GameteFrom Wikipedia, the free encyclopedia

A gamete (from Ancient Greek γαμετή gamete "wife"[1]) is a cell that fuses with another cell duringfertilization (conception) in organisms that sexually reproduce. In species that produce twomorphologically distinct types of gametes, and in which each individual produces only one type, afemale is any individual that produces the larger type of gamete—called an ovum (or egg)—and amale produces the smaller tadpole-like type—called a sperm. This is an example of anisogamy orheterogamy, the condition in where females and males produce gametes of different sizes (this is thecase in humans; the human ovum has approximately 100,000 times the volume of a single humansperm cell[2][3]). In contrast, isogamy is the state of gametes from both sexes being the same size andshape, and given arbitrary designators for mating type. The name gamete was introduced by theAustrian biologist Gregor Mendel. Gametes carry half the genetic information of an individual, 1n ofeach type.

Contents

1 Dissimilarity2 Plants3 Sex determination4 Notes and references

DissimilarityIn contrast to a gamete, the diploid somatic cells of an individual contain one copy of thechromosome set from the sperm and one copy of the chromosome set from the egg; that is, the cellsof the offspring have genes expressing characteristics of both the father and the mother. A gamete'schromosomes are not exact duplicates of either of the sets of chromosomes carried in the dfschromosomes, and often undergo random mutations resulting in modified DNA (and subsequently,new proteins and phenotypes).

PlantsPlants which reproduce sexually also have gametes. However, since plants have an alternation ofdiploid and haploid generations some differences exist. In flowering plants the flowers use meiosis toproduce a haploid generation which produce gametes through mitosis. The female haploid is calledthe ovule and is produced by the ovary of the flower. When mature the haploid ovule produces thefemale gamete which are ready for fertilization. The male haploid is pollen and is produced by theanther, when pollen lands on a mature stigma (botany) of a flower it grows a pollen tube down intothe flower. The haploid pollen then produces sperm by mitosis and releases them for fertilization.

Sex determination

Gamete - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Gamete

1 of 2 26/05/2014 7:50 pm

In humans, an ovum can carry only an X chromosome (of the X and Y chromosomes), whereas asperm may carry either an X or a Y; thus the male sperm determines the sex of any resulting zygote,if the zygote has two X chromosomes it will develop into a female, if it has an X and a Ychromosome, it will develop into a male.[4] For birds, the female ovum determines the sex of theoffspring, through the ZW sex-determination system.[4]

Notes and references

^ "gamete" (http://www.etymonline.com/index.php?term=gamete&allowed_in_frame=0). OnlineEtymology Dictionary.

1.

^ Marshall, A. M. 1893. Vertebrate embryology: a text-book for students and practitioners. GP Putnam'ssons.

2.

^ Yeung, C., M. Anapolski, M. Depenbusch, M. Zitzmann, and T. Cooper. 2003. Human sperm volumeregulation. Response to physiological changes in osmolality, channel blockers and potential spermosmolytes. Human Reproduction 18:1029.

3.

^ a b Jay Phelan (30 April 2009). What Is Life?: A Guide to Biology W/Prep-U (http://books.google.com/books?id=F4okAxTXPtIC&pg=PA237). Macmillan. pp. 237–. ISBN 978-1-4292-2318-8. Retrieved 8October 2010.

4.

Retrieved from "http://en.wikipedia.org/w/index.php?title=Gamete&oldid=609461345"Categories: Classical genetics Germ cells Reproductive system

This page was last modified on 21 May 2014 at 01:27.Text is available under the Creative Commons Attribution-ShareAlike License; additionalterms may apply. By using this site, you agree to the Terms of Use and Privacy Policy.Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profitorganization.

Gamete - Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Gamete

2 of 2 26/05/2014 7:50 pm