If there are no centriole in ovum then how did previous division occured?
In the creation of the Ovum a cell divides and takes almost all the cytoplasm and 1/2 the chromosomes. The resultant "other half" polar body has the other half and almost no cytoplasm, so it atrophies and disappears (except in possible twinning). Therefore, all that needs to happen to restart the process is for the 26 missing chromosones from the male gamete to re-enter the the female sex cell (Ovum) and now you have the trigger to start mitosis. The process of going from diploid to haploid is the vague answer.... I am a little out of field here beyond this.
How are centrioles related to sperms?
A sperm has a centriole, also known as a basal body, at the base of its flagellum (tail). After all cell divisions (meiosis I & II) are done, the resulting cell (spermatid) goes through a process called spermiogenesis. During that time, the microtubules of the tail grow from that centriole.
Which orgenelle is absent in a human cell but present in a plant cell?
There are two cell organelles which are present in plant cell and absentin animal cell. They are:1)Plastids2) vacuolesPlastids:Plastids are the site of manufacture and storage of important chemical compounds used by the cell. They often contain pigments used in photosynthesis. Plastids can also store products like starch and can synthesize fatty acids and terpenes which can be used for producing energy and as raw material.Basically there are 3 types of plastids which are mentioned into textbooks, i.e. CHROMOPLAST: coloured plasmids. They are for synthesis and storage.CHLOROPLAST: For photosynthesisLEUCOPLAST : For monoterpene synthesis.Vacuoles :Vacuole is a membrane bound organelle. They are d of vesicle. Vacuoles are closed sacs, made of membrane with inorganic or organic molecules inside, such as enzymes
If there is no centriole in the oocyte, then how does Meosis 1 take place?
Without the centriole the Fertilized egg cannot undergo cell division. The Primary oocyte undergoes Meiosis I creating the 4 daughter cells of which 3 are polar bodies the remaining one marked to form the ovum has haploid nucleus and one centriole as it is during Ootidogenesis (meiosis II) the cell is halted in metaphase II until fertilization, once the sperm nuclear material combine this trigger the centriolar migration and completion of first somatic cell division spurring off the blastocyst formation before differentiation sets in.
Can we take the X chromosome from a female parent and fuse it with the ovum of another female?
It is not possible. If you take only X-chromosome then the other 22 pair will be missing. The Zygote must have 46 chromosomes. Hence when you fuse X-chromosome with the Ovum, you will get 22+X+X = 24 chromosomes.But you can do cloning. You can take an ovum/ egg cell of female parent and denucleate it by certain method. Then insert the nucleus of desired FEMALE parent. If the egg is triggered to cell division than the egg cell will act as zygote and can form morula and blastula.
True or false ? some cell structures are specific to either plant or animal cells?
Animal cells do not have cell walls... Plant cells do. Does that help?