Download Biology Chapter 7 Notes

Biology Chapter 7 Notes
1. What are sex chromosomes?
Chromosomes that determine an organism’s sex (X and Y)
2. What are autosomes?
Any chromosomes that do not directly affect an organism’s sex
3. How is a carrier different from a person who has a genetic
disorder?
A carrier does not show symptoms of a disorder but can pass the
disorder to offspring
4. What are sex-linked genes?
Genes that are located on the sex chromosomes
5. In humans, how does a gamete from a male determine the sex
of offspring?
A female can only pass on X chromosomes, but a male can pass
on either X or Y chromosomes
6. What is incomplete dominance? Give an example of
phenotype.
Neither allele is completely dominant and one allele is not hidden
in a heterozygous individual. The heterozygous phenotype is
somewhere between the homozygous phenotypes.
Ex. Red + White = Pink
7. What is codominance? Give an example of phenotype.
Both alleles are completely expressed (visible) and the
heterozygous phenotype contains the separate products of both
alleles.
Ex. Heterozygous will show both red and white areas (Roan
cattle)
8. What are polygenic traits? Give an example.
Traits produced by 2 or more genes.
Ex. eye color (at least 3 genes affect eye color – maybe more)
9. What factor other than genotype can affect an organism’s
phenotype? Give examples.
The environment may affect gene expression.
Ex. sex determination in sea turtles depends on both genes and
the temperature at which the eggs mature
10. Who can be carriers of autosomal disorders?
Anyone with a recessive disorder-causing allele can pass on the
disorder
11. Why can females, but not males be carriers of sex-linked
genetic disorders?
Males can’t have a normal, dominant allele that would mask the
effect of a recessive, disorder-causing allele
12. What is a pedigree?
A chart that traces phenotypes and genotypes in a family
13. How are phenotypes used in pedigree analysis?
Phenotypes are used to infer (guess) genotypes
14. What is a karyotype and what types of information can it
provide?
A picture of all of the chromosomes in a cell. It can show any
large-scale changes in chromosomes. (extra chromosomes,
missing parts of chromosomes)