Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Questions > Ch7.11 APC > Flashcards

Ch7.11 APC Flashcards

1
Q

What is Familial Adenomatous Polyposis (FAP)?

A

An inherited susceptibility to develop adenomatous polyps in the colon, which can progress to colon cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What percentage of colon cancers is accounted for by Familial Adenomatous Polyposis (FAP)?

A

Less than 1% of all colon cancers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is FAP linked to the APC gene?

A

Mutations in the APC gene cause the development of numerous polyps in the colon, increasing the risk of cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What role do stem cells play in the colonic crypt?

A

They divide to maintain the stem cell pool and produce progenitor cells that differentiate and migrate upwards.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens to enterocytes after they migrate out of the crypts?

A

They differentiate, function briefly, die by apoptosis, and are shed into the colonic lumen within 3-4 days.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does the process of enterocyte turnover defend against colon cancer?

A

Mutations in enterocytes are quickly eliminated as the cells die within days of being formed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What kind of mutation can contribute to colon cancer development in enterocytes?

A

Mutations that block out-migration and apoptosis of enterocytes can lead to cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What signaling pathway regulates the stem cell state in colonic crypts?

A

The Wnt/β-catenin signaling pathway.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the role of β-catenin in colonic stem cells?

A

High levels of β-catenin maintain the stem cell phenotype in enterocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does APC affect β-catenin levels?

A

APC promotes the degradation of β-catenin, lowering its levels as enterocytes migrate out of the crypt.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens when APC is mutated or inactivated?

A

β-catenin accumulates, causing cells to retain a stem cell-like phenotype and preventing migration out of the crypts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the consequence of β-catenin accumulation in colonic enterocytes?

A

It leads to the formation of adenomatous polyps, which can progress to carcinomas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What other gene mutations often follow APC inactivation in colon cancer development?

A

Mutations in genes like K-ras, which cause more aggressive cell growth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of GSK-3β in β-catenin regulation?

A

GSK-3β phosphorylates β-catenin, marking it for degradation via the ubiquitin-proteasome pathway.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the components of the APC degradation complex?

A

APC, axin, conductin, and GSK-3β.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What percentage of sporadic colon carcinomas involve APC inactivation?

A

About 90%.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the two ways APC inactivation can occur in colon cancer?

A

Through mutations in the APC gene or hypermethylation of the APC promoter.

18
Q

How can β-catenin mutations mimic APC inactivation?

A

Mutations in β-catenin can prevent its phosphorylation by GSK-3β, leading to its accumulation.

19
Q

What phenotype do enterocytes exhibit when β-catenin accumulates?

A

A stem cell-like phenotype.

20
Q

What is the consequence of enterocytes retaining a stem cell-like phenotype?

A

They fail to migrate out of the crypt, leading to polyp formation.

21
Q

What is chromosomal instability (CIN)?

A

A condition where cells exhibit inappropriate chromosome segregation during mitosis, leading to aneuploidy.

22
Q

How is APC linked to chromosomal instability?

A

Loss of APC function disrupts mitotic spindle formation, causing errors in chromosome segregation.

23
Q

What can chromosomal instability lead to in cancer development?

A

Accelerated acquisition of advantageous genotypes, promoting tumorigenesis.

24
Q

How does APC affect cell motility?

A

APC enables the formation of cytoplasmic protrusions, which are critical for cell movement.

25
Q

What is the result of reduced cell motility in APC-mutant enterocytes?

A

They are unable to migrate out of colonic crypts.

26
Q

What are the two types of genes often mutated following APC inactivation in colon cancer progression?

A

Growth-promoting genes (e.g., K-ras) and growth-inhibiting genes.

27
Q

What are enterocytes, and what do they do in the colon?

A

Specialized epithelial cells that absorb water and secrete mucin to protect the colonic epithelium.

28
Q

How long does it take for enterocytes to migrate from the crypts to the colonic lumen?

A

3 to 4 days.

29
Q

What protein complex is formed by β-catenin in the nucleus?

A

A complex with Tcf/Lef transcription factors, regulating gene expression.

30
Q

What happens to β-catenin levels as enterocytes migrate upward from the crypts?

A

β-catenin levels decrease due to reduced Wnt signaling and increased APC activity.

31
Q

What is the significance of APC gene inactivation in human colon carcinoma cells?

A

It is the first mutation in a sequence leading to colon cancer development.

32
Q

How does APC gene inactivation contribute to colon polyps?

A

It prevents β-catenin degradation, causing abnormal cell retention and proliferation in the crypts.

33
Q

What does APC stand for?

A

Adenomatous Polyposis Coli.

34
Q

What is the primary function of APC in enterocytes?

A

To control β-catenin degradation, regulating cell proliferation and differentiation.

35
Q

What happens when APC mutations cause premature termination of Apc protein translation?

A

Critical domains needed for β-catenin regulation are lost, leading to β-catenin accumulation.

36
Q

How does Wnt signaling influence β-catenin levels in colonic crypts?

A

Wnt signaling prevents β-catenin degradation, maintaining high levels in stem cells at the crypt base.

37
Q

What is the role of APC in microtubule function during mitosis?

A

APC localizes to microtubules and helps in proper chromosome segregation during anaphase and telophase.

38
Q

What structural feature does APC help form to enable cell movement?

A

Cytoplasmic protrusions.

39
Q

What is the link between dietary factors and colon cancer incidence in Western populations?

A

Still poorly understood, but dietary factors may influence the development of colon polyps.

40
Q

What is the role of enterocyte apoptosis in preventing colon cancer?

A

Apoptosis ensures mutated enterocytes are eliminated, reducing the chance of cancer development.

Questions (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions