Fundamental Notions Part 3

Question 1

What is the primary function of ion channels?

Answer 1

Ion channels facilitate the regulated passage of specific ions across the cell membrane through an aqueous pore.

Question 2

How do ion channels achieve selectivity for specific ions?

Answer 2

Ion channels are designed with specific binding sites and pore sizes that allow only certain ions, such as sodium or potassium, to pass through.

Question 3

What are the two main classes of ion channels?

Answer 3

The two main classes are ligand-gated ion channels and voltage-gated ion channels.

Question 4

What role do blockers play in the context of ion channels?

Answer 4

Blockers bind to the pore of the ion channel, preventing the passage of ions and effectively inhibiting the channel’s function.

Question 5

What is IC50 and why is it important?

Answer 5

IC50 is the concentration of a drug needed to inhibit a biological process by 50%. It serves as a measure of the potency of an inhibitor; a lower IC50 indicates higher potency.

Question 6

How do transporters differ from ion channels?

Answer 6

Transporters facilitate the selective passage of small molecules and do not create open pores like ion channels. They transport substances by alternating between open states on either side of the membrane.

Question 7

What is the difference between passive transporters and active transporters?

Answer 7

Passive transporters allow movement along the concentration gradient without energy input, while active transporters require energy to move substances against the concentration gradient.

Question 8

Can you give an example of a specific transporter and its function?

Answer 8

The Sodium Glucose Transporter (SGLT-2) in the kidney reabsorbs glucose and sodium from urine back into the blood, thus helping to regulate blood glucose levels.

Question 9

What are the types of enzyme inhibitors?

Answer 9

Inhibitors can be reversible or irreversible, and can also be classified as competitive, non-competitive, uncompetitive, or false substrates.

Question 10

What is a competitive inhibitor and how does it function?

Answer 10

A competitive inhibitor binds to the same active site as the substrate, competing for binding and thus reducing the enzyme’s activity.

Question 11

Describe what a non-competitive inhibitor does.

Answer 11

A non-competitive inhibitor binds to a different site on the enzyme, which decreases the enzyme’s activity regardless of whether the substrate is present.

Question 12

What is a prodrug, and how does it work?

Answer 12

A prodrug is an inactive drug that must be metabolized into its active form within the body. For example, codeine is converted into morphine to exert its analgesic effects.

Question 13

How do allosteric inhibitors affect enzyme activity?

Answer 13

Allosteric inhibitors bind to a site other than the active site, causing a conformational change that reduces the enzyme’s activity.

Question 14

What is the significance of glycosylation in proteins?

Answer 14

Glycosylation is the addition of carbohydrate groups to proteins, which plays a crucial role in protein folding, stability, and cell signalling.

Question 15

How do enzymes act as biological catalysts?

Answer 15

Enzymes lower the activation energy required for biochemical reactions, allowing them to proceed more quickly without being consumed in the process.

Question 16

What are the components that make up ion channels?

Answer 16

Ion channels are composed of protein molecules that span the cell membrane, forming an aqueous pore.

Question 17

What types of signals can gate ion channels?

Answer 17

Ion channels can be gated by various signals, including ligand binding, voltage changes, and mechanical stimuli.

Question 18

What is the difference between facilitators and carriers in transporters?

Answer 18

Facilitators allow passive transport of molecules along the concentration gradient, while carriers can facilitate active transport, requiring energy to move substances against the gradient.

Question 19

How do ion channels maintain resting membrane potential?

Answer 19

Ion channels selectively allow certain ions to flow in and out of the cell, which helps maintain the resting membrane potential by balancing ion concentrations.

Question 20

What happens when an ion channel is opened?

Answer 20

When an ion channel opens, ions flow down their concentration gradient, leading to changes in membrane potential and cell signalling.

Question 21

What is the function of topoisomerases in DNA replication?

Answer 21

Topoisomerases prevent DNA tangling (supercoiling) by unwinding and rewinding DNA strands during replication.

Question 22

What is the significance of telomerase in DNA replication?

Answer 22

Telomerase adds telomeres to the ends of chromosomes, protecting them from degradation and maintaining chromosome integrity during replication.

Question 23

How does the RNA polymerase initiate transcription?

Answer 23

RNA polymerase binds to the DNA promoter region, unwinding the DNA and exposing the coding sequence for RNA synthesis.

Question 24

What is splicing in mRNA processing?

Answer 24

Splicing is the process of removing introns (non-coding regions) from the pre-mRNA and joining exons (coding regions) to form mature mRNA.

Question 25

What role do ribosomes play in translation?

Answer 25

Ribosomes synthesize proteins by translating mRNA sequences into polypeptide chains, facilitating the assembly of amino acids.

Question 26

What are codons, and why are they important?

Answer 26

Codons are sets of three nucleotides in mRNA that specify a particular amino acid, guiding protein synthesis.

Question 27

How do allosteric inhibitors affect enzyme kinetics?

Answer 27

Allosteric inhibitors alter the shape of the enzyme, decreasing its activity and potentially shifting the enzyme’s substrate affinity.

Question 28

What distinguishes primary active transporters from secondary active transporters?

Answer 28

Primary active transporters use ATP directly to move molecules against their concentration gradient, while secondary active transporters rely on the gradient created by primary transporters.

Question 29

What is the function of the methylated guanosine cap on mRNA?

Answer 29

The cap protects the mRNA from degradation and aids in the initiation of translation by helping ribosomes recognize the mRNA.

Question 30

How does a false substrate differ from a competitive inhibitor?

Answer 30

A false substrate binds to the enzyme and allows a reaction to occur but produces an abnormal product, while a competitive inhibitor simply competes with the substrate for the active site.

Question 31

What is the role of transporters in nutrient absorption?

Answer 31

Transporters facilitate the uptake of essential nutrients, ions, and other small molecules into cells, playing a key role in nutrient homeostasis.

Question 32

Why are prodrugs used in pharmacology?

Answer 32

Prodrugs are used to improve drug absorption, distribution, and metabolism, ensuring that the active form of the drug is delivered effectively in the body.

Question 33

How do non-competitive inhibitors differ from competitive inhibitors?

Answer 33

Non-competitive inhibitors bind to a site other than the active site, reducing enzyme activity regardless of substrate concentration, whereas competitive inhibitors directly compete for the active site.

Question 34

What is the significance of IC50 in drug development?

Answer 34

IC50 values help researchers assess the potency of a drug and compare its effectiveness against other compounds, aiding in the drug development process.

Question 35

How does glycosylation affect protein function?

Answer 35

Glycosylation can influence protein folding, stability, localization, and interactions with other molecules, impacting the overall function of the protein.