Help im sooo lost-recessive,dominant trait

Genetics as it applies to evolution, molecular biology, and medical aspects.

Moderators: honeev, Leonid, amiradm, BioTeam

Post Reply
Posts: 2
Joined: Sun Apr 16, 2006 3:04 am

Help im sooo lost-recessive,dominant trait

Post by nicole_i87 » Thu Apr 27, 2006 5:06 am

Ok i have worked out that i have a homozygous dominant (AA) man for a trait and a homozygous recessive (aa) woman for a trait.

I have to work out what the chance is that their children will have the trait...but if the trait is recessive on one side of the family and dominant on the other side of the family, what do i use in the punnet square?

They are both homozygous, but bcoz one is dominant it would be AA and one is recessive it would be aa, which means that there would b no chance that the children get the trait coz it would all come out Aa??

Any help would b much appreciated.


Posts: 410
Joined: Thu Feb 16, 2006 6:10 am
Location: Malaysia

Post by kiekyon » Thu Apr 27, 2006 12:57 pm

that's right :wink:

beluga fiction
Posts: 23
Joined: Fri Apr 07, 2006 1:46 pm

Post by beluga fiction » Mon May 15, 2006 11:51 pm

If A is the dominant, all the Aa will have to receive the treatment.

Posts: 167
Joined: Fri May 19, 2006 1:47 am

Post by daniel.kurz » Sat May 20, 2006 2:27 am

The dominant-recessive pattern of inheritance, a relatively simple pattern, involves paired alleles that influence one trait. In this pattern, one of the two alleles contains information for a certain characteristic—the lavender color of sweet pea flowers, for example—while the second allele directs the production of an alternate characteristic—the white flower color. In sweet peas, if these two alleles occur together, the allele for lavender flowers is expressed, and the flowers are lavender. The allele for lavender is therefore called the dominant allele. The allele for white is known as the recessive allele. Lavender flowers also occur when two alleles for lavender color are paired. Only when two alleles for the recessive characteristic are paired do white flowers appear. This genetic rule applies regardless of the organism or the trait. In the dominant recessive pattern, the recessive trait shows up only when two recessive alleles are paired.

In humans, several hundred genetic diseases and disorders follow the dominant-recessive pattern. These conditions result when a mutation, or a change in a normal allele, is found in a sperm or egg, and the mutation causes disease when the child inherits a pair of mutated alleles. If a child inherits one dominant allele and one recessive allele he or she typically does not have the disease. Such individuals are termed carriers, since although healthy, they carry the recessive allele. A carrier can pass either the dominant or recessive allele to their child. If both parents are carriers, these alleles can be passed along in four ways. The child can receive a normal allele from each parent, in which case it does not develop the disease. It can receive a mutated allele from the mother and a normal allele from the father, or a normal allele from the mother and a mutated allele from the father. In both of these cases, the child will be a carrier. The child develops the disease only if he or she receives a mutated allele from each parent. When both parents are carriers, there is a 25 percent chance that a child will be disease-free, a 25 percent chance that it will have the disease, and a 50 percent chance that it will be a carrier. Examples of genetic diseases that follow the dominant-recessive pattern include sickle-cell anemia, beta-thalassemia, cystic fibrosis, and severe combined immunodeficiency disease

Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.

Posts: 149
Joined: Wed Jan 04, 2006 4:48 am

Post by Ultrashogun » Thu May 25, 2006 6:27 pm

You shouldnt need to make a punnet square for this, thats just stupid homework.

Posts: 19
Joined: Sun Jun 11, 2006 6:58 pm
Location: Romania

Post by oana_t » Sun Jun 11, 2006 7:24 pm

well the chances are like this: 25% is AA 25% is aa and 50% is Aa (hope thats right) :)

Post Reply

Who is online

Users browsing this forum: No registered users and 10 guests