in different types of cells?

Answer 10

No….cell membrane is a universal structure, similar in prokaryotic and eukaryotic cells

Question 11

Give the other names of Sandwich model

Answer 11

Trilayered model

Trilaminar model

PLLP model

Question 12

Who gave the Sandwich model and when?

Answer 12

Davson and Danielli (1935)

Question 13

Who gave the Unit Membrane model?

Answer 13

Robertson

Question 14

What did the unit membrabe model suggest?

Answer 14

All membrane of cells and cell organelles are similar in structure and function but may differ in chemical composition and size.

Question 15

Why were the sandwich model and unit membrane rejected?

Answer 15

They were not able to explain the selective permeability of cell membrane

Question 16

Which is the most latest and accepted model of structure of cell membrane?

Answer 16

Fluid- Mosaic model

Question 17

Who gave the fluid mosaic model and when?

Answer 17

Singer and Nicolson (1972)

Question 18

How are the proteins present in phospholipid?

Answer 18

In a mosaic pattern

Question 19

What is the main component of cell membrane which forms continuous framework?

Answer 19

Phospholipids

Question 20

What is its nature with water?

Answer 20

Amphipathic

Question 21

Phospholipids are made up of?

Answer 21

Saturated and unsaturated hydrocarbons

Question 22

The head is ______ in nature

Answer 22

Hydrophilic

Question 23

The tail is ______ in nature

Answer 23

Hydrophobic and non polar

Question 24

What do phospholipids provide?

Answer 24

Liquidity, fluidity and quasi fluid nature

Question 25

What property of cell membrane allows lateral movement of proteins?

Answer 25

Fluid nature

Question 26

Fluidity of cell membrane helps in :-

Answer 26

Cell growth Formation of cellular junction (furrow) Cell diffusion Endocytosis Secretion

Question 27

What is the function of cholesterol?

Answer 27

Provides stability

Question 28

What provides stability in prokaryotic cells since cholesterol is absent in prokaryotic cell?

Answer 28

Hopanoids (pentacyclicsteroids)

Question 29

Intrinsic protein

Answer 29

Integral protein Stable Can not be separated easily Can be partially or completely buried

Question 30

Extrinsic protein

Answer 30

Peripheral protein Unstable Can be separated easily Shows enzymatic activities

Question 31

Carbohydrates

Answer 31

Present as oilgosaccharides (chain of 2 - 10 monosaccharides) Present as glycoprotein or glycolipids Present on outer surface of cell membrane

Question 32

Function of carbohydrates in cell membrane

Answer 32

Helps in cell to cell recognition (fertilization)

Question 33

What is the difference between cytosolic and non cytosolic layer of phospholipids?

Answer 33

Cytosolic layer of phospholipid is a part of cytosol while non cytosolic is not

Question 34

State the broad types of handful molecule transportation occurring through cell membrane

Answer 34

Passive and active

Question 35

Passive transport

Answer 35

Higher to lower concentration ATP not required According to the concentration gradient Simple diffusion occurs when molecules are neutral Facilitated diffusion occurs when molecules are polar through carrier protein and channel protein

Question 36

Active transport

Answer 36

Lower concentration to higher concentration ATP required Against concentration gradient Always facilitated through carrier proteins ( Na+ and K+ pumps)

Question 37

State the broad types of bulk molecule transactions through cell membrane

Answer 37

Endocytosis Exocytosis

Question 38

State the two types of endocytosis

Answer 38

Phagocytosis (cell eating) Pinocytosis (cell drinking)

Question 39

Give an example of phagocytosis

Answer 39

The act of engulfing a foreign particle by WBC

Question 40

What is exocytosis also called

Answer 40

Emiocytosis (cell vomiting)