CELL MEMBRANE- STRUCTURE & TRANSPORT

Question 1

which phospholipid is involved in cell signaling

1. Sphingomyelin
2. Phosphaditylcholine
3. Phosphaditylinositol
4. Phosphaditylethanolamine

Answer 1

3. Phospha-dityl-inositol

(man sterility, cu-zn balance)

Question 2

Glycolipids are Exclusively Found In The Outer Leaflet Of The Plasma Membrane

1. Yes
2. No

Answer 2

1. YES

Question 3

Cholesterol

1. is not able to form a membrane on itself
2. makes the outer part of the cell membrane more fluid at low temperature
3. prevents membranes from freezing

Answer 3

all true

Question 4

which proteins are dissociated from the membrane by a change in the ph

1. peripheral membrane proteins
2. integral membrane proteins

Answer 4

1. peripheral membrane proteins

Question 5

which proteins are released by detergents?

1. integral membrane proteins
2. peripheral proteins

Answer 5

1.

Question 6

true or false?

Cell membranes are made up of a bimolecular layer
of polar lipids, coated on one side with protein films.

Answer 6

false

Cell membranes are made up of a bimolecular layer
of polar lipids, coated on both sides with protein films.

Question 7

Cellular membranes always arise from>……………………………

Answer 7

Cellular membranes always arise from pre-existing
membranes, and the process of assembling new membranes is carried out by the endoplasmic reticulum ER

Question 8

WHAT IS THE EFFECT of fatty acid oxidation by the action of reactive oxygen species, ROS on the cell membranes?

Answer 8

fatty acid oxidation (e.g., by the action of reactive oxygen species, ROS) can cause the membranes to :

lose their fluidity, as well as have an effect on transport mechanisms.

Question 9

true or false:

Microvilli are present on the surface of oocytes, zygotes and early cleavage stage embryos in many species, and in some species (but not humans)

Answer 9

true

Question 10

what are Microtubules ?

Answer 10

Microtubules are hollow polymer tubes made up
of alpha-beta dimers of the protein tubulin.

Microtubules form the spindle for chromosome attachment and movement, During prophase of mitosis or meiosis,

Question 11

what are the Microfilaments ???

Answer 11

Microfilaments are threads of actin protein, usually found in bundles just beneath the cell surface; they play a role in cell motility, and in endo- and exocytosis.

Question 12

Centrioles are??

Answer 12

Centrioles are a pair of hollow tubes at right angles
to each other, just outside the nucleus.

organize the nuclear spindle in preparation for the separation of chromatids during nuclear division.

Question 13

Centromere :

Answer 13

Centromere : constricted region in a chromosome,
which divides it into two “arms.”

It serves as an attachment site for sister chromatids and spindle fibers.

allowing chromosomes to be pulled to different poles.

Question 14

Kinetochore:

Answer 14

structure that forms at the centromere to bind microtubules during mitosis

Question 15

Inositol 1,4,5-trisphosphate (IP3)

Answer 15

Inositol 1,4,5-trisphosphate (IP3)-induced calcium release (IICR) .

IP3 is produced by the action of phospholipase C on plasma membrane lipid phosphatidylinositol bisphosphate,

, and IICR is triggered
by the binding of IP3 to its receptor on the endoplasmic reticulum.

Question 16

Transmembrane Proteins Are

1. peripheral membrane proteins
2. integral membrane proteins

Answer 16

2. integral membrane proteins

Question 17

Porins

1. are peripheral membrane proteins
2. regulate membrane permeability through open aqueous channels in the lipid bilayer

Answer 17

2. regulate membrane permeability through open aqueous channels in the lipid bilayer

Question 18

The glycocalyx is

1. a carbohydrate coat covering the cell
2. a gene responsible for the expression of aquaporins in the membrane bilayer
3. part of the non water soluble inner cell membrane

Answer 18

1. a carbohydrate coat covering the cell

Question 19

Passive Membrane Diffusion??

