40 Questions
What are the sources of DNA damage that can trigger mutations, transcription, replication halts, and the DNA damage response?
Both intrinsic and external sources
What is the result of defects in genes involved in the DNA repair system?
Accumulation of unrepaired DNA and chromosomal damage
What are free radicals defined as?
Molecules possessing an unpaired and reactive electron
What is the effect of reactive oxygen species (ROS) on mitochondrial DNA?
ROS contribute to the accumulation of mutations in mitochondrial DNA
What is the effect of nutritional antioxidants on human health?
They reduce the risk of vascular dementia, heart disease, and cancer
What is the effect of oxygenated free radicals on mitochondrial DNA as people age?
They contribute to mitochondrial DNA damage
What is the result of mutations in mitochondrial DNA?
A gradual loss of bioenergetic capacity
What is the role of reactive oxygen species (ROS) in aging?
They contribute to the aging process
What is a consequence of mitochondrial DNA damage?
Inefficient mitochondrial respiration
What is a characteristic of mtDNA compared to nuclear DNA?
It is more susceptible to mutations
What is the effect of telomere shortening on somatic stem cells?
Impaired function
What is the primary function of telomeres?
To protect chromosome ends from degrading or fusing
What is the result of telomerase-deficient mice?
They have short telomeres and age prematurely
What is the critical determinant in cellular aging?
Telomere length
What is the effect of shorter telomeres on cell viability?
It decreases cell viability
What determines protein activities and functions?
Protein physical and chemical qualities
What is the biological consequence of human aging?
A loss of homeostasis
What is the term used to describe the weakening of an individual's health due to aging?
Senescence
What is the consequence of the accumulation of lipofuscins?
Cellular aging
What is the result of the accumulation of random damage to vital molecules in aging populations?
Functional impairment and death
What is the term used to describe the study of the biology of aging?
Biogerontology
What is the result of changes in the crystal structure or macromolecular aggregation at the molecular level?
Cellular aging
What is the consequence of telomere shortening?
Increase in cellular aging
What is the result of radiation on the aging process?
Increase in mutations and functional impairment
What is affected by the primary sequence of a protein?
Protein folding, final conformation, biochemical activity, stability, and half-life
What is the effect of oxidation of amino acid residues, metal-catalyzed oxidation, and change caused by lipid oxidation products on enzymes?
Decreases the specific activity of enzymes
What is the role of protein acetylation in the aging process?
It improves the function of specific genes
What is the primary cause of the aging process, according to some theories?
A genetically programmed period of growth and maturation
What is the role of longevity genes in determining the full lifetime potential?
They play a role in determining the full lifetime potential
What is the effect of overexpressing the SIR2 gene and its homolog?
It increases the lifespan of yeasts and nematode
What is cellular senescence traditionally regarded as?
A state of irreversible cell-cycle arrest
What is the relationship between cellular senescence and the number of cell divisions?
Cellular senescence is required to determine the proliferative lifespan
What can cause cellular senescence?
Multiple intrinsic and extrinsic factors
What is the result of eliminating senescent cells in adult wildtype mice?
It delays tumor formation
What type of cell death is characterized by the release of cellular components, leading to inflammation?
Necrotic cell death
What is the role of apoptosis in aging and age-related disorders?
It may play a role in aging and age-related disorders
What is the relationship between apoptosis and aging in the central nervous system?
Neuronal apoptosis increases with aging
What is the result of recent studies on the aging process?
Individual mechanisms cannot adequately explain the aging process
What is the result of damaged mitochondria in the context of aging?
They produce more ROS
What is the relationship between cancer rates and age?
Cancer rates increase with age
Study Notes
Molecular Basis of Cell Aging
- Human aging is a progressive, time-related process that corresponds biologically to a loss of homeostasis, an increase in sensitivity and susceptibility to disease and death, and the degeneration of cells, tissues, and organs associated with advancing age.
- The biology of aging (biogerontology) includes aspects of deterioration called senescence, responsible for weakening an individual's health and causing physiological changes in "regular" aging.
DNA Damage
- The molecular mechanisms of aging are still unknown, but DNA damage is a major contributor to aging, caused by the accumulation of random damage to vital molecules in aging populations.
- Sources of DNA damage include radiation, intrinsic sources like replication defects, and external sources like UV and genotoxic drugs.
- DNA damage triggers mutations, transcription, replication halts, and the DNA damage response (DDR), which can lead to cell cycle arrest, repair, apoptosis, or cellular senescence.
Free Radicals
- Free radicals, or reactive oxygen species (ROS), contribute to age-related alterations by reacting with macromolecules and participating in signaling pathways that control gene expression, cell replication, differentiation, and apoptosis.
- The generation of free radicals in organs like the heart, kidney, and liver affects maximal lifespan, and nutritional antioxidants have been shown to reduce the risk of vascular dementia, heart disease, and cancer.
Telomere Shortening
- Telomere shortening is associated with age-related disorders and can impair somatic stem cell function.
- Telomeres are long stretches of TTAGGG repeats at chromosome ends, acting as protectors that prevent degradation or fusion with other chromosome ends.
- Telomerase-deficient mice have short telomeres and age prematurely, while cancer-resistant mice with high telomerase expression have long telomeres and age more slowly.
Protein Modifications
- Proteins play critical roles in cellular and physiological functions, and their chemical and physical properties determine their activities and functions.
- Protein repair and modification play a role in longevity, and the oxidation of amino acid residues, metal-catalyzed oxidation, and changes caused by lipid oxidation products can reduce enzyme activity and affect thermal stability.
Longevity Genes
- The aging process is primarily caused by a genetically programmed period of growth and maturation.
- Specific genes found in many animals play a role in determining the full lifetime potential, controlling life via mechanisms like modulation of stress and resistance, metabolic capacity, and silencing of genes that promote aging.
Cellular Senescence
- Cellular senescence is a state of irreversible cell-cycle arrest elicited by replicative exhaustion or in response to diverse stressors.
- Multiple intrinsic and extrinsic factors, including oxidative stress, DNA damage, oncogene activation, epigenetic stress, and mitotic spindle stress, can cause cellular senescence.
Cell Death
- Cell death methods include energy-dependent programmed cell death (apoptosis) and necrotic cell death mechanisms.
- Apoptosis is a preprogrammed death caused by the progressive activation of caspases, and may play a role in aging and age-related disorders.
This quiz covers the molecular basis of cell aging, a complex process that involves the loss of homeostasis, increased sensitivity to disease and death, and the degeneration of cells, tissues, and organs with age.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
