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This is done by one of Mum's chromosomes swapping a segment of DNA with one of Dad's chromosomes.
In the first prophase of meiosis (prophase I) each chromosome contains two molecules of DNA. You can see these as the two sister-chromatids of each chromosome. During this prophase, each chromosome pairs with the corresponding chromosome from the other set. In other words, the chromosome 1 from the male parent aligns itself beside chromosome 1 from the female parent, the two copies of chromosome 2 do likewise, and so on. The two copies of one chromosome are called homologous chromosomes.
Each pair of chromosomes is called a bivalent, and consists of four chromatids twisted around each other. At various points along this bivalent, two non-sister chromatids will break at the same locus (point along the DNA) and recombine, so that now a stretch of DNA from Mum has attached to a stretch from Dad, and vice versa.
On average, this crossing-over happens three or four times along the length of a chromosome, so that one DNA molecule now consists of alternating segments from each parent.
Because no two parents are genetically identical, the recombined DNA has a base sequence that is different from that supplied by either parent. It is like a linear mosaic.
The positions of crossing-over are pretty well random, so every time meiosis takes place in one individual novel base sequences are generated.
What else can I help you with?
What things do not contribute greatly to evolution?
Things that do not contribute greatly to evolution include individual organism's desires or needs, acquired traits during an organism's lifetime, and random or chance events (such as mutations that do not confer a survival advantage).
Can this difference give an organism an advantage?
It is not possible to tell if the difference give an organism an advantage because you have not given the difference.
What is the process in which DNA changes to form new alleles?
Crossing-over
What is the product of crossing over called?
Recombinant DNA is the product of crossing over.
When does crossing over happen in mitosis 1?
Mitosis does its crossing over in prophase
What advantage does crossing over provide to new organisms?
When breeders cross over new organism they are increasing the organism's chances of getting great survival genes. Breeders typically cross breed organisms with the best genes.
What things do not contribute greatly to evolution?
Things that do not contribute greatly to evolution include individual organism's desires or needs, acquired traits during an organism's lifetime, and random or chance events (such as mutations that do not confer a survival advantage).
What is the importance of crossing-over?
It allows variation in the produced offspring as genes from both parents are present in the organism.
What advantage does a salt water organism have over a fresh water or terrestrial organism?
A salt water has an advantage over other organisms because the earth is made of more salt water then it is fresh water or land. This gives it more space to live and reproduce.
Can this different give an organism an advantage?
It is not possible to tell if the difference give an organism an advantage because you have not given the difference.
Can this difference give an organism an advantage?
It is not possible to tell if the difference give an organism an advantage because you have not given the difference.
If an organism has five pairs of chromosomes how many different gametes could it produce without crossing over?
The organism could produce 32 different gametes without crossing over. This is calculated as 2^n, where n is the number of chromosome pairs. In this case, 2^5 = 32.
Why is S fimicola an ideal organism for the demonstration of crossing-over?
because the location of the ascospores (haploid cell of sordaria) within the ascus shows whether or not crossing over took place. since the formation of ascospores occurs within an ascus, all of the daughter cells are packaged together. if crossing over did not take place, four black ascospores are grouped together next to four tan ascospores. using this as a subject, scientist are easily and accurately able to determine whether or not crossing over occured.
What is the definition of selective advantage and how does it contribute to the survival and evolution of species?
Selective advantage refers to a trait or characteristic that gives an organism a better chance of surviving and reproducing in its environment. This advantage allows the organism to pass on its genes to the next generation, leading to the evolution of the species over time. In essence, selective advantage plays a crucial role in the survival and adaptation of species by favoring traits that increase an organism's chances of thriving in its specific environment.
What is the process in which DNA changes to form new alleles?
Crossing-over
What does crossing over mean?
Crossing Over Means Going To Heaven Which means Crossing over from the world to heaven i think that is what it means.
Why is s.fimicola used as an example of crossing over?
It is used as an example because it is haploid for most of its life cycle. This is incorrect. S. Fimicola is used because it is easy to sustain in a petri dish and it grows extremely fast (in terms of biology). It is also used because it has visible signs of crossing over.
