- What are telomeres?a) Proteins that help in DNA replication
b) Repetitive DNA sequences at the ends of chromosomes
c) Parts of the mitochondria involved in energy production
d) Enzymes that repair damaged DNAAnswer: b) Repetitive DNA sequences at the ends of chromosomes
Explanation: Telomeres are protective caps located at the ends of chromosomes. They consist of repetitive DNA sequences and prevent the loss of important genetic information during DNA replication.
- What happens to telomeres during cell division?a) They remain the same length
b) They shorten
c) They lengthen
d) They replicate separately from the DNAAnswer: b) They shorten
Explanation: During each cell division, telomeres shorten because DNA polymerase cannot fully replicate the very ends of chromosomes. This shortening is associated with aging and cell death.
- Which enzyme is responsible for lengthening telomeres?a) DNA polymerase
b) Telomerase
c) Ligase
d) HelicaseAnswer: b) Telomerase
Explanation: Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of telomeres, preventing them from shortening during cell division.
- What is the primary role of telomeres in cells?a) To assist in protein synthesis
b) To protect the chromosomes from damage and prevent loss of genetic information
c) To repair damaged DNA
d) To assist in the formation of spindle fibers during mitosisAnswer: b) To protect the chromosomes from damage and prevent loss of genetic information
Explanation: Telomeres protect the chromosomes from degradation, damage, and from fusing with other chromosomes, ensuring genetic stability.
- What is the relationship between telomeres and aging?a) Short telomeres are linked to aging and age-related diseases
b) Long telomeres cause faster aging
c) Telomeres have no effect on aging
d) Telomeres only impact the aging process in plantsAnswer: a) Short telomeres are linked to aging and age-related diseases
Explanation: Telomeres shorten with each cell division. When they become too short, cells can no longer divide, leading to cell death and contributing to aging and the development of age-related diseases.
- What is telomerase’s function in relation to aging?a) It prevents telomere shortening, delaying cellular aging
b) It speeds up the process of telomere shortening
c) It enhances the aging process by accelerating cell division
d) It promotes the formation of new chromosomesAnswer: a) It prevents telomere shortening, delaying cellular aging
Explanation: Telomerase helps to counteract the normal shortening of telomeres by adding new DNA sequences to the ends of chromosomes, potentially delaying the aging process.
- In which type of cells is telomerase most active?a) Skin cells
b) Gametes (sperm and eggs)
c) Somatic cells
d) Cancer cellsAnswer: b) Gametes (sperm and eggs)
Explanation: Telomerase is most active in germ cells (sperm and eggs), where it ensures that telomeres are maintained to protect the genetic material for the next generation.
- How does the shortening of telomeres contribute to aging?a) It decreases cellular lifespan, leading to tissue degeneration
b) It accelerates the growth of new cells
c) It increases the number of mitochondria
d) It causes telomeres to lengthenAnswer: a) It decreases cellular lifespan, leading to tissue degeneration
Explanation: Shortened telomeres lead to cellular senescence or apoptosis, reducing the ability of tissues to regenerate and leading to aging and age-related diseases.
- Which of the following is a potential consequence of telomerase dysfunction?a) Accelerated cell division
b) Increased DNA replication errors
c) Shortened telomeres and premature aging
d) Enhanced immune system functionAnswer: c) Shortened telomeres and premature aging
Explanation: Dysfunctional telomerase can lead to accelerated telomere shortening, resulting in premature aging and an increased susceptibility to age-related diseases.
- What is the connection between cancer and telomerase?
a) Telomerase prevents cancer by shortening telomeres
b) Telomerase activity is usually absent in cancer cells
c) Telomerase activity is often reactivated in cancer cells
d) Telomerase causes cancer by preventing cell division
Answer: c) Telomerase activity is often reactivated in cancer cells
Explanation: In most cancer cells, telomerase is reactivated, allowing them to maintain their telomeres and continue dividing uncontrollably, contributing to tumor growth.
