mitosis-meiosis/DNA (1 Viewer)

[psych_girl]

Why can crossing-over occur in Meiosis, but not mitosis.....? just bit confused.........and what is the relationship among gene, chromosome and DNA?

 

[malkin86]

mitosis's goal is 2 genetically identical cells.

meiosis (the sexy one) wants as much variation as possible in the 4 gametes, therefore crossing over can cause variation.

gene: A hereditary unit that occupies a specific location on a chromosome, determines a particular characteristic in an organism by directing the formation of a specific protein, and is capable of replicating itself at each cell division.

chromosome: A threadlike linear strand of DNA and associated proteins in the nucleus of animal and plant cells that carries the genes and functions in the transmission of hereditary information.

DNA: A nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. The sequence of nucleotides determines individual hereditary characteristics.

 

[psych_girl]

Thx very much

 

[Shuter]

gene: A hereditary unit that occupies a specific location on a chromosome, determines a particular characteristic in an organism by directing the formation of a specific protein, and is capable of replicating itself at each cell division.

chromosome: A threadlike linear strand of DNA and associated proteins in the nucleus of animal and plant cells that carries the genes and functions in the transmission of hereditary information.

I'll just add to that because it's probably useful/relevant.

Allele: Alleles are occupy the same locations genes do. An Allele however is a specific type of gene which will thus produce a particular characteristic. For example a Gene may be a Gene determining eye-color. Whilst an Allele for that location may be Blue Eyes (or a different allele for green eyes, a different allele for brown eyes ect). There are multiple types of alleles for the same gene location.

Edit: damnit I said them the wrong way around, fixed now.

 

[em_516]

so an eg of a gene would be the height gene and an eg of it's alleles would be the tall allele and the short allele, right?

 

[withoutaface]

so an eg of a gene would be the height gene and an eg of it's alleles would be the tall allele and the short allele, right?

Correct .

 

[malkin86]

don't say tall and short - say tall and dwarf. eg. daschunds suffer from dwarfism (cos humans decided it was cute).