Origin and function Of Meiosis and Mitosis
Meiosis is ubiquitous among eukaryotes. It occurs in single-celled organisms such as yeast, as well as in multicellular organisms, such as humans. Eukaryotes arose from prokaryotes
more than 1.5 billion years ago, and the earliest eukaryotes were
likely single-celled organisms. To understand meiosis in eukaryotes, it
is necessary to understand
(1) How meiosis arose in single celled eukaryotes,
(2) The function of Meiosis and Mitosis
1) Origin
There are two conflicting theories on how meiosis arose. One is that meiosis evolved from bacterial sex (called transformation) during the evolution of eukaryotes. The other is that meiosis arose from mitosis.
(1) How meiosis arose in single celled eukaryotes,
(2) The function of Meiosis and Mitosis
1) Origin
There are two conflicting theories on how meiosis arose. One is that meiosis evolved from bacterial sex (called transformation) during the evolution of eukaryotes. The other is that meiosis arose from mitosis.
- Theory that meiosis evolved from bacterial sex(transformation)
- Theory that meiosis evolved from mitosis
- Sharing of components during the evolution of meiosis and mitosis
2) Function
Single-celled eukaryotes (protists) generally can reproduce asexually (vegetative reproduction) or sexually, depending on conditions. Asexual reproduction involves mitosis, and sexual reproduction involves meiosis. When sex is not an obligate part of reproduction, it is referred to as facultative sex. Present-day protists, generally, are facultative sexual organisms,
as are many bacteria. The earliest form of sexual reproduction in
eukaryotes was probably facultative, like that of present-day protists.
To understand the function of meiosis in facultative sexual protists, we
next consider under what circumstances these organisms switch from
asexual to sexual reproduction, and what function this transition may
serve.
I am so happy, i never believe i will be this happy again in life, I was working as an air-hoster ( cabby crew ) for 3years but early this year, i loose my job because of this deadly disease called Herpes virus (HSV), I never felt sick or have any symptom, till all workers were ask to bring their doctors report, that was how i got tested and i found out that am HSV positive that make me loose my job, because it was consider as an STD and is incurable disease, i was so depress was thinking of committing suicide, till i explain to a friend of mine, who always said to me a problem share is a problem solved, that was how she directed me to Dr Isibor, that was how i contacted him and get the medication from this doctor and i got cured for real, I just went back to my work and they also carry out the test to be real sure and i was negative. Please contact this doctor if you are herpes positive diseases his email is: drisiborspellhome@gmail.com. or you can call or whatsApp his mobile number +2348107855231.
ReplyDelete