Weekly Genetics Quiz #48: Homozygous and Heterozygous
Whenever specific gene mutations are discussed, homozygosity and heterozygosity are mentioned. This week’s genetics quiz question is:
What does it mean when a person has a homozygous genotype? Heterozygous genotype?
Answer:
All of our genes are inherited from our parents in pairs. We have a total of 46 chromosomes that come in 23 pairs or homologous chromosomes – one chromsome comes from our mother and one from our father. On these chromosomes lie genes that also come in pairs; one each from our mothers and fathers. Each member of the gene pair is called an allele so each gene has two alleles or two allelic forms.
A person who is homozygous for a mutation has two identical alleles for that gene. Both his/her parents passed along the same form of the gene.
A person who is heterozygous for a mutation has two different alleles for the gene. His/her parents had different forms of the gene that was passed down.
For more information, click on the picture above and visit TeachNet Ireland’s genetics page.
Technorati Tags: homozygous, heterozygous, genetics, genes, dna, alleles, homologous chromosomes, quizzes, quiz, test, exam
ummmmm, so how would you explain what we could do to determine whether a thing, person is heterozygous or homozygous using a punnet?
just use a punnett and if the two aleeles are the same (dominant or recessive) its homozygous which means pure bred heterozugous mean hybrid which would b the squares in the punnett with the two different alleles
precious: It’s not possible to tell whether a person is heterozygous or homozygous for a particular gene variant unless a DNA test is done. A Punnett square is only useful after the fact.
During a medical immunology masters, I discovered that I was homozygous with respect to tissue-typing
antigens.
Are there any consequences?
laurence: Not that I’m aware of. With tissue type, the comparison is between two people who will be part of an organ donor-recipient pair. If you’re concerned, I would advise you to speak to your personal physician. There’s also more info at WebMD. All the best!
What makes traits dominant or recessive? I was wondering, and I would like it if somebody knew and replied. Thank you
i would like to know exactly how to extract genetic information from one of my friends and how i can use it to dominate the world