Answer 19

Passive Membrane Diffusion

1. is a non-selective process allowing molecules to dissolve in the phospholipid bilayer
2. allows only small hydrophobic molecules to diffuse at significant rates
3. does not allow charged molecules of any size to pass the plasma membrane

Question 20

Facilitated Membrane Diffusion

Answer 20

Facilitated Membrane Diffusion

is mediated by channel and carrier proteins

Question 21

Carrier proteins facilitate the membrane diffusion of…………….

Answer 21

1. sugars
2. amino acids
3. nucleosides

Question 22

Transport Through Ion Channels Made by Channel Proteins:

1. is extremely rapid
2. is very slow
3. is very selective
4. is continuous
5. is extremely rapid and very selective

Answer 22

5. is extremely rapid and very selective

Question 23

Which Is Correct

1. Na+ is not pumped out the cell
2. K+ is actively pumped out of the cell
3. Na+ and K+ are both actively pumped out the cell
4. Na+ and K+ are both actively pumped in the cell
5. K+ is actively pumped in the cell, and Na+ is actively pumped out the cell

Answer 23

5. K+ is actively pumped in the cell, while,

Na+ is actively pumped out the cell

Question 24

The quantitative relationship between the ion concentration and the membrane potential is given by

1. The Avogadro Equitation
2. the Nernst equation
3. the Henderson Hasselbalch equation

Answer 24

2. the Nernst equation

Question 25

what is the **Sodium Potassium Pump?**

Answer 25

**Sodium Potassium Pump** * consume 25% of the total amount of ATP utilized by the cell * maintain a 100x higher K+ concentration inside than outside the cell * maintain a 100x Na+ concentration outside than inside the cell * are active transport mechanisms driven by ATP .hydrolysis

Question 26

**The Calcium Pump**

Answer 26

**The Calcium Pump** * transports Calcium out -and- into of the cell * maintains the Calcium concentration in the cell extremely low

Question 27

**Cystic Fibrosis** Is Caused By 1. a defective Na+ membrane transport 2. a defective K+ membrane transport 3. a defective Cl- membrane transport 4. all of the above

Answer 27

3. a defective **Cl-** membrane transport

Question 28

Active Membrane Transport Involves 1. ATP Hydrolysis 2. Ion gradients 3. none of the above

Answer 28

1, 2

Question 29

Cholesterol Uptake 1. involves receptor mediated endocytosis 2. involves Clathrin Coated Vesicles 3. involves a Low Density Lipoprotein 4. all of the above 5. non of the above

Answer 29

4. all of the above

Question 30

Extra Cellular Matrix 1. contains collagen as major structural protein 2. is composed of fibrous proteins embedded in a gel-like polysacharide ground substance 3. fills the spaces between cells and bind cells together 4. contains no glycosaminoglycans (heparyna, hyaluronian are glycosaminoglycan)

Answer 30

1,2 and 3

Question 31

**Hyaluronan**

Answer 31

1. is the only glycosaminoglycan that occurs as a single polysacharide 2. its structure is not modified by the addition of sulfate groups 3. can interact with a number of proteoglycans to form large complexes

Question 32

Which Is Not A Adhesion Protein 1. Fibronectin 2. Lamminin 3. Integrin

Answer 32

3.

Question 33

Which Are Not **Cell Adhesion Molecules** 1. Selectins 2. Integrin 3. Cadherins 4. Immunoglobulin superfamily 5. Lamminins

Answer 33

5.

Question 34

**function of Tight Junctions:-**

Answer 34

1. prevent the passage of molecules between the cells of epithelia sheets 2. separate the apical and the basolateral domains of the plasma membrane 3. prevent free diffusion of lipids and membrane proteins

Question 35

what is NOT TRUE About **Gap Junctions** 1. serve a s direct connection between cytoplasma and adjacent cells 2. provide open through the plasma membrane 3. allow ions and small molecules to diffuse freely between adjacent cells 4. allow the passage of proteins and nucleic acids 5. are constructed of membrane proteins called connexins

Answer 35

4.