sexual cycle


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cycle

 [si´k'l]
a succession or recurring series of events.
cardiac cycle a complete cardiac movement, or heart beat, including systole, diastole, and the intervening pause.
Cardiac cycle. From Applegate, 2000.
cell cycle the cycle of biochemical and morphological events occurring in a reproducing cell population; it consists of the S phase, occurring toward the end of interphase, in which DNA is synthesized; the G2 phase, a relatively quiescent period; the M phase, consisting of the four phases of mitosis; and the G1 phase of interphase, which lasts until the S phase of the next cycle.
citric acid cycle tricarboxylic acid cycle.
estrous cycle the recurring periods of estrus in adult females of most mammalian species and the correlated changes in the reproductive tract from one period to another.
hair cycle the successive phases of the production and then loss of hair, consisting of anagen, catagen, and telogen.
menstrual cycle see menstrual cycle.
ovarian cycle the sequence of physiologic changes in the ovary involved in ovulation; see also ovulation and reproduction.
reproductive cycle the cycle of physiologic changes in the reproductive organs, from the time of fertilization of the ovum through gestation and childbirth; see also reproduction.
sex cycle (sexual cycle)
1. the physiologic changes that recur regularly in the reproductive organs of nonpregnant female mammals.
2. the period of sexual reproduction in an organism that also reproduces asexually.
tricarboxylic acid cycle the cyclic metabolic mechanism by which the complete oxidation of the acetyl portion of acetyl-coenzyme A is effected; the process is the chief source of mammalian energy, during which carbon chains of sugars, fatty acids, and amino acids are metabolized to yield carbon dioxide, water, and high-energy phosphate bonds. Called also citric acid cycle, Krebs cycle, and TCA cycle.
 Central pathways of metabolism: How the body produces energy from the energy-containing nutrients using the tricarboxylic acid cycle. From Davis and Sherer, 1994.
urea cycle a cyclic series of reactions that produce urea; it is a major route for removal of the ammonia produced in the metabolism of amino acids in the liver and kidney.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

sexual cycle

the series of events in which generations are linked via GAMETES and MEIOSIS takes place. For example, in a DIPLOID (1) organism such as a human, HAPLOID (1) gametes are produced by meiosis and once fertilization has occurred the diploid number is restored in the ZYGOTE. In haploid organisms such as many fungi, meiosis is postzygotic, occurring after fertilization and with the function of restoring the haploid number.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
The study of the sexual cycle of Donax trunculus in the Gulf of Annaba by histological analysis of female gonads during the period which runs from January to December, allowed us to see that the gonadal development starts from December in both sites.
"What we found is that the sexual cycle has a new way to create genetic diversity, and it provides a unique vantage point from which we can explore the mechanisms of sexual reproduction.
Table II Cycle effects for the four life-history variables measured over subsequent asexual and sexual cycles Cycle Eggs Testis Buds per Cycle number per bud area zooid duration 1 1.12 0.64 2.25 - 2 1.63 0.99 1.85 6.74 3 1.61 0.78 1.11 8.10 4 2.01 0.79 1.01 7.22 5 2.21 0.99 1.08 7.06 6 1.57 0.80 0.96 7.78 7 1.34 0.58 8.17 Note: Least square means, adjusted for genotype and replicate nested within genotype effects, are reported for each cycle.
Although other members of the budding-yeast family have sexual cycles, C.
Throughout the book, Poole modestly describes her groundbreaking research on sexual cycles in male elephants.
Molecular parasites should thus be more successful in genomes that reproduce sexually than in those that replicate clonally (Hickey 1982), Chlamydomonas reinhardtii is a unicellular, heterothallic chlorophyte alga well suited to testing this prediction because it can be maintained with or without sex, and because its low doubling time permits the passage of hundreds of asexual generations or dozens of sexual cycles per year (Harris 1989).
Well, I know trainers don't train for the benefit of punters, and I realise that the effect of fillies' sexual cycles on racecourse performance is not an exact science, but most of us would have forgiven Candy for making excuses if it had meant we had a bit more relevant information at our disposal before backing a drifting 11-8 shot.
Better timing of the animals' sexual cycles could improve success in zoo breeding, says Hsueh.