Cell Membrane And Transport

Question 1

Some membrane proteins are enzymes such as…..

Answer 1

Digestive enzymes found in cell surface membrane of cell lining the small intestine

Question 2

What is Cytoskeleton? And its function?

Answer 2

A system of protein filaments inside the cell

These proteins help to maintain and decide the shape of cells or may be involved in changes of shape when cells move

Question 3

Myelin sheath is made up of…..

Answer 3

Many layers of cell surface membrane

Question 4

Roles of cholesterol in membrane….

Answer 4

Important for mechanical stability of membrane

It strengthens membrane by getting in between the phospholipids and reducing fluidity

Hydrophobic regions of cholesterol help to prevent ions or polar molecules from passing through membrane

Prevent phospholipid tails from packing closer at low temperature(maintaining correct fluidity) so cell can survive colder temperatures

Question 5

Whats the effect of ions leakage on myelin sheath?

Answer 5

Leakage of ions would slow down the nerve impulses

Question 6

Example of ion channel resulting in changes of membrane potential

Answer 6

Nicotine accepting acetylcholine receptors

Question 7

Example of a receptor acting directly as a membrane-bound enzyme

Answer 7

Glucagon receptors

Question 8

Example of receptors acting as a intercellular receptors when the initial signal passes straight through the cell surface membrane

Answer 8

Oestrogen receptor in the nucleus and directly controls gene expression when combined with oestrogen

Question 9

Example of direct cell-to-cell contact

Answer 9

Lymphocytes detect foreign antigens

Question 10

Types of signalling pathways

Answer 10

Electrical(nervous system)

Chemical (hormones)

Question 11

The point at which the plasmolysis is about to occur is referred to as….

Answer 11

Incipient ابتداییplasmolysis

Question 12

How many types of transport proteins are there and what’s their name?

Answer 12

Two types of transport protein are there:

1.channel proteins

2.carrier proteins

Question 13

Why active transport requires energy?

Answer 13

Because movement occurs up a concentration gradient rather than down

Question 14

An example of a carrier protein used for active transport……!

Answer 14

Sodium-potassium pump

Question 15

Name some examples in which the active transport is important…!

Answer 15

Active transport is important in:

Reabsorption in the kidney (certain useful molecules and ions have to be reabsorbed into the blood after filtration into the kidney tubules)

Also involved in absorption of some products of digestion from the gut.

Question 16

Examples of active transport in plants….!

Answer 16

Active transport is used to load sugar from photosynthesising cells of leaves into the phloem بافت ابکشیtissue for transport around the plant

And to load inorganic ions from the soil into root hairs

Question 17

what is plasmolysis?

Answer 17

As the protoplast continues to shrink, it begins to pull away from the cell wall.this is called plasmolysis

Question 18

Is the energy used for active transport always ATP?

Answer 18

No most often is ATP