All of the following statements are true for cell aging except -
Ans. is 'a' i.e., Enlargement of telomereThere occurs chrotnosomal telomeric shoening with age. This is one of the hypothesis for genetic mechanisms of aging. There occurs loss of DNA from telomeric ends of chromosome with age. This leads to deletion of genes and thus aging and limiting of life span.Morphological changes associated with acingA. Cellular changesi) Cell loss : - There is decrease in cell size and number (more evident in brain & hea).ii) Organelle changes : - Changes are seen in following organelles : ?a) Ribosomes become free from endoplasmic reticulum.b) Mitochondria shows abnormality in shape, size and their number decreases.c) Increased number of phagolysosomal vacuoles.iii) DNA abnormalities : - Defect in DNA repair.iv) Non-enzymatic glycosylation of protein.B. Connective tissue changesi) Elastic tissue changesa) There is loss of elasticity and wrinkling skin.b) Systolic pressure is increased due to loss of elasticity in aery.c) Senile emphysema due to loss of elasticity in lungii) Ground glass substance changes : - Cataract can develop.iii) Cailage & bone changes : - Osteoahritis, Osteoporosis, kyphosis.C. Changes in immunityi) Decreased total lymphocytes --> Decreased T cell, B cell and plasma cells.ii) Decreased suppressor cellsiii) Decreased antibodies
Enlargement of telomere
Decrease number of mitochondria
Glycolysation of DNA
Glycolysation of RNA