Ch 8: Genetics Flashcards
What term refers to an organism’s observable traits?
Phenotype
What term refers to an organism’s genes responsible for observable traits?
Genotype
What are versions of a gene called?
allele
What term refers to the fact that the gene responsible for a particular observable trait might exist in more than one version?
allele
If one allele in a member of a homologous chromosome pair codes for blue eye color and a corresponding allele on the other codes for brown eye color, the organism is said to be _________ for eye color.
heterozygous
What does it mean if an organism is homozygous for a trait?
Its two alleles are in agreement
What does it mean if an organism is heterozygous for a trait?
Their two alleles don’t agree
What is codominance?
In the case of multiple alleles, a heterozygote expresses a mixture of the traits of both alleles
What are all chromosomes besides sex chromosomes called?
autosomes
What is a monohybrid cross?
Crossing 2 true breeds for 1 trait to study 1 trait
What is the Law of Dominance?
One trait masks the effects of another trait
What is the Law of Segregation?
Alleles can segregate and recombine
What is the Law of Independent Assortment?
Traits can segregate and recombine independently of other traits
What is a test cross?
Using a recessive organism to determine the genotype of an organism of unknown genotype
What is a sex-linked trait?
A trait whose allele is carried on one of the sex chromosomes- X CHROMOSOME for test
What are the 3 X-linked traits to know for the test?
hemophilia
color blindness
male pattern baldness
What does it mean if a trait is an X-linked recessive trait?
A female can only get it if she’s homozygous for the X chromosome that carries the allele for the trait
What is a female who is heterozygous for an X-linked recessive trait?
Carrier- don’t express the trait but carry the allele for it
If a male is carrying the allele for hemophilia on his X chromosome, is his phenotype hemophilia?
Yes- there is no normal X chromosome to dominate it
X-linked recessive diseases are much more common in males than females because:
Females have to be homozygous for it and males only have to carry it on the X chromosome
An X-linked recessive trait cannot go from ______.
father to son
In pedigrees, males are represented by _____ and females by ______
squares, circles
