Mendell's Laws (1 Viewer)

[misbahf]

I'm having a lot of trouble determining what these laws actually mean:

Law of segregation: members of a pair of homologous chromosomes separate during the formation of gametes and are distributed to different gametes so that every gamete receives only one member of the pair

Law of independent assortment: each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random

If anyone could explain this in simple terms it would be appreciated!

Thanks in advanced.

 

[rooeys2]

independent assortment is another way of saying random fertilisation, thats wat it says in the syllabus
random fertilisation means that there can be different combinations of different gametes be fertilised, this creates genetic variation as there can be many combinations
random segregation is the different gene combinations formed in meiosis that are eventually differnt to the parent cells, thus the genes on differnt chromosomes can sort themselves independently (again, creating variation)

dont worry im pretty much confused myself, its really difficult to memorise and iv tried several times but sometimes i still have to look back at my notes to remind myself

 

[misbahf]

Wait so...

Independent assortment: Pretty much what punnet squares tell us...different genes from parents combine to make numerous kinds of possibilities that could be inherited by the offspring

Segregation: ......??? Sorry i'm still lost

 

[rooeys2]

mm not really, i probably didnt explain it well i suggest you look at the heineman bio txtbook pg 187, it explains it in detail, and if ur still lost try excel bio cuz its got diagrams that might be more helpful, its kind of hard to verbally explain it, drawing it out its much better.
and by the way, no the punett square results is different, all these laws occur in MEIOSIS, punett square cannot sort themselves independently, these processes such as segregation, random fertilisation are RANDOM, you cant randomly get results from punett squares

 

[Undermyskin]

Concisely:

1st: factors occur in pair. During the formation of gametes, they separate. During fertilisation, Each member pair up with another member of the pair from the other organism.

eg: BB--> B and B

AA from 'the other organism' forms A and A

In fertilisation, A goes to B while the other B goes to A.

Notes, AA and BB is to help the understanding, not the presumable alleles. (it can be heterozygous, mind you)

2nd: During formation of gametes, each member of the chromosome pairs can go to the gamete with either member of the other chromosome pair. This leads to mutation (not so sure. My teacher said st that crossing over is slightly different to the source of mutation)

eg: AaBb (see, I use lower case a and b now) crosses with CCDD

During the formation of gametes you have: AB, Ab, aB or ab. Very random! That's how we say it's random separation. They can pair up however you like. What we hope to get is only the principle expectation.

Hooray!

 

[misbahf]

thank you

 

[Lebstr]

i learn medel law of segregation = characterisics where determined by factors (genes) and these factors came in pairs
1 sex cell will hve 1 of these factors,
during fertilsation these factors pair up together (do not mix)
therefore 1 has to b dominant over the other