sex linked traits
by melody franco
To determine the gender of a child, you must look at the chromosomes of the mother and father. (Picture above).
Every female is made up of an xx set of chromosomes. Every male is made up of an xy set of chromosomes. *Chance of having a boy- 50% Change of having a girl- 50% *This is because y is a dominant chromosome and x is a recessive chromosome Who determines which gender you will actually have? Since the mom will always be xx, it is the dad. It all depends on which sperm (x or y) reaches the egg first, thus determining if the child will be a boy (y) or a girl (x). |
Every x chromosome in your body has 1500 genes while a y chromosome has only 78. This is because the y chromosomes main purpose is to determine the gender of children.
This also can be applied to different mutations, such as bladder cancer. If a woman has x and x(b) - b is bladder cancer - then the woman would be a carrier, not actually have bladder cancer because x is dominant over the cancer. But if a woman has x(b) and x(b) then she will have bladder cancer because the mutation is in both chromosomes. If a man has x(b) and y then he will have bladder cancer because he has no chromosome to dominate over the mutation. So a man has a 1/26 chance but a woman has a 1/676 chance because they have two x chromosomes. |
Look at the picture above.
Pretend that all of the runners are racing to the hamburger that represents the egg in a male. Each person runner in the race represents a chromosome that is either x or y and will determine if the child is a male or a female. In this picture, each female will represent x and each male runner will represent y. If the lady in the pink jacket, wins, or the x chromosome, then the child will be a baby girl, or vice versa.
Co dominance
"when both alleles are dominant, so they show up together."
Helpful tips:
1.) Think "co"= together (like a coworker)
2.) Both show up 100%
3.) Examples are spots and stripes
1.) Think "co"= together (like a coworker)
2.) Both show up 100%
3.) Examples are spots and stripes
For example:
When white bunnies mate with black bunnies, all of the offspring have black and white spots. What types of offspring will be produced if a black bunny and spotted bunny are mated?
When white bunnies mate with black bunnies, all of the offspring have black and white spots. What types of offspring will be produced if a black bunny and spotted bunny are mated?
Step 1: Find the phenotype of each parent.
BB x BW... Because one parent is black and one has black and white spots.
Step 2: Fill in the Punnett Square
(Picture above). Match the top allele with the allele on the side to fill in each box.
Step 3: Percentages
If a box says "BB" then it is black. If it is "WW" then it is white. If it is "BW" then it has spots. In this case, their is a 50% chance of the bunny being black and a 50% the bunny will have spots.
This is one reason the children of both sets of married twins will have children that look similar. Just like the bunnies had a chance of being black or having spots, the twins children will also not be guaranteed all of the same traits.
Remember: Both will show up!
BB x BW... Because one parent is black and one has black and white spots.
Step 2: Fill in the Punnett Square
(Picture above). Match the top allele with the allele on the side to fill in each box.
Step 3: Percentages
If a box says "BB" then it is black. If it is "WW" then it is white. If it is "BW" then it has spots. In this case, their is a 50% chance of the bunny being black and a 50% the bunny will have spots.
This is one reason the children of both sets of married twins will have children that look similar. Just like the bunnies had a chance of being black or having spots, the twins children will also not be guaranteed all of the same traits.
Remember: Both will show up!