silveryhair

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What is the difference between these two? I know autosomal is not the sex chromosomes. So what is the homologous? i know that it means the same genotype expression like AA. but what is the difference? Thanks!
 

xylem29

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Autosomal refers to all the chromosomes other than the sex chromosomes.

Homologous chromosomes refer to each pair of chromosomes.

Ex. Chromosome #1 exists in two forms, ie. a pair. The pair of chromosome #1 is homologous and autosomal (b/c it's not the sex chromosomes).

Ex.2: The 23rd pair of chromosomes in females is comprised of the X and X - these are homologous but are not autosomal.
 

AndyK

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Homologous chromosomes are chromosomes that are genetically different but are similar in terms of size, shape, centromere position, banding pattern and other physical charactarisitcs. In humans, you have 23 paternal chromosomes and 23 maternal chromosome. For every paternal chromosome, there is a maternal chromosome that it is homologous to. This is what determines your genotype.

For example: Your paternal chromosome 12 has allele "A" at a locus, and your maternal chromosome 12 has allele "a" at the same locus. This makes you "Aa" or heterozygous. If your maternal chromosome 12 had the "A" allele, you would be "AA" or homozygous dominant. Paternal chromosome 12 and maternal chromosome 12 are homologous!

Homologous chromosomes are also important in meiotic crossing over.

I would suggest reading or re-reading this section in your textbook or study reference...
 
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