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CENG | CMB | MI > Chapter 3 CMB Cell Membrane > Flashcards

Chapter 3 CMB Cell Membrane Flashcards

1
Q

What are the 3 functions of proteins?

A

-Enzyme activity
-Signal transduction
-Transport

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2
Q

What are the 3 membrane proteins?

A

-Transmembrane proteins
-Integral proteins
-Peripheral proteins

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3
Q

What is a mosaic model of membrane structure?

A

Mixed composition of different kinds of macromolecules such as integral proteins, peripheral proteins, glycoproteins, phospholipids, glycolipids, etc.

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4
Q

What is a fluid model of membrane structure?

A

because of its (flexible) hydrophobic integral components such as lipids and membrane proteins move laterally or sideways throughout the membrane

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5
Q

What are the 2 types of transports of proteins?

A

Passive and active

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6
Q

What is the function of transport protein?

A

Transport molecules across plasma membrane

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7
Q

What is passive transport?

A

-Movement is from higher concentration to lower concentration
-No energy (ATP) required

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8
Q

What is active transport?

A

-Movement is from lower to higher concentration
(against concentration gradient)
-Energy ATP required

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9
Q

Examples of passive transport?

A

O2 and CO2

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10
Q

Examples of active transport?

A

Sodium-potassium pump

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11
Q

Function of enzymes?

A

Enzymes attached to interior surface of membrane help to catalyse chemical reactions

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12
Q

Function of receptors?

A

-For chemical messages from other cells
-The binding of a messenger to a receptor may trigger signal transduction

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13
Q

Function of structural protein?

A

Supports shape of membranes

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14
Q

Example of structural protein?

A

Biconcave shape of red blood cell is due to scaffold of proteins linking membrane with cytoskeleton

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15
Q

Function of cell adhesion proteins?

A

Special proteins that glue cells to one another

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16
Q

What are glycolipids and state its function

A

-Cell surface markers
Tissue recognition by lipid/carbohydrate chain shape characteristic to tissue

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17
Q

What are glycoproteins and state its function

A

-Cell surface markers
“Self”- recognition with protein/carbohydrate chain shape unique to individual

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18
Q

Example of glycoproteins?

A

major histocompatibility complex protein (MHC) in organ transplant

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19
Q

Example of glycolipids?

A

ABO blood group markers

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20
Q

Function of plasma membrane?

A

-Plasma membrane keeps essential substances inside the cell
-Regulates passage of materials between cell and its environment

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21
Q

Function of phospholipid bilayer?

A

Phospholipid bilayer acts primarily as a barrier

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22
Q

What do proteins on the plasma membranes act as?

A

Protein act as selective gates (protein channels/ transport proteins)
selectively permeable membrane

23
Q

State the 3 passive processes

A

Diffusion
Facilitated diffusion
Osmosis (liquid only)

24
Q

State the 3 active processes

A

Active transport
Endocytosis
Exocytosis

25
Q

What is passive diffusion?

A

-Substances diffuse through membranes without work by the cell
-Substances move from areas of high concentration to areas of lower concentration

26
Q

State examples of passive diffusion

A

-Oxygen (needed for metabolism) enters red blood cells from lungs
-Carbon dioxide (metabolic waste) passed out of red blood cells to lungs
-Oxygen & Carbon dioxide are small non-polar molecules.

27
Q

What is facilitated diffusion?

A

-Polar molecules (Ions) cannot easily cross without assistance
-A form ofpassive transport, like diffusion, and thereforedoes not require any energy input.
-Movement of substancesfrom higher to lower concentration

28
Q

What is facilitated diffusion facilitated by?

A

channel or transport proteins.

29
Q

Example of facilitated diffusion?

A

glucose transport

30
Q

What is osmosis?

A

-Passive transport of water across a membrane
-water travels from an area of lower solute concentration (high water) to an area of higher solute concentration

31
Q

What are hypotonic solution and cell?

A

Lower solute and more water concentrations than cell cytoplasm

32
Q

What happens when water enters a hypotonic cell?

A

It swells

33
Q

What are hypertonic solution and cell?

A

higher solute and lower water concentration than the cell cytoplasm

34
Q

What happens when water leaves a hypertonic cell?

A

It shrinks

35
Q

What is an isotonic solution and cell?

A

Solute and water concentrations are same inside and outside of the cell

36
Q

Does the volume in isotonic solution and cell change?

A

No net movement of water. Hence, volume of the cell remains the same

37
Q

What are active transports?

A

-Transport proteins can move solutes across a membrane against a concentration gradient
-Active transport requires ATP
-The transport / channel protein changes its structure in order the move the substances

38
Q

What are the 4 steps of active transport? SPTP

A
  1. Solute binding
  2. Phosphorylation
  3. Transport
  4. Protein reversion
39
Q

Examples of active transport across a membrane?

A

-sodium-potassium pump
proteins transport sodium ions out of cells and potassium ions into cells, both against steep concentration gradients
-nerve cells have internal potassium concentrations 30x greater than the extra-cellular fluid due to the pumping activity of the proteins. These ionic gradients are utilised in transmission of nerve impulses

40
Q

What is exocytosis?

A

To move large molecules or particles out of cells through plasma membrane
A vesicle containing molecules or particles fuse with the membrane and expel its contents

41
Q

Examples of exocytosis?

A

E.g. Removal waste from cells
-Secretion of mucus from cells lining stomach wall
-Salty solution containing proteins from cells in tear glands
-Insulin from pancreatic cells into the bloodstream

42
Q

What is endocytosis?

A

Uptake of materials too large to penetrate the membrane.

43
Q

Explain the process of endocytosis

A
  1. The membrane fold inward, trapping material from the outside.
  2. Materials are enclosed within invaginations (vesicles) of the plasma membrane which subsequently pinched off to form cytoplasmic vesicles.
44
Q

What are the 3 types of endocytosis?

A
  1. Phagocytosis
  2. Pinocytosis
  3. Receptor-mediated endocytosis
45
Q

What is phagocytosis?

A

Ingestion of large solid particles

46
Q

Example of phagocytosis?

A

Cell (e.g. white blood cell) ingest large particles e.g. bacteria / pathogens

47
Q

What is pinocytosis?

A

Cell ingests liquid, dissolved solutes and small suspended particles

48
Q

What is Receptor-mediated endocytosis

A

Plasma membrane indents to form a pit lined with receptor proteins that have picked up particular molecules. Pit will close to form vesicle, carrying the molecules into cytoplasm.

49
Q

What are the 3 types of cell junctions?

A
  1. Tight junctions
  2. Anchoring junctions
  3. Communicating junctions
50
Q

What are tight junctions?

A

Bind cells together to form a leak proof sheet

51
Q

Example of tight junctions?

A

Eg sheet of tissues line the digestive tract preventing contents from leaking into surrounding tissues

52
Q

What are anchoring junctions?

A

Attach adjacent cells to one another

53
Q

What are communicating junctions?

A
  1. Allow water and small molecules to flow between neighbouring cells
  2. Allow passage of small moecules from cell to cell in a tissue.

CENG | CMB | MI (25 decks)

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