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Eukaryotes > Plasma membrane > Flashcards

Plasma membrane Flashcards

1
Q

P M is also known as

A

Plasmalemma/ cell membrane / biological membrane

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2
Q

PM is which layer

A

Think, elastic, universal layer as well

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3
Q

Living or dead??

A

Living

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4
Q

Selectively permeable or freely permeable

A

Selectively permeable

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5
Q

What kind of symmetry does P M have?

A

Asymmetrical

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6
Q

Why does PM has asymmetrical symmetry?

A

Due to lipids associated with the membrane which are asymmetric because of their polar and non polar ends.

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7
Q

Plasma membrane is amphipathic in nature. What does amphipathic mean?

A

It means that it has both hydrophobic and hydrophilic end.

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8
Q

PM is which fluid in nature?

A

Quasi fluid.

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9
Q

Plasma membrane was first observed by

A

Schwann

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10
Q

PM was the name given by

A

Nageli and Cramer

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11
Q

Plasmalemma was the term given by

A

Plowe

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12
Q

Normal cell has lipids percentage

A

40%

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13
Q

Normal cell has proteins percentage

A

58-59%

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14
Q

Normal cell has carbohydrates percentage

A

1-2%

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15
Q

What is the one specific feature of human RBCs PM?

A

It is used for detailed study of PM using electron microscope.

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16
Q

Lipid percentage in RBCs?

A

40%

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17
Q

Protein percentage in RBCs?

A

52%

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18
Q

Name the three models for the study of PM

A

Danielle Davson Model (sandwich model)
Robertson Model (unit membrane model)
Fluid mosaic model (by Singer and Nicolson)

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19
Q

According to DD model PM consists of layers?

A

4 layers
2- of phospholipid
2- of globular protein

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20
Q

In DD model, what are held by electrostatic forces?

A

Proteins and head of phospholipid.

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21
Q

In DD model, phospholipid are held together by which forces?

A

Vanderwood forces

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22
Q

According to Robertson model, PM consists of how many layers?

A

3 layers
->a phospholipid bilayer
-> dense layer of protein present on both sides

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23
Q

PM is also called

A

Trilaminar

24
Q

Thickness of PM acc to Robertson model is about

A

75°A

25
Q

All biomembranes are either ________

A

Made up of a unit membrane or their multiple

26
Q

What is fluid mosaic model

A

In this, proteins are considered as icebergs floating in the sea of lipids.
Proteins and phospholipids are arranged in mosaic pattern.

27
Q

Types of protein on the basis of extraction

A
  1. Extrinsic protein
  2. Intrinsic protein
28
Q

What are extrinsic proteins?

A

The ones that are present on the periphery and can get easily extracted.
Eg:- Spectrin present on the periphery of PM.

29
Q

What are intrinsic proteins?

A

The ones that are embedded within the PM and cannot be easily extracted.
Eg:- Glycophorin is a protein responsible for transport of glucose across the membrane.

30
Q

What are the types of intrinsic proteins?

A

Partially embedded proteins and fully embedded proteins

31
Q

Describe partially embedded proteins.

A

Half embedded in the PM.
They do not allow the movement of substances across the membrane.

32
Q

Describe fully embedded proteins.

A

They are also known as transmembrane proteins.
They allow the movement of substances across the membrane.

33
Q

Types of transmembrane proteins?

A

1.Tunnel/channel proteins
2.Carrier proteins

34
Q

What makes tunnel protein different from carrier proteins?

A

In tunnel proteins, pores are present, whereas in carrier proteins pores are absent.

35
Q

All transmembrane proteins are intrinsic proteins but all intrinsic proteins are not transmembrane proteins.
True/False

A

True

36
Q

What are the types of proteins on the basis of function?

A
  1. Structural protein
  2. Carrier protein
  3. Enzymatic protein
37
Q

Which type of protein provides support to the plasma membrane?

A

Structural protein

38
Q

Which type of protein helps in transport of substances across the membrane?

A

Carrier protein

39
Q

Which type of protein helps in performing catalytic activity?

A

Enzymatic protein

40
Q

In which forms are lipids present?

A

Phospholipid,
Glycolipid,
Sterol.

41
Q

What does simple lipid consists of?

A

1 Glycerol + 3 Fatty acids

42
Q

What does a phospholipid consists of?

A

1 Glycerol + 2 Fatty acids + 1 phosphate group

43
Q

Why are lipids important?

A

Because they provide elasticity and flexibility
Eg:- lecithin, cephalin, etc.

44
Q

Name some membrane stabilizers?

A
  1. Cholesterol - animal cells
  2. Hopanoids - bacterial cells
  3. Campesterol - plant cells
  4. Ergasterol - fungi
45
Q

Lipid shows what kind of movements?

A
  1. Rotational
  2. Flip flop
  3. Lateral movement
46
Q

Proteins show what kind of movements?

A
  1. Rotational
  2. Lateral movement
    Not flip flop because their molecular weight is very high.
47
Q

Where are carbohydrates present?

A

On the outer side of PM

48
Q

What is it called when carbohydrate attached with lipid?

A

The process is called glycosidation and it is called glycolipid.

49
Q

What is it called when carbohydrate attached with protein?

A

The process is called glycosylation and it is called glycoprotein.

50
Q

What are the functions of carbohydrates?

A
  1. They help is cell to cell recognition
    Eg: male gamete recognises female gamete during syngamy.
  2. They act as surface antigens.
51
Q

What are the functions of PM?

A
  1. They separate cell cytoplasm from external environment.
  2. Fluidity in PM can perform:
    - Cell growth
    - Cell division
    - Cell expansion
    - Endocytosis
    - Exocytosis
  3. Transport of molecules across PM (Major function)
52
Q

Define Endocytosis and it’s types.

A

Endocytosis - Movement of substances inside the cell.
Types of Endocytosis:-
1. Phagocytosis - entry of food in solid form. ( Cell eating)
2. Pinocytosis - entry of food in liquid form. (Cell drinking)

53
Q

What is cell vomiting?

A

Exocytosis or cell vomiting is movement of substances outside the cell.

54
Q

What is passive transport?

A
  1. Movement of substances from higher concentration to lower concentration.
  2. It’s takes place ALONG the concentration gradient.
  3. No energy is required.
  4. For neutral solutes- they easily cross the PM by simple diffusion.
    For charged molecules - they cross the PM through transmembrane proteins by facilitated diffusion.
  5. It’s a downhill movement.
55
Q

What is active transport?

A
  1. Movement of substances from low concentration to high concentration.
  2. Movement takes place against the concentration gradient.
  3. Energy is required in the form of ATP.
  4. Proton pumps/ carrier proteins are required to move across the proteins.
    Eg:- Na-K pumps
  5. Uphill movement.

Eukaryotes (7 decks)

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