Intro to Cell Membrane 2

Question 1

What shows us the tensile strength of red blood cells?

Answer 1

Optical tweezers

Question 2

Name a good model for studying membranes and membrane proteins?

Answer 2

RBC’s or red blood

Question 3

Where is the cytoskeleton linked to?

Answer 3

Plasma membrane

Question 4

What is spectrin?

Answer 4

A major cytoskeletal protein found in many eukaryotic cells, especially abundant in red blood cells.

Question 5

What does mutations in spectrin cause?

Answer 5

Mutations in spectrin cause
certain types of hemolytic
anemia (hereditary
elliptocytosis and hereditary
spherocytosis)

Question 6

What are the key features of biological membranes?

Answer 6

1. Membranes are asymmetric.
2. Proteins always have the same the same orientation in the membrane.
3. The lipid composition of each of the two halves of the bilayer is different

Question 7

When is membrane asymmetry important?

Answer 7

1. Cell Signalling
2. Vesicle trafficking
3. Cell adhesion and migration.
4. Apoptosis
5. Blood coagulation
6. Neurotransmission

Question 8

How is the blood group of an individual determined?

Answer 8

The blood group of an individual is determined by the structure of the oligosaccharides attached to sphingomyelin and proteins in the red blood cell membrane and to proteins in plasma and other body fluids.

Question 9

How does membranes transport proteins of small molecules?

Answer 9

1. Active Transport
2. Electrochemical gradients
3. Carriers and channels

Question 10

What acts as a barrier to the diffusions of many different solutes?

Answer 10

The phospholipid bilayer

Question 11

What are membrane transport proteins?

Answer 11

Membrane transport proteins are specialized proteins embedded in the cell membrane that facilitate the movement of specific molecules (e.g., sugars, amino acids, ions) across the membrane.

Question 12

Why are membrane transport proteins important?

Answer 12

Selectivity: Transport proteins allow for the selective movement of molecules across the membrane, regulating the cell’s internal environment.
Hydrophobicity: They provide a hydrophilic pathway for solutes to pass through the membrane, preventing direct contact with the hydrophobic core of the membrane.
Essential for cellular functions: Transport proteins are crucial for various cellular processes, such as nutrient uptake, waste removal, maintaining ion gradients, and cell signaling.

Normal font is extra information

Question 13

What is passive transport?

Answer 13

Passive transport is the movement of molecules across a cell membrane from an area of high concentration to an area of low concentration. It does not require energy and can occur through channels or carriers.

Question 14

What is active transport?

Answer 14

Active transport is the movement of molecules across a cell membrane

against their concentration gradient, from an area of 1 low concentration to an area of high concentration. This process requires energy, typically in the form of ATP, 2 and is always mediated by carrier proteins

Question 15

What factors influence the transport of solutes across a membrane?

Answer 15

Electrochemical Gradient:

This is the combination of two forces:
* Concentration Gradient: The difference in solute concentration across the membrane.
* Membrane Potential: The electrical voltage difference across the membrane.

Question 16

How does membrane potential contribute to the electrochemical gradient?

Answer 16

• Membrane Potential: Arises from the uneven distribution of charged ions across the membrane, creating a voltage difference.
• Influence on Transport: The membrane potential interacts with the concentration gradient to drive the movement of charged solutes. For example, positively charged ions (cations) are attracted to the negatively charged side of the membrane, while negatively charged ions (anions) are repelled.

Question 17

What are electrochemical gradients?

Answer 17

Electrochemical gradients are established by differences in ion concentration and charge across a membrane. They are generated through the action of ion channels and carrier proteins (pumps).

Question 18

What are the functions of electrochemical gradients?

Answer 18

Electrochemical gradients play crucial roles in various cellular processes, including:

Driving the transport of ions and other molecules across membranes.
Generating electrical signals in nerve cells (action potentials).
Producing ATP in mitochondria, chloroplasts, and bacterial membranes (oxidative phosphorylation and photosynthesis).

Question 19

What transports solute faster that carriers and why?

Answer 19

Channels because they only interact very weakly with solute and carriers proteins directly bind to the solute slowing down transport

Question 20

What are ion channels?

Answer 20

Ion channels are integral membrane proteins that form narrow, hydrophilic pores through the cell membrane.

They allow the rapid movement of ions down their concentration or electrochemical gradient.

Question 21

What is the key characteristic of ion channels?

Answer 21

Ion channels are highly selective

. Each channel type is specific for a particular ion, such as potassium (K+) or sodium (Na+). This selectivity ensures that only the appropriate ions can pass through.

Question 22

What are some additional facts about ion channels?

Answer 22

Diversity: There are over 100 different types of ion channels with varying properties, such as selectivity, gating mechanisms, and expression patterns.
Targets for toxins and drugs: Ion channels are targets for many toxins (like scorpion venom) and drugs.
Clinical relevance: Mutations in ion channels can lead to various diseases, such as congenital insensitivity to pain (due to mutations in the SCN9A voltage-gated sodium channel).

Question 23

Do carriers undergo confrontational changes to transport solute?

Answer 23

Yes

Question 24

What are the three types of carrier- mediated transport?

Answer 24

1. Uniport
2. Symport
3. Antiport

2 and 3 are coupled transport

Question 25

Which process enhances the rate of transport?

Answer 25

Carrier mediated diffusion

Question 26

How is transport achieved in the mammalian plasma membrane?

Answer 26

Transport driven by Na+ gradients

Question 27

How is transport achieved in the Bacteria, yeast, intracellular membranes?

Answer 27

transport driven by H+ gradients

Question 28

What drives the uptake of glucose?

Answer 28

Glucose uptake is driven by an electrochemical gradient

Question 29

How is glucose transported across intestinal epithelial cells?

Answer 29

Through a coupled transport system:

Apical Na+/Glucose Symporter: Brings glucose and Na+ into the cell.
Basolateral Na+/K+ Pump: Maintains low intracellular Na+, driving symporter.
Basolateral Glucose Transporter: Facilitates glucose exit into the bloodstream.