Navigation Links
Anaphase


Anaphase (Greek: ανά = up and φάσις = stage) is the stage of meiosis or mitosis when chromosomes separate. Each chromatid moves to opposite poles of the cell (opposite ends of the nuclear spindle ).

Anaphase is preceded by metaphase, by the end of which fully condensed sister chromatids are arranged in pairs, their centromeres lying along a surface known as the metaphase plate. Spindle fibres (microtubules containing γ-tubulin) extend from the spindle poles to the centromeres . The point of contact is a protein complex called the kinetochore, and these fibres are sometimes referred to as spindle microtubules. Other spindle fibres do not contact the chromosomes but either connect directly with spindle fibres from the opposing pole (overlap microtubules) or with the cell cortex; these are astral microtubules.

Anaphase begins abruptly with the highly-regulated triggering of the metaphase-to-anaphase transition. At this point the Anaphase Promoting Complex (APC) becomes activated. This terminates metaphase (M-phase) activity by cleaving and inactivating the M-phase cyclin required for the function of M-phase cyclin dependent kinases (M-Cdks). It also cleaves securin, a protein that had been inhibiting separase. Separase then cleaves cohesin, the protein responsible for holding sister chromatids together. They immediately separate, marking the cytological onset of anaphase. After separation they are referred to as daughter chromatids.

Within anaphase two distinct processes occur. During anaphase A the chromatids abruptly separate and move towards the spindle poles. This is achieved by shortening of the kinetochore microtubules, and forces are mainly exerted at the kinetochores. When the chromatids are fully separated anaphase B begins. This involves the overlap microtubules elongating and sliding relative to each other to drive the spindle poles further apart.

Anaphases A and B were originally distinguished by their different sensitivities to drugs, and mechanistically they are distinct processes. Anaphase A involves shortening kinetochore mictrotubules by depolymerisation at both ends. During this, motor proteins at the kinetochores pull on the kinetochore microtubules. Anaphase B involves both the elongation of overlap microtubules and the use of two distinct sets of motor proteins: one of these pulls overlap microtubules past each other, the other pulls on astral microtubules that have attached to the cell cortex.

The contributions of anaphase A and anaphase B to anaphase vary with cell type. In mammalian cells anaphase B follows shortly after anaphase A and extends the spindle to around twice its metaphase length; in contrast yeast and certain protozoa use anaphase B as the main means of chromosome separation and can extend the spindle to up to 15 times its metaphase length in the process.

See also


'"/>


(Date:7/31/2015)... juillet 2015 La 10e Conférence internationale ... organisée par le BGI du 22 au 25 ... en Chine. La conférence célèbre son ... 2006, l,ICG est devenue l,une des réunions annuelles ... « omiques » et c,est aussi la plus dynamique, la ...
(Date:7/31/2015)... OXFORD, Conn. , Jul. 31, 2015 NXT-ID, ... a biometric authentication company focused on the growing mobile ... announces that it has filed provisional patent 62/198989 for ... This invention highlights a method to advance crypto-currencies ... technology by introducing a common, uniform way to manage ...
(Date:7/27/2015)... Calif. , July 27, 2015  Synaptics ... of human interface solutions, today announced that Huawei ... touchscreen solution for its stylish smartwatch. Huawei ... its proven reliability, low power and highly responsive ... wet finger. Huawei designers also required a classic ...
Breaking Biology News(10 mins):La 10e International Conference on Genomics (ICG-10) doit s'ouvrir en octobre 2La 10e International Conference on Genomics (ICG-10) doit s'ouvrir en octobre 3NXT-ID Patents Electronic Crypto-Currency Management Technology 2NXT-ID Patents Electronic Crypto-Currency Management Technology 3NXT-ID Patents Electronic Crypto-Currency Management Technology 4Synaptics Touchscreen Solution Powers New Huawei Watch 2Synaptics Touchscreen Solution Powers New Huawei Watch 3
... Although Antarctic krill (Euphausia superba) are one of the ... their life cycle have remained murky. , Understanding krill ... birds, and marine mammals, yet they are vulnerable to ... issue of BioScience, the monthly journal of the American ...
... Division of Cellegy Pharmaceuticals, Inc. today announced a non-exclusive ... the prevention of HIV and other sexually transmitted diseases. ... the agreement are in various stages of development and ... Savvy, which is currently in Phase III clinical trials ...
... five percent of deaths from SIDS (sudden infant death syndrome) ... gene and half of those deaths result from a common ... abnormal heart rhythm during times of environmental stress, a research ... February 2006 issue of the Journal of Clinical Investigation. ...
Cached Biology News:New licensing agreement to maximize AIDS drug development 2Gene variation increases SIDS risk in African Americans 2Gene variation increases SIDS risk in African Americans 3
Other biology definitionOther Tags