Cell Division and Types

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Questions and Answers

What is the primary function of mitotic cells in the body?

To facilitate cell death

To undertake specialized functions

To provide structural support

To replenish and regenerate tissues (correct)

Which of the following cells are examples of post-mitotic cells?

Neurons and heart muscle cells (correct)

Epithelial cells and fibroblast cells

Stem cells and endothelial cells

Fibroblast cells and heart muscle cells

What is the primary difference between mitotic cells and post-mitotic cells?

Their function in the nervous system

Their location in the body

Their structure and composition

Their ability to undergo mitosis (correct)

How do post-mitotic tissues regenerate?

Through the help of tissue-specific stem cells Signup and view all the answers

What is true about the regeneration of post-mitotic tissues?

It occurs slowly Signup and view all the answers

Which of the following is an example of a mitotic cell?

Epithelial cell Signup and view all the answers

What is the term used to describe cells that are capable of dividing by mitosis?

Mitotic cells Signup and view all the answers

What is a key limitation of post-mitotic cells?

Their limited ability to repair or regenerate tissues Signup and view all the answers

What is the main purpose of DNA replication in mitosis?

To copy a full set of DNA to pass on to each daughter cell Signup and view all the answers

What is the shape of DNA in eukaryotes like humans?

Linear Signup and view all the answers

What is the function of telomeres?

To prevent DNA damage during copying Signup and view all the answers

What happens to telomeres each time DNA is copied?

They get shorter Signup and view all the answers

What is the approximate number of cell divisions a cell can undergo before reaching senescence?

60-70 Signup and view all the answers

What is the term for the number of times a cell can divide before reaching senescence?

Hayflick limit Signup and view all the answers

What is the state of a cell that has reached senescence?

Nondividing and senescent Signup and view all the answers

What happens to a senescent cell?

It becomes nondividing and undergoes changes Signup and view all the answers

What is the term for the type of senescence caused by telomere shortening?

Replicative senescence Signup and view all the answers

What is the role of senescent cells in the body?

To contribute to tissue structure but not divide Signup and view all the answers

What is the function of Telomerase during cell replication?

To add telomeres to the DNA Signup and view all the answers

What happens to somatic cells when they develop a mutation that causes them to express Telomerase?

They gain the ability to replicate indefinitely Signup and view all the answers

What is the significance of Telomerase in stem cells?

It allows stem cells to replicate indefinitely Signup and view all the answers

What is the Hayflick limit?

The maximum number of times a cell can replicate Signup and view all the answers

What is a potential consequence of somatic cells expressing Telomerase?

Cancer Signup and view all the answers

What is the effect of Telomerase on telomere length during cell replication?

It lengthens telomeres Signup and view all the answers

What is the primary reason why cells transform into a senescent state?

To prevent impending DNA damage and cancer Signup and view all the answers

What is the outcome when a cell reaches its Hayflick limit?

The cell's ability to divide gets turned off Signup and view all the answers

What can cause a cell to become senescent?

Any event that threatens DNA integrity, such as telomere dysfunction, DNA damage, or toxin exposure Signup and view all the answers

What is a potential consequence of having senescent cells in tissues?

Increased risk of age-related diseases like cataracts Signup and view all the answers

Which cells are capable of undergoing replicative senescence?

Only mitotic cells Signup and view all the answers

What is the main difference between somatic cells and stem cells in terms of cell division capacity?

Stem cells maintain a high cell division capacity despite multiple doublings Signup and view all the answers

What enzyme is responsible for maintaining telomere length in stem cells?

Telomerase Signup and view all the answers

What is the relationship between the number of doublings and cell division capacity in somatic cells?

The more doublings, the lower the cell division capacity Signup and view all the answers

What is a benefit of cellular senescence?

It prevents tumors and cancers from forming Signup and view all the answers

What is the current understanding of senescent cells in relation to age-related diseases?

There is evidence linking senescent cells to age-related diseases, such as cataracts, but more research is needed Signup and view all the answers

Study Notes

Cell Division and Senescence

Cells in the body can be divided into two types: mitotic cells and post-mitotic cells
Mitotic cells can divide by mitosis to replenish and regenerate tissues, including epithelial cells, fibroblast cells, and endothelial cells
Post-mitotic cells, such as neurons and heart muscle cells, are incapable of proliferation and have a limited ability to repair or regenerate tissues

Telomeres and DNA Replication

Telomeres are caps at the ends of linear DNA strands that prevent damage during DNA replication
DNA replication machinery does not copy DNA all the way to the end, resulting in telomere shortening with each replication cycle
Telomeres shorten with each cell division, and when they become too short, the cell reaches replicative senescence

Replicative Senescence

Replicative senescence is a state where a cell can no longer divide due to telomere shortening
The number of times a cell can divide before reaching senescence is called the Hayflick limit (around 60-70 divisions)
Senescent cells undergo changes, such as gene expression, appearance, and cellular response, and are no longer allowed to replicate to prevent DNA damage and potential cancer

Causes of Senescence

Telomere shortening due to DNA replication
DNA damage from mutations or toxins
Abnormal telomere function
Other causes that threaten DNA integrity

Problems with Senescent Cells

Senescent cells can help prevent tumors by stopping division, but as tissues accumulate more senescent cells, the tissue's ability to repair itself is impaired
Evidence links senescent cells to age-related diseases, such as cataracts

Types of Cells and Division Capacity

Mitotic cells have a high cell division capacity, but it decreases with the number of doublings
Stem cells have a high cell division capacity that remains constant due to telomerase, an enzyme that maintains telomere length
Somatic cells can develop a mutation causing them to express telomerase, allowing them to escape senescence and potentially lead to cancer

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Description

This quiz covers cell division, particularly mitosis, and different types of cells such as epithelial, fibroblast, and endothelial cells. It also discusses their functions and locations in the body.