- What is the main cause of telomere shortening in somatic cells?
a) Aging
b) Genetic mutation
c) Lack of exercise
d) Stress
Answer: a) Aging
Explanation: Telomeres naturally shorten as cells divide throughout an organism’s lifespan, particularly in somatic cells, which don’t produce telomerase to replenish their telomeres.
- How can telomeres be related to age-related diseases such as Alzheimer’s?
a) Shortened telomeres can disrupt normal cell function, leading to disease
b) Telomeres play no role in age-related diseases
c) Long telomeres promote the development of diseases
d) Telomeres can prevent the onset of diseases by enhancing immunity
Answer: a) Shortened telomeres can disrupt normal cell function, leading to disease
Explanation: Shortened telomeres can impair the function of cells in various tissues, leading to degenerative diseases like Alzheimer’s, as they may no longer divide properly or regenerate.
- Which of the following methods could potentially reverse telomere shortening?
a) Genetic modification to activate telomerase
b) Reducing the rate of cell division
c) Increasing oxygen intake
d) Activating the immune system
Answer: a) Genetic modification to activate telomerase
Explanation: Scientists are exploring genetic modifications or therapies to activate telomerase in somatic cells to potentially reverse or delay telomere shortening and the associated effects of aging.
- How does oxidative stress affect telomeres?
a) It lengthens telomeres
b) It accelerates telomere shortening
c) It has no effect on telomeres
d) It protects telomeres from damage
Answer: b) It accelerates telomere shortening
Explanation: Oxidative stress leads to the accumulation of free radicals that can damage the DNA and accelerate the shortening of telomeres, contributing to cellular aging.
- Which of the following lifestyle changes could slow telomere shortening?
a) Regular physical exercise
b) Excessive alcohol consumption
c) Smoking
d) Excessive sun exposure
Answer: a) Regular physical exercise
Explanation: Regular physical activity has been shown to reduce oxidative stress and inflammation, which can slow telomere shortening and promote overall health.
- What is cellular senescence?
a) The process by which cells rapidly divide
b) The permanent arrest of cell division due to telomere shortening
c) The process of DNA replication
d) The formation of new chromosomes
Answer: b) The permanent arrest of cell division due to telomere shortening
Explanation: Cellular senescence occurs when a cell reaches a critical level of telomere shortening, causing it to stop dividing, which can contribute to aging and tissue degeneration.
- Which of the following factors does NOT influence telomere length?
a) Genetics
b) Diet and nutrition
c) Environmental toxins
d) Hormonal levels
Answer: d) Hormonal levels
Explanation: Genetics, diet, and environmental factors have been shown to influence telomere length. However, hormonal levels do not directly impact telomere shortening or maintenance.
- What role does telomerase play in stem cells?
a) It helps maintain telomere length, enabling indefinite division
b) It prevents the aging of stem cells
c) It promotes differentiation of stem cells
d) It stops stem cells from dividing
Answer: a) It helps maintain telomere length, enabling indefinite division
Explanation: Telomerase is active in stem cells, helping maintain their telomeres and allowing them to divide indefinitely, which is crucial for tissue regeneration.
- How does telomere shortening contribute to the development of cancer?
a) It promotes the uncontrolled division of cells
b) It leads to the rapid repair of damaged DNA
c) It makes cells more susceptible to mutations
d) It causes the loss of genetic information
Answer: c) It makes cells more susceptible to mutations
Explanation: Shortened telomeres can lead to chromosomal instability, increasing the likelihood of mutations and genetic abnormalities that contribute to cancer development.
- What is the “Hayflick limit”?
a) The point at which a cell can divide indefinitely
b) The number of divisions a cell undergoes before it becomes senescent
c) The ability of a cell to replicate its DNA without errors
d) The number of mutations a cell can accumulate before it becomes cancerous
Answer: b) The number of divisions a cell undergoes before it becomes senescent
Explanation: The Hayflick limit refers to the number of times a normal, somatic cell can divide before it enters senescence due to telomere shortening.
