Sex
hideIn biology, sex is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into male and female types (or sexes). Sexual reproduction involves combining specialized cells (gametes) to form offspring that inherit traits from both parents. Gametes can be identical in form and function (known as isogametes), but in many cases an asymmetry has evolved such that two sex-specific types of gametes (heterogametes) exist: male gametes are small, motile, and optimized to transport their genetic information over a distance, while female gametes are large, non-motile and contain the nutrients necessary for the early development of the young organism.
An organism's sex is defined by the gametes it produces: males produce male gametes (spermatozoa, or sperm) while females produce female gametes (ova, or egg cells); individual organisms which produce both male and female gametes are termed hermaphroditic. Frequently, physical differences are associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience.
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News tagged with sex
UNAIDS: Sex main cause for HIV spreading in China
Medicine & Health / HIV & AIDS
9 hours ago |
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(AP) -- The virus that causes AIDS is now spreading fastest in China through heterosexual sex, a trend demanding new strategies to stave off a rebound in the epidemic after years of progress in containing ...
Flaxseed oil and osteoporosis
Nov 23, 2009 |
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Animal studies suggest that adding flaxseed oil to the diet could reduce the risk of osteoporosis in post-menopausal women and women with diabetes, according to a report to be published in the International Journal of Fo ...
What's eating the breadwinners?
Medicine & Health / Psychology & Psychiatry
Nov 18, 2009 |
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Control, independence, ambition, pressure, worry, guilt and resentment are all experienced by female breadwinners, according to Dr. Rebecca Meisenbach from the University of Missouri in Columbia, USA. Dr. Meisenbach explored ...
Heart and bone damage from low vitamin D tied to declines in sex hormones
Nov 15, 2009 |
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Researchers at Johns Hopkins are reporting what is believed to be the first conclusive evidence in men that the long-term ill effects of vitamin D deficiency are amplified by lower levels of the key sex hormone estrogen, ...
Enjoying school key to tackling teenage pregnancy
Nov 13, 2009 |
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Youth development programmes that tackle deprivation and help children and young people enjoy school are successful in reducing teenage pregnancy rates, say researchers in BMJ today.
Rethinking sexism: Study examines how society maintains the status quo
Other Sciences / Social Sciences
Nov 12, 2009 |
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There is a tendency to think that only men treat women in a sexist way, but a new study by a University of Miami researcher and his daughter shows that both men and women participate in maintaining a gender hierarchy in our ...
WHO: AIDS leading cause of death, disease in women
Medicine & Health / HIV & AIDS
Nov 09, 2009 |
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(AP) -- In its first study of women's health around the globe, the World Health Organization said Monday that the AIDS virus is the leading cause of death and disease among women between the ages of 15 and 44.
Obesity causes 100,000 US cancers every year: study
Nov 06, 2009 |
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Obesity causes more than 100,000 incidents of cancer in the US every year, the American Institute for Cancer Research said in estimates published Friday.
Researchers to perform sex change operation on papaya
Nov 02, 2009 |
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The complicated sex life of the papaya is about to get even more interesting, thanks to a $3.1 million grant from the National Science Foundation. The grant will fund basic research on the papaya sex chromosomes ...
New insights into Australia's unique platypus
Nov 02, 2009 |
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(PhysOrg.com) -- New insights into the biology of the platypus and echidna have been published, providing a collection of unique research data about the world's only monotremes.
Placental precursor stem cells require testosterone-free environment to survive
Oct 29, 2009 |
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Trophoblast stem cells (TSCs), cells found in the layer of peripheral embryonic stem cells from which the placenta is formed, are thought to exhibit "immune privilege" that aids cell survivability and is potentially beneficial ...
HPV vaccine makes girls more cautious about sex
Oct 27, 2009 |
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(PhysOrg.com) -- Nearly 80% of girls say that having the HPV vaccine makes them think twice about the risks of having sex, according to a University of Manchester study published in the British Journal of ...
Researchers discover mechanism that prevents two species from reproducing
Oct 26, 2009 |
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Cornell researchers have discovered a genetic mechanism in fruit flies that prevents two closely related species from reproducing, a finding that offers clues to how species evolve.
Internet fuels virtual subculture for sex trade, study finds
Other Sciences / Social Sciences
Oct 21, 2009 |
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The Internet has spawned a virtual subculture of "johns" who share information electronically about prostitution, potentially making them harder to catch, according to a new study co-authored by a Michigan ...
Hardness is the way to happiness: sex survey
Oct 19, 2009 |
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Men's confidence in their erections varies widely across Europe with Spanish men most worried and Germans the happiest, a survey for the makers of Viagra showed on Monday.
