The process of passing genetic material from one generation to the next depends completely on how cells grow and divide. To reproduce, a simple organism such as bacteria or yeast simply copies its DNA (through a process called replication) and splits in two. But organisms that reproduce sexually go through a complicated dance that includes mixing and matching strands of DNA (a process called recombination) and then reducing the amount of DNA in special sex cells to arrive at completely new genetic combinations for their offspring.
There are two basic kinds of organisms — ones with a nucleus and those without a nucleus (a compartment filled with DNA surrounded by a membrane called a nuclear envelope):
<span>Prokaryotes: Organisms whose cells lack a nucleus and therefore have DNA floating loosely in the liquid center of the cell. Prokaryotes divide, and thus reproduce, by simple mitosis.</span><span>Eukaryotes: Organisms that have a well-defined nucleus to house and protect the DNA. Eukaryotes divide by meiosis for sexual reproduction.</span>
Mitosis is a cell division in which, before the true division, DNA replication takes place, temporarily doubling the number of chromatids. This stages that, at the end of the cell division, daughter cells will have the same number of chromosomes as the parent cell
The difference in the concentration of a substance across a space is called a concentration (equilibrium/gradient). ... (equilibrium/diffusion) is the simplest type of passive transport. diffusion. the diffusion of water through a selectively permeable membrane is called (osmosis/diffusion).
