Meiosis in humans happens before birth in females, and constantly after puberty in males. Meiosis is the production of gametes, the cells used in sexual reproduction, and females possess nearly their full complement of partially developed eggs at birth. Males, on the other hand, don't even begin producing sperm until puberty, after which they create tens of millions to billions per day.
Meiosis is the method by which all multicellular animals create the cells for sexual reproduction. It relies on germ cells, which have paired chromosomes, in the testes or ovaries. They divide to create cells with unpaired chromosomes, thus containing only half the DNA of the parent cell. The process of meiosis is rather complex, but in the end it produces four cells with unpaired chromosomes. When this process creates sperm, all four of the resulting cells are used. When it creates eggs, only one of the resulting cells actually survives. The three others are known as polar bodies, and they disintegrate shortly after creation.
Despite the similarities in the basic mechanism of meiosis in males and females, in humans the resulting cells are vastly different. Eggs are complex cells of relatively great size that are actually visible to the naked eye, in the right circumstances. Sperm cells, on the other hand, are tiny and simple.Learn More
The mitochondria inside a cell produces ATP, or adenosine triphosphate. Cellular respiration is responsible for ATP production, a process in which ATP production occurs after biochemical energy from nutrients is converted.Full Answer >
The simplified reaction for aerobic cellular respiration is: C6H12O6 (s) + 6 O2 (g) ? 6 CO2 (g) + 6 H2O (l) + energy. The process of cellular respiration uses one molecule of glucose and, in the presence of molecular oxygen, turns it into adenosine triphosphate.Full Answer >
The best analogy for the nucleolus in eukaryotic cells is a factory that makes tools that are used to build other resources. The primary function of the nucleolus is to combine and construct ribosomes. The primary function of ribosomes is to build proteins necessary for the cell.Full Answer >
An electron is a negatively charged subatomic particle that orbits around the nucleus of an atom. The negative charge of the electrons is balanced by the positive charge of the protons in the nucleus. Electrons have a much lower mass than protons.Full Answer >