Is Meiosis happening in our body all the time?
Or is it just before the sperm and ova meet?
Hi Rudy,
Great question. Recall that meiosis is the production of gametes, or sperm and egg/ova cells in animals, pollen or ovule in plants. In humans, male gametes are formed continuously following puberty, right up to death. In females, egg cells are formed by meiosis while the female is still in her mothers womb. The process then pauses and continues after puberty at a rate of one egg cell every month or so. Sperm can remain in the testes of a male for about 72 days before being recycled if not ejaculated.
Fertilisation is the joining of a sperm and egg cell, which can only happen after the gametes have been produced by meiosis. Normally quite some time after.
I hope that answers your question. Please feel free to ask if you would like further clarification.
Both meiosis and fertilisation were discussed in this webinar: NCEA Level 1 Science: Genetics AS 90948 Exam Preparation Webinar - YouTube
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Hey Rudy,
Just to add on to what Doug has already mentioned, a common misunderstanding from students is that meiosis happens in the sperm and egg. This is incorrect.
Meiosis occurs in your gonads (testes and ovaries) and it produces the gametes (sperm/egg)
If you go through the definition of meiosis (which is important for your upcoming external) - it is a process of cell division that occurs in the sex organs/gonads (not cells), that produces 4 genetically non-identical gametes.
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Wait so meoisis occurs every 72 days after being recycled in males?
But how come in the diagram, in your genetics presentation there is a blue and red chromosome? Doesn’t that mean one female and male chromosome?. And then it goes through to fertilize an egg and then become a zygote, with it going through crossing over and other processes
Wait so meoisis occurs every 72 days after being recycled in males?
But how come in the diagram, in your genetics presentation there is a blue and red chromosome? Doesn’t that mean one female and male chromosome?. And then it goes through to fertilize an egg and then become a zygote, with it going through crossing over and other processes
But isnt there like millions of sperm not just 4 non identical sperm?
Nope. You don’t have to know how often meiosis happens. It would also be different for different people and species - so not quite important.
I’m assuming this is the one from the webinar Doug linked.
Chromosomes come in homologous pairs. The Blue and Red chromosomes indicate that one comes from the mum, while the other comes from the dad. Both of them are a “pair”.(In the same way you would have a left and right glove.)
A sperm receives 23 chromosomes from the dad, while the egg receives 23 from the mum. When they fuse during fertilisation, they form a zygote which has 23 “pairs” (Hence 46 chromosomes in total)
Meiosis describes the process of it happening in one cell. So when meiosis occurs, it produces 4 genetically non-identical cell. However, meiosis is happening in the (cells in the) testes/ovaries.
Hope that helps.
But as Doug said “Recall that meiosis is the production of gametes, or sperm and egg/ova cells in animals, pollen or ovule in plants. In humans, male gametes are formed continuously following puberty, right up to death.” Then how can a female sex cell mix with a male sex cell if it’s a male body?
But as Doug said “Recall that meiosis is the production of gametes, or sperm and egg/ova cells in animals, pollen or ovule in plants. In humans, male gametes are formed continuously following puberty, right up to death.” Then how can a female sex cell mix with a male sex cell if it’s a male body?
Hi Rudy,
During sexual reproduction some of the male gametes, which have already been produced by meiosis, are released from the male’s body into the female’s reproductive system, and one successful sperm will fertilise the egg. In humans the egg is still inside the female’s reproductive system when fertilisation takes place. In other species both the sperm and the egg are released and fertilisation takes place externally (eg. most fish). This video might help your understanding of meiosis and fertilisation - just be aware that there is far more detail in the meiosis mentioned here than what you need for L1 Genetics.
In response to your earlier question, the sperm are created continuously. kloh is correct in that you don’t need to know this for your exam. However to try and clear up your understanding, human males produce around 1,500 sperm cells per second, through the process of meiosis. These are stored until released. They are only recycled (after about 72 hours) if not released.
Thank you so much for the help it helped my understanding.
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