multiple alleles – blood type
DESCRIPTION
i. The best example for humans is blood . There 3 alleles for blood types in humans: A , B and O . A and B are co dominant while O is recessive. d. Multiple Alleles – Instead of having two forms of an allele, there are more than two for one gene. - PowerPoint PPT PresentationTRANSCRIPT
d. Multiple Alleles – Instead of having two forms of an allele, there are more than two for one gene.
i. The best example for humans is blood. There 3 alleles for blood types in humans: A, B and O. A and B are co dominant while O is recessive.
Multiple Alleles – Blood Type
Type A genotypes could be: IAIA or IAi.
Type B genotypes could be: IBIB or IBi.
Type AB genotype is: IAIB
Type O genotype is: ii
Practice
A man who is heterozygous for type A blood marries a woman who is heterozygous for type B blood. Find the possible outcomes
e. Sex linked traits
i. Autonomies – there are 44 (22, pairs) of non sex chromosomes.
ii. Sex Chromosomes – the 23rd pair of chromosomes are the sex chromosomes.
The genotype for females is XX; the genotype for males is XY.
e. Sex linked traits
iii. Sex linked traits – Are genes located on the X chromosome. There is almost no information located on the Y chromosome.
Since males have only one X chromosome they show whatever allele is on the X chromosome, regardless of whether it is dominant or recessive.
e. Sex linked traits
iii. This is the only time that a single recessive allele is expressed.
Two examples of sex-linked traits in humans are red/green colorblindness and hemophillia. (A recessive sex linked trait that keeps your blood from clotting.)
Color Test
Color Test
Color Test
Color Test
Sex linked traits - Colorblindness1. If normal vision (N) is
dominant to colorblindness (n) give the genotypes for each of the following:
A female carrier: XNXn
A homozygous dominant female: XNXN
Colorblind male: XnYColorblind female: XnXn
A male with normal vision: XNY
Sex linked traits• Who does the male get
the X chromosome from? Mother
• Who does a male inherit recessive sex linked traits from? Mother
• Who are colorblind more often, men or women? Men; no information on Y to mask the recessive trait on X.
Practice
A female carrier has a child with a male with normal vision. What are the chances of colorblindness occuring in:
Son?
Daughter?
Practice
A colorblind male has a child with a normal female. Fill out the cross.