Which of the following will not occur in response to UV...

Which of the following will not occur in response to UV exposure if a p53 mutation inactivates the p53
protein?
1. Damage to DNA
2. p53 activation
3. p21 activation
4. Apoptosis
a. 1, 2, and 3
b. 3 and 4
c. 3
d. 2, 3, and 4

Key Concepts

p21

p21 is a cyclin-dependent kinase inhibitor whose expression is upregulated by activated p53. It plays a significant role in halting cell cycle progression, thereby allowing time for DNA repair. Without functional p53, the signaling necessary for p21 activation is compromised, interfering with effective cell cycle control.

Apoptosis

Apoptosis is a regulated process of programmed cell death that eliminates damaged or potentially harmful cells. It is typically induced by severe DNA damage as a protective measure, with p53 serving as a key regulator of this pathway. When p53 is inactivated, the ability to trigger apoptosis in response to damage is substantially reduced.

p53 Protein

The p53 protein is a crucial tumor suppressor that regulates the cell cycle and helps maintain genomic stability by initiating DNA repair, cell cycle arrest, or apoptosis in response to DNA damage. Its activation is essential for preventing the propagation of mutations, and mutations in p53 can disrupt these protective cellular processes.

DNA Damage Response

The DNA damage response is a complex network of cellular pathways that detect and respond to various types of DNA damage, including that caused by ultraviolet exposure. It involves sensing damage, activating repair mechanisms or cell cycle checkpoints, and, if necessary, initiating apoptosis. p53 is central to orchestrating many aspects of this response.

Transcript

00:01 Okay, we are given a pathway and we are asked what would happen if one of these links in the pathway would become dysfunctional.

00:16 So first things first, let's see that or let's notice that all of the effects that the previous node has on the following node is positive, meaning that an increase in one level results.

00:31 In the increase in all subsequent level.

00:34 So uv induces skin exposure, so skin exposure to uv induces dna damage, which induces activation of p53, that induces activation of p21, that induces activation of apoptosis.

00:51 When the cells die, then they are shed in skin peals, right? so all the arrows lead up.

00:57 So there's a positive increase in all of these processes with the exposure of uv light and the answer of the question is asking what would happen if p53 is mutated so what would happen if this guy right here becomes unresponsive okay so you would have this would still occur normally you skin exposure to increase uv would cause dna damage but then here you would have no well so actually you would have increased p53 as well it's just that the p53 would be dysfunctional so it wouldn't have an effect on the downstream events so nothing would happen to p21 nothing would happen to apoptosis and your skin wouldn't peel so basically this is where the chain fails after p53 so let's let's look at our answer choices.

02:05 So answer choices are a combination of four different options.

02:08 The options are damage to dna.

02:11 Damage to dna will still occur.

02:14 So option one is not there.

02:18 So we are not looking for, actually, i drew that at the wrong place.

02:24 So damage to dna is still occurring.

02:26 So option one is not included in our correct choice.

02:30 P53 activation.

02:34 Yeah, because even though you are increasing p53, i would consider p53 activation if p53 is actually doing its function...