Marshall Biology

Homework: 310: 3, 5, 6

CHAPTER 11 BIOLOGY

Monohybrid Cross: Crossing of one trait

PUNNETT SQUARES: Help predict the offspring of a cross between two known genotypes

INCOMPLETE DOMINANCE:

When a dominant allele is not completely dominant… it does not mask the recessive trait.

Example: Roses: Red: RR, White: rr, Pink: Rr

CO-DOMINANCE: When each dominant trait shows itself

            Example: Blood Types A, B, AB, O

                        Dominant: A, B

                        Recessive: O

CHROMOSOMES:

46 Chromosomes in our body… 23 pairs of chromosomes

            22 pairs are called AUTOSOMAL: Everything else in your body, determines your eye color, etc.

1 Pair of SEX CHROMOSOMES: determines if you will be a boy or a girl.

            X Chromosomes: FEMALE Genotype(XX)

            Y Chromosomes: MALE: Genotype (XY) (The guy determines the sex of the baby)

                                    23^rd Chromosome tells you if it will be a boy or girl.

AUTOSOMES:

Any chromosome not considered a sex chromosome, or is not involved in deciding the sex (if a boy or girl)

SEX LINKED TRAITS:

            Example: Baldness, Colorblindness

Y: does not carry a trait… so if the woman has the trait for baldness, and the boy has the recessive trait….then the child will be bald…. So basically the woman decides baldness for boys.

                        B: Not Bald

                        b: Bald