Overall, life expectancy fell by one-tenth of a year, from 78.9 in 2014 to 78.8 in 2015, according to the latest data. The last time U.S. life expectancy at birth declined was in 1993, when it dropped from 75.6 to 75.4, according to World Bank data. The overall death rate rose 1.2 percent in 2015, its first uptick since 1999. More than 2.7 million people died, about 45 percent of them from heart disease or cancer.
The process by which new cells are made is called cell division. Cell division is occurring all the time. Around two trillion cell divisions occur in the average human body every day! Types of Cell Division. There are three main types of cell division: binary fission, mitosis, and meiosis.
Five Key Differences. 1  In meiosis, homologous chromosomes pair with each other (i.e., they form tetrads) and crossing-over occurs. In mitosis, neither of these things occur. 2  In metaphase I of meiosis, tetrads align on the metaphase plate. In metaphase of mitosis, individual chromosomes align there. In anaphase I of meiosis, centromeres don't divide, and sister chromatids don't separate. In mitotic anaphase, they do. In meiosis there are two successive divisions, ultimately producing four daughter cells. In mitosis, there is only one division and it produces two daughter cells. Another important difference in comparing mitosis versus meiosis is that meiotic prophase I lasts far longer than does mitotic prophase. In fact, it is broken into several named substages, which is not the case for mitotic prophase.