Search results
Results From The WOW.Com Content Network
In addition, as noted by Wilkins and Holliday, [9] there are four novel steps needed in meiosis that are not present in mitosis. These are: (1) pairing of homologous chromosomes , (2) extensive recombination between homologs; (3) suppression of sister chromatid separation in the first meiotic division; and (4) avoiding chromosome replication ...
The preparatory steps that lead up to meiosis are identical in pattern and name to interphase of the mitotic cell cycle. [10] Interphase is divided into three phases: Growth 1 (G 1 ) phase : In this very active phase, the cell synthesizes its vast array of proteins, including the enzymes and structural proteins it will need for growth.
Ndt80 is a meiosis-specific transcription factor required for successful completion of meiosis and spore formation. [17] The protein recognizes and binds to the middle sporulation element (MSE) 5'-C[AG]CAAA[AT]-3' in the promoter region of stage-specific genes that are required for progression through meiosis and sporulation.
In the first stage of sexual reproduction, meiosis, the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). During fertilisation, haploid gametes come together to form a diploid zygote, and the original number of chromosomes is restored.
There are two popular and overlapping theories that explain the origins of crossing-over, coming from the different theories on the origin of meiosis.The first theory rests upon the idea that meiosis evolved as another method of DNA repair, and thus crossing-over is a novel way to replace possibly damaged sections of DNA. [9]
A meiocyte is a type of cell that differentiates into a gamete through the process of meiosis. Through meiosis, the diploid meiocyte divides into four genetically different haploid gametes. [ 1 ] [ 2 ] The control of the meiocyte through the meiotic cell cycle varies between different groups of organisms.
The hyper phosphorylation of Rb is considered the late G1 restriction point, after which the cell cannot go backwards in the cell cycle. At this point, E2F 1-3 proteins bind to DNA and transcribe Cyclin A and Cdc 6. [11] Cyclin-dependent kinase inhibitor 1B (CDKN1B), also known as p27, binds to and prevents the activation of CyclinE:Cdk2 by ...
Studies in male mouse meiosis have shown that after DNA damaging treatments like gamma irradiation, two types of repair responses occur depending on the meiotic stage: [5] From leptotene to early pachytene, exogenous DNA damage triggers widespread presence of the repair protein gammaH2AX in the nucleus, associated with homologous recombination ...