Ch15

Human sex chromosomes consist of __________ and __________.

X and Y

The X chromosome in humans has approximately __________ genes.

1000

The Y chromosome in humans has approximately __________ genes.

50

In humans, a zygote receives one sex chromosome from each parent: X from mom and __________ from dad.

X or Y

In fruit flies, the red-eye phenotype is considered __________, while the white-eye phenotype is __________.

wild-type; recessive

The inheritance pattern of X-linked genes is described as __________ inheritance.

crisscross

If a male has an X-linked recessive trait, he will pass the trait to all of his __________ but none of his __________.

daughters; sons

Mitochondrial DNA is inherited exclusively from __________.

the mother

The __________ hypothesis supports that mitochondria and chloroplasts have their own DNA and ribosomes.

endosymbiotic

The ratio of female to male offspring is approximately __________.

1:1

Most genes in mitochondria are encoded by __________ genes.

nuclear

In humans, the common mutation leading to red-green color blindness is in the __________ gene.

opsin

During meiosis, X and Y chromosomes must pair in a region of __________ to ensure correct segregation.

homology

In reciprocal crosses involving X-linked traits, the resulting progeny may be __________ depending on the sex of the parent.

different

Affected males with X-linked recessive traits do not pass the trait to __________ but do to __________.

sons; daughters

Approximately __________% of males are affected by red-green color blindness.

8

Mitochondrial DNA encodes __________ proteins out of approximately 1000 present in mitochondria.

14

In X-linked inheritance, the male offspring receive their X chromosome from their __________.

mother