Z8600021 at 12:41, 31 July 2012

2012-07-31T12:41:15Z

← Older revision		Revision as of 23:41, 31 July 2012
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	=~~= Sex Determination ==~~		{\| border='0px'
	~~Mammalian sex determination is regulated by chromosomes.~~
	* Females have two X chromosomes. ('''XX''')
	* Males have a single X and a small Y. ('''XY''')
	* The X and Y chromosome are morphologically and functionally different from each other.
	* Evolutionary studies have shown that the Y was once the homologous pair for X.
	* It is only in the last 5 years that we have some idea about how these two types of chromosomes may be regulated and genes of importance located upon them.

	~~===X chromosome===~~		\|-
	{\|		\| [[File:Follicle 001 icon.jpg\|90px\|link=Development_Animation_-_Ovulation]]
	\| [[File:~~Human idiogram-chromosome X~~.jpg\|~~Human idiogram~~-~~chromosome X~~.jpg]]		\| [[File:Fertilization 002 icon.jpg\|90px\|link=Development_Animation_-_Fertilization]]
	\|		\| [[File:Pronuclear_fusion 001 icon.jpg\|90px\|link=Development_Animation_-_Pronuclear_Fusion]]
	~~'''In females''' - the main scientific problem was understanding gene dosage, only one copy of X chromosome is needed to be genetically active the other copy is inactivated (More?~~ [[~~Molecular_Development_~~-~~_X_Inactivation\|X Inactivation~~]].		\| [[File:Week1 001 icon.jpg\|90px\|link=Development_Animation_-_Week_1]]
			\| [[File:Ovulation_icon.jpg\|90px\|link=Movie_-_Ovulation 01]]
	~~About the X Chromosome~~		\| [[File:Fertilization 001 icon.jpg\|90px\|link=Movie_-_Fertilization 01]]
	* 155 million base pairs		\| [[File:Human-blastocyst-day-3-6-icon.jpg\|120px\|link=Quicktime_Movie_-_Blastocyst_Development]]
	* In contrast to the Y chromosome, the X chromosome contains about 5% of the haploid genome and encodes house-keeping and specialized functions.		\|-
	* Genes such as Wnt-~~4 and DAX-1 necessary for initiation of female pathway ovary development~~		\| [[Development_Animation_-_Ovulation\|Ovulation]]
	* An early discovery (1961) was that in order to have correct levels of X chromosome gene/protein expression (gene dosage), females must "inactivate" a single copy of the X chromosome in each and every cell. The initiator of the X inactivation process was discovered (1991) to be regulated by a region on the inactivating X chromosome encoding an '''X''' '''i'''nactive '''s'''pecific '''t'''ranscript (XIST), that acts as RNA and does not encode a protein.		\| [[Development_Animation_-_Fertilization\|Fertilization]]
	* The genetic content of the X chromosome has been strongly conserved between species because these genes have become adapted to working as a single dose - ~~Ohno's law~~		\| [[Development_Animation_-_Pronuclear_Fusion\|Pronuclear Fusion]]
	* X inactivation occurs randomly throughout the embryo, generating a mosaic of maternal and paternally derived X chromosome activity in all tissues and organs. ~~This can be seen in the fur colour of tortoiseshell cats.~~		\| [[Development_Animation_-_Week_1\|Week 1]]
	\|}		\| [[Movie_-_Ovulation 01\|Ovulation in the rabbit]]
			\| [[Movie_-_Fertilization 01\|Fertilization in the mouse]]
	=~~==Y chromosome ===~~		\| [[Quicktime_Movie_-_Blastocyst_Development\|Blastocyst Development]]
	{\|		\|-
	\| [[File:~~Human_idiogram~~-~~chromosome_Y~~.jpg]]
	\|
	~~'''In males'''~~ - ~~the main scientific problem was understanding what on the Y chromosome determined "maleness", and how this is done.~~

	~~About~~ the ~~Y Chromosome~~
	* 59 million base pairs, hypervariable in ~~length, mostly non-functional repeats~~
	* Current known protein-~~coding genes = 48 including ''SRY''~~
	* ''SRY'' encodes a 204 amino acid protein that is a member of the HMG (High mobility group) box class of DNA-~~binding proteins. Transcription factors bind to specific sites of DNA and regulates the transcription (expression) of other genes.~~
	\|}		\|}

Z8600021: Created page with "== Sex Determination == Mammalian sex determination is regulated by chromosomes. * Females have two X chromosomes. ('''XX''') * Males have a single X and a small Y. ('''XY''..."

2012-07-27T05:07:37Z

Created page with "== Sex Determination == Mammalian sex determination is regulated by chromosomes. * Females have two X chromosomes. ('''XX''') * Males have a single X and a small Y. ('''XY''..."

New page

== Sex Determination ==
Mammalian sex determination is regulated by chromosomes.
* Females have two X chromosomes. ('''XX''')
* Males have a single X and a small Y. ('''XY''')
* The X and Y chromosome are morphologically and functionally different from each other.
* Evolutionary studies have shown that the Y was once the homologous pair for X.
* It is only in the last 5 years that we have some idea about how these two types of chromosomes may be regulated and genes of importance located upon them.

===X chromosome===
{|
| [[File:Human idiogram-chromosome X.jpg|Human idiogram-chromosome X.jpg]]
|
'''In females''' - the main scientific problem was understanding gene dosage, only one copy of X chromosome is needed to be genetically active the other copy is inactivated (More? [[Molecular_Development_-_X_Inactivation|X Inactivation]].

About the X Chromosome
* 155 million base pairs
* In contrast to the Y chromosome, the X chromosome contains about 5% of the haploid genome and encodes house-keeping and specialized functions.
* Genes such as Wnt-4 and DAX-1 necessary for initiation of female pathway ovary development
* An early discovery (1961) was that in order to have correct levels of X chromosome gene/protein expression (gene dosage), females must "inactivate" a single copy of the X chromosome in each and every cell. The initiator of the X inactivation process was discovered (1991) to be regulated by a region on the inactivating X chromosome encoding an '''X''' '''i'''nactive '''s'''pecific '''t'''ranscript (XIST), that acts as RNA and does not encode a protein.
* The genetic content of the X chromosome has been strongly conserved between species because these genes have become adapted to working as a single dose - Ohno's law
* X inactivation occurs randomly throughout the embryo, generating a mosaic of maternal and paternally derived X chromosome activity in all tissues and organs. This can be seen in the fur colour of tortoiseshell cats.
|}

===Y chromosome ===
{|
| [[File:Human_idiogram-chromosome_Y.jpg]]
|
'''In males''' - the main scientific problem was understanding what on the Y chromosome determined "maleness", and how this is done.

About the Y Chromosome
* 59 million base pairs, hypervariable in length, mostly non-functional repeats
* Current known protein-coding genes = 48 including ''SRY''
* ''SRY'' encodes a 204 amino acid protein that is a member of the HMG (High mobility group) box class of DNA-binding proteins. Transcription factors bind to specific sites of DNA and regulates the transcription (expression) of other genes.
|}

Talk:ANAT2341 Lab 2 - Week 1 - Revision history

Z8600021 at 12:41, 31 July 2012

Z8600021: Created page with "== Sex Determination == Mammalian sex determination is regulated by chromosomes. * Females have two X chromosomes. ('''XX''') * Males have a single X and a small Y. ('''XY''..."