Genetic Variation Watch

TTTA
Badges: 1
Rep:
?
#1
Report Thread starter 9 years ago
#1
How does crossing over and independant assortment lead to genetic variation?
This seems to be a popular exam question could anyone help please?
0
reply
JFJ
Badges: 8
Rep:
?
#2
Report 9 years ago
#2
crossing over gives a random assortment of genes on the sister chromatids.

Independent assortment means not all the chromosomes from one parent go to one daughter cell, as each is randomly distributed.

Therefore there are differences between the genes of the daughter and the parent cells and each of the daughter cells, thus genetic variation.
0
reply
Democracy
Badges: 20
Rep:
?
#3
Report 9 years ago
#3
It allows exchange of chromosomal material, the mixing and matching allows for new genes to become present in the population, and may unmask previously hidden genes, leading to new genotypes and phenotypes, which contribute to more variance in future populations.

Independent assortment is the second of Mendel's laws. It helps ensure diversity and variation because gametes assort independently of the parent's genotype, so gametes formed can be of any chromosomal combination i.e. leading to the existance of non parental genotypes. The number of possible gamete combinations is 2^n where n is the number of homologous chromosome pairs, so in humans the number of possibilities is 2^23 or 8,388,608 combinations.

Hope that helped :awesome:
0
reply
Rosyred809
Badges: 0
Rep:
?
#4
Report 9 years ago
#4
Crossing over leads to greater genetic variation because alleles are swapped over and therefore a wider range of characteristics are possible Meaning in each bivalent chromosomes there is a chance of different alleles being swapped over and a greater variety of characteristics.

Independent assortment leads to greater genetic variation because the 4 daughter haploid cells formed from meiosis have a completely differ rent assortment of chromosomes leading to a greater wider range of combinations.
0
reply
MGIL
Badges: 0
Rep:
?
#5
Report 9 years ago
#5
(Original post by Democracy)
It allows exchange of chromosomal material, the mixing and matching allows for new genes to become present in the population, and may unmask previously hidden genes, leading to new genotypes and phenotypes, which contribute to more variance in future populations.

Independent assortment is the second of Mendel's laws. It helps ensure diversity and variation because gametes assort independently of the parent's genotype, so gametes formed can be of any chromosomal combination i.e. leading to the existance of non parental genotypes. The number of possible gamete combinations is 2^n where n is the number of homologous chromosome pairs, so in humans the number of possibilities is 2^23 or 8,388,608 combinations.

Hope that helped :awesome:
your answers, although great, are too complex for a mere AS; good luck with your degree though:top:
0
reply
Democracy
Badges: 20
Rep:
?
#6
Report 9 years ago
#6
(Original post by MGIL)
your answers, although great, are too complex for a mere AS; good luck with your degree though
Oh :sad: Sorry :getmecoat:
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • Cranfield University
    Cranfield Forensic MSc Programme Open Day Postgraduate
    Thu, 25 Apr '19
  • University of the Arts London
    Open day: MA Footwear and MA Fashion Artefact Postgraduate
    Thu, 25 Apr '19
  • Cardiff Metropolitan University
    Undergraduate Open Day - Llandaff Campus Undergraduate
    Sat, 27 Apr '19

Have you registered to vote?

Yes! (273)
38.18%
No - but I will (51)
7.13%
No - I don't want to (51)
7.13%
No - I can't vote (<18, not in UK, etc) (340)
47.55%

Watched Threads

View All
Latest
My Feed