generation time

generation time

1. (also called division time) the time required for a population of cells to double in number.
2. the time required for a generation of individuals to be born, reach sexual maturity and reproduce. The generation time is a critical factor in population growth rates and efforts are being made (particularly in China) to extend the human generation time so as to slow down the rate of population increase.

generation

1. the process of reproduction.

2. a class composed of all individuals removed by the same number of successive ancestors from a common predecessor, or occupying positions on the same level in a genealogical (pedigree) chart. Said also of antibiotics or other chemicals derived from parent compounds.

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alternate generation

reproduction by alternate asexual and sexual means in an animal or plant species.

asexual generation

production of a new organism not originating from union of gametes. Called also direct generation.

direct generation

see asexual generation (above).

filial generation (first)

the first generation offspring of two parents; symbol F₁.

filial generation (second)

all of the offspring produced by two individuals of the first filial generation; symbol F₂.

generation interval

the mean age of the parents when the animals that are to replace them are born.

parental generation

the generation with which a particular genetic study is begun; symbol P₁.

sexual generation

production of a new organism from the zygote formed by the union of gametes.

spontaneous generation

the discredited concept of continuous generation of living organisms from nonliving matter.

generation time

1. in epidemiological terms the time required between infection occurring and the patient reaching full infectivity.

2. in histological terms the time required to complete one full cell cycle; average of 20 hours for mammalian cells.