the mitochondria are located in midpiece in the sperm.
the mitochondria are located in midpiece in the sperm.
where are the mitochondria located in the sperm?
midpiece
motile sperm cells typically move via flagella and require a water medium in order to swim toward the egg for fertilization. in animals most of the energy for sperm motility is derived from the metabolism of fructose carried in the seminal fluid. this takes place in the mitochondria located in the sperm's midpiece (at the base of the sperm head). these cells cannot swim backwards due to the nature of their propulsion. the uniflagellated sperm cells (with one flagellum) of animals are referred to as spermatozoa, and are known to vary in size.
sperm
an individual's mitochondrial genes are not inherited by the same mechanism as nuclear genes. typically, the mitochondria are inherited from one parent only. in humans, when an egg cell is fertilized by a sperm, the egg nucleus and sperm nucleus each contribute equally to the genetic makeup of the zygote nucleus. in contrast, the mitochondria, and therefore the mitochondrial dna, usually come from the egg only. the sperm's mitochondria enter the egg, but do not contribute genetic information to the embryo. instead, paternal mitochondria are marked with ubiquitin to select them for later destruction inside the embryo. the egg cell contains relatively few mitochondria, but it is these mitochondria that survive and divide to populate the cells of the adult organism. mitochondria are, therefore, in most cases inherited only from mothers, a pattern known as maternal inheritance. this mode is seen in most organisms, including the majority of animals. however, mitochondria in some species can sometimes be inherited paternally. this is the norm among certain coniferous plants, although not in pine trees and yews. for mytilids, paternal inheritance only occurs within males of the species. it has been suggested that it occurs at a very low level in humans. there is a recent suggestion that mitochondria that shorten male lifespan stay in the system because they are inherited only through the mother. by contrast, natural selection weeds out mitochondria that reduce female survival as such mitochondria are less likely to be passed on to the next generation. therefore, it is suggested that human females and female animals tend to live longer than males. the authors claim that this is a partial explanation.
mitochondrion